diff --git a/src/interfaces/chain.cpp b/src/interfaces/chain.cpp
index 34108297e..1c6b0364a 100644
--- a/src/interfaces/chain.cpp
+++ b/src/interfaces/chain.cpp
@@ -1,395 +1,394 @@
 // Copyright (c) 2018 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <interfaces/chain.h>
 
 #include <chain.h>
 #include <chainparams.h>
 #include <interfaces/handler.h>
 #include <interfaces/wallet.h>
 #include <net.h>
 #include <node/coin.h>
 #include <policy/mempool.h>
 #include <policy/policy.h>
 #include <policy/settings.h>
 #include <primitives/block.h>
 #include <primitives/blockhash.h>
 #include <primitives/transaction.h>
 #include <protocol.h>
 #include <rpc/protocol.h>
 #include <rpc/server.h>
 #include <shutdown.h>
 #include <sync.h>
 #include <threadsafety.h>
 #include <timedata.h>
 #include <txmempool.h>
 #include <ui_interface.h>
 #include <univalue.h>
 #include <util/system.h>
 #include <validation.h>
 #include <validationinterface.h>
 
 #include <memory>
 #include <utility>
 
 namespace interfaces {
 namespace {
 
     class LockImpl : public Chain::Lock, public UniqueLock<RecursiveMutex> {
         Optional<int> getHeight() override {
             int height = ::ChainActive().Height();
             if (height >= 0) {
                 return height;
             }
             return nullopt;
         }
         Optional<int> getBlockHeight(const BlockHash &hash) override {
             CBlockIndex *block = LookupBlockIndex(hash);
             if (block && ::ChainActive().Contains(block)) {
                 return block->nHeight;
             }
             return nullopt;
         }
         int getBlockDepth(const BlockHash &hash) override {
             const Optional<int> tip_height = getHeight();
             const Optional<int> height = getBlockHeight(hash);
             return tip_height && height ? *tip_height - *height + 1 : 0;
         }
         BlockHash getBlockHash(int height) override {
             CBlockIndex *block = ::ChainActive()[height];
             assert(block != nullptr);
             return block->GetBlockHash();
         }
         int64_t getBlockTime(int height) override {
             CBlockIndex *block = ::ChainActive()[height];
             assert(block != nullptr);
             return block->GetBlockTime();
         }
         int64_t getBlockMedianTimePast(int height) override {
             CBlockIndex *block = ::ChainActive()[height];
             assert(block != nullptr);
             return block->GetMedianTimePast();
         }
         bool haveBlockOnDisk(int height) override {
             CBlockIndex *block = ::ChainActive()[height];
             return block && (block->nStatus.hasData() != 0) && block->nTx > 0;
         }
         Optional<int>
         findFirstBlockWithTimeAndHeight(int64_t time, int height,
                                         BlockHash *hash) override {
             CBlockIndex *block =
                 ::ChainActive().FindEarliestAtLeast(time, height);
             if (block) {
                 if (hash) {
                     *hash = block->GetBlockHash();
                 }
                 return block->nHeight;
             }
             return nullopt;
         }
         Optional<int> findPruned(int start_height,
                                  Optional<int> stop_height) override {
             if (::fPruneMode) {
                 CBlockIndex *block = stop_height ? ::ChainActive()[*stop_height]
                                                  : ::ChainActive().Tip();
                 while (block && block->nHeight >= start_height) {
                     if (block->nStatus.hasData() == 0) {
                         return block->nHeight;
                     }
                     block = block->pprev;
                 }
             }
             return nullopt;
         }
         Optional<int> findFork(const BlockHash &hash,
                                Optional<int> *height) override {
             const CBlockIndex *block = LookupBlockIndex(hash);
             const CBlockIndex *fork =
                 block ? ::ChainActive().FindFork(block) : nullptr;
             if (height) {
                 if (block) {
                     *height = block->nHeight;
                 } else {
                     height->reset();
                 }
             }
             if (fork) {
                 return fork->nHeight;
             }
             return nullopt;
         }
         CBlockLocator getTipLocator() override {
             return ::ChainActive().GetLocator();
         }
         Optional<int> findLocatorFork(const CBlockLocator &locator) override {
             LockAnnotation lock(::cs_main);
             if (CBlockIndex *fork =
                     FindForkInGlobalIndex(::ChainActive(), locator)) {
                 return fork->nHeight;
             }
             return nullopt;
         }
         bool contextualCheckTransactionForCurrentBlock(
             const Consensus::Params &params, const CTransaction &tx,
             CValidationState &state) override {
             LockAnnotation lock(::cs_main);
             return ContextualCheckTransactionForCurrentBlock(params, tx, state);
         }
         bool submitToMemoryPool(const Config &config, CTransactionRef tx,
                                 Amount absurd_fee,
                                 CValidationState &state) override {
             LockAnnotation lock(::cs_main);
             return AcceptToMemoryPool(config, ::g_mempool, state, tx,
                                       nullptr /* missing inputs */,
                                       false /* bypass limits */, absurd_fee);
         }
 
         using UniqueLock::UniqueLock;
     };
 
     class NotificationsHandlerImpl : public Handler, CValidationInterface {
     public:
         explicit NotificationsHandlerImpl(Chain &chain,
                                           Chain::Notifications &notifications)
             : m_chain(chain), m_notifications(&notifications) {
             RegisterValidationInterface(this);
         }
         ~NotificationsHandlerImpl() override { disconnect(); }
         void disconnect() override {
             if (m_notifications) {
                 m_notifications = nullptr;
                 UnregisterValidationInterface(this);
             }
         }
         void TransactionAddedToMempool(const CTransactionRef &tx) override {
             m_notifications->TransactionAddedToMempool(tx);
         }
         void TransactionRemovedFromMempool(const CTransactionRef &tx) override {
             m_notifications->TransactionRemovedFromMempool(tx);
         }
         void BlockConnected(
             const std::shared_ptr<const CBlock> &block,
             const CBlockIndex *index,
             const std::vector<CTransactionRef> &tx_conflicted) override {
             m_notifications->BlockConnected(*block, tx_conflicted);
         }
         void
         BlockDisconnected(const std::shared_ptr<const CBlock> &block) override {
             m_notifications->BlockDisconnected(*block);
         }
         void UpdatedBlockTip(const CBlockIndex *index,
                              const CBlockIndex *fork_index,
                              bool is_ibd) override {
             m_notifications->UpdatedBlockTip();
         }
         void ChainStateFlushed(const CBlockLocator &locator) override {
             m_notifications->ChainStateFlushed(locator);
         }
         Chain &m_chain;
         Chain::Notifications *m_notifications;
     };
 
     class RpcHandlerImpl : public Handler {
     public:
         RpcHandlerImpl(const CRPCCommand &command)
             : m_command(command), m_wrapped_command(&command) {
             m_command.actor = [this](Config &config,
                                      const JSONRPCRequest &request,
                                      UniValue &result, bool last_handler) {
                 if (!m_wrapped_command) {
                     return false;
                 }
                 try {
                     return m_wrapped_command->actor(config, request, result,
                                                     last_handler);
                 } catch (const UniValue &e) {
                     // If this is not the last handler and a wallet not found
                     // exception was thrown, return false so the next handler
                     // can try to handle the request. Otherwise, reraise the
                     // exception.
                     if (!last_handler) {
                         const UniValue &code = e["code"];
                         if (code.isNum() &&
                             code.get_int() == RPC_WALLET_NOT_FOUND) {
                             return false;
                         }
                     }
                     throw;
                 }
             };
             ::tableRPC.appendCommand(m_command.name, &m_command);
         }
 
         void disconnect() override final {
             if (m_wrapped_command) {
                 m_wrapped_command = nullptr;
                 ::tableRPC.removeCommand(m_command.name, &m_command);
             }
         }
 
         ~RpcHandlerImpl() override { disconnect(); }
 
         CRPCCommand m_command;
         const CRPCCommand *m_wrapped_command;
     };
 
     class ChainImpl : public Chain {
     public:
         std::unique_ptr<Chain::Lock> lock(bool try_lock) override {
             auto lock = std::make_unique<LockImpl>(
                 ::cs_main, "cs_main", __FILE__, __LINE__, try_lock);
             if (try_lock && lock && !*lock) {
                 return {};
             }
             // Temporary to avoid CWG 1579
             std::unique_ptr<Chain::Lock> result = std::move(lock);
             return result;
         }
         bool findBlock(const BlockHash &hash, CBlock *block, int64_t *time,
                        int64_t *time_max) override {
             CBlockIndex *index;
             {
                 LOCK(cs_main);
                 index = LookupBlockIndex(hash);
                 if (!index) {
                     return false;
                 }
                 if (time) {
                     *time = index->GetBlockTime();
                 }
                 if (time_max) {
                     *time_max = index->GetBlockTimeMax();
                 }
             }
             if (block &&
                 !ReadBlockFromDisk(*block, index, Params().GetConsensus())) {
                 block->SetNull();
             }
             return true;
         }
         void findCoins(std::map<COutPoint, Coin> &coins) override {
             return FindCoins(coins);
         }
         double guessVerificationProgress(const BlockHash &block_hash) override {
             LOCK(cs_main);
             return GuessVerificationProgress(Params().TxData(),
                                              LookupBlockIndex(block_hash));
         }
         bool hasDescendantsInMempool(const TxId &txid) override {
             LOCK(::g_mempool.cs);
             auto it = ::g_mempool.GetIter(txid);
             return it && (*it)->GetCountWithDescendants() > 1;
         }
         void relayTransaction(const TxId &txid) override {
             CInv inv(MSG_TX, txid);
             g_connman->ForEachNode(
                 [&inv](CNode *node) { node->PushInventory(inv); });
         }
         void getTransactionAncestry(const TxId &txid, size_t &ancestors,
                                     size_t &descendants) override {
             ::g_mempool.GetTransactionAncestry(txid, ancestors, descendants);
         }
         bool checkChainLimits(const CTransactionRef &tx) override {
             LockPoints lp;
             CTxMemPoolEntry entry(tx, Amount(), 0, 0, false, 0, lp);
             CTxMemPool::setEntries ancestors;
             auto limit_ancestor_count =
                 gArgs.GetArg("-limitancestorcount", DEFAULT_ANCESTOR_LIMIT);
             auto limit_ancestor_size =
                 gArgs.GetArg("-limitancestorsize",
                              DEFAULT_ANCESTOR_SIZE_LIMIT) *
                 1000;
             auto limit_descendant_count =
                 gArgs.GetArg("-limitdescendantcount", DEFAULT_DESCENDANT_LIMIT);
             auto limit_descendant_size =
                 gArgs.GetArg("-limitdescendantsize",
                              DEFAULT_DESCENDANT_SIZE_LIMIT) *
                 1000;
             std::string unused_error_string;
             LOCK(::g_mempool.cs);
             return ::g_mempool.CalculateMemPoolAncestors(
                 entry, ancestors, limit_ancestor_count, limit_ancestor_size,
                 limit_descendant_count, limit_descendant_size,
                 unused_error_string);
         }
         CFeeRate estimateFee() const override {
             return ::g_mempool.estimateFee();
         }
         CFeeRate relayMinFee() override { return ::minRelayTxFee; }
         CFeeRate relayDustFee() override { return ::dustRelayFee; }
-        Amount maxTxFee() override { return ::maxTxFee; }
         bool getPruneMode() override { return ::fPruneMode; }
         bool p2pEnabled() override { return g_connman != nullptr; }
         bool isReadyToBroadcast() override {
             return !::fImporting && !::fReindex && !isInitialBlockDownload();
         }
         bool isInitialBlockDownload() override {
             return ::ChainstateActive().IsInitialBlockDownload();
         }
         bool shutdownRequested() override { return ShutdownRequested(); }
         int64_t getAdjustedTime() override { return GetAdjustedTime(); }
         void initMessage(const std::string &message) override {
             ::uiInterface.InitMessage(message);
         }
         void initWarning(const std::string &message) override {
             InitWarning(message);
         }
         void initError(const std::string &message) override {
             InitError(message);
         }
         void loadWallet(std::unique_ptr<Wallet> wallet) override {
             ::uiInterface.LoadWallet(wallet);
         }
         void showProgress(const std::string &title, int progress,
                           bool resume_possible) override {
             ::uiInterface.ShowProgress(title, progress, resume_possible);
         }
         std::unique_ptr<Handler>
         handleNotifications(Notifications &notifications) override {
             return std::make_unique<NotificationsHandlerImpl>(*this,
                                                               notifications);
         }
         void waitForNotificationsIfNewBlocksConnected(
             const BlockHash &old_tip) override {
             if (!old_tip.IsNull()) {
                 LOCK(::cs_main);
                 if (old_tip == ::ChainActive().Tip()->GetBlockHash()) {
                     return;
                 }
                 CBlockIndex *block = LookupBlockIndex(old_tip);
                 if (block && block->GetAncestor(::ChainActive().Height()) ==
                                  ::ChainActive().Tip()) {
                     return;
                 }
             }
             SyncWithValidationInterfaceQueue();
         }
 
         std::unique_ptr<Handler>
         handleRpc(const CRPCCommand &command) override {
             return std::make_unique<RpcHandlerImpl>(command);
         }
         bool rpcEnableDeprecated(const std::string &method) override {
             return IsDeprecatedRPCEnabled(gArgs, method);
         }
         void rpcRunLater(const std::string &name, std::function<void()> fn,
                          int64_t seconds) override {
             RPCRunLater(name, std::move(fn), seconds);
         }
         int rpcSerializationFlags() override { return RPCSerializationFlags(); }
         void requestMempoolTransactions(Notifications &notifications) override {
             LOCK2(::cs_main, ::g_mempool.cs);
             for (const CTxMemPoolEntry &entry : ::g_mempool.mapTx) {
                 notifications.TransactionAddedToMempool(entry.GetSharedTx());
             }
         }
     };
 
 } // namespace
 
 std::unique_ptr<Chain> MakeChain() {
     return std::make_unique<ChainImpl>();
 }
 
 } // namespace interfaces
diff --git a/src/interfaces/chain.h b/src/interfaces/chain.h
index cf9316cca..d8af0c158 100644
--- a/src/interfaces/chain.h
+++ b/src/interfaces/chain.h
@@ -1,325 +1,319 @@
 // Copyright (c) 2018 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_INTERFACES_CHAIN_H
 #define BITCOIN_INTERFACES_CHAIN_H
 
 #include <optional.h>
 #include <primitives/transaction.h>
 #include <primitives/txid.h>
 
 #include <cstddef>
 #include <cstdint>
 #include <memory>
 #include <string>
 #include <vector>
 
 struct BlockHash;
 class CBlock;
 struct CBlockLocator;
 class CChainParams;
 class Coin;
 class Config;
 class CRPCCommand;
 class CScheduler;
 class CValidationState;
 namespace Consensus {
 struct Params;
 }
 
 namespace interfaces {
 
 class Handler;
 class Wallet;
 
 //! Interface giving clients (wallet processes, maybe other analysis tools in
 //! the future) ability to access to the chain state, receive notifications,
 //! estimate fees, and submit transactions.
 //!
 //! TODO: Current chain methods are too low level, exposing too much of the
 //! internal workings of the bitcoin node, and not being very convenient to use.
 //! Chain methods should be cleaned up and simplified over time. Examples:
 //!
 //! * The Chain::lock() method, which lets clients delay chain tip updates
 //!   should be removed when clients are able to respond to updates
 //!   asynchronously
 //!   (https://github.com/bitcoin/bitcoin/pull/10973#issuecomment-380101269).
 //!
 //! * The relayTransactions() and submitToMemoryPool() methods could be replaced
 //!   with a higher-level broadcastTransaction method
 //!   (https://github.com/bitcoin/bitcoin/pull/14978#issuecomment-459373984).
 //!
 //! * The initMessages() and loadWallet() methods which the wallet uses to send
 //!   notifications to the GUI should go away when GUI and wallet can directly
 //!   communicate with each other without going through the node
 //!   (https://github.com/bitcoin/bitcoin/pull/15288#discussion_r253321096).
 //!
 //! * The handleRpc, registerRpcs, rpcEnableDeprecated methods and other RPC
 //!   methods can go away if wallets listen for HTTP requests on their own
 //!   ports instead of registering to handle requests on the node HTTP port.
 class Chain {
 public:
     virtual ~Chain() {}
 
     //! Interface for querying locked chain state, used by legacy code that
     //! assumes state won't change between calls. New code should avoid using
     //! the Lock interface and instead call higher-level Chain methods
     //! that return more information so the chain doesn't need to stay locked
     //! between calls.
     class Lock {
     public:
         virtual ~Lock() {}
 
         //! Get current chain height, not including genesis block (returns 0 if
         //! chain only contains genesis block, nullopt if chain does not contain
         //! any blocks).
         virtual Optional<int> getHeight() = 0;
 
         //! Get block height above genesis block. Returns 0 for genesis block,
         //! 1 for following block, and so on. Returns nullopt for a block not
         //! included in the current chain.
         virtual Optional<int> getBlockHeight(const BlockHash &hash) = 0;
 
         //! Get block depth. Returns 1 for chain tip, 2 for preceding block, and
         //! so on. Returns 0 for a block not included in the current chain.
         virtual int getBlockDepth(const BlockHash &hash) = 0;
 
         //! Get block hash. Height must be valid or this function will abort.
         virtual BlockHash getBlockHash(int height) = 0;
 
         //! Get block time. Height must be valid or this function will abort.
         virtual int64_t getBlockTime(int height) = 0;
 
         //! Get block median time past. Height must be valid or this function
         //! will abort.
         virtual int64_t getBlockMedianTimePast(int height) = 0;
 
         //! Check that the block is available on disk (i.e. has not been
         //! pruned), and contains transactions.
         virtual bool haveBlockOnDisk(int height) = 0;
 
         //! Return height of the first block in the chain with timestamp equal
         //! or greater than the given time and height equal or greater than the
         //! given height, or nullopt if there is no block with a high enough
         //! timestamp and height. Also return the block hash as an optional
         //! output parameter (to avoid the cost of a second lookup in case this
         //! information is needed.)
         virtual Optional<int>
         findFirstBlockWithTimeAndHeight(int64_t time, int height,
                                         BlockHash *hash) = 0;
 
         //! Return height of last block in the specified range which is pruned,
         //! or nullopt if no block in the range is pruned. Range is inclusive.
         virtual Optional<int>
         findPruned(int start_height = 0,
                    Optional<int> stop_height = nullopt) = 0;
 
         //! Return height of the highest block on the chain that is an ancestor
         //! of the specified block, or nullopt if no common ancestor is found.
         //! Also return the height of the specified block as an optional output
         //! parameter (to avoid the cost of a second hash lookup in case this
         //! information is desired).
         virtual Optional<int> findFork(const BlockHash &hash,
                                        Optional<int> *height) = 0;
 
         //! Get locator for the current chain tip.
         virtual CBlockLocator getTipLocator() = 0;
 
         //! Return height of the latest block common to locator and chain, which
         //! is guaranteed to be an ancestor of the block used to create the
         //! locator.
         virtual Optional<int> findLocatorFork(const CBlockLocator &locator) = 0;
 
         //! Check if transaction will be final given chain height current time.
         virtual bool contextualCheckTransactionForCurrentBlock(
             const Consensus::Params &params, const CTransaction &tx,
             CValidationState &state) = 0;
 
         //! Add transaction to memory pool if the transaction fee is below the
         //! amount specified by absurd_fee (as a safeguard). */
         virtual bool submitToMemoryPool(const Config &config,
                                         CTransactionRef tx, Amount absurd_fee,
                                         CValidationState &state) = 0;
     };
 
     //! Return Lock interface. Chain is locked when this is called, and
     //! unlocked when the returned interface is freed.
     virtual std::unique_ptr<Lock> lock(bool try_lock = false) = 0;
 
     //! Return whether node has the block and optionally return block metadata
     //! or contents.
     //!
     //! If a block pointer is provided to retrieve the block contents, and the
     //! block exists but doesn't have data (for example due to pruning), the
     //! block will be empty and all fields set to null.
     virtual bool findBlock(const BlockHash &hash, CBlock *block = nullptr,
                            int64_t *time = nullptr,
                            int64_t *max_time = nullptr) = 0;
 
     //! Look up unspent output information. Returns coins in the mempool and in
     //! the current chain UTXO set. Iterates through all the keys in the map and
     //! populates the values.
     virtual void findCoins(std::map<COutPoint, Coin> &coins) = 0;
 
     //! Estimate fraction of total transactions verified if blocks up to
     //! the specified block hash are verified.
     virtual double guessVerificationProgress(const BlockHash &block_hash) = 0;
 
     //! Check if transaction has descendants in mempool.
     virtual bool hasDescendantsInMempool(const TxId &txid) = 0;
 
     //! Calculate mempool ancestor and descendant counts for the given
     //! transaction.
     virtual void getTransactionAncestry(const TxId &txid, size_t &ancestors,
                                         size_t &descendants) = 0;
 
     //! Relay transaction.
     virtual void relayTransaction(const TxId &txid) = 0;
 
     //! Check if transaction will pass the mempool's chain limits.
     virtual bool checkChainLimits(const CTransactionRef &tx) = 0;
 
     //! Estimate fee
     virtual CFeeRate estimateFee() const = 0;
 
     //! Relay current minimum fee (from -minrelaytxfee settings).
     virtual CFeeRate relayMinFee() = 0;
 
     //! Relay dust fee setting (-dustrelayfee), reflecting lowest rate it's
     //! economical to spend.
     virtual CFeeRate relayDustFee() = 0;
 
-    //! Get node max tx fee setting (-maxtxfee).
-    //! This could be replaced by a per-wallet max fee, as proposed at
-    //! https://github.com/bitcoin/bitcoin/issues/15355
-    //! But for the time being, wallets call this to access the node setting.
-    virtual Amount maxTxFee() = 0;
-
     //! Check if pruning is enabled.
     virtual bool getPruneMode() = 0;
 
     //! Check if p2p enabled.
     virtual bool p2pEnabled() = 0;
 
     //! Check if the node is ready to broadcast transactions.
     virtual bool isReadyToBroadcast() = 0;
 
     //! Check if in IBD.
     virtual bool isInitialBlockDownload() = 0;
 
     //! Check if shutdown requested.
     virtual bool shutdownRequested() = 0;
 
     //! Get adjusted time.
     virtual int64_t getAdjustedTime() = 0;
 
     //! Send init message.
     virtual void initMessage(const std::string &message) = 0;
 
     //! Send init warning.
     virtual void initWarning(const std::string &message) = 0;
 
     //! Send init error.
     virtual void initError(const std::string &message) = 0;
 
     //! Send wallet load notification to the GUI.
     virtual void loadWallet(std::unique_ptr<Wallet> wallet) = 0;
 
     //! Send progress indicator.
     virtual void showProgress(const std::string &title, int progress,
                               bool resume_possible) = 0;
 
     //! Chain notifications.
     class Notifications {
     public:
         virtual ~Notifications() {}
         virtual void TransactionAddedToMempool(const CTransactionRef &tx) {}
         virtual void TransactionRemovedFromMempool(const CTransactionRef &ptx) {
         }
         virtual void
         BlockConnected(const CBlock &block,
                        const std::vector<CTransactionRef> &tx_conflicted) {}
         virtual void BlockDisconnected(const CBlock &block) {}
         virtual void UpdatedBlockTip() {}
         virtual void ChainStateFlushed(const CBlockLocator &locator) {}
     };
 
     //! Register handler for notifications.
     virtual std::unique_ptr<Handler>
     handleNotifications(Notifications &notifications) = 0;
 
     //! Wait for pending notifications to be processed unless block hash points
     //! to the current chain tip, or to a possible descendant of the current
     //! chain tip that isn't currently connected.
     virtual void
     waitForNotificationsIfNewBlocksConnected(const BlockHash &old_tip) = 0;
 
     //! Register handler for RPC. Command is not copied, so reference
     //! needs to remain valid until Handler is disconnected.
     virtual std::unique_ptr<Handler> handleRpc(const CRPCCommand &command) = 0;
 
     //! Check if deprecated RPC is enabled.
     virtual bool rpcEnableDeprecated(const std::string &method) = 0;
 
     //! Run function after given number of seconds. Cancel any previous calls
     //! with same name.
     virtual void rpcRunLater(const std::string &name, std::function<void()> fn,
                              int64_t seconds) = 0;
 
     //! Current RPC serialization flags.
     virtual int rpcSerializationFlags() = 0;
 
     //! Synchronously send TransactionAddedToMempool notifications about all
     //! current mempool transactions to the specified handler and return after
     //! the last one is sent. These notifications aren't coordinated with async
     //! notifications sent by handleNotifications, so out of date async
     //! notifications from handleNotifications can arrive during and after
     //! synchronous notifications from requestMempoolTransactions. Clients need
     //! to be prepared to handle this by ignoring notifications about unknown
     //! removed transactions and already added new transactions.
     virtual void requestMempoolTransactions(Notifications &notifications) = 0;
 };
 
 //! Interface to let node manage chain clients (wallets, or maybe tools for
 //! monitoring and analysis in the future).
 class ChainClient {
 public:
     virtual ~ChainClient() {}
 
     //! Register rpcs.
     virtual void registerRpcs() = 0;
 
     //! Check for errors before loading.
     virtual bool verify(const CChainParams &chainParams) = 0;
 
     //! Load saved state.
     virtual bool load(const CChainParams &chainParams) = 0;
 
     //! Start client execution and provide a scheduler.
     virtual void start(CScheduler &scheduler) = 0;
 
     //! Save state to disk.
     virtual void flush() = 0;
 
     //! Shut down client.
     virtual void stop() = 0;
 };
 
 //! Return implementation of Chain interface.
 std::unique_ptr<Chain> MakeChain();
 
 //! Return implementation of ChainClient interface for a wallet client. This
 //! function will be undefined in builds where ENABLE_WALLET is false.
 //!
 //! Currently, wallets are the only chain clients. But in the future, other
 //! types of chain clients could be added, such as tools for monitoring,
 //! analysis, or fee estimation. These clients need to expose their own
 //! MakeXXXClient functions returning their implementations of the ChainClient
 //! interface.
 std::unique_ptr<ChainClient>
 MakeWalletClient(Chain &chain, std::vector<std::string> wallet_filenames);
 
 } // namespace interfaces
 
 #endif // BITCOIN_INTERFACES_CHAIN_H
diff --git a/src/interfaces/node.cpp b/src/interfaces/node.cpp
index 3628fa6db..54c62e7fd 100644
--- a/src/interfaces/node.cpp
+++ b/src/interfaces/node.cpp
@@ -1,344 +1,343 @@
 // Copyright (c) 2018 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <interfaces/node.h>
 
 #include <addrdb.h>
 #include <amount.h>
 #include <banman.h>
 #include <chain.h>
 #include <chainparams.h>
 #include <config.h>
 #include <init.h>
 #include <interfaces/chain.h>
 #include <interfaces/handler.h>
 #include <interfaces/wallet.h>
 #include <net.h>
 #include <net_processing.h>
 #include <netaddress.h>
 #include <netbase.h>
 #include <policy/fees.h>
 #include <policy/policy.h>
 #include <policy/settings.h>
 #include <primitives/block.h>
 #include <rpc/server.h>
 #include <scheduler.h>
 #include <shutdown.h>
 #include <sync.h>
 #include <txmempool.h>
 #include <ui_interface.h>
 #include <util/system.h>
 #include <validation.h>
 #include <warnings.h>
 
 #if defined(HAVE_CONFIG_H)
 #include <config/bitcoin-config.h>
 #endif
 
 #include <univalue.h>
 
 #include <atomic>
 
 class HTTPRPCRequestProcessor;
 class CWallet;
 fs::path GetWalletDir();
 std::vector<fs::path> ListWalletDir();
 std::vector<std::shared_ptr<CWallet>> GetWallets();
 std::shared_ptr<CWallet> LoadWallet(const CChainParams &chainParams,
                                     interfaces::Chain &chain,
                                     const std::string &name, std::string &error,
                                     std::string &warning);
 
 namespace interfaces {
 
 class Wallet;
 
 namespace {
 
     class NodeImpl : public Node {
     public:
         NodeImpl() { m_context.chain = MakeChain(); }
         void initError(const std::string &message) override {
             InitError(message);
         }
         bool parseParameters(int argc, const char *const argv[],
                              std::string &error) override {
             return gArgs.ParseParameters(argc, argv, error);
         }
         bool readConfigFiles(std::string &error) override {
             return gArgs.ReadConfigFiles(error, true);
         }
         bool softSetArg(const std::string &arg,
                         const std::string &value) override {
             return gArgs.SoftSetArg(arg, value);
         }
         bool softSetBoolArg(const std::string &arg, bool value) override {
             return gArgs.SoftSetBoolArg(arg, value);
         }
         void selectParams(const std::string &network) override {
             SelectParams(network);
         }
         uint64_t getAssumedBlockchainSize() override {
             return Params().AssumedBlockchainSize();
         }
         uint64_t getAssumedChainStateSize() override {
             return Params().AssumedChainStateSize();
         }
         std::string getNetwork() override { return Params().NetworkIDString(); }
         void initLogging() override { InitLogging(); }
         void initParameterInteraction() override { InitParameterInteraction(); }
         std::string getWarnings(const std::string &type) override {
             return GetWarnings(type);
         }
         bool baseInitialize(Config &config) override {
             return AppInitBasicSetup() && AppInitParameterInteraction(config) &&
                    AppInitSanityChecks() && AppInitLockDataDirectory();
         }
         bool
         appInitMain(Config &config, RPCServer &rpcServer,
                     HTTPRPCRequestProcessor &httpRPCRequestProcessor) override {
             return AppInitMain(config, rpcServer, httpRPCRequestProcessor,
                                m_context);
         }
         void appShutdown() override {
             Interrupt();
             Shutdown(m_context);
         }
         void startShutdown() override { StartShutdown(); }
         bool shutdownRequested() override { return ShutdownRequested(); }
         void mapPort(bool use_upnp) override {
             if (use_upnp) {
                 StartMapPort();
             } else {
                 InterruptMapPort();
                 StopMapPort();
             }
         }
         void setupServerArgs() override { return SetupServerArgs(); }
         bool getProxy(Network net, proxyType &proxy_info) override {
             return GetProxy(net, proxy_info);
         }
         size_t getNodeCount(CConnman::NumConnections flags) override {
             return g_connman ? g_connman->GetNodeCount(flags) : 0;
         }
         bool getNodesStats(NodesStats &stats) override {
             stats.clear();
 
             if (g_connman) {
                 std::vector<CNodeStats> stats_temp;
                 g_connman->GetNodeStats(stats_temp);
 
                 stats.reserve(stats_temp.size());
                 for (auto &node_stats_temp : stats_temp) {
                     stats.emplace_back(std::move(node_stats_temp), false,
                                        CNodeStateStats());
                 }
 
                 // Try to retrieve the CNodeStateStats for each node.
                 TRY_LOCK(::cs_main, lockMain);
                 if (lockMain) {
                     for (auto &node_stats : stats) {
                         std::get<1>(node_stats) =
                             GetNodeStateStats(std::get<0>(node_stats).nodeid,
                                               std::get<2>(node_stats));
                     }
                 }
                 return true;
             }
             return false;
         }
         bool getBanned(banmap_t &banmap) override {
             if (g_banman) {
                 g_banman->GetBanned(banmap);
                 return true;
             }
             return false;
         }
         bool ban(const CNetAddr &net_addr, BanReason reason,
                  int64_t ban_time_offset) override {
             if (g_banman) {
                 g_banman->Ban(net_addr, reason, ban_time_offset);
                 return true;
             }
             return false;
         }
         bool unban(const CSubNet &ip) override {
             if (g_banman) {
                 g_banman->Unban(ip);
                 return true;
             }
             return false;
         }
         bool disconnect(const CNetAddr &net_addr) override {
             if (g_connman) {
                 return g_connman->DisconnectNode(net_addr);
             }
             return false;
         }
         bool disconnect(NodeId id) override {
             if (g_connman) {
                 return g_connman->DisconnectNode(id);
             }
             return false;
         }
         int64_t getTotalBytesRecv() override {
             return g_connman ? g_connman->GetTotalBytesRecv() : 0;
         }
         int64_t getTotalBytesSent() override {
             return g_connman ? g_connman->GetTotalBytesSent() : 0;
         }
         size_t getMempoolSize() override { return g_mempool.size(); }
         size_t getMempoolDynamicUsage() override {
             return g_mempool.DynamicMemoryUsage();
         }
         bool getHeaderTip(int &height, int64_t &block_time) override {
             LOCK(::cs_main);
             if (::pindexBestHeader) {
                 height = ::pindexBestHeader->nHeight;
                 block_time = ::pindexBestHeader->GetBlockTime();
                 return true;
             }
             return false;
         }
         int getNumBlocks() override {
             LOCK(::cs_main);
             return ::ChainActive().Height();
         }
         int64_t getLastBlockTime() override {
             LOCK(::cs_main);
             if (::ChainActive().Tip()) {
                 return ::ChainActive().Tip()->GetBlockTime();
             }
             // Genesis block's time of current network
             return Params().GenesisBlock().GetBlockTime();
         }
         double getVerificationProgress() override {
             const CBlockIndex *tip;
             {
                 LOCK(::cs_main);
                 tip = ::ChainActive().Tip();
             }
             return GuessVerificationProgress(Params().TxData(), tip);
         }
         bool isInitialBlockDownload() override {
             return ::ChainstateActive().IsInitialBlockDownload();
         }
         bool getReindex() override { return ::fReindex; }
         bool getImporting() override { return ::fImporting; }
         void setNetworkActive(bool active) override {
             if (g_connman) {
                 g_connman->SetNetworkActive(active);
             }
         }
         bool getNetworkActive() override {
             return g_connman && g_connman->GetNetworkActive();
         }
-        Amount getMaxTxFee() override { return ::maxTxFee; }
         CFeeRate estimateSmartFee() override { return g_mempool.estimateFee(); }
         CFeeRate getDustRelayFee() override { return ::dustRelayFee; }
         UniValue executeRpc(Config &config, const std::string &command,
                             const UniValue &params,
                             const std::string &uri) override {
             JSONRPCRequest req;
             req.params = params;
             req.strMethod = command;
             req.URI = uri;
             return ::tableRPC.execute(config, req);
         }
         std::vector<std::string> listRpcCommands() override {
             return ::tableRPC.listCommands();
         }
         void rpcSetTimerInterfaceIfUnset(RPCTimerInterface *iface) override {
             RPCSetTimerInterfaceIfUnset(iface);
         }
         void rpcUnsetTimerInterface(RPCTimerInterface *iface) override {
             RPCUnsetTimerInterface(iface);
         }
         bool getUnspentOutput(const COutPoint &output, Coin &coin) override {
             LOCK(::cs_main);
             return ::pcoinsTip->GetCoin(output, coin);
         }
         std::string getWalletDir() override { return GetWalletDir().string(); }
         std::vector<std::string> listWalletDir() override {
             std::vector<std::string> paths;
             for (auto &path : ListWalletDir()) {
                 paths.push_back(path.string());
             }
             return paths;
         }
         std::vector<std::unique_ptr<Wallet>> getWallets() override {
             std::vector<std::unique_ptr<Wallet>> wallets;
             for (const std::shared_ptr<CWallet> &wallet : GetWallets()) {
                 wallets.emplace_back(MakeWallet(wallet));
             }
             return wallets;
         }
         std::unique_ptr<Wallet>
         loadWallet(const CChainParams &params, const std::string &name,
                    std::string &error, std::string &warning) const override {
             return MakeWallet(
                 LoadWallet(params, *m_context.chain, name, error, warning));
         }
         std::unique_ptr<Handler> handleInitMessage(InitMessageFn fn) override {
             return MakeHandler(::uiInterface.InitMessage_connect(fn));
         }
         std::unique_ptr<Handler> handleMessageBox(MessageBoxFn fn) override {
             return MakeHandler(::uiInterface.ThreadSafeMessageBox_connect(fn));
         }
         std::unique_ptr<Handler> handleQuestion(QuestionFn fn) override {
             return MakeHandler(::uiInterface.ThreadSafeQuestion_connect(fn));
         }
         std::unique_ptr<Handler>
         handleShowProgress(ShowProgressFn fn) override {
             return MakeHandler(::uiInterface.ShowProgress_connect(fn));
         }
         std::unique_ptr<Handler> handleLoadWallet(LoadWalletFn fn) override {
             return MakeHandler(::uiInterface.LoadWallet_connect(
                 [fn](std::unique_ptr<Wallet> &wallet) {
                     fn(std::move(wallet));
                 }));
         }
         std::unique_ptr<Handler> handleNotifyNumConnectionsChanged(
             NotifyNumConnectionsChangedFn fn) override {
             return MakeHandler(
                 ::uiInterface.NotifyNumConnectionsChanged_connect(fn));
         }
         std::unique_ptr<Handler> handleNotifyNetworkActiveChanged(
             NotifyNetworkActiveChangedFn fn) override {
             return MakeHandler(
                 ::uiInterface.NotifyNetworkActiveChanged_connect(fn));
         }
         std::unique_ptr<Handler>
         handleNotifyAlertChanged(NotifyAlertChangedFn fn) override {
             return MakeHandler(::uiInterface.NotifyAlertChanged_connect(fn));
         }
         std::unique_ptr<Handler>
         handleBannedListChanged(BannedListChangedFn fn) override {
             return MakeHandler(::uiInterface.BannedListChanged_connect(fn));
         }
         std::unique_ptr<Handler>
         handleNotifyBlockTip(NotifyBlockTipFn fn) override {
             return MakeHandler(::uiInterface.NotifyBlockTip_connect(
                 [fn](bool initial_download, const CBlockIndex *block) {
                     fn(initial_download, block->nHeight, block->GetBlockTime(),
                        GuessVerificationProgress(Params().TxData(), block));
                 }));
         }
         std::unique_ptr<Handler>
         handleNotifyHeaderTip(NotifyHeaderTipFn fn) override {
             return MakeHandler(::uiInterface.NotifyHeaderTip_connect(
                 [fn](bool initial_download, const CBlockIndex *block) {
                     fn(initial_download, block->nHeight, block->GetBlockTime(),
                        GuessVerificationProgress(Params().TxData(), block));
                 }));
         }
         NodeContext m_context;
     };
 } // namespace
 
 std::unique_ptr<Node> MakeNode() {
     return std::make_unique<NodeImpl>();
 }
 
 } // namespace interfaces
diff --git a/src/interfaces/node.h b/src/interfaces/node.h
index 6e4d220d4..a209124a6 100644
--- a/src/interfaces/node.h
+++ b/src/interfaces/node.h
@@ -1,280 +1,277 @@
 // Copyright (c) 2018 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_INTERFACES_NODE_H
 #define BITCOIN_INTERFACES_NODE_H
 
 #include <addrdb.h>     // For banmap_t
 #include <amount.h>     // For Amount
 #include <net.h>        // For CConnman::NumConnections
 #include <netaddress.h> // For Network
 
 #include <cstddef>
 #include <cstdint>
 #include <functional>
 #include <memory>
 #include <string>
 #include <tuple>
 #include <vector>
 
 class BanMan;
 class CCoinControl;
 class CFeeRate;
 struct CNodeStateStats;
 struct CNodeStats;
 class Coin;
 class Config;
 class HTTPRPCRequestProcessor;
 class proxyType;
 class RPCServer;
 class RPCTimerInterface;
 class UniValue;
 
 namespace interfaces {
 class Handler;
 class Wallet;
 
 //! Top-level interface for a bitcoin node (bitcoind process).
 class Node {
 public:
     virtual ~Node() {}
 
     //! Send init error.
     virtual void initError(const std::string &message) = 0;
 
     //! Set command line arguments.
     virtual bool parseParameters(int argc, const char *const argv[],
                                  std::string &error) = 0;
 
     //! Set a command line argument if it doesn't already have a value
     virtual bool softSetArg(const std::string &arg,
                             const std::string &value) = 0;
 
     //! Set a command line boolean argument if it doesn't already have a value
     virtual bool softSetBoolArg(const std::string &arg, bool value) = 0;
 
     //! Load settings from configuration file.
     virtual bool readConfigFiles(std::string &error) = 0;
 
     //! Choose network parameters.
     virtual void selectParams(const std::string &network) = 0;
 
     //! Get the (assumed) blockchain size.
     virtual uint64_t getAssumedBlockchainSize() = 0;
 
     //! Get the (assumed) chain state size.
     virtual uint64_t getAssumedChainStateSize() = 0;
 
     //! Get network name.
     virtual std::string getNetwork() = 0;
 
     //! Init logging.
     virtual void initLogging() = 0;
 
     //! Init parameter interaction.
     virtual void initParameterInteraction() = 0;
 
     //! Get warnings.
     virtual std::string getWarnings(const std::string &type) = 0;
 
     //! Initialize app dependencies.
     virtual bool baseInitialize(Config &config) = 0;
 
     //! Start node.
     virtual bool
     appInitMain(Config &config, RPCServer &rpcServer,
                 HTTPRPCRequestProcessor &httpRPCRequestProcessor) = 0;
 
     //! Stop node.
     virtual void appShutdown() = 0;
 
     //! Start shutdown.
     virtual void startShutdown() = 0;
 
     //! Return whether shutdown was requested.
     virtual bool shutdownRequested() = 0;
 
     //! Setup arguments
     virtual void setupServerArgs() = 0;
 
     //! Map port.
     virtual void mapPort(bool use_upnp) = 0;
 
     //! Get proxy.
     virtual bool getProxy(Network net, proxyType &proxy_info) = 0;
 
     //! Get number of connections.
     virtual size_t getNodeCount(CConnman::NumConnections flags) = 0;
 
     //! Get stats for connected nodes.
     using NodesStats =
         std::vector<std::tuple<CNodeStats, bool, CNodeStateStats>>;
     virtual bool getNodesStats(NodesStats &stats) = 0;
 
     //! Get ban map entries.
     virtual bool getBanned(banmap_t &banmap) = 0;
 
     //! Ban node.
     virtual bool ban(const CNetAddr &net_addr, BanReason reason,
                      int64_t ban_time_offset) = 0;
 
     //! Unban node.
     virtual bool unban(const CSubNet &ip) = 0;
 
     //! Disconnect node by address.
     virtual bool disconnect(const CNetAddr &net_addr) = 0;
 
     //! Disconnect node by id.
     virtual bool disconnect(NodeId id) = 0;
 
     //! Get total bytes recv.
     virtual int64_t getTotalBytesRecv() = 0;
 
     //! Get total bytes sent.
     virtual int64_t getTotalBytesSent() = 0;
 
     //! Get mempool size.
     virtual size_t getMempoolSize() = 0;
 
     //! Get mempool dynamic usage.
     virtual size_t getMempoolDynamicUsage() = 0;
 
     //! Get header tip height and time.
     virtual bool getHeaderTip(int &height, int64_t &block_time) = 0;
 
     //! Get num blocks.
     virtual int getNumBlocks() = 0;
 
     //! Get last block time.
     virtual int64_t getLastBlockTime() = 0;
 
     //! Get verification progress.
     virtual double getVerificationProgress() = 0;
 
     //! Is initial block download.
     virtual bool isInitialBlockDownload() = 0;
 
     //! Get reindex.
     virtual bool getReindex() = 0;
 
     //! Get importing.
     virtual bool getImporting() = 0;
 
     //! Set network active.
     virtual void setNetworkActive(bool active) = 0;
 
     //! Get network active.
     virtual bool getNetworkActive() = 0;
 
-    //! Get max tx fee.
-    virtual Amount getMaxTxFee() = 0;
-
     //! Estimate smart fee.
     virtual CFeeRate estimateSmartFee() = 0;
 
     //! Get dust relay fee.
     virtual CFeeRate getDustRelayFee() = 0;
 
     //! Execute rpc command.
     virtual UniValue executeRpc(Config &config, const std::string &command,
                                 const UniValue &params,
                                 const std::string &uri) = 0;
 
     //! List rpc commands.
     virtual std::vector<std::string> listRpcCommands() = 0;
 
     //! Set RPC timer interface if unset.
     virtual void rpcSetTimerInterfaceIfUnset(RPCTimerInterface *iface) = 0;
 
     //! Unset RPC timer interface.
     virtual void rpcUnsetTimerInterface(RPCTimerInterface *iface) = 0;
 
     //! Get unspent outputs associated with a transaction.
     virtual bool getUnspentOutput(const COutPoint &output, Coin &coin) = 0;
 
     //! Return default wallet directory.
     virtual std::string getWalletDir() = 0;
 
     //! Return available wallets in wallet directory.
     virtual std::vector<std::string> listWalletDir() = 0;
 
     //! Return interfaces for accessing wallets (if any).
     virtual std::vector<std::unique_ptr<Wallet>> getWallets() = 0;
 
     //! Attempts to load a wallet from file or directory.
     //! The loaded wallet is also notified to handlers previously registered
     //! with handleLoadWallet.
     virtual std::unique_ptr<Wallet> loadWallet(const CChainParams &params,
                                                const std::string &name,
                                                std::string &error,
                                                std::string &warning) const = 0;
 
     //! Register handler for init messages.
     using InitMessageFn = std::function<void(const std::string &message)>;
     virtual std::unique_ptr<Handler> handleInitMessage(InitMessageFn fn) = 0;
 
     //! Register handler for message box messages.
     using MessageBoxFn =
         std::function<bool(const std::string &message,
                            const std::string &caption, unsigned int style)>;
     virtual std::unique_ptr<Handler> handleMessageBox(MessageBoxFn fn) = 0;
 
     //! Register handler for question messages.
     using QuestionFn = std::function<bool(
         const std::string &message, const std::string &non_interactive_message,
         const std::string &caption, unsigned int style)>;
     virtual std::unique_ptr<Handler> handleQuestion(QuestionFn fn) = 0;
 
     //! Register handler for progress messages.
     using ShowProgressFn = std::function<void(
         const std::string &title, int progress, bool resume_possible)>;
     virtual std::unique_ptr<Handler> handleShowProgress(ShowProgressFn fn) = 0;
 
     //! Register handler for load wallet messages.
     using LoadWalletFn = std::function<void(std::unique_ptr<Wallet> wallet)>;
     virtual std::unique_ptr<Handler> handleLoadWallet(LoadWalletFn fn) = 0;
 
     //! Register handler for number of connections changed messages.
     using NotifyNumConnectionsChangedFn =
         std::function<void(int new_num_connections)>;
     virtual std::unique_ptr<Handler>
     handleNotifyNumConnectionsChanged(NotifyNumConnectionsChangedFn fn) = 0;
 
     //! Register handler for network active messages.
     using NotifyNetworkActiveChangedFn =
         std::function<void(bool network_active)>;
     virtual std::unique_ptr<Handler>
     handleNotifyNetworkActiveChanged(NotifyNetworkActiveChangedFn fn) = 0;
 
     //! Register handler for notify alert messages.
     using NotifyAlertChangedFn = std::function<void()>;
     virtual std::unique_ptr<Handler>
     handleNotifyAlertChanged(NotifyAlertChangedFn fn) = 0;
 
     //! Register handler for ban list messages.
     using BannedListChangedFn = std::function<void()>;
     virtual std::unique_ptr<Handler>
     handleBannedListChanged(BannedListChangedFn fn) = 0;
 
     //! Register handler for block tip messages.
     using NotifyBlockTipFn =
         std::function<void(bool initial_download, int height,
                            int64_t block_time, double verification_progress)>;
     virtual std::unique_ptr<Handler>
     handleNotifyBlockTip(NotifyBlockTipFn fn) = 0;
 
     //! Register handler for header tip messages.
     using NotifyHeaderTipFn =
         std::function<void(bool initial_download, int height,
                            int64_t block_time, double verification_progress)>;
     virtual std::unique_ptr<Handler>
     handleNotifyHeaderTip(NotifyHeaderTipFn fn) = 0;
 };
 
 //! Return implementation of Node interface.
 std::unique_ptr<Node> MakeNode();
 
 } // namespace interfaces
 
 #endif // BITCOIN_INTERFACES_NODE_H
diff --git a/src/interfaces/wallet.cpp b/src/interfaces/wallet.cpp
index 3f33f2b6c..c46dd249c 100644
--- a/src/interfaces/wallet.cpp
+++ b/src/interfaces/wallet.cpp
@@ -1,535 +1,538 @@
 // Copyright (c) 2018 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <interfaces/wallet.h>
 
 #include <amount.h>
 #include <chain.h>
 #include <consensus/validation.h>
 #include <init.h>
 #include <interfaces/chain.h>
 #include <interfaces/handler.h>
 #include <net.h>
 #include <policy/fees.h>
 #include <policy/policy.h>
 #include <primitives/transaction.h>
 #include <rpc/server.h>
 #include <scheduler.h>
 #include <script/ismine.h>
 #include <script/standard.h>
 #include <support/allocators/secure.h>
 #include <sync.h>
 #include <timedata.h>
 #include <ui_interface.h>
 #include <util/system.h>
 #include <validation.h>
 #include <wallet/fees.h>
 #include <wallet/load.h>
 #include <wallet/rpcdump.h>
 #include <wallet/rpcwallet.h>
 #include <wallet/wallet.h>
 #include <wallet/walletutil.h>
 
 #include <memory>
 #include <string>
 #include <utility>
 #include <vector>
 
 namespace interfaces {
 namespace {
 
     class PendingWalletTxImpl : public PendingWalletTx {
     public:
         explicit PendingWalletTxImpl(CWallet &wallet)
             : m_wallet(wallet), m_key(&wallet) {}
 
         const CTransaction &get() override { return *m_tx; }
 
         bool commit(WalletValueMap value_map, WalletOrderForm order_form,
                     std::string &reject_reason) override {
             auto locked_chain = m_wallet.chain().lock();
             LOCK(m_wallet.cs_wallet);
             CValidationState state;
             if (!m_wallet.CommitTransaction(m_tx, std::move(value_map),
                                             std::move(order_form), m_key,
                                             state)) {
                 reject_reason = state.GetRejectReason();
                 return false;
             }
             return true;
         }
 
         CTransactionRef m_tx;
         CWallet &m_wallet;
         CReserveKey m_key;
     };
 
     //! Construct wallet tx struct.
     static WalletTx MakeWalletTx(interfaces::Chain::Lock &locked_chain,
                                  CWallet &wallet, const CWalletTx &wtx) {
         WalletTx result;
         result.tx = wtx.tx;
         result.txin_is_mine.reserve(wtx.tx->vin.size());
         for (const auto &txin : wtx.tx->vin) {
             result.txin_is_mine.emplace_back(wallet.IsMine(txin));
         }
         result.txout_is_mine.reserve(wtx.tx->vout.size());
         result.txout_address.reserve(wtx.tx->vout.size());
         result.txout_address_is_mine.reserve(wtx.tx->vout.size());
         for (const auto &txout : wtx.tx->vout) {
             result.txout_is_mine.emplace_back(wallet.IsMine(txout));
             result.txout_address.emplace_back();
             result.txout_address_is_mine.emplace_back(
                 ExtractDestination(txout.scriptPubKey,
                                    result.txout_address.back())
                     ? IsMine(wallet, result.txout_address.back())
                     : ISMINE_NO);
         }
         result.credit = wtx.GetCredit(locked_chain, ISMINE_ALL);
         result.debit = wtx.GetDebit(ISMINE_ALL);
         result.change = wtx.GetChange();
         result.time = wtx.GetTxTime();
         result.value_map = wtx.mapValue;
         result.is_coinbase = wtx.IsCoinBase();
         return result;
     }
 
     //! Construct wallet tx status struct.
     static WalletTxStatus
     MakeWalletTxStatus(interfaces::Chain::Lock &locked_chain,
                        const CWalletTx &wtx) {
         WalletTxStatus result;
         result.block_height =
             locked_chain.getBlockHeight(wtx.hashBlock)
                 .get_value_or(std::numeric_limits<int>::max());
         result.blocks_to_maturity = wtx.GetBlocksToMaturity(locked_chain);
         result.depth_in_main_chain = wtx.GetDepthInMainChain(locked_chain);
         result.time_received = wtx.nTimeReceived;
         result.lock_time = wtx.tx->nLockTime;
         CValidationState state;
         result.is_final =
             locked_chain.contextualCheckTransactionForCurrentBlock(
                 Params().GetConsensus(), *wtx.tx, state);
         result.is_trusted = wtx.IsTrusted(locked_chain);
         result.is_abandoned = wtx.isAbandoned();
         result.is_coinbase = wtx.IsCoinBase();
         result.is_in_main_chain = wtx.IsInMainChain(locked_chain);
         return result;
     }
 
     //! Construct wallet TxOut struct.
     static WalletTxOut MakeWalletTxOut(interfaces::Chain::Lock &locked_chain,
                                        CWallet &wallet, const CWalletTx &wtx,
                                        int n, int depth)
         EXCLUSIVE_LOCKS_REQUIRED(wallet.cs_wallet) {
         WalletTxOut result;
         result.txout = wtx.tx->vout[n];
         result.time = wtx.GetTxTime();
         result.depth_in_main_chain = depth;
         result.is_spent =
             wallet.IsSpent(locked_chain, COutPoint(wtx.GetId(), n));
         return result;
     }
 
     class WalletImpl : public Wallet {
     public:
         explicit WalletImpl(const std::shared_ptr<CWallet> &wallet)
             : m_shared_wallet(wallet), m_wallet(*wallet.get()) {}
 
         bool encryptWallet(const SecureString &wallet_passphrase) override {
             return m_wallet.EncryptWallet(wallet_passphrase);
         }
         bool isCrypted() override { return m_wallet.IsCrypted(); }
         bool lock() override { return m_wallet.Lock(); }
         bool unlock(const SecureString &wallet_passphrase) override {
             return m_wallet.Unlock(wallet_passphrase);
         }
         bool isLocked() override { return m_wallet.IsLocked(); }
         bool changeWalletPassphrase(
             const SecureString &old_wallet_passphrase,
             const SecureString &new_wallet_passphrase) override {
             return m_wallet.ChangeWalletPassphrase(old_wallet_passphrase,
                                                    new_wallet_passphrase);
         }
         void abortRescan() override { m_wallet.AbortRescan(); }
         bool backupWallet(const std::string &filename) override {
             return m_wallet.BackupWallet(filename);
         }
         std::string getWalletName() override { return m_wallet.GetName(); }
         std::set<CTxDestination>
         getLabelAddresses(const std::string &label) override {
             return m_wallet.GetLabelAddresses(label);
         };
         bool getKeyFromPool(bool internal, CPubKey &pub_key) override {
             return m_wallet.GetKeyFromPool(pub_key, internal);
         }
         const CChainParams &getChainParams() override {
             return m_wallet.chainParams;
         }
         bool getPubKey(const CKeyID &address, CPubKey &pub_key) override {
             return m_wallet.GetPubKey(address, pub_key);
         }
         bool getPrivKey(const CKeyID &address, CKey &key) override {
             return m_wallet.GetKey(address, key);
         }
         bool isSpendable(const CTxDestination &dest) override {
             return IsMine(m_wallet, dest) & ISMINE_SPENDABLE;
         }
         bool haveWatchOnly() override { return m_wallet.HaveWatchOnly(); };
         bool setAddressBook(const CTxDestination &dest, const std::string &name,
                             const std::string &purpose) override {
             return m_wallet.SetAddressBook(dest, name, purpose);
         }
         bool delAddressBook(const CTxDestination &dest) override {
             return m_wallet.DelAddressBook(dest);
         }
         bool getAddress(const CTxDestination &dest, std::string *name,
                         isminetype *is_mine, std::string *purpose) override {
             LOCK(m_wallet.cs_wallet);
             auto it = m_wallet.mapAddressBook.find(dest);
             if (it == m_wallet.mapAddressBook.end()) {
                 return false;
             }
             if (name) {
                 *name = it->second.name;
             }
             if (is_mine) {
                 *is_mine = IsMine(m_wallet, dest);
             }
             if (purpose) {
                 *purpose = it->second.purpose;
             }
             return true;
         }
         std::vector<WalletAddress> getAddresses() override {
             LOCK(m_wallet.cs_wallet);
             std::vector<WalletAddress> result;
             for (const auto &item : m_wallet.mapAddressBook) {
                 result.emplace_back(item.first, IsMine(m_wallet, item.first),
                                     item.second.name, item.second.purpose);
             }
             return result;
         }
         void learnRelatedScripts(const CPubKey &key, OutputType type) override {
             m_wallet.LearnRelatedScripts(key, type);
         }
         bool addDestData(const CTxDestination &dest, const std::string &key,
                          const std::string &value) override {
             LOCK(m_wallet.cs_wallet);
             return m_wallet.AddDestData(dest, key, value);
         }
         bool eraseDestData(const CTxDestination &dest,
                            const std::string &key) override {
             LOCK(m_wallet.cs_wallet);
             return m_wallet.EraseDestData(dest, key);
         }
         std::vector<std::string>
         getDestValues(const std::string &prefix) override {
             return m_wallet.GetDestValues(prefix);
         }
         void lockCoin(const COutPoint &output) override {
             auto locked_chain = m_wallet.chain().lock();
             LOCK(m_wallet.cs_wallet);
             return m_wallet.LockCoin(output);
         }
         void unlockCoin(const COutPoint &output) override {
             auto locked_chain = m_wallet.chain().lock();
             LOCK(m_wallet.cs_wallet);
             return m_wallet.UnlockCoin(output);
         }
         bool isLockedCoin(const COutPoint &output) override {
             auto locked_chain = m_wallet.chain().lock();
             LOCK(m_wallet.cs_wallet);
             return m_wallet.IsLockedCoin(output);
         }
         void listLockedCoins(std::vector<COutPoint> &outputs) override {
             auto locked_chain = m_wallet.chain().lock();
             LOCK(m_wallet.cs_wallet);
             return m_wallet.ListLockedCoins(outputs);
         }
         std::unique_ptr<PendingWalletTx>
         createTransaction(const std::vector<CRecipient> &recipients,
                           const CCoinControl &coin_control, bool sign,
                           int &change_pos, Amount &fee,
                           std::string &fail_reason) override {
             auto locked_chain = m_wallet.chain().lock();
             LOCK(m_wallet.cs_wallet);
             auto pending = std::make_unique<PendingWalletTxImpl>(m_wallet);
             if (!m_wallet.CreateTransaction(
                     *locked_chain, recipients, pending->m_tx, pending->m_key,
                     fee, change_pos, fail_reason, coin_control, sign)) {
                 return {};
             }
             return pending;
         }
         bool transactionCanBeAbandoned(const TxId &txid) override {
             return m_wallet.TransactionCanBeAbandoned(txid);
         }
         bool abandonTransaction(const TxId &txid) override {
             auto locked_chain = m_wallet.chain().lock();
             LOCK(m_wallet.cs_wallet);
             return m_wallet.AbandonTransaction(*locked_chain, txid);
         }
         CTransactionRef getTx(const TxId &txid) override {
             auto locked_chain = m_wallet.chain().lock();
             LOCK(m_wallet.cs_wallet);
             auto mi = m_wallet.mapWallet.find(txid);
             if (mi != m_wallet.mapWallet.end()) {
                 return mi->second.tx;
             }
             return {};
         }
         WalletTx getWalletTx(const TxId &txid) override {
             auto locked_chain = m_wallet.chain().lock();
             LOCK(m_wallet.cs_wallet);
             auto mi = m_wallet.mapWallet.find(txid);
             if (mi != m_wallet.mapWallet.end()) {
                 return MakeWalletTx(*locked_chain, m_wallet, mi->second);
             }
             return {};
         }
         std::vector<WalletTx> getWalletTxs() override {
             auto locked_chain = m_wallet.chain().lock();
             LOCK(m_wallet.cs_wallet);
             std::vector<WalletTx> result;
             result.reserve(m_wallet.mapWallet.size());
             for (const auto &entry : m_wallet.mapWallet) {
                 result.emplace_back(
                     MakeWalletTx(*locked_chain, m_wallet, entry.second));
             }
             return result;
         }
         bool tryGetTxStatus(const TxId &txid,
                             interfaces::WalletTxStatus &tx_status,
                             int &num_blocks, int64_t &block_time) override {
             auto locked_chain = m_wallet.chain().lock(true /* try_lock */);
             if (!locked_chain) {
                 return false;
             }
             TRY_LOCK(m_wallet.cs_wallet, locked_wallet);
             if (!locked_wallet) {
                 return false;
             }
             auto mi = m_wallet.mapWallet.find(txid);
             if (mi == m_wallet.mapWallet.end()) {
                 return false;
             }
             if (Optional<int> height = locked_chain->getHeight()) {
                 num_blocks = *height;
                 block_time = locked_chain->getBlockTime(*height);
             } else {
                 num_blocks = -1;
                 block_time = -1;
             }
             tx_status = MakeWalletTxStatus(*locked_chain, mi->second);
             return true;
         }
         WalletTx getWalletTxDetails(const TxId &txid, WalletTxStatus &tx_status,
                                     WalletOrderForm &order_form,
                                     bool &in_mempool,
                                     int &num_blocks) override {
             auto locked_chain = m_wallet.chain().lock();
             LOCK(m_wallet.cs_wallet);
             auto mi = m_wallet.mapWallet.find(txid);
             if (mi != m_wallet.mapWallet.end()) {
                 num_blocks = locked_chain->getHeight().value_or(-1);
                 in_mempool = mi->second.InMempool();
                 order_form = mi->second.vOrderForm;
                 tx_status = MakeWalletTxStatus(*locked_chain, mi->second);
                 return MakeWalletTx(*locked_chain, m_wallet, mi->second);
             }
             return {};
         }
         WalletBalances getBalances() override {
             const auto bal = m_wallet.GetBalance();
             WalletBalances result;
             result.balance = bal.m_mine_trusted;
             result.unconfirmed_balance = bal.m_mine_untrusted_pending;
             result.immature_balance = bal.m_mine_immature;
             result.have_watch_only = m_wallet.HaveWatchOnly();
             if (result.have_watch_only) {
                 result.watch_only_balance = bal.m_watchonly_trusted;
                 result.unconfirmed_watch_only_balance =
                     bal.m_watchonly_untrusted_pending;
                 result.immature_watch_only_balance = bal.m_watchonly_immature;
             }
             return result;
         }
         bool tryGetBalances(WalletBalances &balances,
                             int &num_blocks) override {
             auto locked_chain = m_wallet.chain().lock(true /* try_lock */);
             if (!locked_chain) {
                 return false;
             }
             TRY_LOCK(m_wallet.cs_wallet, locked_wallet);
             if (!locked_wallet) {
                 return false;
             }
             balances = getBalances();
             num_blocks = locked_chain->getHeight().value_or(-1);
             return true;
         }
         Amount getBalance() override {
             return m_wallet.GetBalance().m_mine_trusted;
         }
         Amount getAvailableBalance(const CCoinControl &coin_control) override {
             return m_wallet.GetAvailableBalance(&coin_control);
         }
         isminetype txinIsMine(const CTxIn &txin) override {
             auto locked_chain = m_wallet.chain().lock();
             LOCK(m_wallet.cs_wallet);
             return m_wallet.IsMine(txin);
         }
         isminetype txoutIsMine(const CTxOut &txout) override {
             auto locked_chain = m_wallet.chain().lock();
             LOCK(m_wallet.cs_wallet);
             return m_wallet.IsMine(txout);
         }
         Amount getDebit(const CTxIn &txin, isminefilter filter) override {
             auto locked_chain = m_wallet.chain().lock();
             LOCK(m_wallet.cs_wallet);
             return m_wallet.GetDebit(txin, filter);
         }
         Amount getCredit(const CTxOut &txout, isminefilter filter) override {
             auto locked_chain = m_wallet.chain().lock();
             LOCK(m_wallet.cs_wallet);
             return m_wallet.GetCredit(txout, filter);
         }
         CoinsList listCoins() override {
             auto locked_chain = m_wallet.chain().lock();
             LOCK(m_wallet.cs_wallet);
             CoinsList result;
             for (const auto &entry : m_wallet.ListCoins(*locked_chain)) {
                 auto &group = result[entry.first];
                 for (const auto &coin : entry.second) {
                     group.emplace_back(COutPoint(coin.tx->GetId(), coin.i),
                                        MakeWalletTxOut(*locked_chain, m_wallet,
                                                        *coin.tx, coin.i,
                                                        coin.nDepth));
                 }
             }
             return result;
         }
         std::vector<WalletTxOut>
         getCoins(const std::vector<COutPoint> &outputs) override {
             auto locked_chain = m_wallet.chain().lock();
             LOCK(m_wallet.cs_wallet);
             std::vector<WalletTxOut> result;
             result.reserve(outputs.size());
             for (const auto &output : outputs) {
                 result.emplace_back();
                 auto it = m_wallet.mapWallet.find(output.GetTxId());
                 if (it != m_wallet.mapWallet.end()) {
                     int depth = it->second.GetDepthInMainChain(*locked_chain);
                     if (depth >= 0) {
                         result.back() =
                             MakeWalletTxOut(*locked_chain, m_wallet, it->second,
                                             output.GetN(), depth);
                     }
                 }
             }
             return result;
         }
         bool hdEnabled() override { return m_wallet.IsHDEnabled(); }
         OutputType getDefaultAddressType() override {
             return m_wallet.m_default_address_type;
         }
         bool canGetAddresses() override { return m_wallet.CanGetAddresses(); }
         bool IsWalletFlagSet(uint64_t flag) override {
             return m_wallet.IsWalletFlagSet(flag);
         }
         OutputType getDefaultChangeType() override {
             return m_wallet.m_default_change_type;
         }
+        Amount getDefaultMaxTxFee() override {
+            return m_wallet.m_default_max_tx_fee;
+        }
         void remove() override { RemoveWallet(m_shared_wallet); }
         std::unique_ptr<Handler> handleUnload(UnloadFn fn) override {
             return MakeHandler(m_wallet.NotifyUnload.connect(fn));
         }
         std::unique_ptr<Handler>
         handleShowProgress(ShowProgressFn fn) override {
             return MakeHandler(m_wallet.ShowProgress.connect(fn));
         }
         std::unique_ptr<Handler>
         handleStatusChanged(StatusChangedFn fn) override {
             return MakeHandler(m_wallet.NotifyStatusChanged.connect(
                 [fn](CCryptoKeyStore *) { fn(); }));
         }
         std::unique_ptr<Handler>
         handleAddressBookChanged(AddressBookChangedFn fn) override {
             return MakeHandler(m_wallet.NotifyAddressBookChanged.connect(
                 [fn](CWallet *, const CTxDestination &address,
                      const std::string &label, bool is_mine,
                      const std::string &purpose, ChangeType status) {
                     fn(address, label, is_mine, purpose, status);
                 }));
         }
         std::unique_ptr<Handler>
         handleTransactionChanged(TransactionChangedFn fn) override {
             return MakeHandler(m_wallet.NotifyTransactionChanged.connect(
                 [fn](CWallet *, const TxId &txid, ChangeType status) {
                     fn(txid, status);
                 }));
         }
         std::unique_ptr<Handler>
         handleWatchOnlyChanged(WatchOnlyChangedFn fn) override {
             return MakeHandler(m_wallet.NotifyWatchonlyChanged.connect(fn));
         }
         std::unique_ptr<Handler>
         handleCanGetAddressesChanged(CanGetAddressesChangedFn fn) override {
             return MakeHandler(
                 m_wallet.NotifyCanGetAddressesChanged.connect(fn));
         }
         Amount getRequiredFee(unsigned int tx_bytes) override {
             return GetRequiredFee(m_wallet, tx_bytes);
         }
         Amount getMinimumFee(unsigned int tx_bytes,
                              const CCoinControl &coin_control) override {
             return GetMinimumFee(m_wallet, tx_bytes, coin_control);
         }
 
         std::shared_ptr<CWallet> m_shared_wallet;
         CWallet &m_wallet;
     };
 
     class WalletClientImpl : public ChainClient {
     public:
         WalletClientImpl(Chain &chain,
                          std::vector<std::string> wallet_filenames)
             : m_chain(chain), m_wallet_filenames(std::move(wallet_filenames)) {}
 
         void registerRpcs() override {
             RegisterWalletRPCCommands(m_chain, m_rpc_handlers);
             RegisterDumpRPCCommands(m_chain, m_rpc_handlers);
         }
         bool verify(const CChainParams &chainParams) override {
             return VerifyWallets(chainParams, m_chain, m_wallet_filenames);
         }
         bool load(const CChainParams &chainParams) override {
             return LoadWallets(chainParams, m_chain, m_wallet_filenames);
         }
         void start(CScheduler &scheduler) override {
             return StartWallets(scheduler);
         }
         void flush() override { return FlushWallets(); }
         void stop() override { return StopWallets(); }
         ~WalletClientImpl() override { UnloadWallets(); }
 
         Chain &m_chain;
         std::vector<std::string> m_wallet_filenames;
         std::vector<std::unique_ptr<Handler>> m_rpc_handlers;
     };
 
 } // namespace
 
 std::unique_ptr<Wallet> MakeWallet(const std::shared_ptr<CWallet> &wallet) {
     return wallet ? std::make_unique<WalletImpl>(wallet) : nullptr;
 }
 
 std::unique_ptr<ChainClient>
 MakeWalletClient(Chain &chain, std::vector<std::string> wallet_filenames) {
     return std::make_unique<WalletClientImpl>(chain,
                                               std::move(wallet_filenames));
 }
 
 } // namespace interfaces
diff --git a/src/interfaces/wallet.h b/src/interfaces/wallet.h
index 5dec36d6c..c9f0cc6c3 100644
--- a/src/interfaces/wallet.h
+++ b/src/interfaces/wallet.h
@@ -1,369 +1,372 @@
 // Copyright (c) 2018 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_INTERFACES_WALLET_H
 #define BITCOIN_INTERFACES_WALLET_H
 
 #include <amount.h>                 // For Amount
 #include <primitives/transaction.h> // For CTxOut
 #include <pubkey.h> // For CKeyID and CScriptID (definitions needed in CTxDestination instantiation)
 #include <script/ismine.h>             // For isminefilter, isminetype
 #include <script/standard.h>           // For CTxDestination
 #include <support/allocators/secure.h> // For SecureString
 #include <ui_interface.h>              // For ChangeType
 
 #include <cstdint>
 #include <functional>
 #include <map>
 #include <memory>
 #include <string>
 #include <tuple>
 #include <utility>
 #include <vector>
 
 class CChainParams;
 class CCoinControl;
 class CKey;
 class CMutableTransaction;
 class COutPoint;
 class CTransaction;
 class CWallet;
 enum class OutputType;
 struct CRecipient;
 struct TxId;
 
 namespace interfaces {
 
 class Handler;
 class PendingWalletTx;
 struct WalletAddress;
 struct WalletBalances;
 struct WalletTx;
 struct WalletTxOut;
 struct WalletTxStatus;
 
 using WalletOrderForm = std::vector<std::pair<std::string, std::string>>;
 using WalletValueMap = std::map<std::string, std::string>;
 
 //! Interface for accessing a wallet.
 class Wallet {
 public:
     virtual ~Wallet() {}
 
     //! Encrypt wallet.
     virtual bool encryptWallet(const SecureString &wallet_passphrase) = 0;
 
     //! Return whether wallet is encrypted.
     virtual bool isCrypted() = 0;
 
     //! Lock wallet.
     virtual bool lock() = 0;
 
     //! Unlock wallet.
     virtual bool unlock(const SecureString &wallet_passphrase) = 0;
 
     //! Return whether wallet is locked.
     virtual bool isLocked() = 0;
 
     //! Change wallet passphrase.
     virtual bool
     changeWalletPassphrase(const SecureString &old_wallet_passphrase,
                            const SecureString &new_wallet_passphrase) = 0;
 
     //! Abort a rescan.
     virtual void abortRescan() = 0;
 
     //! Back up wallet.
     virtual bool backupWallet(const std::string &filename) = 0;
 
     //! Get wallet name.
     virtual std::string getWalletName() = 0;
 
     //! Get chainparams.
     virtual const CChainParams &getChainParams() = 0;
 
     //! Get set of addresses corresponding to a given label.
     virtual std::set<CTxDestination>
     getLabelAddresses(const std::string &label) = 0;
 
     //! Get key from pool.
     virtual bool getKeyFromPool(bool internal, CPubKey &pub_key) = 0;
 
     //! Get public key.
     virtual bool getPubKey(const CKeyID &address, CPubKey &pub_key) = 0;
 
     //! Get private key.
     virtual bool getPrivKey(const CKeyID &address, CKey &key) = 0;
 
     //! Return whether wallet has private key.
     virtual bool isSpendable(const CTxDestination &dest) = 0;
 
     //! Return whether wallet has watch only keys.
     virtual bool haveWatchOnly() = 0;
 
     //! Add or update address.
     virtual bool setAddressBook(const CTxDestination &dest,
                                 const std::string &name,
                                 const std::string &purpose) = 0;
 
     // Remove address.
     virtual bool delAddressBook(const CTxDestination &dest) = 0;
 
     //! Look up address in wallet, return whether exists.
     virtual bool getAddress(const CTxDestination &dest, std::string *name,
                             isminetype *is_mine, std::string *purpose) = 0;
 
     //! Get wallet address list.
     virtual std::vector<WalletAddress> getAddresses() = 0;
 
     //! Add scripts to key store so old so software versions opening the wallet
     //! database can detect payments to newer address types.
     virtual void learnRelatedScripts(const CPubKey &key, OutputType type) = 0;
 
     //! Add dest data.
     virtual bool addDestData(const CTxDestination &dest, const std::string &key,
                              const std::string &value) = 0;
 
     //! Erase dest data.
     virtual bool eraseDestData(const CTxDestination &dest,
                                const std::string &key) = 0;
 
     //! Get dest values with prefix.
     virtual std::vector<std::string>
     getDestValues(const std::string &prefix) = 0;
 
     //! Lock coin.
     virtual void lockCoin(const COutPoint &output) = 0;
 
     //! Unlock coin.
     virtual void unlockCoin(const COutPoint &output) = 0;
 
     //! Return whether coin is locked.
     virtual bool isLockedCoin(const COutPoint &output) = 0;
 
     //! List locked coins.
     virtual void listLockedCoins(std::vector<COutPoint> &outputs) = 0;
 
     //! Create transaction.
     virtual std::unique_ptr<PendingWalletTx>
     createTransaction(const std::vector<CRecipient> &recipients,
                       const CCoinControl &coin_control, bool sign,
                       int &change_pos, Amount &fee,
                       std::string &fail_reason) = 0;
 
     //! Return whether transaction can be abandoned.
     virtual bool transactionCanBeAbandoned(const TxId &txid) = 0;
 
     //! Abandon transaction.
     virtual bool abandonTransaction(const TxId &txid) = 0;
 
     //! Get a transaction.
     virtual CTransactionRef getTx(const TxId &txid) = 0;
 
     //! Get transaction information.
     virtual WalletTx getWalletTx(const TxId &txid) = 0;
 
     //! Get list of all wallet transactions.
     virtual std::vector<WalletTx> getWalletTxs() = 0;
 
     //! Try to get updated status for a particular transaction, if possible
     //! without blocking.
     virtual bool tryGetTxStatus(const TxId &txid, WalletTxStatus &tx_status,
                                 int &num_blocks, int64_t &block_time) = 0;
 
     //! Get transaction details.
     virtual WalletTx getWalletTxDetails(const TxId &txid,
                                         WalletTxStatus &tx_status,
                                         WalletOrderForm &order_form,
                                         bool &in_mempool, int &num_blocks) = 0;
 
     //! Get balances.
     virtual WalletBalances getBalances() = 0;
 
     //! Get balances if possible without blocking.
     virtual bool tryGetBalances(WalletBalances &balances, int &num_blocks) = 0;
 
     //! Get balance.
     virtual Amount getBalance() = 0;
 
     //! Get available balance.
     virtual Amount getAvailableBalance(const CCoinControl &coin_control) = 0;
 
     //! Return whether transaction input belongs to wallet.
     virtual isminetype txinIsMine(const CTxIn &txin) = 0;
 
     //! Return whether transaction output belongs to wallet.
     virtual isminetype txoutIsMine(const CTxOut &txout) = 0;
 
     //! Return debit amount if transaction input belongs to wallet.
     virtual Amount getDebit(const CTxIn &txin, isminefilter filter) = 0;
 
     //! Return credit amount if transaction input belongs to wallet.
     virtual Amount getCredit(const CTxOut &txout, isminefilter filter) = 0;
 
     //! Return AvailableCoins + LockedCoins grouped by wallet address.
     //! (put change in one group with wallet address)
     using CoinsList = std::map<CTxDestination,
                                std::vector<std::tuple<COutPoint, WalletTxOut>>>;
     virtual CoinsList listCoins() = 0;
 
     //! Return wallet transaction output information.
     virtual std::vector<WalletTxOut>
     getCoins(const std::vector<COutPoint> &outputs) = 0;
 
     //! Get required fee.
     virtual Amount getRequiredFee(unsigned int tx_bytes) = 0;
 
     //! Get minimum fee.
     virtual Amount getMinimumFee(unsigned int tx_bytes,
                                  const CCoinControl &coin_control) = 0;
 
     // Return whether HD enabled.
     virtual bool hdEnabled() = 0;
 
     // Return whether the wallet is blank.
     virtual bool canGetAddresses() = 0;
 
     // Check if a certain wallet flag is set.
     virtual bool IsWalletFlagSet(uint64_t flag) = 0;
 
     // Get default address type.
     virtual OutputType getDefaultAddressType() = 0;
 
     // Get default change type.
     virtual OutputType getDefaultChangeType() = 0;
 
+    //! Get max tx fee.
+    virtual Amount getDefaultMaxTxFee() = 0;
+
     // Remove wallet.
     virtual void remove() = 0;
 
     //! Register handler for unload message.
     using UnloadFn = std::function<void()>;
     virtual std::unique_ptr<Handler> handleUnload(UnloadFn fn) = 0;
 
     //! Register handler for show progress messages.
     using ShowProgressFn =
         std::function<void(const std::string &title, int progress)>;
     virtual std::unique_ptr<Handler> handleShowProgress(ShowProgressFn fn) = 0;
 
     //! Register handler for status changed messages.
     using StatusChangedFn = std::function<void()>;
     virtual std::unique_ptr<Handler>
     handleStatusChanged(StatusChangedFn fn) = 0;
 
     //! Register handler for address book changed messages.
     using AddressBookChangedFn = std::function<void(
         const CTxDestination &address, const std::string &label, bool is_mine,
         const std::string &purpose, ChangeType status)>;
     virtual std::unique_ptr<Handler>
     handleAddressBookChanged(AddressBookChangedFn fn) = 0;
 
     //! Register handler for transaction changed messages.
     using TransactionChangedFn =
         std::function<void(const TxId &txid, ChangeType status)>;
     virtual std::unique_ptr<Handler>
     handleTransactionChanged(TransactionChangedFn fn) = 0;
 
     //! Register handler for watchonly changed messages.
     using WatchOnlyChangedFn = std::function<void(bool have_watch_only)>;
     virtual std::unique_ptr<Handler>
     handleWatchOnlyChanged(WatchOnlyChangedFn fn) = 0;
 
     //! Register handler for keypool changed messages.
     using CanGetAddressesChangedFn = std::function<void()>;
     virtual std::unique_ptr<Handler>
     handleCanGetAddressesChanged(CanGetAddressesChangedFn fn) = 0;
 };
 
 //! Tracking object returned by CreateTransaction and passed to
 //! CommitTransaction.
 class PendingWalletTx {
 public:
     virtual ~PendingWalletTx() {}
 
     //! Get transaction data.
     virtual const CTransaction &get() = 0;
 
     //! Send pending transaction and commit to wallet.
     virtual bool commit(WalletValueMap value_map, WalletOrderForm order_form,
                         std::string &reject_reason) = 0;
 };
 
 //! Information about one wallet address.
 struct WalletAddress {
     CTxDestination dest;
     isminetype is_mine;
     std::string name;
     std::string purpose;
 
     WalletAddress(CTxDestination destIn, isminetype isMineIn,
                   std::string nameIn, std::string purposeIn)
         : dest(std::move(destIn)), is_mine(isMineIn), name(std::move(nameIn)),
           purpose(std::move(purposeIn)) {}
 };
 
 //! Collection of wallet balances.
 struct WalletBalances {
     Amount balance = Amount::zero();
     Amount unconfirmed_balance = Amount::zero();
     Amount immature_balance = Amount::zero();
     bool have_watch_only = false;
     Amount watch_only_balance = Amount::zero();
     Amount unconfirmed_watch_only_balance = Amount::zero();
     Amount immature_watch_only_balance = Amount::zero();
 
     bool balanceChanged(const WalletBalances &prev) const {
         return balance != prev.balance ||
                unconfirmed_balance != prev.unconfirmed_balance ||
                immature_balance != prev.immature_balance ||
                watch_only_balance != prev.watch_only_balance ||
                unconfirmed_watch_only_balance !=
                    prev.unconfirmed_watch_only_balance ||
                immature_watch_only_balance != prev.immature_watch_only_balance;
     }
 };
 
 // Wallet transaction information.
 struct WalletTx {
     CTransactionRef tx;
     std::vector<isminetype> txin_is_mine;
     std::vector<isminetype> txout_is_mine;
     std::vector<CTxDestination> txout_address;
     std::vector<isminetype> txout_address_is_mine;
     Amount credit;
     Amount debit;
     Amount change;
     int64_t time;
     std::map<std::string, std::string> value_map;
     bool is_coinbase;
 };
 
 //! Updated transaction status.
 struct WalletTxStatus {
     int block_height;
     int blocks_to_maturity;
     int depth_in_main_chain;
     unsigned int time_received;
     uint32_t lock_time;
     bool is_final;
     bool is_trusted;
     bool is_abandoned;
     bool is_coinbase;
     bool is_in_main_chain;
 };
 
 //! Wallet transaction output.
 struct WalletTxOut {
     CTxOut txout;
     int64_t time;
     int depth_in_main_chain = -1;
     bool is_spent = false;
 };
 
 //! Return implementation of Wallet interface. This function is defined in
 //! dummywallet.cpp and throws if the wallet component is not compiled.
 std::unique_ptr<Wallet> MakeWallet(const std::shared_ptr<CWallet> &wallet);
 
 } // namespace interfaces
 
 #endif // BITCOIN_INTERFACES_WALLET_H
diff --git a/src/qt/sendcoinsdialog.cpp b/src/qt/sendcoinsdialog.cpp
index 5b091b1e1..5a3202161 100644
--- a/src/qt/sendcoinsdialog.cpp
+++ b/src/qt/sendcoinsdialog.cpp
@@ -1,963 +1,963 @@
 // Copyright (c) 2011-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #if defined(HAVE_CONFIG_H)
 #include <config/bitcoin-config.h>
 #endif
 
 #include <qt/forms/ui_sendcoinsdialog.h>
 #include <qt/sendcoinsdialog.h>
 
 #include <chainparams.h>
 #include <interfaces/node.h>
 #include <key_io.h>
 #include <qt/addresstablemodel.h>
 #include <qt/bitcoinunits.h>
 #include <qt/clientmodel.h>
 #include <qt/coincontroldialog.h>
 #include <qt/guiutil.h>
 #include <qt/optionsmodel.h>
 #include <qt/platformstyle.h>
 #include <qt/sendcoinsentry.h>
 #include <txmempool.h>
 #include <ui_interface.h>
 #include <wallet/coincontrol.h>
 #include <wallet/fees.h>
 #include <wallet/wallet.h>
 
 #include <QMessageBox>
 #include <QScrollBar>
 #include <QSettings>
 #include <QTextDocument>
 #include <QTimer>
 
 SendCoinsDialog::SendCoinsDialog(const PlatformStyle *_platformStyle,
                                  WalletModel *_model, QWidget *parent)
     : QDialog(parent), ui(new Ui::SendCoinsDialog), clientModel(nullptr),
       model(_model), fNewRecipientAllowed(true), fFeeMinimized(true),
       platformStyle(_platformStyle) {
     ui->setupUi(this);
 
     if (!_platformStyle->getImagesOnButtons()) {
         ui->addButton->setIcon(QIcon());
         ui->clearButton->setIcon(QIcon());
         ui->sendButton->setIcon(QIcon());
     } else {
         ui->addButton->setIcon(_platformStyle->SingleColorIcon(":/icons/add"));
         ui->clearButton->setIcon(
             _platformStyle->SingleColorIcon(":/icons/remove"));
         ui->sendButton->setIcon(
             _platformStyle->SingleColorIcon(":/icons/send"));
     }
 
     GUIUtil::setupAddressWidget(ui->lineEditCoinControlChange, this);
 
     addEntry();
 
     connect(ui->addButton, &QPushButton::clicked, this,
             &SendCoinsDialog::addEntry);
     connect(ui->clearButton, &QPushButton::clicked, this,
             &SendCoinsDialog::clear);
 
     // Coin Control
     connect(ui->pushButtonCoinControl, &QPushButton::clicked, this,
             &SendCoinsDialog::coinControlButtonClicked);
     connect(ui->checkBoxCoinControlChange, &QCheckBox::stateChanged, this,
             &SendCoinsDialog::coinControlChangeChecked);
     connect(ui->lineEditCoinControlChange, &QValidatedLineEdit::textEdited,
             this, &SendCoinsDialog::coinControlChangeEdited);
 
     // Coin Control: clipboard actions
     QAction *clipboardQuantityAction = new QAction(tr("Copy quantity"), this);
     QAction *clipboardAmountAction = new QAction(tr("Copy amount"), this);
     QAction *clipboardFeeAction = new QAction(tr("Copy fee"), this);
     QAction *clipboardAfterFeeAction = new QAction(tr("Copy after fee"), this);
     QAction *clipboardBytesAction = new QAction(tr("Copy bytes"), this);
     QAction *clipboardLowOutputAction = new QAction(tr("Copy dust"), this);
     QAction *clipboardChangeAction = new QAction(tr("Copy change"), this);
     connect(clipboardQuantityAction, &QAction::triggered, this,
             &SendCoinsDialog::coinControlClipboardQuantity);
     connect(clipboardAmountAction, &QAction::triggered, this,
             &SendCoinsDialog::coinControlClipboardAmount);
     connect(clipboardFeeAction, &QAction::triggered, this,
             &SendCoinsDialog::coinControlClipboardFee);
     connect(clipboardAfterFeeAction, &QAction::triggered, this,
             &SendCoinsDialog::coinControlClipboardAfterFee);
     connect(clipboardBytesAction, &QAction::triggered, this,
             &SendCoinsDialog::coinControlClipboardBytes);
     connect(clipboardLowOutputAction, &QAction::triggered, this,
             &SendCoinsDialog::coinControlClipboardLowOutput);
     connect(clipboardChangeAction, &QAction::triggered, this,
             &SendCoinsDialog::coinControlClipboardChange);
     ui->labelCoinControlQuantity->addAction(clipboardQuantityAction);
     ui->labelCoinControlAmount->addAction(clipboardAmountAction);
     ui->labelCoinControlFee->addAction(clipboardFeeAction);
     ui->labelCoinControlAfterFee->addAction(clipboardAfterFeeAction);
     ui->labelCoinControlBytes->addAction(clipboardBytesAction);
     ui->labelCoinControlLowOutput->addAction(clipboardLowOutputAction);
     ui->labelCoinControlChange->addAction(clipboardChangeAction);
 
     // init transaction fee section
     QSettings settings;
     if (!settings.contains("fFeeSectionMinimized")) {
         settings.setValue("fFeeSectionMinimized", true);
     }
     // compatibility
     if (!settings.contains("nFeeRadio") &&
         settings.contains("nTransactionFee") &&
         settings.value("nTransactionFee").toLongLong() > 0) {
         // custom
         settings.setValue("nFeeRadio", 1);
     }
     if (!settings.contains("nFeeRadio")) {
         // recommended
         settings.setValue("nFeeRadio", 0);
     }
     // compatibility
     if (!settings.contains("nCustomFeeRadio") &&
         settings.contains("nTransactionFee") &&
         settings.value("nTransactionFee").toLongLong() > 0) {
         // total at least
         settings.setValue("nCustomFeeRadio", 1);
     }
     if (!settings.contains("nCustomFeeRadio")) {
         // per kilobyte
         settings.setValue("nCustomFeeRadio", 0);
     }
     if (!settings.contains("nTransactionFee")) {
         settings.setValue("nTransactionFee",
                           qint64(DEFAULT_PAY_TX_FEE / SATOSHI));
     }
     if (!settings.contains("fPayOnlyMinFee")) {
         settings.setValue("fPayOnlyMinFee", false);
     }
     ui->groupFee->setId(ui->radioSmartFee, 0);
     ui->groupFee->setId(ui->radioCustomFee, 1);
     ui->groupFee
         ->button(
             std::max<int>(0, std::min(1, settings.value("nFeeRadio").toInt())))
         ->setChecked(true);
     ui->groupCustomFee->setId(ui->radioCustomPerKilobyte, 0);
     ui->groupCustomFee->button(0)->setChecked(true);
     ui->customFee->setValue(
         int64_t(settings.value("nTransactionFee").toLongLong()) * SATOSHI);
     ui->checkBoxMinimumFee->setChecked(
         settings.value("fPayOnlyMinFee").toBool());
     minimizeFeeSection(settings.value("fFeeSectionMinimized").toBool());
 
     // Set the model properly.
     setModel(model);
 }
 
 void SendCoinsDialog::setClientModel(ClientModel *_clientModel) {
     this->clientModel = _clientModel;
 
     if (_clientModel) {
         connect(_clientModel, &ClientModel::numBlocksChanged, this,
                 &SendCoinsDialog::updateSmartFeeLabel);
     }
 }
 
 void SendCoinsDialog::setModel(WalletModel *_model) {
     this->model = _model;
 
     if (_model && _model->getOptionsModel()) {
         for (int i = 0; i < ui->entries->count(); ++i) {
             SendCoinsEntry *entry = qobject_cast<SendCoinsEntry *>(
                 ui->entries->itemAt(i)->widget());
             if (entry) {
                 entry->setModel(_model);
             }
         }
 
         interfaces::WalletBalances balances = _model->wallet().getBalances();
         setBalance(balances);
         connect(_model, &WalletModel::balanceChanged, this,
                 &SendCoinsDialog::setBalance);
         connect(_model->getOptionsModel(), &OptionsModel::displayUnitChanged,
                 this, &SendCoinsDialog::updateDisplayUnit);
         updateDisplayUnit();
 
         // Coin Control
         connect(_model->getOptionsModel(), &OptionsModel::displayUnitChanged,
                 this, &SendCoinsDialog::coinControlUpdateLabels);
         connect(_model->getOptionsModel(),
                 &OptionsModel::coinControlFeaturesChanged, this,
                 &SendCoinsDialog::coinControlFeatureChanged);
         ui->frameCoinControl->setVisible(
             _model->getOptionsModel()->getCoinControlFeatures());
         coinControlUpdateLabels();
 
         // fee section
         connect(ui->groupFee,
                 static_cast<void (QButtonGroup::*)(int)>(
                     &QButtonGroup::buttonClicked),
                 this, &SendCoinsDialog::updateFeeSectionControls);
         connect(ui->groupFee,
                 static_cast<void (QButtonGroup::*)(int)>(
                     &QButtonGroup::buttonClicked),
                 this, &SendCoinsDialog::coinControlUpdateLabels);
         connect(ui->groupCustomFee,
                 static_cast<void (QButtonGroup::*)(int)>(
                     &QButtonGroup::buttonClicked),
                 this, &SendCoinsDialog::coinControlUpdateLabels);
         connect(ui->customFee, &BitcoinAmountField::valueChanged, this,
                 &SendCoinsDialog::coinControlUpdateLabels);
         connect(ui->checkBoxMinimumFee, &QCheckBox::stateChanged, this,
                 &SendCoinsDialog::setMinimumFee);
         connect(ui->checkBoxMinimumFee, &QCheckBox::stateChanged, this,
                 &SendCoinsDialog::updateFeeSectionControls);
         connect(ui->checkBoxMinimumFee, &QCheckBox::stateChanged, this,
                 &SendCoinsDialog::coinControlUpdateLabels);
 
         ui->customFee->setSingleStep(model->wallet().getRequiredFee(1000));
         updateFeeSectionControls();
         updateMinFeeLabel();
         updateSmartFeeLabel();
     }
 }
 
 SendCoinsDialog::~SendCoinsDialog() {
     QSettings settings;
     settings.setValue("fFeeSectionMinimized", fFeeMinimized);
     settings.setValue("nFeeRadio", ui->groupFee->checkedId());
     settings.setValue("nCustomFeeRadio", ui->groupCustomFee->checkedId());
     settings.setValue("nTransactionFee",
                       qint64(ui->customFee->value() / SATOSHI));
     settings.setValue("fPayOnlyMinFee", ui->checkBoxMinimumFee->isChecked());
 
     delete ui;
 }
 
 void SendCoinsDialog::on_sendButton_clicked() {
     if (!model || !model->getOptionsModel()) {
         return;
     }
 
     QList<SendCoinsRecipient> recipients;
     bool valid = true;
 
     for (int i = 0; i < ui->entries->count(); ++i) {
         SendCoinsEntry *entry =
             qobject_cast<SendCoinsEntry *>(ui->entries->itemAt(i)->widget());
         if (entry) {
             if (entry->validate(model->node())) {
                 recipients.append(entry->getValue());
             } else {
                 valid = false;
             }
         }
     }
 
     if (!valid || recipients.isEmpty()) {
         return;
     }
 
     fNewRecipientAllowed = false;
     WalletModel::UnlockContext ctx(model->requestUnlock());
     if (!ctx.isValid()) {
         // Unlock wallet was cancelled
         fNewRecipientAllowed = true;
         return;
     }
 
     // prepare transaction for getting txFee earlier
     WalletModelTransaction currentTransaction(recipients);
     WalletModel::SendCoinsReturn prepareStatus;
 
     // Always use a CCoinControl instance, use the CoinControlDialog instance if
     // CoinControl has been enabled
     CCoinControl ctrl;
     if (model->getOptionsModel()->getCoinControlFeatures()) {
         ctrl = *CoinControlDialog::coinControl();
     }
 
     updateCoinControlState(ctrl);
 
     prepareStatus = model->prepareTransaction(currentTransaction, ctrl);
 
     // process prepareStatus and on error generate message shown to user
     processSendCoinsReturn(
         prepareStatus,
         BitcoinUnits::formatWithUnit(model->getOptionsModel()->getDisplayUnit(),
                                      currentTransaction.getTransactionFee()));
 
     if (prepareStatus.status != WalletModel::OK) {
         fNewRecipientAllowed = true;
         return;
     }
 
     Amount txFee = currentTransaction.getTransactionFee();
 
     // Format confirmation message
     QStringList formatted;
     for (const SendCoinsRecipient &rcp : currentTransaction.getRecipients()) {
         // generate bold amount string with wallet name in case of multiwallet
         QString amount =
             "<b>" + BitcoinUnits::formatHtmlWithUnit(
                         model->getOptionsModel()->getDisplayUnit(), rcp.amount);
         if (model->isMultiwallet()) {
             amount.append(
                 " <u>" +
                 tr("from wallet %1")
                     .arg(GUIUtil::HtmlEscape(model->getWalletName())) +
                 "</u> ");
         }
         amount.append("</b>");
         // generate monospace address string
         QString address =
             "<span style='font-family: monospace;'>" + rcp.address;
         address.append("</span>");
 
         QString recipientElement;
         recipientElement = "<br />";
 
 #ifdef ENABLE_BIP70
         // normal payment
         if (!rcp.paymentRequest.IsInitialized())
 #endif
         {
             if (rcp.label.length() > 0) {
                 // label with address
                 recipientElement.append(
                     tr("%1 to %2").arg(amount, GUIUtil::HtmlEscape(rcp.label)));
                 recipientElement.append(QString(" (%1)").arg(address));
             } else {
                 // just address
                 recipientElement.append(tr("%1 to %2").arg(amount, address));
             }
         }
 #ifdef ENABLE_BIP70
         // authenticated payment request
         else if (!rcp.authenticatedMerchant.isEmpty()) {
             recipientElement.append(
                 tr("%1 to %2")
                     .arg(amount,
                          GUIUtil::HtmlEscape(rcp.authenticatedMerchant)));
         } else {
             // unauthenticated payment request
             recipientElement.append(tr("%1 to %2").arg(amount, address));
         }
 #endif
 
         formatted.append(recipientElement);
     }
 
     QString questionString = tr("Are you sure you want to send?");
     questionString.append("<br /><span style='font-size:10pt;'>");
     questionString.append(tr("Please, review your transaction."));
     questionString.append("</span><br />%1");
 
     if (txFee > Amount::zero()) {
         // append fee string if a fee is required
         questionString.append("<hr /><b>");
         questionString.append(tr("Transaction fee"));
         questionString.append("</b>");
 
         // append transaction size
         questionString.append(
             " (" +
             QString::number((double)currentTransaction.getTransactionSize() /
                             1000) +
             " kB): ");
 
         // append transaction fee value
         questionString.append(
             "<span style='color:#aa0000; font-weight:bold;'>");
         questionString.append(BitcoinUnits::formatHtmlWithUnit(
             model->getOptionsModel()->getDisplayUnit(), txFee));
         questionString.append("</span><br />");
     }
 
     // add total amount in all subdivision units
     questionString.append("<hr />");
     Amount totalAmount = currentTransaction.getTotalTransactionAmount() + txFee;
     QStringList alternativeUnits;
     for (const BitcoinUnits::Unit u : BitcoinUnits::availableUnits()) {
         if (u != model->getOptionsModel()->getDisplayUnit()) {
             alternativeUnits.append(
                 BitcoinUnits::formatHtmlWithUnit(u, totalAmount));
         }
     }
     questionString.append(
         QString("<b>%1</b>: <b>%2</b>")
             .arg(tr("Total Amount"))
             .arg(BitcoinUnits::formatHtmlWithUnit(
                 model->getOptionsModel()->getDisplayUnit(), totalAmount)));
     questionString.append(
         QString("<br /><span style='font-size:10pt; "
                 "font-weight:normal;'>(=%1)</span>")
             .arg(alternativeUnits.join(" " + tr("or") + " ")));
 
     SendConfirmationDialog confirmationDialog(
         tr("Confirm send coins"), questionString.arg(formatted.join("<br />")),
         SEND_CONFIRM_DELAY, this);
     confirmationDialog.exec();
     QMessageBox::StandardButton retval =
         static_cast<QMessageBox::StandardButton>(confirmationDialog.result());
 
     if (retval != QMessageBox::Yes) {
         fNewRecipientAllowed = true;
         return;
     }
 
     // now send the prepared transaction
     WalletModel::SendCoinsReturn sendStatus =
         model->sendCoins(currentTransaction);
     // process sendStatus and on error generate message shown to user
     processSendCoinsReturn(sendStatus);
 
     if (sendStatus.status == WalletModel::OK) {
         accept();
         CoinControlDialog::coinControl()->UnSelectAll();
         coinControlUpdateLabels();
         Q_EMIT coinsSent(currentTransaction.getWtx()->get().GetId());
     }
     fNewRecipientAllowed = true;
 }
 
 void SendCoinsDialog::clear() {
     // Clear coin control settings
     CoinControlDialog::coinControl()->UnSelectAll();
     ui->checkBoxCoinControlChange->setChecked(false);
     ui->lineEditCoinControlChange->clear();
     coinControlUpdateLabels();
 
     // Remove entries until only one left
     while (ui->entries->count()) {
         ui->entries->takeAt(0)->widget()->deleteLater();
     }
     addEntry();
 
     updateTabsAndLabels();
 }
 
 void SendCoinsDialog::reject() {
     clear();
 }
 
 void SendCoinsDialog::accept() {
     clear();
 }
 
 SendCoinsEntry *SendCoinsDialog::addEntry() {
     SendCoinsEntry *entry = new SendCoinsEntry(platformStyle, model, this);
     ui->entries->addWidget(entry);
     connect(entry, &SendCoinsEntry::removeEntry, this,
             &SendCoinsDialog::removeEntry);
     connect(entry, &SendCoinsEntry::useAvailableBalance, this,
             &SendCoinsDialog::useAvailableBalance);
     connect(entry, &SendCoinsEntry::payAmountChanged, this,
             &SendCoinsDialog::coinControlUpdateLabels);
     connect(entry, &SendCoinsEntry::subtractFeeFromAmountChanged, this,
             &SendCoinsDialog::coinControlUpdateLabels);
 
     // Focus the field, so that entry can start immediately
     entry->clear();
     entry->setFocus();
     ui->scrollAreaWidgetContents->resize(
         ui->scrollAreaWidgetContents->sizeHint());
     qApp->processEvents();
     QScrollBar *bar = ui->scrollArea->verticalScrollBar();
     if (bar) {
         bar->setSliderPosition(bar->maximum());
     }
 
     updateTabsAndLabels();
     return entry;
 }
 
 void SendCoinsDialog::updateTabsAndLabels() {
     setupTabChain(nullptr);
     coinControlUpdateLabels();
 }
 
 void SendCoinsDialog::removeEntry(SendCoinsEntry *entry) {
     entry->hide();
 
     // If the last entry is about to be removed add an empty one
     if (ui->entries->count() == 1) {
         addEntry();
     }
 
     entry->deleteLater();
 
     updateTabsAndLabels();
 }
 
 QWidget *SendCoinsDialog::setupTabChain(QWidget *prev) {
     for (int i = 0; i < ui->entries->count(); ++i) {
         SendCoinsEntry *entry =
             qobject_cast<SendCoinsEntry *>(ui->entries->itemAt(i)->widget());
         if (entry) {
             prev = entry->setupTabChain(prev);
         }
     }
     QWidget::setTabOrder(prev, ui->sendButton);
     QWidget::setTabOrder(ui->sendButton, ui->clearButton);
     QWidget::setTabOrder(ui->clearButton, ui->addButton);
     return ui->addButton;
 }
 
 void SendCoinsDialog::setAddress(const QString &address) {
     SendCoinsEntry *entry = nullptr;
     // Replace the first entry if it is still unused
     if (ui->entries->count() == 1) {
         SendCoinsEntry *first =
             qobject_cast<SendCoinsEntry *>(ui->entries->itemAt(0)->widget());
         if (first->isClear()) {
             entry = first;
         }
     }
     if (!entry) {
         entry = addEntry();
     }
 
     entry->setAddress(address);
 }
 
 void SendCoinsDialog::pasteEntry(const SendCoinsRecipient &rv) {
     if (!fNewRecipientAllowed) {
         return;
     }
 
     SendCoinsEntry *entry = nullptr;
     // Replace the first entry if it is still unused
     if (ui->entries->count() == 1) {
         SendCoinsEntry *first =
             qobject_cast<SendCoinsEntry *>(ui->entries->itemAt(0)->widget());
         if (first->isClear()) {
             entry = first;
         }
     }
     if (!entry) {
         entry = addEntry();
     }
 
     entry->setValue(rv);
     updateTabsAndLabels();
 }
 
 bool SendCoinsDialog::handlePaymentRequest(const SendCoinsRecipient &rv) {
     // Just paste the entry, all pre-checks are done in paymentserver.cpp.
     pasteEntry(rv);
     return true;
 }
 
 void SendCoinsDialog::setBalance(const interfaces::WalletBalances &balances) {
     if (model && model->getOptionsModel()) {
         ui->labelBalance->setText(BitcoinUnits::formatWithUnit(
             model->getOptionsModel()->getDisplayUnit(), balances.balance));
     }
 }
 
 void SendCoinsDialog::updateDisplayUnit() {
     setBalance(model->wallet().getBalances());
     ui->customFee->setDisplayUnit(model->getOptionsModel()->getDisplayUnit());
     updateMinFeeLabel();
     updateSmartFeeLabel();
 }
 
 void SendCoinsDialog::processSendCoinsReturn(
     const WalletModel::SendCoinsReturn &sendCoinsReturn,
     const QString &msgArg) {
     QPair<QString, CClientUIInterface::MessageBoxFlags> msgParams;
     // Default to a warning message, override if error message is needed
     msgParams.second = CClientUIInterface::MSG_WARNING;
 
     // This comment is specific to SendCoinsDialog usage of
     // WalletModel::SendCoinsReturn.
     // WalletModel::TransactionCommitFailed is used only in
     // WalletModel::sendCoins() all others are used only in
     // WalletModel::prepareTransaction()
     switch (sendCoinsReturn.status) {
         case WalletModel::InvalidAddress:
             msgParams.first =
                 tr("The recipient address is not valid. Please recheck.");
             break;
         case WalletModel::InvalidAmount:
             msgParams.first = tr("The amount to pay must be larger than 0.");
             break;
         case WalletModel::AmountExceedsBalance:
             msgParams.first = tr("The amount exceeds your balance.");
             break;
         case WalletModel::AmountWithFeeExceedsBalance:
             msgParams.first = tr("The total exceeds your balance when the %1 "
                                  "transaction fee is included.")
                                   .arg(msgArg);
             break;
         case WalletModel::DuplicateAddress:
             msgParams.first = tr("Duplicate address found: addresses should "
                                  "only be used once each.");
             break;
         case WalletModel::TransactionCreationFailed:
             msgParams.first = tr("Transaction creation failed!");
             msgParams.second = CClientUIInterface::MSG_ERROR;
             break;
         case WalletModel::TransactionCommitFailed:
             msgParams.first =
                 tr("The transaction was rejected with the following reason: %1")
                     .arg(sendCoinsReturn.reasonCommitFailed);
             msgParams.second = CClientUIInterface::MSG_ERROR;
             break;
         case WalletModel::AbsurdFee:
             msgParams.first =
                 tr("A fee higher than %1 is considered an absurdly high fee.")
                     .arg(BitcoinUnits::formatWithUnit(
                         model->getOptionsModel()->getDisplayUnit(),
-                        model->node().getMaxTxFee()));
+                        model->wallet().getDefaultMaxTxFee()));
             break;
         case WalletModel::PaymentRequestExpired:
             msgParams.first = tr("Payment request expired.");
             msgParams.second = CClientUIInterface::MSG_ERROR;
             break;
         // included to prevent a compiler warning.
         case WalletModel::OK:
         default:
             return;
     }
 
     Q_EMIT message(tr("Send Coins"), msgParams.first, msgParams.second);
 }
 
 void SendCoinsDialog::minimizeFeeSection(bool fMinimize) {
     ui->labelFeeMinimized->setVisible(fMinimize);
     ui->buttonChooseFee->setVisible(fMinimize);
     ui->buttonMinimizeFee->setVisible(!fMinimize);
     ui->frameFeeSelection->setVisible(!fMinimize);
     ui->horizontalLayoutSmartFee->setContentsMargins(0, (fMinimize ? 0 : 6), 0,
                                                      0);
     fFeeMinimized = fMinimize;
 }
 
 void SendCoinsDialog::on_buttonChooseFee_clicked() {
     minimizeFeeSection(false);
 }
 
 void SendCoinsDialog::on_buttonMinimizeFee_clicked() {
     updateFeeMinimizedLabel();
     minimizeFeeSection(true);
 }
 
 void SendCoinsDialog::useAvailableBalance(SendCoinsEntry *entry) {
     // Get CCoinControl instance if CoinControl is enabled or create a new one.
     CCoinControl coin_control;
     if (model->getOptionsModel()->getCoinControlFeatures()) {
         coin_control = *CoinControlDialog::coinControl();
     }
 
     // Calculate available amount to send.
     Amount amount = model->wallet().getAvailableBalance(coin_control);
     for (int i = 0; i < ui->entries->count(); ++i) {
         SendCoinsEntry *e =
             qobject_cast<SendCoinsEntry *>(ui->entries->itemAt(i)->widget());
         if (e && !e->isHidden() && e != entry) {
             amount -= e->getValue().amount;
         }
     }
 
     if (amount > Amount::zero()) {
         entry->checkSubtractFeeFromAmount();
         entry->setAmount(amount);
     } else {
         entry->setAmount(Amount::zero());
     }
 }
 
 void SendCoinsDialog::setMinimumFee() {
     ui->radioCustomPerKilobyte->setChecked(true);
     ui->customFee->setValue(model->wallet().getRequiredFee(1000));
 }
 
 void SendCoinsDialog::updateFeeSectionControls() {
     ui->labelSmartFee->setEnabled(ui->radioSmartFee->isChecked());
     ui->labelSmartFee2->setEnabled(ui->radioSmartFee->isChecked());
     ui->labelFeeEstimation->setEnabled(ui->radioSmartFee->isChecked());
     ui->checkBoxMinimumFee->setEnabled(ui->radioCustomFee->isChecked());
     ui->labelMinFeeWarning->setEnabled(ui->radioCustomFee->isChecked());
     ui->radioCustomPerKilobyte->setEnabled(
         ui->radioCustomFee->isChecked() &&
         !ui->checkBoxMinimumFee->isChecked());
     ui->customFee->setEnabled(ui->radioCustomFee->isChecked() &&
                               !ui->checkBoxMinimumFee->isChecked());
 }
 
 void SendCoinsDialog::updateFeeMinimizedLabel() {
     if (!model || !model->getOptionsModel()) {
         return;
     }
 
     if (ui->radioSmartFee->isChecked()) {
         ui->labelFeeMinimized->setText(ui->labelSmartFee->text());
     } else {
         ui->labelFeeMinimized->setText(
             BitcoinUnits::formatWithUnit(
                 model->getOptionsModel()->getDisplayUnit(),
                 ui->customFee->value()) +
             ((ui->radioCustomPerKilobyte->isChecked()) ? "/kB" : ""));
     }
 }
 
 void SendCoinsDialog::updateMinFeeLabel() {
     if (model && model->getOptionsModel()) {
         ui->checkBoxMinimumFee->setText(
             tr("Pay only the required fee of %1")
                 .arg(BitcoinUnits::formatWithUnit(
                          model->getOptionsModel()->getDisplayUnit(),
                          model->wallet().getRequiredFee(1000)) +
                      "/kB"));
     }
 }
 
 void SendCoinsDialog::updateCoinControlState(CCoinControl &ctrl) {
     if (ui->radioCustomFee->isChecked()) {
         ctrl.m_feerate = CFeeRate(ui->customFee->value());
     } else {
         ctrl.m_feerate.reset();
     }
 }
 
 void SendCoinsDialog::updateSmartFeeLabel() {
     if (!model || !model->getOptionsModel()) {
         return;
     }
 
     CCoinControl coin_control;
     updateCoinControlState(coin_control);
     // Explicitly use only fee estimation rate for smart fee labels
     coin_control.m_feerate.reset();
     CFeeRate feeRate(model->wallet().getMinimumFee(1000, coin_control));
 
     ui->labelSmartFee->setText(
         BitcoinUnits::formatWithUnit(model->getOptionsModel()->getDisplayUnit(),
                                      feeRate.GetFeePerK()) +
         "/kB");
     // not enough data => minfee
     if (feeRate <= CFeeRate(Amount::zero())) {
         // (Smart fee not initialized yet. This usually takes a few blocks...)
         ui->labelSmartFee2->show();
         ui->labelFeeEstimation->setText("");
     } else {
         ui->labelSmartFee2->hide();
         ui->labelFeeEstimation->setText(
             tr("Estimated to begin confirmation by next block."));
     }
 
     updateFeeMinimizedLabel();
 }
 
 // Coin Control: copy label "Quantity" to clipboard
 void SendCoinsDialog::coinControlClipboardQuantity() {
     GUIUtil::setClipboard(ui->labelCoinControlQuantity->text());
 }
 
 // Coin Control: copy label "Amount" to clipboard
 void SendCoinsDialog::coinControlClipboardAmount() {
     GUIUtil::setClipboard(ui->labelCoinControlAmount->text().left(
         ui->labelCoinControlAmount->text().indexOf(" ")));
 }
 
 // Coin Control: copy label "Fee" to clipboard
 void SendCoinsDialog::coinControlClipboardFee() {
     GUIUtil::setClipboard(
         ui->labelCoinControlFee->text()
             .left(ui->labelCoinControlFee->text().indexOf(" "))
             .replace(ASYMP_UTF8, ""));
 }
 
 // Coin Control: copy label "After fee" to clipboard
 void SendCoinsDialog::coinControlClipboardAfterFee() {
     GUIUtil::setClipboard(
         ui->labelCoinControlAfterFee->text()
             .left(ui->labelCoinControlAfterFee->text().indexOf(" "))
             .replace(ASYMP_UTF8, ""));
 }
 
 // Coin Control: copy label "Bytes" to clipboard
 void SendCoinsDialog::coinControlClipboardBytes() {
     GUIUtil::setClipboard(
         ui->labelCoinControlBytes->text().replace(ASYMP_UTF8, ""));
 }
 
 // Coin Control: copy label "Dust" to clipboard
 void SendCoinsDialog::coinControlClipboardLowOutput() {
     GUIUtil::setClipboard(ui->labelCoinControlLowOutput->text());
 }
 
 // Coin Control: copy label "Change" to clipboard
 void SendCoinsDialog::coinControlClipboardChange() {
     GUIUtil::setClipboard(
         ui->labelCoinControlChange->text()
             .left(ui->labelCoinControlChange->text().indexOf(" "))
             .replace(ASYMP_UTF8, ""));
 }
 
 // Coin Control: settings menu - coin control enabled/disabled by user
 void SendCoinsDialog::coinControlFeatureChanged(bool checked) {
     ui->frameCoinControl->setVisible(checked);
 
     // coin control features disabled
     if (!checked && model) {
         CoinControlDialog::coinControl()->SetNull();
     }
 
     coinControlUpdateLabels();
 }
 
 // Coin Control: button inputs -> show actual coin control dialog
 void SendCoinsDialog::coinControlButtonClicked() {
     CoinControlDialog dlg(platformStyle);
     dlg.setModel(model);
     dlg.exec();
     coinControlUpdateLabels();
 }
 
 // Coin Control: checkbox custom change address
 void SendCoinsDialog::coinControlChangeChecked(int state) {
     if (state == Qt::Unchecked) {
         CoinControlDialog::coinControl()->destChange = CNoDestination();
         ui->labelCoinControlChangeLabel->clear();
     } else {
         // use this to re-validate an already entered address
         coinControlChangeEdited(ui->lineEditCoinControlChange->text());
     }
 
     ui->lineEditCoinControlChange->setEnabled((state == Qt::Checked));
 }
 
 // Coin Control: custom change address changed
 void SendCoinsDialog::coinControlChangeEdited(const QString &text) {
     if (model && model->getAddressTableModel()) {
         // Default to no change address until verified
         CoinControlDialog::coinControl()->destChange = CNoDestination();
         ui->labelCoinControlChangeLabel->setStyleSheet("QLabel{color:red;}");
 
         const CTxDestination dest =
             DecodeDestination(text.toStdString(), model->getChainParams());
 
         if (text.isEmpty()) {
             // Nothing entered
             ui->labelCoinControlChangeLabel->setText("");
         } else if (!IsValidDestination(dest)) {
             // Invalid address
             ui->labelCoinControlChangeLabel->setText(
                 tr("Warning: Invalid Bitcoin address"));
         } else {
             // Valid address
             if (!model->wallet().isSpendable(dest)) {
                 ui->labelCoinControlChangeLabel->setText(
                     tr("Warning: Unknown change address"));
 
                 // confirmation dialog
                 QMessageBox::StandardButton btnRetVal = QMessageBox::question(
                     this, tr("Confirm custom change address"),
                     tr("The address you selected for change is not part of "
                        "this wallet. Any or all funds in your wallet may be "
                        "sent to this address. Are you sure?"),
                     QMessageBox::Yes | QMessageBox::Cancel,
                     QMessageBox::Cancel);
 
                 if (btnRetVal == QMessageBox::Yes) {
                     CoinControlDialog::coinControl()->destChange = dest;
                 } else {
                     ui->lineEditCoinControlChange->setText("");
                     ui->labelCoinControlChangeLabel->setStyleSheet(
                         "QLabel{color:black;}");
                     ui->labelCoinControlChangeLabel->setText("");
                 }
             } else {
                 // Known change address
                 ui->labelCoinControlChangeLabel->setStyleSheet(
                     "QLabel{color:black;}");
 
                 // Query label
                 QString associatedLabel =
                     model->getAddressTableModel()->labelForAddress(text);
                 if (!associatedLabel.isEmpty()) {
                     ui->labelCoinControlChangeLabel->setText(associatedLabel);
                 } else {
                     ui->labelCoinControlChangeLabel->setText(tr("(no label)"));
                 }
 
                 CoinControlDialog::coinControl()->destChange = dest;
             }
         }
     }
 }
 
 // Coin Control: update labels
 void SendCoinsDialog::coinControlUpdateLabels() {
     if (!model || !model->getOptionsModel()) {
         return;
     }
 
     updateCoinControlState(*CoinControlDialog::coinControl());
 
     // set pay amounts
     CoinControlDialog::payAmounts.clear();
     CoinControlDialog::fSubtractFeeFromAmount = false;
     for (int i = 0; i < ui->entries->count(); ++i) {
         SendCoinsEntry *entry =
             qobject_cast<SendCoinsEntry *>(ui->entries->itemAt(i)->widget());
         if (entry && !entry->isHidden()) {
             SendCoinsRecipient rcp = entry->getValue();
             CoinControlDialog::payAmounts.append(rcp.amount);
             if (rcp.fSubtractFeeFromAmount) {
                 CoinControlDialog::fSubtractFeeFromAmount = true;
             }
         }
     }
 
     if (CoinControlDialog::coinControl()->HasSelected()) {
         // actual coin control calculation
         CoinControlDialog::updateLabels(model, this);
 
         // show coin control stats
         ui->labelCoinControlAutomaticallySelected->hide();
         ui->widgetCoinControl->show();
     } else {
         // hide coin control stats
         ui->labelCoinControlAutomaticallySelected->show();
         ui->widgetCoinControl->hide();
         ui->labelCoinControlInsuffFunds->hide();
     }
 }
 
 SendConfirmationDialog::SendConfirmationDialog(const QString &title,
                                                const QString &text,
                                                int _secDelay, QWidget *parent)
     : QMessageBox(QMessageBox::Question, title, text,
                   QMessageBox::Yes | QMessageBox::Cancel, parent),
       secDelay(_secDelay) {
     setDefaultButton(QMessageBox::Cancel);
     yesButton = button(QMessageBox::Yes);
     updateYesButton();
     connect(&countDownTimer, &QTimer::timeout, this,
             &SendConfirmationDialog::countDown);
 }
 
 int SendConfirmationDialog::exec() {
     updateYesButton();
     countDownTimer.start(1000);
     return QMessageBox::exec();
 }
 
 void SendConfirmationDialog::countDown() {
     secDelay--;
     updateYesButton();
 
     if (secDelay <= 0) {
         countDownTimer.stop();
     }
 }
 
 void SendConfirmationDialog::updateYesButton() {
     if (secDelay > 0) {
         yesButton->setEnabled(false);
         yesButton->setText(tr("Yes") + " (" + QString::number(secDelay) + ")");
     } else {
         yesButton->setEnabled(true);
         yesButton->setText(tr("Yes"));
     }
 }
diff --git a/src/qt/walletmodel.cpp b/src/qt/walletmodel.cpp
index 2c155c956..c5b1fc98f 100644
--- a/src/qt/walletmodel.cpp
+++ b/src/qt/walletmodel.cpp
@@ -1,535 +1,535 @@
 // Copyright (c) 2011-2019 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #if defined(HAVE_CONFIG_H)
 #include <config/bitcoin-config.h>
 #endif
 
 #include <qt/walletmodel.h>
 
 #include <cashaddrenc.h>
 #include <interfaces/handler.h>
 #include <interfaces/node.h>
 #include <key_io.h>
 #include <qt/addresstablemodel.h>
 #include <qt/guiconstants.h>
 #include <qt/paymentserver.h>
 #include <qt/recentrequeststablemodel.h>
 #include <qt/transactiontablemodel.h>
 #include <ui_interface.h>
 #include <util/system.h> // for GetBoolArg
 #include <wallet/coincontrol.h>
 #include <wallet/wallet.h>
 
 #include <QDebug>
 #include <QSet>
 #include <QTimer>
 
 #include <cstdint>
 
 WalletModel::WalletModel(std::unique_ptr<interfaces::Wallet> wallet,
                          interfaces::Node &node,
                          const PlatformStyle *platformStyle,
                          OptionsModel *_optionsModel, QObject *parent)
     : QObject(parent), m_wallet(std::move(wallet)), m_node(node),
       optionsModel(_optionsModel), addressTableModel(nullptr),
       transactionTableModel(nullptr), recentRequestsTableModel(nullptr),
       cachedEncryptionStatus(Unencrypted), cachedNumBlocks(0) {
     fHaveWatchOnly = m_wallet->haveWatchOnly();
     addressTableModel = new AddressTableModel(this);
     transactionTableModel = new TransactionTableModel(platformStyle, this);
     recentRequestsTableModel = new RecentRequestsTableModel(this);
 
     // This timer will be fired repeatedly to update the balance
     pollTimer = new QTimer(this);
     connect(pollTimer, &QTimer::timeout, this,
             &WalletModel::pollBalanceChanged);
     pollTimer->start(MODEL_UPDATE_DELAY);
 
     subscribeToCoreSignals();
 }
 
 WalletModel::~WalletModel() {
     unsubscribeFromCoreSignals();
 }
 
 void WalletModel::updateStatus() {
     EncryptionStatus newEncryptionStatus = getEncryptionStatus();
 
     if (cachedEncryptionStatus != newEncryptionStatus) {
         Q_EMIT encryptionStatusChanged();
     }
 }
 
 void WalletModel::pollBalanceChanged() {
     // Try to get balances and return early if locks can't be acquired. This
     // avoids the GUI from getting stuck on periodical polls if the core is
     // holding the locks for a longer time - for example, during a wallet
     // rescan.
     interfaces::WalletBalances new_balances;
     int numBlocks = -1;
     if (!m_wallet->tryGetBalances(new_balances, numBlocks)) {
         return;
     }
 
     if (fForceCheckBalanceChanged || m_node.getNumBlocks() != cachedNumBlocks) {
         fForceCheckBalanceChanged = false;
 
         // Balance and number of transactions might have changed
         cachedNumBlocks = m_node.getNumBlocks();
 
         checkBalanceChanged(new_balances);
         if (transactionTableModel) {
             transactionTableModel->updateConfirmations();
         }
     }
 }
 
 void WalletModel::checkBalanceChanged(
     const interfaces::WalletBalances &new_balances) {
     if (new_balances.balanceChanged(m_cached_balances)) {
         m_cached_balances = new_balances;
         Q_EMIT balanceChanged(new_balances);
     }
 }
 
 void WalletModel::updateTransaction() {
     // Balance and number of transactions might have changed
     fForceCheckBalanceChanged = true;
 }
 
 void WalletModel::updateAddressBook(const QString &address,
                                     const QString &label, bool isMine,
                                     const QString &purpose, int status) {
     if (addressTableModel) {
         addressTableModel->updateEntry(address, label, isMine, purpose, status);
     }
 }
 
 void WalletModel::updateWatchOnlyFlag(bool fHaveWatchonly) {
     fHaveWatchOnly = fHaveWatchonly;
     Q_EMIT notifyWatchonlyChanged(fHaveWatchonly);
 }
 
 bool WalletModel::validateAddress(const QString &address) {
     return IsValidDestinationString(address.toStdString(), getChainParams());
 }
 
 WalletModel::SendCoinsReturn
 WalletModel::prepareTransaction(WalletModelTransaction &transaction,
                                 const CCoinControl &coinControl) {
     Amount total = Amount::zero();
     bool fSubtractFeeFromAmount = false;
     QList<SendCoinsRecipient> recipients = transaction.getRecipients();
     std::vector<CRecipient> vecSend;
 
     if (recipients.empty()) {
         return OK;
     }
 
     // Used to detect duplicates
     QSet<QString> setAddress;
     int nAddresses = 0;
 
     // Pre-check input data for validity
     for (const SendCoinsRecipient &rcp : recipients) {
         if (rcp.fSubtractFeeFromAmount) {
             fSubtractFeeFromAmount = true;
         }
 
 #ifdef ENABLE_BIP70
         // PaymentRequest...
         if (rcp.paymentRequest.IsInitialized()) {
             Amount subtotal = Amount::zero();
             const payments::PaymentDetails &details =
                 rcp.paymentRequest.getDetails();
             for (int i = 0; i < details.outputs_size(); i++) {
                 const payments::Output &out = details.outputs(i);
                 if (out.amount() <= 0) {
                     continue;
                 }
 
                 subtotal += int64_t(out.amount()) * SATOSHI;
                 const uint8_t *scriptStr = (const uint8_t *)out.script().data();
                 CScript scriptPubKey(scriptStr,
                                      scriptStr + out.script().size());
                 Amount nAmount = int64_t(out.amount()) * SATOSHI;
                 CRecipient recipient = {scriptPubKey, nAmount,
                                         rcp.fSubtractFeeFromAmount};
                 vecSend.push_back(recipient);
             }
 
             if (subtotal <= Amount::zero()) {
                 return InvalidAmount;
             }
             total += subtotal;
         }
 
         // User-entered bitcoin address / amount:
         else
 #endif
         {
             if (!validateAddress(rcp.address)) {
                 return InvalidAddress;
             }
             if (rcp.amount <= Amount::zero()) {
                 return InvalidAmount;
             }
             setAddress.insert(rcp.address);
             ++nAddresses;
 
             CScript scriptPubKey = GetScriptForDestination(
                 DecodeDestination(rcp.address.toStdString(), getChainParams()));
             CRecipient recipient = {scriptPubKey, Amount(rcp.amount),
                                     rcp.fSubtractFeeFromAmount};
             vecSend.push_back(recipient);
 
             total += rcp.amount;
         }
     }
     if (setAddress.size() != nAddresses) {
         return DuplicateAddress;
     }
 
     Amount nBalance = m_wallet->getAvailableBalance(coinControl);
 
     if (total > nBalance) {
         return AmountExceedsBalance;
     }
 
     Amount nFeeRequired = Amount::zero();
     int nChangePosRet = -1;
     std::string strFailReason;
 
     auto &newTx = transaction.getWtx();
     newTx =
         m_wallet->createTransaction(vecSend, coinControl, true /* sign */,
                                     nChangePosRet, nFeeRequired, strFailReason);
     transaction.setTransactionFee(nFeeRequired);
     if (fSubtractFeeFromAmount && newTx) {
         transaction.reassignAmounts(nChangePosRet);
     }
 
     if (!newTx) {
         if (!fSubtractFeeFromAmount && (total + nFeeRequired) > nBalance) {
             return SendCoinsReturn(AmountWithFeeExceedsBalance);
         }
         Q_EMIT message(tr("Send Coins"), QString::fromStdString(strFailReason),
                        CClientUIInterface::MSG_ERROR);
         return TransactionCreationFailed;
     }
 
-    // reject absurdly high fee. (This can never happen because the
-    // wallet caps the fee at maxTxFee. This merely serves as a
+    // reject absurdly high fee. (This can never happen because the wallet caps
+    // the fee at m_default_max_tx_fee. This merely serves as a
     // belt-and-suspenders check)
-    if (nFeeRequired > m_node.getMaxTxFee()) {
+    if (nFeeRequired > m_wallet->getDefaultMaxTxFee()) {
         return AbsurdFee;
     }
 
     return SendCoinsReturn(OK);
 }
 
 WalletModel::SendCoinsReturn
 WalletModel::sendCoins(WalletModelTransaction &transaction) {
     /* store serialized transaction */
     QByteArray transaction_array;
 
     std::vector<std::pair<std::string, std::string>> vOrderForm;
     for (const SendCoinsRecipient &rcp : transaction.getRecipients()) {
 #ifdef ENABLE_BIP70
         if (rcp.paymentRequest.IsInitialized()) {
             // Make sure any payment requests involved are still valid.
             if (PaymentServer::verifyExpired(rcp.paymentRequest.getDetails())) {
                 return PaymentRequestExpired;
             }
 
             // Store PaymentRequests in wtx.vOrderForm in wallet.
             std::string value;
             rcp.paymentRequest.SerializeToString(&value);
             vOrderForm.emplace_back("PaymentRequest", std::move(value));
         } else
 #endif
         {
             if (!rcp.message.isEmpty()) {
                 // Message from normal bitcoincash:URI
                 // (bitcoincash:123...?message=example)
                 vOrderForm.emplace_back("Message", rcp.message.toStdString());
             }
         }
     }
 
     auto &newTx = transaction.getWtx();
     std::string rejectReason;
     if (!newTx->commit({} /* mapValue */, std::move(vOrderForm),
                        rejectReason)) {
         return SendCoinsReturn(TransactionCommitFailed,
                                QString::fromStdString(rejectReason));
     }
 
     CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION);
     ssTx << newTx->get();
     transaction_array.append(&(ssTx[0]), ssTx.size());
 
     // Add addresses / update labels that we've sent to the address book, and
     // emit coinsSent signal for each recipient
     for (const SendCoinsRecipient &rcp : transaction.getRecipients()) {
         // Don't touch the address book when we have a payment request
 #ifdef ENABLE_BIP70
         if (!rcp.paymentRequest.IsInitialized())
 #endif
         {
             std::string strAddress = rcp.address.toStdString();
             CTxDestination dest =
                 DecodeDestination(strAddress, getChainParams());
             std::string strLabel = rcp.label.toStdString();
             // Check if we have a new address or an updated label
             std::string name;
             if (!m_wallet->getAddress(dest, &name, /* is_mine= */ nullptr,
                                       /* purpose= */ nullptr)) {
                 m_wallet->setAddressBook(dest, strLabel, "send");
             } else if (name != strLabel) {
                 // "" means don't change purpose
                 m_wallet->setAddressBook(dest, strLabel, "");
             }
         }
         Q_EMIT coinsSent(this, rcp, transaction_array);
     }
 
     // update balance immediately, otherwise there could be a short noticeable
     // delay until pollBalanceChanged hits
     checkBalanceChanged(m_wallet->getBalances());
 
     return SendCoinsReturn(OK);
 }
 
 OptionsModel *WalletModel::getOptionsModel() {
     return optionsModel;
 }
 
 AddressTableModel *WalletModel::getAddressTableModel() {
     return addressTableModel;
 }
 
 TransactionTableModel *WalletModel::getTransactionTableModel() {
     return transactionTableModel;
 }
 
 RecentRequestsTableModel *WalletModel::getRecentRequestsTableModel() {
     return recentRequestsTableModel;
 }
 
 WalletModel::EncryptionStatus WalletModel::getEncryptionStatus() const {
     if (!m_wallet->isCrypted()) {
         return Unencrypted;
     } else if (m_wallet->isLocked()) {
         return Locked;
     } else {
         return Unlocked;
     }
 }
 
 bool WalletModel::setWalletEncrypted(bool encrypted,
                                      const SecureString &passphrase) {
     if (encrypted) {
         // Encrypt
         return m_wallet->encryptWallet(passphrase);
     } else {
         // Decrypt -- TODO; not supported yet
         return false;
     }
 }
 
 bool WalletModel::setWalletLocked(bool locked, const SecureString &passPhrase) {
     if (locked) {
         // Lock
         return m_wallet->lock();
     } else {
         // Unlock
         return m_wallet->unlock(passPhrase);
     }
 }
 
 bool WalletModel::changePassphrase(const SecureString &oldPass,
                                    const SecureString &newPass) {
     // Make sure wallet is locked before attempting pass change
     m_wallet->lock();
     return m_wallet->changeWalletPassphrase(oldPass, newPass);
 }
 
 // Handlers for core signals
 static void NotifyUnload(WalletModel *walletModel) {
     qDebug() << "NotifyUnload";
     bool invoked = QMetaObject::invokeMethod(walletModel, "unload");
     assert(invoked);
 }
 
 static void NotifyKeyStoreStatusChanged(WalletModel *walletmodel) {
     qDebug() << "NotifyKeyStoreStatusChanged";
     bool invoked = QMetaObject::invokeMethod(walletmodel, "updateStatus",
                                              Qt::QueuedConnection);
     assert(invoked);
 }
 
 static void NotifyAddressBookChanged(WalletModel *walletmodel,
                                      const CTxDestination &address,
                                      const std::string &label, bool isMine,
                                      const std::string &purpose,
                                      ChangeType status) {
     QString strAddress = QString::fromStdString(
         EncodeCashAddr(address, walletmodel->getChainParams()));
     QString strLabel = QString::fromStdString(label);
     QString strPurpose = QString::fromStdString(purpose);
 
     qDebug() << "NotifyAddressBookChanged: " + strAddress + " " + strLabel +
                     " isMine=" + QString::number(isMine) +
                     " purpose=" + strPurpose +
                     " status=" + QString::number(status);
     bool invoked = QMetaObject::invokeMethod(
         walletmodel, "updateAddressBook", Qt::QueuedConnection,
         Q_ARG(QString, strAddress), Q_ARG(QString, strLabel),
         Q_ARG(bool, isMine), Q_ARG(QString, strPurpose), Q_ARG(int, status));
     assert(invoked);
 }
 
 static void NotifyTransactionChanged(WalletModel *walletmodel, const TxId &hash,
                                      ChangeType status) {
     Q_UNUSED(hash);
     Q_UNUSED(status);
     bool invoked = QMetaObject::invokeMethod(walletmodel, "updateTransaction",
                                              Qt::QueuedConnection);
     assert(invoked);
 }
 
 static void ShowProgress(WalletModel *walletmodel, const std::string &title,
                          int nProgress) {
     // emits signal "showProgress"
     bool invoked = QMetaObject::invokeMethod(
         walletmodel, "showProgress", Qt::QueuedConnection,
         Q_ARG(QString, QString::fromStdString(title)), Q_ARG(int, nProgress));
     assert(invoked);
 }
 
 static void NotifyWatchonlyChanged(WalletModel *walletmodel,
                                    bool fHaveWatchonly) {
     bool invoked = QMetaObject::invokeMethod(walletmodel, "updateWatchOnlyFlag",
                                              Qt::QueuedConnection,
                                              Q_ARG(bool, fHaveWatchonly));
     assert(invoked);
 }
 
 static void NotifyCanGetAddressesChanged(WalletModel *walletmodel) {
     bool invoked =
         QMetaObject::invokeMethod(walletmodel, "canGetAddressesChanged");
     assert(invoked);
 }
 
 void WalletModel::subscribeToCoreSignals() {
     // Connect signals to wallet
     m_handler_unload = m_wallet->handleUnload(std::bind(&NotifyUnload, this));
     m_handler_status_changed = m_wallet->handleStatusChanged(
         std::bind(&NotifyKeyStoreStatusChanged, this));
     m_handler_address_book_changed = m_wallet->handleAddressBookChanged(
         std::bind(NotifyAddressBookChanged, this, std::placeholders::_1,
                   std::placeholders::_2, std::placeholders::_3,
                   std::placeholders::_4, std::placeholders::_5));
     m_handler_transaction_changed = m_wallet->handleTransactionChanged(
         std::bind(NotifyTransactionChanged, this, std::placeholders::_1,
                   std::placeholders::_2));
     m_handler_show_progress = m_wallet->handleShowProgress(std::bind(
         ShowProgress, this, std::placeholders::_1, std::placeholders::_2));
     m_handler_watch_only_changed = m_wallet->handleWatchOnlyChanged(
         std::bind(NotifyWatchonlyChanged, this, std::placeholders::_1));
     m_handler_can_get_addrs_changed = m_wallet->handleCanGetAddressesChanged(
         std::bind(NotifyCanGetAddressesChanged, this));
 }
 
 void WalletModel::unsubscribeFromCoreSignals() {
     // Disconnect signals from wallet
     m_handler_unload->disconnect();
     m_handler_status_changed->disconnect();
     m_handler_address_book_changed->disconnect();
     m_handler_transaction_changed->disconnect();
     m_handler_show_progress->disconnect();
     m_handler_watch_only_changed->disconnect();
     m_handler_can_get_addrs_changed->disconnect();
 }
 
 // WalletModel::UnlockContext implementation
 WalletModel::UnlockContext WalletModel::requestUnlock() {
     bool was_locked = getEncryptionStatus() == Locked;
     if (was_locked) {
         // Request UI to unlock wallet
         Q_EMIT requireUnlock();
     }
     // If wallet is still locked, unlock was failed or cancelled, mark context
     // as invalid
     bool valid = getEncryptionStatus() != Locked;
 
     return UnlockContext(this, valid, was_locked);
 }
 
 WalletModel::UnlockContext::UnlockContext(WalletModel *_wallet, bool _valid,
                                           bool _relock)
     : wallet(_wallet), valid(_valid), relock(_relock) {}
 
 WalletModel::UnlockContext::~UnlockContext() {
     if (valid && relock) {
         wallet->setWalletLocked(true);
     }
 }
 
 void WalletModel::UnlockContext::CopyFrom(const UnlockContext &rhs) {
     // Transfer context; old object no longer relocks wallet
     *this = rhs;
     rhs.relock = false;
 }
 
 void WalletModel::loadReceiveRequests(
     std::vector<std::string> &vReceiveRequests) {
     // receive request
     vReceiveRequests = m_wallet->getDestValues("rr");
 }
 
 bool WalletModel::saveReceiveRequest(const std::string &sAddress,
                                      const int64_t nId,
                                      const std::string &sRequest) {
     CTxDestination dest = DecodeDestination(sAddress, getChainParams());
 
     std::stringstream ss;
     ss << nId;
     // "rr" prefix = "receive request" in destdata
     std::string key = "rr" + ss.str();
 
     return sRequest.empty() ? m_wallet->eraseDestData(dest, key)
                             : m_wallet->addDestData(dest, key, sRequest);
 }
 
 bool WalletModel::isWalletEnabled() {
     return !gArgs.GetBoolArg("-disablewallet", DEFAULT_DISABLE_WALLET);
 }
 
 bool WalletModel::privateKeysDisabled() const {
     return m_wallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS);
 }
 
 bool WalletModel::canGetAddresses() const {
     return m_wallet->canGetAddresses();
 }
 
 QString WalletModel::getWalletName() const {
     return QString::fromStdString(m_wallet->getWalletName());
 }
 
 QString WalletModel::getDisplayName() const {
     const QString name = getWalletName();
     return name.isEmpty() ? "[" + tr("default wallet") + "]" : name;
 }
 
 bool WalletModel::isMultiwallet() {
     return m_node.getWallets().size() > 1;
 }
 
 const CChainParams &WalletModel::getChainParams() const {
     return Params();
 }
diff --git a/src/validation.cpp b/src/validation.cpp
index 8ca430dcb..c73a21dda 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -1,5645 +1,5644 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2018 The Bitcoin Core developers
 // Copyright (c) 2017-2020 The Bitcoin developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <validation.h>
 
 #include <arith_uint256.h>
 #include <avalanche.h>
 #include <blockvalidity.h>
 #include <chainparams.h>
 #include <checkpoints.h>
 #include <checkqueue.h>
 #include <config.h>
 #include <consensus/activation.h>
 #include <consensus/consensus.h>
 #include <consensus/merkle.h>
 #include <consensus/tx_check.h>
 #include <consensus/tx_verify.h>
 #include <consensus/validation.h>
 #include <flatfile.h>
 #include <fs.h>
 #include <hash.h>
 #include <index/txindex.h>
 #include <minerfund.h>
 #include <policy/fees.h>
 #include <policy/mempool.h>
 #include <policy/policy.h>
 #include <policy/settings.h>
 #include <pow.h>
 #include <primitives/block.h>
 #include <primitives/transaction.h>
 #include <random.h>
 #include <reverse_iterator.h>
 #include <script/script.h>
 #include <script/scriptcache.h>
 #include <script/sigcache.h>
 #include <script/standard.h>
 #include <shutdown.h>
 #include <timedata.h>
 #include <tinyformat.h>
 #include <txdb.h>
 #include <txmempool.h>
 #include <ui_interface.h>
 #include <undo.h>
 #include <util/moneystr.h>
 #include <util/strencodings.h>
 #include <util/system.h>
 #include <util/translation.h>
 #include <util/validation.h>
 #include <validationinterface.h>
 #include <warnings.h>
 
 #include <boost/algorithm/string/replace.hpp>
 #include <boost/thread.hpp> // boost::this_thread::interruption_point() (mingw)
 
 #include <atomic>
 #include <future>
 #include <sstream>
 #include <string>
 #include <thread>
 
 #define MICRO 0.000001
 #define MILLI 0.001
 
 CChainState g_chainstate;
 
 CChainState &ChainstateActive() {
     return g_chainstate;
 }
 
 CChain &ChainActive() {
     return g_chainstate.m_chain;
 }
 
 /**
  * Global state
  *
  * Mutex to guard access to validation specific variables, such as reading
  * or changing the chainstate.
  *
  * This may also need to be locked when updating the transaction pool, e.g. on
  * AcceptToMemoryPool. See CTxMemPool::cs comment for details.
  *
  * The transaction pool has a separate lock to allow reading from it and the
  * chainstate at the same time.
  */
 RecursiveMutex cs_main;
 
 BlockMap &mapBlockIndex = ::ChainstateActive().mapBlockIndex;
 CBlockIndex *pindexBestHeader = nullptr;
 Mutex g_best_block_mutex;
 std::condition_variable g_best_block_cv;
 uint256 g_best_block;
 int nScriptCheckThreads = 0;
 std::atomic_bool fImporting(false);
 std::atomic_bool fReindex(false);
 bool fHavePruned = false;
 bool fPruneMode = false;
 bool fRequireStandard = true;
 bool fCheckBlockIndex = false;
 bool fCheckpointsEnabled = DEFAULT_CHECKPOINTS_ENABLED;
 size_t nCoinCacheUsage = 5000 * 300;
 uint64_t nPruneTarget = 0;
 int64_t nMaxTipAge = DEFAULT_MAX_TIP_AGE;
 
 BlockHash hashAssumeValid;
 arith_uint256 nMinimumChainWork;
 
 CFeeRate minRelayTxFee = CFeeRate(DEFAULT_MIN_RELAY_TX_FEE_PER_KB);
-Amount maxTxFee = DEFAULT_TRANSACTION_MAXFEE;
 
 CTxMemPool g_mempool;
 
 /** Constant stuff for coinbase transactions we create: */
 CScript COINBASE_FLAGS;
 
 // Internal stuff
 namespace {
 CBlockIndex *&pindexBestInvalid = ::ChainstateActive().pindexBestInvalid;
 CBlockIndex *&pindexBestParked = ::ChainstateActive().pindexBestParked;
 
 /**
  * The best finalized block.
  * This block cannot be reorged in any way, shape or form.
  */
 CBlockIndex const *&pindexFinalized = ::ChainstateActive().pindexFinalized;
 
 /**
  * All pairs A->B, where A (or one of its ancestors) misses transactions, but B
  * has transactions. Pruned nodes may have entries where B is missing data.
  */
 std::multimap<CBlockIndex *, CBlockIndex *> &mapBlocksUnlinked =
     ::ChainstateActive().mapBlocksUnlinked;
 
 RecursiveMutex cs_LastBlockFile;
 std::vector<CBlockFileInfo> vinfoBlockFile;
 int nLastBlockFile = 0;
 /**
  * Global flag to indicate we should check to see if there are block/undo files
  * that should be deleted. Set on startup or if we allocate more file space when
  * we're in prune mode.
  */
 bool fCheckForPruning = false;
 
 /** Dirty block index entries. */
 std::set<const CBlockIndex *> setDirtyBlockIndex;
 
 /** Dirty block file entries. */
 std::set<int> setDirtyFileInfo;
 } // namespace
 
 BlockValidationOptions::BlockValidationOptions(const Config &config)
     : excessiveBlockSize(config.GetMaxBlockSize()), checkPoW(true),
       checkMerkleRoot(true) {}
 
 CBlockIndex *FindForkInGlobalIndex(const CChain &chain,
                                    const CBlockLocator &locator) {
     AssertLockHeld(cs_main);
 
     // Find the first block the caller has in the main chain
     for (const BlockHash &hash : locator.vHave) {
         CBlockIndex *pindex = LookupBlockIndex(hash);
         if (pindex) {
             if (chain.Contains(pindex)) {
                 return pindex;
             }
             if (pindex->GetAncestor(chain.Height()) == chain.Tip()) {
                 return chain.Tip();
             }
         }
     }
     return chain.Genesis();
 }
 
 std::unique_ptr<CCoinsViewDB> pcoinsdbview;
 std::unique_ptr<CCoinsViewCache> pcoinsTip;
 std::unique_ptr<CBlockTreeDB> pblocktree;
 
 // See definition for documentation
 static void FindFilesToPruneManual(std::set<int> &setFilesToPrune,
                                    int nManualPruneHeight);
 static void FindFilesToPrune(std::set<int> &setFilesToPrune,
                              uint64_t nPruneAfterHeight);
 static FILE *OpenUndoFile(const FlatFilePos &pos, bool fReadOnly = false);
 static FlatFileSeq BlockFileSeq();
 static FlatFileSeq UndoFileSeq();
 static uint32_t GetNextBlockScriptFlags(const Consensus::Params &params,
                                         const CBlockIndex *pindex);
 
 bool TestLockPointValidity(const LockPoints *lp) {
     AssertLockHeld(cs_main);
     assert(lp);
     // If there are relative lock times then the maxInputBlock will be set
     // If there are no relative lock times, the LockPoints don't depend on the
     // chain
     if (lp->maxInputBlock) {
         // Check whether ::ChainActive() is an extension of the block at which
         // the LockPoints calculation was valid. If not LockPoints are no longer
         // valid.
         if (!::ChainActive().Contains(lp->maxInputBlock)) {
             return false;
         }
     }
 
     // LockPoints still valid
     return true;
 }
 
 bool CheckSequenceLocks(const CTxMemPool &pool, const CTransaction &tx,
                         int flags, LockPoints *lp, bool useExistingLockPoints) {
     AssertLockHeld(cs_main);
     AssertLockHeld(pool.cs);
 
     CBlockIndex *tip = ::ChainActive().Tip();
     assert(tip != nullptr);
 
     CBlockIndex index;
     index.pprev = tip;
     // CheckSequenceLocks() uses ::ChainActive().Height()+1 to evaluate height
     // based locks because when SequenceLocks() is called within ConnectBlock(),
     // the height of the block *being* evaluated is what is used. Thus if we
     // want to know if a transaction can be part of the *next* block, we need to
     // use one more than ::ChainActive().Height()
     index.nHeight = tip->nHeight + 1;
 
     std::pair<int, int64_t> lockPair;
     if (useExistingLockPoints) {
         assert(lp);
         lockPair.first = lp->height;
         lockPair.second = lp->time;
     } else {
         // pcoinsTip contains the UTXO set for ::ChainActive().Tip()
         CCoinsViewMemPool viewMemPool(pcoinsTip.get(), pool);
         std::vector<int> prevheights;
         prevheights.resize(tx.vin.size());
         for (size_t txinIndex = 0; txinIndex < tx.vin.size(); txinIndex++) {
             const CTxIn &txin = tx.vin[txinIndex];
             Coin coin;
             if (!viewMemPool.GetCoin(txin.prevout, coin)) {
                 return error("%s: Missing input", __func__);
             }
             if (coin.GetHeight() == MEMPOOL_HEIGHT) {
                 // Assume all mempool transaction confirm in the next block
                 prevheights[txinIndex] = tip->nHeight + 1;
             } else {
                 prevheights[txinIndex] = coin.GetHeight();
             }
         }
         lockPair = CalculateSequenceLocks(tx, flags, &prevheights, index);
         if (lp) {
             lp->height = lockPair.first;
             lp->time = lockPair.second;
             // Also store the hash of the block with the highest height of all
             // the blocks which have sequence locked prevouts. This hash needs
             // to still be on the chain for these LockPoint calculations to be
             // valid.
             // Note: It is impossible to correctly calculate a maxInputBlock if
             // any of the sequence locked inputs depend on unconfirmed txs,
             // except in the special case where the relative lock time/height is
             // 0, which is equivalent to no sequence lock. Since we assume input
             // height of tip+1 for mempool txs and test the resulting lockPair
             // from CalculateSequenceLocks against tip+1. We know
             // EvaluateSequenceLocks will fail if there was a non-zero sequence
             // lock on a mempool input, so we can use the return value of
             // CheckSequenceLocks to indicate the LockPoints validity.
             int maxInputHeight = 0;
             for (const int height : prevheights) {
                 // Can ignore mempool inputs since we'll fail if they had
                 // non-zero locks.
                 if (height != tip->nHeight + 1) {
                     maxInputHeight = std::max(maxInputHeight, height);
                 }
             }
             lp->maxInputBlock = tip->GetAncestor(maxInputHeight);
         }
     }
     return EvaluateSequenceLocks(index, lockPair);
 }
 
 // Command-line argument "-replayprotectionactivationtime=<timestamp>" will
 // cause the node to switch to replay protected SigHash ForkID value when the
 // median timestamp of the previous 11 blocks is greater than or equal to
 // <timestamp>. Defaults to the pre-defined timestamp when not set.
 static bool IsReplayProtectionEnabled(const Consensus::Params &params,
                                       int64_t nMedianTimePast) {
     return nMedianTimePast >= gArgs.GetArg("-replayprotectionactivationtime",
                                            params.axionActivationTime);
 }
 
 static bool IsReplayProtectionEnabled(const Consensus::Params &params,
                                       const CBlockIndex *pindexPrev) {
     if (pindexPrev == nullptr) {
         return false;
     }
 
     return IsReplayProtectionEnabled(params, pindexPrev->GetMedianTimePast());
 }
 
 // Returns the script flags which should be checked for mempool admission when
 // the tip is at the given block.
 static uint32_t GetStandardScriptFlags(const Consensus::Params &params,
                                        const CBlockIndex *pindexTip) {
     // Use the consensus flags for the next block as a basis, and mix in the
     // declared-standard flags.
     uint32_t flags = GetNextBlockScriptFlags(params, pindexTip) |
                      STANDARD_SCRIPT_VERIFY_FLAGS;
 
     // Disable input sigchecks limit for mempool admission, prior to its
     // proper activation.
     flags &= ~SCRIPT_VERIFY_INPUT_SIGCHECKS;
 
     if (IsPhononEnabled(params, pindexTip)) {
         flags |= SCRIPT_VERIFY_INPUT_SIGCHECKS;
     }
 
     return flags;
 }
 
 // Used to avoid mempool polluting consensus critical paths if CCoinsViewMempool
 // were somehow broken and returning the wrong scriptPubKeys
 static bool CheckInputsFromMempoolAndCache(
     const CTransaction &tx, CValidationState &state,
     const CCoinsViewCache &view, const CTxMemPool &pool, const uint32_t flags,
     bool cacheSigStore, PrecomputedTransactionData &txdata, int &nSigChecksOut)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
     AssertLockHeld(cs_main);
 
     // pool.cs should be locked already, but go ahead and re-take the lock here
     // to enforce that mempool doesn't change between when we check the view and
     // when we actually call through to CheckInputs
     LOCK(pool.cs);
 
     assert(!tx.IsCoinBase());
     for (const CTxIn &txin : tx.vin) {
         const Coin &coin = view.AccessCoin(txin.prevout);
 
         // At this point we haven't actually checked if the coins are all
         // available (or shouldn't assume we have, since CheckInputs does). So
         // we just return failure if the inputs are not available here, and then
         // only have to check equivalence for available inputs.
         if (coin.IsSpent()) {
             return false;
         }
 
         const CTransactionRef &txFrom = pool.get(txin.prevout.GetTxId());
         if (txFrom) {
             assert(txFrom->GetId() == txin.prevout.GetTxId());
             assert(txFrom->vout.size() > txin.prevout.GetN());
             assert(txFrom->vout[txin.prevout.GetN()] == coin.GetTxOut());
         } else {
             const Coin &coinFromDisk = pcoinsTip->AccessCoin(txin.prevout);
             assert(!coinFromDisk.IsSpent());
             assert(coinFromDisk.GetTxOut() == coin.GetTxOut());
         }
     }
 
     return CheckInputs(tx, state, view, true, flags, cacheSigStore, true,
                        txdata, nSigChecksOut);
 }
 
 static bool
 AcceptToMemoryPoolWorker(const Config &config, CTxMemPool &pool,
                          CValidationState &state, const CTransactionRef &ptx,
                          bool *pfMissingInputs, int64_t nAcceptTime,
                          bool bypass_limits, const Amount nAbsurdFee,
                          std::vector<COutPoint> &coins_to_uncache,
                          bool test_accept) EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
     AssertLockHeld(cs_main);
 
     const Consensus::Params &consensusParams =
         config.GetChainParams().GetConsensus();
 
     const CTransaction &tx = *ptx;
     const TxId txid = tx.GetId();
 
     // mempool "read lock" (held through
     // GetMainSignals().TransactionAddedToMempool())
     LOCK(pool.cs);
     if (pfMissingInputs) {
         *pfMissingInputs = false;
     }
 
     // Coinbase is only valid in a block, not as a loose transaction.
     if (!CheckRegularTransaction(tx, state)) {
         // state filled in by CheckRegularTransaction.
         return false;
     }
 
     // Rather not work on nonstandard transactions (unless -testnet)
     std::string reason;
     if (fRequireStandard && !IsStandardTx(tx, reason)) {
         return state.DoS(0, false, REJECT_NONSTANDARD, reason);
     }
 
     // Only accept nLockTime-using transactions that can be mined in the next
     // block; we don't want our mempool filled up with transactions that can't
     // be mined yet.
     CValidationState ctxState;
     if (!ContextualCheckTransactionForCurrentBlock(
             consensusParams, tx, ctxState, STANDARD_LOCKTIME_VERIFY_FLAGS)) {
         // We copy the state from a dummy to ensure we don't increase the
         // ban score of peer for transaction that could be valid in the future.
         return state.DoS(
             0, false, REJECT_NONSTANDARD, ctxState.GetRejectReason(),
             ctxState.CorruptionPossible(), ctxState.GetDebugMessage());
     }
 
     // Is it already in the memory pool?
     if (pool.exists(txid)) {
         return state.Invalid(false, REJECT_DUPLICATE, "txn-already-in-mempool");
     }
 
     // Check for conflicts with in-memory transactions
     for (const CTxIn &txin : tx.vin) {
         auto itConflicting = pool.mapNextTx.find(txin.prevout);
         if (itConflicting != pool.mapNextTx.end()) {
             // Disable replacement feature for good
             return state.Invalid(false, REJECT_DUPLICATE,
                                  "txn-mempool-conflict");
         }
     }
 
     {
         CCoinsView dummy;
         CCoinsViewCache view(&dummy);
 
         LockPoints lp;
         CCoinsViewMemPool viewMemPool(pcoinsTip.get(), pool);
         view.SetBackend(viewMemPool);
 
         // Do all inputs exist?
         for (const CTxIn &txin : tx.vin) {
             if (!pcoinsTip->HaveCoinInCache(txin.prevout)) {
                 coins_to_uncache.push_back(txin.prevout);
             }
 
             if (!view.HaveCoin(txin.prevout)) {
                 // Are inputs missing because we already have the tx?
                 for (size_t out = 0; out < tx.vout.size(); out++) {
                     // Optimistically just do efficient check of cache for
                     // outputs.
                     if (pcoinsTip->HaveCoinInCache(COutPoint(txid, out))) {
                         return state.Invalid(false, REJECT_DUPLICATE,
                                              "txn-already-known");
                     }
                 }
 
                 // Otherwise assume this might be an orphan tx for which we just
                 // haven't seen parents yet.
                 if (pfMissingInputs) {
                     *pfMissingInputs = true;
                 }
 
                 // fMissingInputs and !state.IsInvalid() is used to detect this
                 // condition, don't set state.Invalid()
                 return false;
             }
         }
 
         // Are the actual inputs available?
         if (!view.HaveInputs(tx)) {
             return state.Invalid(false, REJECT_DUPLICATE,
                                  "bad-txns-inputs-spent");
         }
 
         // Bring the best block into scope.
         view.GetBestBlock();
 
         // We have all inputs cached now, so switch back to dummy, so we don't
         // need to keep lock on mempool.
         view.SetBackend(dummy);
 
         // Only accept BIP68 sequence locked transactions that can be mined in
         // the next block; we don't want our mempool filled up with transactions
         // that can't be mined yet. Must keep pool.cs for this unless we change
         // CheckSequenceLocks to take a CoinsViewCache instead of create its
         // own.
         if (!CheckSequenceLocks(pool, tx, STANDARD_LOCKTIME_VERIFY_FLAGS,
                                 &lp)) {
             return state.DoS(0, false, REJECT_NONSTANDARD, "non-BIP68-final");
         }
 
         Amount nFees = Amount::zero();
         if (!Consensus::CheckTxInputs(tx, state, view, GetSpendHeight(view),
                                       nFees)) {
             return error("%s: Consensus::CheckTxInputs: %s, %s", __func__,
                          tx.GetId().ToString(), FormatStateMessage(state));
         }
 
         const uint32_t nextBlockScriptVerifyFlags =
             GetNextBlockScriptFlags(consensusParams, ::ChainActive().Tip());
 
         // Check for non-standard pay-to-script-hash in inputs
         if (fRequireStandard &&
             !AreInputsStandard(tx, view, nextBlockScriptVerifyFlags)) {
             return state.Invalid(false, REJECT_NONSTANDARD,
                                  "bad-txns-nonstandard-inputs");
         }
 
         // nModifiedFees includes any fee deltas from PrioritiseTransaction
         Amount nModifiedFees = nFees;
         pool.ApplyDelta(txid, nModifiedFees);
 
         // Keep track of transactions that spend a coinbase, which we re-scan
         // during reorgs to ensure COINBASE_MATURITY is still met.
         bool fSpendsCoinbase = false;
         for (const CTxIn &txin : tx.vin) {
             const Coin &coin = view.AccessCoin(txin.prevout);
             if (coin.IsCoinBase()) {
                 fSpendsCoinbase = true;
                 break;
             }
         }
 
         unsigned int nSize = tx.GetTotalSize();
 
         // No transactions are allowed below minRelayTxFee except from
         // disconnected blocks.
         // Do not change this to use virtualsize without coordinating a network
         // policy upgrade.
         if (!bypass_limits && nModifiedFees < minRelayTxFee.GetFee(nSize)) {
             return state.DoS(0, false, REJECT_INSUFFICIENTFEE,
                              "min relay fee not met");
         }
 
         if (nAbsurdFee != Amount::zero() && nFees > nAbsurdFee) {
             return state.Invalid(false, REJECT_HIGHFEE, "absurdly-high-fee",
                                  strprintf("%d > %d", nFees, nAbsurdFee));
         }
 
         // Validate input scripts against standard script flags.
         const uint32_t scriptVerifyFlags =
             GetStandardScriptFlags(consensusParams, ::ChainActive().Tip());
         PrecomputedTransactionData txdata(tx);
         int nSigChecksStandard;
         if (!CheckInputs(tx, state, view, true, scriptVerifyFlags, true, false,
                          txdata, nSigChecksStandard)) {
             // State filled in by CheckInputs.
             return false;
         }
 
         CTxMemPoolEntry entry(ptx, nFees, nAcceptTime, ::ChainActive().Height(),
                               fSpendsCoinbase, nSigChecksStandard, lp);
 
         unsigned int nVirtualSize = entry.GetTxVirtualSize();
 
         Amount mempoolRejectFee =
             pool.GetMinFee(
                     gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) *
                     1000000)
                 .GetFee(nVirtualSize);
         if (!bypass_limits && mempoolRejectFee > Amount::zero() &&
             nModifiedFees < mempoolRejectFee) {
             return state.DoS(
                 0, false, REJECT_INSUFFICIENTFEE, "mempool min fee not met",
                 false, strprintf("%d < %d", nModifiedFees, mempoolRejectFee));
         }
 
         // Calculate in-mempool ancestors, up to a limit.
         CTxMemPool::setEntries setAncestors;
         size_t nLimitAncestors = gArgs.GetArg(
             "-limitancestorcount",
             GetDefaultAncestorLimit(consensusParams, ::ChainActive().Tip()));
         size_t nLimitAncestorSize =
             gArgs.GetArg("-limitancestorsize", DEFAULT_ANCESTOR_SIZE_LIMIT) *
             1000;
         size_t nLimitDescendants = gArgs.GetArg(
             "-limitdescendantcount",
             GetDefaultDescendantLimit(consensusParams, ::ChainActive().Tip()));
         size_t nLimitDescendantSize =
             gArgs.GetArg("-limitdescendantsize",
                          DEFAULT_DESCENDANT_SIZE_LIMIT) *
             1000;
         std::string errString;
         if (!pool.CalculateMemPoolAncestors(
                 entry, setAncestors, nLimitAncestors, nLimitAncestorSize,
                 nLimitDescendants, nLimitDescendantSize, errString)) {
             return state.DoS(0, false, REJECT_NONSTANDARD,
                              "too-long-mempool-chain", false, errString);
         }
 
         // Check again against the next block's script verification flags
         // to cache our script execution flags.
         //
         // This is also useful in case of bugs in the standard flags that cause
         // transactions to pass as valid when they're actually invalid. For
         // instance the STRICTENC flag was incorrectly allowing certain CHECKSIG
         // NOT scripts to pass, even though they were invalid.
         //
         // There is a similar check in CreateNewBlock() to prevent creating
         // invalid blocks (using TestBlockValidity), however allowing such
         // transactions into the mempool can be exploited as a DoS attack.
         int nSigChecksConsensus;
         if (!CheckInputsFromMempoolAndCache(tx, state, view, pool,
                                             nextBlockScriptVerifyFlags, true,
                                             txdata, nSigChecksConsensus)) {
             // This can occur under some circumstances, if the node receives an
             // unrequested tx which is invalid due to new consensus rules not
             // being activated yet (during IBD).
             return error("%s: BUG! PLEASE REPORT THIS! CheckInputs failed "
                          "against next-block but not STANDARD flags %s, %s",
                          __func__, txid.ToString(), FormatStateMessage(state));
         }
 
         if (nSigChecksStandard != nSigChecksConsensus) {
             // We can't accept this transaction as we've used the standard count
             // for the mempool/mining, but the consensus count will be enforced
             // in validation (we don't want to produce bad block templates).
             return error(
                 "%s: BUG! PLEASE REPORT THIS! SigChecks count differed between "
                 "standard and consensus flags in %s",
                 __func__, txid.ToString());
         }
 
         if (test_accept) {
             // Tx was accepted, but not added
             return true;
         }
 
         // Store transaction in memory.
         pool.addUnchecked(entry, setAncestors);
 
         // Trim mempool and check if tx was trimmed.
         if (!bypass_limits) {
             pool.LimitSize(
                 gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000,
                 gArgs.GetArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY) * 60 *
                     60);
             if (!pool.exists(txid)) {
                 return state.DoS(0, false, REJECT_INSUFFICIENTFEE,
                                  "mempool full");
             }
         }
     }
 
     GetMainSignals().TransactionAddedToMempool(ptx);
     return true;
 }
 
 /**
  * (try to) add transaction to memory pool with a specified acceptance time.
  */
 static bool
 AcceptToMemoryPoolWithTime(const Config &config, CTxMemPool &pool,
                            CValidationState &state, const CTransactionRef &tx,
                            bool *pfMissingInputs, int64_t nAcceptTime,
                            bool bypass_limits, const Amount nAbsurdFee,
                            bool test_accept) EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
     AssertLockHeld(cs_main);
     std::vector<COutPoint> coins_to_uncache;
     bool res = AcceptToMemoryPoolWorker(
         config, pool, state, tx, pfMissingInputs, nAcceptTime, bypass_limits,
         nAbsurdFee, coins_to_uncache, test_accept);
     if (!res) {
         for (const COutPoint &outpoint : coins_to_uncache) {
             pcoinsTip->Uncache(outpoint);
         }
     }
 
     // After we've (potentially) uncached entries, ensure our coins cache is
     // still within its size limits
     CValidationState stateDummy;
     ::ChainstateActive().FlushStateToDisk(config.GetChainParams(), stateDummy,
                                           FlushStateMode::PERIODIC);
     return res;
 }
 
 bool AcceptToMemoryPool(const Config &config, CTxMemPool &pool,
                         CValidationState &state, const CTransactionRef &tx,
                         bool *pfMissingInputs, bool bypass_limits,
                         const Amount nAbsurdFee, bool test_accept) {
     return AcceptToMemoryPoolWithTime(config, pool, state, tx, pfMissingInputs,
                                       GetTime(), bypass_limits, nAbsurdFee,
                                       test_accept);
 }
 
 /**
  * Return transaction in txOut, and if it was found inside a block, its hash is
  * placed in hashBlock. If blockIndex is provided, the transaction is fetched
  * from the corresponding block.
  */
 bool GetTransaction(const TxId &txid, CTransactionRef &txOut,
                     const Consensus::Params &params, BlockHash &hashBlock,
                     const CBlockIndex *const block_index) {
     LOCK(cs_main);
 
     if (block_index == nullptr) {
         CTransactionRef ptx = g_mempool.get(txid);
         if (ptx) {
             txOut = ptx;
             return true;
         }
 
         if (g_txindex) {
             return g_txindex->FindTx(txid, hashBlock, txOut);
         }
     } else {
         CBlock block;
         if (ReadBlockFromDisk(block, block_index, params)) {
             for (const auto &tx : block.vtx) {
                 if (tx->GetId() == txid) {
                     txOut = tx;
                     hashBlock = block_index->GetBlockHash();
                     return true;
                 }
             }
         }
     }
 
     return false;
 }
 
 //////////////////////////////////////////////////////////////////////////////
 //
 // CBlock and CBlockIndex
 //
 
 static bool WriteBlockToDisk(const CBlock &block, FlatFilePos &pos,
                              const CMessageHeader::MessageMagic &messageStart) {
     // Open history file to append
     CAutoFile fileout(OpenBlockFile(pos), SER_DISK, CLIENT_VERSION);
     if (fileout.IsNull()) {
         return error("WriteBlockToDisk: OpenBlockFile failed");
     }
 
     // Write index header
     unsigned int nSize = GetSerializeSize(block, fileout.GetVersion());
     fileout << messageStart << nSize;
 
     // Write block
     long fileOutPos = ftell(fileout.Get());
     if (fileOutPos < 0) {
         return error("WriteBlockToDisk: ftell failed");
     }
 
     pos.nPos = (unsigned int)fileOutPos;
     fileout << block;
 
     return true;
 }
 
 bool ReadBlockFromDisk(CBlock &block, const FlatFilePos &pos,
                        const Consensus::Params &params) {
     block.SetNull();
 
     // Open history file to read
     CAutoFile filein(OpenBlockFile(pos, true), SER_DISK, CLIENT_VERSION);
     if (filein.IsNull()) {
         return error("ReadBlockFromDisk: OpenBlockFile failed for %s",
                      pos.ToString());
     }
 
     // Read block
     try {
         filein >> block;
     } catch (const std::exception &e) {
         return error("%s: Deserialize or I/O error - %s at %s", __func__,
                      e.what(), pos.ToString());
     }
 
     // Check the header
     if (!CheckProofOfWork(block.GetHash(), block.nBits, params)) {
         return error("ReadBlockFromDisk: Errors in block header at %s",
                      pos.ToString());
     }
 
     return true;
 }
 
 bool ReadBlockFromDisk(CBlock &block, const CBlockIndex *pindex,
                        const Consensus::Params &params) {
     FlatFilePos blockPos;
     {
         LOCK(cs_main);
         blockPos = pindex->GetBlockPos();
     }
 
     if (!ReadBlockFromDisk(block, blockPos, params)) {
         return false;
     }
 
     if (block.GetHash() != pindex->GetBlockHash()) {
         return error("ReadBlockFromDisk(CBlock&, CBlockIndex*): GetHash() "
                      "doesn't match index for %s at %s",
                      pindex->ToString(), pindex->GetBlockPos().ToString());
     }
 
     return true;
 }
 
 Amount GetBlockSubsidy(int nHeight, const Consensus::Params &consensusParams) {
     int halvings = nHeight / consensusParams.nSubsidyHalvingInterval;
     // Force block reward to zero when right shift is undefined.
     if (halvings >= 64) {
         return Amount::zero();
     }
 
     Amount nSubsidy = 50 * COIN;
     // Subsidy is cut in half every 210,000 blocks which will occur
     // approximately every 4 years.
     return ((nSubsidy / SATOSHI) >> halvings) * SATOSHI;
 }
 
 // Note that though this is marked const, we may end up modifying
 // `m_cached_finished_ibd`, which is a performance-related implementation
 // detail. This function must be marked `const` so that `CValidationInterface`
 // clients (which are given a `const CChainState*`) can call it.
 //
 bool CChainState::IsInitialBlockDownload() const {
     // Optimization: pre-test latch before taking the lock.
     if (m_cached_finished_ibd.load(std::memory_order_relaxed)) {
         return false;
     }
 
     LOCK(cs_main);
     if (m_cached_finished_ibd.load(std::memory_order_relaxed)) {
         return false;
     }
     if (fImporting || fReindex) {
         return true;
     }
     if (m_chain.Tip() == nullptr) {
         return true;
     }
     if (m_chain.Tip()->nChainWork < nMinimumChainWork) {
         return true;
     }
     if (m_chain.Tip()->GetBlockTime() < (GetTime() - nMaxTipAge)) {
         return true;
     }
     LogPrintf("Leaving InitialBlockDownload (latching to false)\n");
     m_cached_finished_ibd.store(true, std::memory_order_relaxed);
     return false;
 }
 
 CBlockIndex const *pindexBestForkTip = nullptr;
 CBlockIndex const *pindexBestForkBase = nullptr;
 
 static void AlertNotify(const std::string &strMessage) {
     uiInterface.NotifyAlertChanged();
     std::string strCmd = gArgs.GetArg("-alertnotify", "");
     if (strCmd.empty()) {
         return;
     }
 
     // Alert text should be plain ascii coming from a trusted source, but to be
     // safe we first strip anything not in safeChars, then add single quotes
     // around the whole string before passing it to the shell:
     std::string singleQuote("'");
     std::string safeStatus = SanitizeString(strMessage);
     safeStatus = singleQuote + safeStatus + singleQuote;
     boost::replace_all(strCmd, "%s", safeStatus);
 
     std::thread t(runCommand, strCmd);
     // thread runs free
     t.detach();
 }
 
 static void CheckForkWarningConditions() EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
     AssertLockHeld(cs_main);
     // Before we get past initial download, we cannot reliably alert about forks
     // (we assume we don't get stuck on a fork before finishing our initial
     // sync)
     if (::ChainstateActive().IsInitialBlockDownload()) {
         return;
     }
 
     // If our best fork is no longer within 72 blocks (+/- 12 hours if no one
     // mines it) of our head, drop it
     if (pindexBestForkTip &&
         ::ChainActive().Height() - pindexBestForkTip->nHeight >= 72) {
         pindexBestForkTip = nullptr;
     }
 
     if (pindexBestForkTip ||
         (pindexBestInvalid &&
          pindexBestInvalid->nChainWork >
              ::ChainActive().Tip()->nChainWork +
                  (GetBlockProof(*::ChainActive().Tip()) * 6))) {
         if (!GetfLargeWorkForkFound() && pindexBestForkBase) {
             std::string warning =
                 std::string("'Warning: Large-work fork detected, forking after "
                             "block ") +
                 pindexBestForkBase->phashBlock->ToString() + std::string("'");
             AlertNotify(warning);
         }
 
         if (pindexBestForkTip && pindexBestForkBase) {
             LogPrintf("%s: Warning: Large fork found\n  forking the "
                       "chain at height %d (%s)\n  lasting to height %d "
                       "(%s).\nChain state database corruption likely.\n",
                       __func__, pindexBestForkBase->nHeight,
                       pindexBestForkBase->phashBlock->ToString(),
                       pindexBestForkTip->nHeight,
                       pindexBestForkTip->phashBlock->ToString());
             SetfLargeWorkForkFound(true);
         } else {
             LogPrintf("%s: Warning: Found invalid chain at least ~6 blocks "
                       "longer than our best chain.\nChain state database "
                       "corruption likely.\n",
                       __func__);
             SetfLargeWorkInvalidChainFound(true);
         }
     } else {
         SetfLargeWorkForkFound(false);
         SetfLargeWorkInvalidChainFound(false);
     }
 }
 
 static void CheckForkWarningConditionsOnNewFork(CBlockIndex *pindexNewForkTip)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
     AssertLockHeld(cs_main);
     // If we are on a fork that is sufficiently large, set a warning flag.
     const CBlockIndex *pfork = ::ChainActive().FindFork(pindexNewForkTip);
 
     // We define a condition where we should warn the user about as a fork of at
     // least 7 blocks with a tip within 72 blocks (+/- 12 hours if no one mines
     // it) of ours. We use 7 blocks rather arbitrarily as it represents just
     // under 10% of sustained network hash rate operating on the fork, or a
     // chain that is entirely longer than ours and invalid (note that this
     // should be detected by both). We define it this way because it allows us
     // to only store the highest fork tip (+ base) which meets the 7-block
     // condition and from this always have the most-likely-to-cause-warning fork
     if (pfork &&
         (!pindexBestForkTip ||
          pindexNewForkTip->nHeight > pindexBestForkTip->nHeight) &&
         pindexNewForkTip->nChainWork - pfork->nChainWork >
             (GetBlockProof(*pfork) * 7) &&
         ::ChainActive().Height() - pindexNewForkTip->nHeight < 72) {
         pindexBestForkTip = pindexNewForkTip;
         pindexBestForkBase = pfork;
     }
 
     CheckForkWarningConditions();
 }
 
 static void InvalidChainFound(CBlockIndex *pindexNew)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
     AssertLockHeld(cs_main);
     if (!pindexBestInvalid ||
         pindexNew->nChainWork > pindexBestInvalid->nChainWork) {
         pindexBestInvalid = pindexNew;
     }
 
     // If the invalid chain found is supposed to be finalized, we need to move
     // back the finalization point.
     if (IsBlockFinalized(pindexNew)) {
         pindexFinalized = pindexNew->pprev;
     }
 
     LogPrintf("%s: invalid block=%s  height=%d  log2_work=%.8g  date=%s\n",
               __func__, pindexNew->GetBlockHash().ToString(),
               pindexNew->nHeight,
               log(pindexNew->nChainWork.getdouble()) / log(2.0),
               FormatISO8601DateTime(pindexNew->GetBlockTime()));
     CBlockIndex *tip = ::ChainActive().Tip();
     assert(tip);
     LogPrintf("%s:  current best=%s  height=%d  log2_work=%.8g  date=%s\n",
               __func__, tip->GetBlockHash().ToString(),
               ::ChainActive().Height(),
               log(tip->nChainWork.getdouble()) / log(2.0),
               FormatISO8601DateTime(tip->GetBlockTime()));
 }
 
 void CChainState::InvalidBlockFound(CBlockIndex *pindex,
                                     const CValidationState &state) {
     if (!state.CorruptionPossible()) {
         pindex->nStatus = pindex->nStatus.withFailed();
         m_failed_blocks.insert(pindex);
         setDirtyBlockIndex.insert(pindex);
         InvalidChainFound(pindex);
     }
 }
 
 void SpendCoins(CCoinsViewCache &view, const CTransaction &tx, CTxUndo &txundo,
                 int nHeight) {
     // Mark inputs spent.
     if (tx.IsCoinBase()) {
         return;
     }
 
     txundo.vprevout.reserve(tx.vin.size());
     for (const CTxIn &txin : tx.vin) {
         txundo.vprevout.emplace_back();
         bool is_spent = view.SpendCoin(txin.prevout, &txundo.vprevout.back());
         assert(is_spent);
     }
 }
 
 void UpdateCoins(CCoinsViewCache &view, const CTransaction &tx, CTxUndo &txundo,
                  int nHeight) {
     SpendCoins(view, tx, txundo, nHeight);
     AddCoins(view, tx, nHeight);
 }
 
 void UpdateCoins(CCoinsViewCache &view, const CTransaction &tx, int nHeight) {
     // Mark inputs spent.
     if (!tx.IsCoinBase()) {
         for (const CTxIn &txin : tx.vin) {
             bool is_spent = view.SpendCoin(txin.prevout);
             assert(is_spent);
         }
     }
 
     // Add outputs.
     AddCoins(view, tx, nHeight);
 }
 
 bool CScriptCheck::operator()() {
     const CScript &scriptSig = ptxTo->vin[nIn].scriptSig;
     if (!VerifyScript(scriptSig, scriptPubKey, nFlags,
                       CachingTransactionSignatureChecker(ptxTo, nIn, amount,
                                                          cacheStore, txdata),
                       metrics, &error)) {
         return false;
     }
     if ((pTxLimitSigChecks &&
          !pTxLimitSigChecks->consume_and_check(metrics.nSigChecks)) ||
         (pBlockLimitSigChecks &&
          !pBlockLimitSigChecks->consume_and_check(metrics.nSigChecks))) {
         // we can't assign a meaningful script error (since the script
         // succeeded), but remove the ScriptError::OK which could be
         // misinterpreted.
         error = ScriptError::SIGCHECKS_LIMIT_EXCEEDED;
         return false;
     }
     return true;
 }
 
 int GetSpendHeight(const CCoinsViewCache &inputs) {
     LOCK(cs_main);
     CBlockIndex *pindexPrev = LookupBlockIndex(inputs.GetBestBlock());
     return pindexPrev->nHeight + 1;
 }
 
 bool CheckInputs(const CTransaction &tx, CValidationState &state,
                  const CCoinsViewCache &inputs, bool fScriptChecks,
                  const uint32_t flags, bool sigCacheStore,
                  bool scriptCacheStore,
                  const PrecomputedTransactionData &txdata, int &nSigChecksOut,
                  TxSigCheckLimiter &txLimitSigChecks,
                  CheckInputsLimiter *pBlockLimitSigChecks,
                  std::vector<CScriptCheck> *pvChecks) {
     AssertLockHeld(cs_main);
     assert(!tx.IsCoinBase());
 
     if (pvChecks) {
         pvChecks->reserve(tx.vin.size());
     }
 
     // Skip script verification when connecting blocks under the assumevalid
     // block. Assuming the assumevalid block is valid this is safe because
     // block merkle hashes are still computed and checked, of course, if an
     // assumed valid block is invalid due to false scriptSigs this optimization
     // would allow an invalid chain to be accepted.
     if (!fScriptChecks) {
         return true;
     }
 
     // First check if script executions have been cached with the same flags.
     // Note that this assumes that the inputs provided are correct (ie that the
     // transaction hash which is in tx's prevouts properly commits to the
     // scriptPubKey in the inputs view of that transaction).
     ScriptCacheKey hashCacheEntry(tx, flags);
     if (IsKeyInScriptCache(hashCacheEntry, !scriptCacheStore, nSigChecksOut)) {
         if (!txLimitSigChecks.consume_and_check(nSigChecksOut) ||
             (pBlockLimitSigChecks &&
              !pBlockLimitSigChecks->consume_and_check(nSigChecksOut))) {
             return state.Invalid(false, REJECT_NONSTANDARD,
                                  strprintf("too-many-sigchecks"));
         }
         return true;
     }
 
     int nSigChecksTotal = 0;
 
     for (size_t i = 0; i < tx.vin.size(); i++) {
         const COutPoint &prevout = tx.vin[i].prevout;
         const Coin &coin = inputs.AccessCoin(prevout);
         assert(!coin.IsSpent());
 
         // We very carefully only pass in things to CScriptCheck which are
         // clearly committed to by tx's hash. This provides a sanity
         // check that our caching is not introducing consensus failures through
         // additional data in, eg, the coins being spent being checked as a part
         // of CScriptCheck.
         const CScript &scriptPubKey = coin.GetTxOut().scriptPubKey;
         const Amount amount = coin.GetTxOut().nValue;
 
         // Verify signature
         CScriptCheck check(scriptPubKey, amount, tx, i, flags, sigCacheStore,
                            txdata, &txLimitSigChecks, pBlockLimitSigChecks);
         if (pvChecks) {
             pvChecks->push_back(std::move(check));
         } else if (!check()) {
             ScriptError scriptError = check.GetScriptError();
             // Compute flags without the optional standardness flags.
             // This differs from MANDATORY_SCRIPT_VERIFY_FLAGS as it contains
             // additional upgrade flags (see AcceptToMemoryPoolWorker variable
             // extraFlags).
             uint32_t mandatoryFlags =
                 flags & ~STANDARD_NOT_MANDATORY_VERIFY_FLAGS;
             if (flags != mandatoryFlags) {
                 // Check whether the failure was caused by a non-mandatory
                 // script verification check. If so, don't trigger DoS
                 // protection to avoid splitting the network on the basis of
                 // relay policy disagreements.
                 CScriptCheck check2(scriptPubKey, amount, tx, i, mandatoryFlags,
                                     sigCacheStore, txdata);
                 if (check2()) {
                     return state.Invalid(
                         false, REJECT_NONSTANDARD,
                         strprintf("non-mandatory-script-verify-flag (%s)",
                                   ScriptErrorString(scriptError)));
                 }
                 // update the error message to reflect the mandatory violation.
                 scriptError = check2.GetScriptError();
             }
 
             // Failures of other flags indicate a transaction that is invalid in
             // new blocks, e.g. a invalid P2SH. We DoS ban such nodes as they
             // are not following the protocol. That said during an upgrade
             // careful thought should be taken as to the correct behavior - we
             // may want to continue peering with non-upgraded nodes even after
             // soft-fork super-majority signaling has occurred.
             return state.DoS(
                 100, false, REJECT_INVALID,
                 strprintf("mandatory-script-verify-flag-failed (%s)",
                           ScriptErrorString(scriptError)));
         }
 
         nSigChecksTotal += check.GetScriptExecutionMetrics().nSigChecks;
     }
 
     nSigChecksOut = nSigChecksTotal;
 
     if (scriptCacheStore && !pvChecks) {
         // We executed all of the provided scripts, and were told to cache the
         // result. Do so now.
         AddKeyInScriptCache(hashCacheEntry, nSigChecksTotal);
     }
 
     return true;
 }
 
 namespace {
 
 bool UndoWriteToDisk(const CBlockUndo &blockundo, FlatFilePos &pos,
                      const uint256 &hashBlock,
                      const CMessageHeader::MessageMagic &messageStart) {
     // Open history file to append
     CAutoFile fileout(OpenUndoFile(pos), SER_DISK, CLIENT_VERSION);
     if (fileout.IsNull()) {
         return error("%s: OpenUndoFile failed", __func__);
     }
 
     // Write index header
     unsigned int nSize = GetSerializeSize(blockundo, fileout.GetVersion());
     fileout << messageStart << nSize;
 
     // Write undo data
     long fileOutPos = ftell(fileout.Get());
     if (fileOutPos < 0) {
         return error("%s: ftell failed", __func__);
     }
     pos.nPos = (unsigned int)fileOutPos;
     fileout << blockundo;
 
     // calculate & write checksum
     CHashWriter hasher(SER_GETHASH, PROTOCOL_VERSION);
     hasher << hashBlock;
     hasher << blockundo;
     fileout << hasher.GetHash();
 
     return true;
 }
 
 static bool UndoReadFromDisk(CBlockUndo &blockundo, const CBlockIndex *pindex) {
     FlatFilePos pos = pindex->GetUndoPos();
     if (pos.IsNull()) {
         return error("%s: no undo data available", __func__);
     }
 
     // Open history file to read
     CAutoFile filein(OpenUndoFile(pos, true), SER_DISK, CLIENT_VERSION);
     if (filein.IsNull()) {
         return error("%s: OpenUndoFile failed", __func__);
     }
 
     // Read block
     uint256 hashChecksum;
     // We need a CHashVerifier as reserializing may lose data
     CHashVerifier<CAutoFile> verifier(&filein);
     try {
         verifier << pindex->pprev->GetBlockHash();
         verifier >> blockundo;
         filein >> hashChecksum;
     } catch (const std::exception &e) {
         return error("%s: Deserialize or I/O error - %s", __func__, e.what());
     }
 
     // Verify checksum
     if (hashChecksum != verifier.GetHash()) {
         return error("%s: Checksum mismatch", __func__);
     }
 
     return true;
 }
 
 /** Abort with a message */
 static bool AbortNode(const std::string &strMessage,
                       const std::string &userMessage = "") {
     SetMiscWarning(strMessage);
     LogPrintf("*** %s\n", strMessage);
     uiInterface.ThreadSafeMessageBox(
         userMessage.empty() ? _("Error: A fatal internal error occurred, see "
                                 "debug.log for details")
                                   .translated
                             : userMessage,
         "", CClientUIInterface::MSG_ERROR);
     StartShutdown();
     return false;
 }
 
 static bool AbortNode(CValidationState &state, const std::string &strMessage,
                       const std::string &userMessage = "") {
     AbortNode(strMessage, userMessage);
     return state.Error(strMessage);
 }
 
 } // namespace
 
 /** Restore the UTXO in a Coin at a given COutPoint. */
 DisconnectResult UndoCoinSpend(const Coin &undo, CCoinsViewCache &view,
                                const COutPoint &out) {
     bool fClean = true;
 
     if (view.HaveCoin(out)) {
         // Overwriting transaction output.
         fClean = false;
     }
 
     if (undo.GetHeight() == 0) {
         // Missing undo metadata (height and coinbase). Older versions included
         // this information only in undo records for the last spend of a
         // transactions' outputs. This implies that it must be present for some
         // other output of the same tx.
         const Coin &alternate = AccessByTxid(view, out.GetTxId());
         if (alternate.IsSpent()) {
             // Adding output for transaction without known metadata
             return DisconnectResult::FAILED;
         }
 
         // This is somewhat ugly, but hopefully utility is limited. This is only
         // useful when working from legacy on disck data. In any case, putting
         // the correct information in there doesn't hurt.
         const_cast<Coin &>(undo) = Coin(undo.GetTxOut(), alternate.GetHeight(),
                                         alternate.IsCoinBase());
     }
 
     // The potential_overwrite parameter to AddCoin is only allowed to be false
     // if we know for sure that the coin did not already exist in the cache. As
     // we have queried for that above using HaveCoin, we don't need to guess.
     // When fClean is false, a coin already existed and it is an overwrite.
     view.AddCoin(out, std::move(undo), !fClean);
 
     return fClean ? DisconnectResult::OK : DisconnectResult::UNCLEAN;
 }
 
 /**
  * Undo the effects of this block (with given index) on the UTXO set represented
  * by coins. When FAILED is returned, view is left in an indeterminate state.
  */
 DisconnectResult CChainState::DisconnectBlock(const CBlock &block,
                                               const CBlockIndex *pindex,
                                               CCoinsViewCache &view) {
     CBlockUndo blockUndo;
     if (!UndoReadFromDisk(blockUndo, pindex)) {
         error("DisconnectBlock(): failure reading undo data");
         return DisconnectResult::FAILED;
     }
 
     return ApplyBlockUndo(blockUndo, block, pindex, view);
 }
 
 DisconnectResult ApplyBlockUndo(const CBlockUndo &blockUndo,
                                 const CBlock &block, const CBlockIndex *pindex,
                                 CCoinsViewCache &view) {
     bool fClean = true;
 
     if (blockUndo.vtxundo.size() + 1 != block.vtx.size()) {
         error("DisconnectBlock(): block and undo data inconsistent");
         return DisconnectResult::FAILED;
     }
 
     // First, restore inputs.
     for (size_t i = 1; i < block.vtx.size(); i++) {
         const CTransaction &tx = *(block.vtx[i]);
         const CTxUndo &txundo = blockUndo.vtxundo[i - 1];
         if (txundo.vprevout.size() != tx.vin.size()) {
             error("DisconnectBlock(): transaction and undo data inconsistent");
             return DisconnectResult::FAILED;
         }
 
         for (size_t j = 0; j < tx.vin.size(); j++) {
             const COutPoint &out = tx.vin[j].prevout;
             const Coin &undo = txundo.vprevout[j];
             DisconnectResult res = UndoCoinSpend(undo, view, out);
             if (res == DisconnectResult::FAILED) {
                 return DisconnectResult::FAILED;
             }
             fClean = fClean && res != DisconnectResult::UNCLEAN;
         }
     }
 
     // Second, revert created outputs.
     for (const auto &ptx : block.vtx) {
         const CTransaction &tx = *ptx;
         const TxId &txid = tx.GetId();
         const bool is_coinbase = tx.IsCoinBase();
 
         // Check that all outputs are available and match the outputs in the
         // block itself exactly.
         for (size_t o = 0; o < tx.vout.size(); o++) {
             if (tx.vout[o].scriptPubKey.IsUnspendable()) {
                 continue;
             }
 
             COutPoint out(txid, o);
             Coin coin;
             bool is_spent = view.SpendCoin(out, &coin);
             if (!is_spent || tx.vout[o] != coin.GetTxOut() ||
                 uint32_t(pindex->nHeight) != coin.GetHeight() ||
                 is_coinbase != coin.IsCoinBase()) {
                 // transaction output mismatch
                 fClean = false;
             }
         }
     }
 
     // Move best block pointer to previous block.
     view.SetBestBlock(block.hashPrevBlock);
 
     return fClean ? DisconnectResult::OK : DisconnectResult::UNCLEAN;
 }
 
 static void FlushBlockFile(bool fFinalize = false) {
     LOCK(cs_LastBlockFile);
 
     FlatFilePos block_pos_old(nLastBlockFile,
                               vinfoBlockFile[nLastBlockFile].nSize);
     FlatFilePos undo_pos_old(nLastBlockFile,
                              vinfoBlockFile[nLastBlockFile].nUndoSize);
 
     bool status = true;
     status &= BlockFileSeq().Flush(block_pos_old, fFinalize);
     status &= UndoFileSeq().Flush(undo_pos_old, fFinalize);
     if (!status) {
         AbortNode("Flushing block file to disk failed. This is likely the "
                   "result of an I/O error.");
     }
 }
 
 static bool FindUndoPos(CValidationState &state, int nFile, FlatFilePos &pos,
                         unsigned int nAddSize);
 
 static bool WriteUndoDataForBlock(const CBlockUndo &blockundo,
                                   CValidationState &state, CBlockIndex *pindex,
                                   const CChainParams &chainparams) {
     // Write undo information to disk
     if (pindex->GetUndoPos().IsNull()) {
         FlatFilePos _pos;
         if (!FindUndoPos(state, pindex->nFile, _pos,
                          ::GetSerializeSize(blockundo, CLIENT_VERSION) + 40)) {
             return error("ConnectBlock(): FindUndoPos failed");
         }
         if (!UndoWriteToDisk(blockundo, _pos, pindex->pprev->GetBlockHash(),
                              chainparams.DiskMagic())) {
             return AbortNode(state, "Failed to write undo data");
         }
 
         // update nUndoPos in block index
         pindex->nUndoPos = _pos.nPos;
         pindex->nStatus = pindex->nStatus.withUndo();
         setDirtyBlockIndex.insert(pindex);
     }
 
     return true;
 }
 
 static CCheckQueue<CScriptCheck> scriptcheckqueue(128);
 
 void ThreadScriptCheck(int worker_num) {
     util::ThreadRename(strprintf("scriptch.%i", worker_num));
     scriptcheckqueue.Thread();
 }
 
 VersionBitsCache versionbitscache GUARDED_BY(cs_main);
 
 int32_t ComputeBlockVersion(const CBlockIndex *pindexPrev,
                             const Consensus::Params &params) {
     LOCK(cs_main);
     int32_t nVersion = VERSIONBITS_TOP_BITS;
 
     for (int i = 0; i < (int)Consensus::MAX_VERSION_BITS_DEPLOYMENTS; i++) {
         ThresholdState state = VersionBitsState(
             pindexPrev, params, static_cast<Consensus::DeploymentPos>(i),
             versionbitscache);
         if (state == ThresholdState::LOCKED_IN ||
             state == ThresholdState::STARTED) {
             nVersion |= VersionBitsMask(
                 params, static_cast<Consensus::DeploymentPos>(i));
         }
     }
 
     // Clear the last 4 bits (miner fund activation).
     return nVersion & ~uint32_t(0x0f);
 }
 
 // Returns the script flags which should be checked for the block after
 // the given block.
 static uint32_t GetNextBlockScriptFlags(const Consensus::Params &params,
                                         const CBlockIndex *pindex) {
     uint32_t flags = SCRIPT_VERIFY_NONE;
 
     // Start enforcing P2SH (BIP16)
     if ((pindex->nHeight + 1) >= params.BIP16Height) {
         flags |= SCRIPT_VERIFY_P2SH;
     }
 
     // Start enforcing the DERSIG (BIP66) rule.
     if ((pindex->nHeight + 1) >= params.BIP66Height) {
         flags |= SCRIPT_VERIFY_DERSIG;
     }
 
     // Start enforcing CHECKLOCKTIMEVERIFY (BIP65) rule.
     if ((pindex->nHeight + 1) >= params.BIP65Height) {
         flags |= SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY;
     }
 
     // Start enforcing CSV (BIP68, BIP112 and BIP113) rule.
     if ((pindex->nHeight + 1) >= params.CSVHeight) {
         flags |= SCRIPT_VERIFY_CHECKSEQUENCEVERIFY;
     }
 
     // If the UAHF is enabled, we start accepting replay protected txns
     if (IsUAHFenabled(params, pindex)) {
         flags |= SCRIPT_VERIFY_STRICTENC;
         flags |= SCRIPT_ENABLE_SIGHASH_FORKID;
     }
 
     // If the DAA HF is enabled, we start rejecting transaction that use a high
     // s in their signature. We also make sure that signature that are supposed
     // to fail (for instance in multisig or other forms of smart contracts) are
     // null.
     if (IsDAAEnabled(params, pindex)) {
         flags |= SCRIPT_VERIFY_LOW_S;
         flags |= SCRIPT_VERIFY_NULLFAIL;
     }
 
     // When the magnetic anomaly fork is enabled, we start accepting
     // transactions using the OP_CHECKDATASIG opcode and it's verify
     // alternative. We also start enforcing push only signatures and
     // clean stack.
     if (IsMagneticAnomalyEnabled(params, pindex)) {
         flags |= SCRIPT_VERIFY_CHECKDATASIG_SIGOPS;
         flags |= SCRIPT_VERIFY_SIGPUSHONLY;
         flags |= SCRIPT_VERIFY_CLEANSTACK;
     }
 
     if (IsGravitonEnabled(params, pindex)) {
         flags |= SCRIPT_ENABLE_SCHNORR_MULTISIG;
         flags |= SCRIPT_VERIFY_MINIMALDATA;
     }
 
     if (IsPhononEnabled(params, pindex)) {
         flags |= SCRIPT_REPORT_SIGCHECKS;
     }
 
     // We make sure this node will have replay protection during the next hard
     // fork.
     if (IsReplayProtectionEnabled(params, pindex)) {
         flags |= SCRIPT_ENABLE_REPLAY_PROTECTION;
     }
 
     return flags;
 }
 
 static int64_t nTimeCheck = 0;
 static int64_t nTimeForks = 0;
 static int64_t nTimeVerify = 0;
 static int64_t nTimeConnect = 0;
 static int64_t nTimeIndex = 0;
 static int64_t nTimeCallbacks = 0;
 static int64_t nTimeTotal = 0;
 static int64_t nBlocksTotal = 0;
 
 /**
  * Apply the effects of this block (with given index) on the UTXO set
  * represented by coins. Validity checks that depend on the UTXO set are also
  * done; ConnectBlock() can fail if those validity checks fail (among other
  * reasons).
  */
 bool CChainState::ConnectBlock(const CBlock &block, CValidationState &state,
                                CBlockIndex *pindex, CCoinsViewCache &view,
                                const CChainParams &params,
                                BlockValidationOptions options,
                                bool fJustCheck) {
     AssertLockHeld(cs_main);
     assert(pindex);
     assert(*pindex->phashBlock == block.GetHash());
     int64_t nTimeStart = GetTimeMicros();
 
     const Consensus::Params &consensusParams = params.GetConsensus();
 
     // Check it again in case a previous version let a bad block in
     // NOTE: We don't currently (re-)invoke ContextualCheckBlock() or
     // ContextualCheckBlockHeader() here. This means that if we add a new
     // consensus rule that is enforced in one of those two functions, then we
     // may have let in a block that violates the rule prior to updating the
     // software, and we would NOT be enforcing the rule here. Fully solving
     // upgrade from one software version to the next after a consensus rule
     // change is potentially tricky and issue-specific.
     // Also, currently the rule against blocks more than 2 hours in the future
     // is enforced in ContextualCheckBlockHeader(); we wouldn't want to
     // re-enforce that rule here (at least until we make it impossible for
     // GetAdjustedTime() to go backward).
     if (!CheckBlock(block, state, consensusParams,
                     options.withCheckPoW(!fJustCheck)
                         .withCheckMerkleRoot(!fJustCheck))) {
         if (state.CorruptionPossible()) {
             // We don't write down blocks to disk if they may have been
             // corrupted, so this should be impossible unless we're having
             // hardware problems.
             return AbortNode(state, "Corrupt block found indicating potential "
                                     "hardware failure; shutting down");
         }
         return error("%s: Consensus::CheckBlock: %s", __func__,
                      FormatStateMessage(state));
     }
 
     // Verify that the view's current state corresponds to the previous block
     BlockHash hashPrevBlock =
         pindex->pprev == nullptr ? BlockHash() : pindex->pprev->GetBlockHash();
     assert(hashPrevBlock == view.GetBestBlock());
 
     // Special case for the genesis block, skipping connection of its
     // transactions (its coinbase is unspendable)
     if (block.GetHash() == consensusParams.hashGenesisBlock) {
         if (!fJustCheck) {
             view.SetBestBlock(pindex->GetBlockHash());
         }
 
         return true;
     }
 
     nBlocksTotal++;
 
     bool fScriptChecks = true;
     if (!hashAssumeValid.IsNull()) {
         // We've been configured with the hash of a block which has been
         // externally verified to have a valid history. A suitable default value
         // is included with the software and updated from time to time. Because
         // validity relative to a piece of software is an objective fact these
         // defaults can be easily reviewed. This setting doesn't force the
         // selection of any particular chain but makes validating some faster by
         // effectively caching the result of part of the verification.
         BlockMap::const_iterator it = mapBlockIndex.find(hashAssumeValid);
         if (it != mapBlockIndex.end()) {
             if (it->second->GetAncestor(pindex->nHeight) == pindex &&
                 pindexBestHeader->GetAncestor(pindex->nHeight) == pindex &&
                 pindexBestHeader->nChainWork >= nMinimumChainWork) {
                 // This block is a member of the assumed verified chain and an
                 // ancestor of the best header. The equivalent time check
                 // discourages hash power from extorting the network via DOS
                 // attack into accepting an invalid block through telling users
                 // they must manually set assumevalid. Requiring a software
                 // change or burying the invalid block, regardless of the
                 // setting, makes it hard to hide the implication of the demand.
                 // This also avoids having release candidates that are hardly
                 // doing any signature verification at all in testing without
                 // having to artificially set the default assumed verified block
                 // further back. The test against nMinimumChainWork prevents the
                 // skipping when denied access to any chain at least as good as
                 // the expected chain.
                 fScriptChecks =
                     (GetBlockProofEquivalentTime(
                          *pindexBestHeader, *pindex, *pindexBestHeader,
                          consensusParams) <= 60 * 60 * 24 * 7 * 2);
             }
         }
     }
 
     int64_t nTime1 = GetTimeMicros();
     nTimeCheck += nTime1 - nTimeStart;
     LogPrint(BCLog::BENCH, "    - Sanity checks: %.2fms [%.2fs (%.2fms/blk)]\n",
              MILLI * (nTime1 - nTimeStart), nTimeCheck * MICRO,
              nTimeCheck * MILLI / nBlocksTotal);
 
     // Do not allow blocks that contain transactions which 'overwrite' older
     // transactions, unless those are already completely spent. If such
     // overwrites are allowed, coinbases and transactions depending upon those
     // can be duplicated to remove the ability to spend the first instance --
     // even after being sent to another address. See BIP30 and
     // http://r6.ca/blog/20120206T005236Z.html for more information. This logic
     // is not necessary for memory pool transactions, as AcceptToMemoryPool
     // already refuses previously-known transaction ids entirely. This rule was
     // originally applied to all blocks with a timestamp after March 15, 2012,
     // 0:00 UTC. Now that the whole chain is irreversibly beyond that time it is
     // applied to all blocks except the two in the chain that violate it. This
     // prevents exploiting the issue against nodes during their initial block
     // download.
     bool fEnforceBIP30 = !((pindex->nHeight == 91842 &&
                             pindex->GetBlockHash() ==
                                 uint256S("0x00000000000a4d0a398161ffc163c503763"
                                          "b1f4360639393e0e4c8e300e0caec")) ||
                            (pindex->nHeight == 91880 &&
                             pindex->GetBlockHash() ==
                                 uint256S("0x00000000000743f190a18c5577a3c2d2a1f"
                                          "610ae9601ac046a38084ccb7cd721")));
 
     // Once BIP34 activated it was not possible to create new duplicate
     // coinbases and thus other than starting with the 2 existing duplicate
     // coinbase pairs, not possible to create overwriting txs. But by the time
     // BIP34 activated, in each of the existing pairs the duplicate coinbase had
     // overwritten the first before the first had been spent. Since those
     // coinbases are sufficiently buried it's no longer possible to create
     // further duplicate transactions descending from the known pairs either. If
     // we're on the known chain at height greater than where BIP34 activated, we
     // can save the db accesses needed for the BIP30 check.
     assert(pindex->pprev);
     CBlockIndex *pindexBIP34height =
         pindex->pprev->GetAncestor(consensusParams.BIP34Height);
     // Only continue to enforce if we're below BIP34 activation height or the
     // block hash at that height doesn't correspond.
     fEnforceBIP30 =
         fEnforceBIP30 &&
         (!pindexBIP34height ||
          !(pindexBIP34height->GetBlockHash() == consensusParams.BIP34Hash));
 
     if (fEnforceBIP30) {
         for (const auto &tx : block.vtx) {
             for (size_t o = 0; o < tx->vout.size(); o++) {
                 if (view.HaveCoin(COutPoint(tx->GetId(), o))) {
                     return state.DoS(
                         100,
                         error("ConnectBlock(): tried to overwrite transaction"),
                         REJECT_INVALID, "bad-txns-BIP30");
                 }
             }
         }
     }
 
     // Start enforcing BIP68 (sequence locks).
     int nLockTimeFlags = 0;
     if (pindex->nHeight >= consensusParams.CSVHeight) {
         nLockTimeFlags |= LOCKTIME_VERIFY_SEQUENCE;
     }
 
     const uint32_t flags =
         GetNextBlockScriptFlags(consensusParams, pindex->pprev);
 
     int64_t nTime2 = GetTimeMicros();
     nTimeForks += nTime2 - nTime1;
     LogPrint(BCLog::BENCH, "    - Fork checks: %.2fms [%.2fs (%.2fms/blk)]\n",
              MILLI * (nTime2 - nTime1), nTimeForks * MICRO,
              nTimeForks * MILLI / nBlocksTotal);
 
     std::vector<int> prevheights;
     Amount nFees = Amount::zero();
     int nInputs = 0;
 
     // Limit the total executed signature operations in the block, a consensus
     // rule. Tracking during the CPU-consuming part (validation of uncached
     // inputs) is per-input atomic and validation in each thread stops very
     // quickly after the limit is exceeded, so an adversary cannot cause us to
     // exceed the limit by much at all.
     CheckInputsLimiter nSigChecksBlockLimiter(
         GetMaxBlockSigChecksCount(options.getExcessiveBlockSize()));
 
     std::vector<TxSigCheckLimiter> nSigChecksTxLimiters;
     nSigChecksTxLimiters.resize(block.vtx.size() - 1);
 
     CBlockUndo blockundo;
     blockundo.vtxundo.resize(block.vtx.size() - 1);
 
     CCheckQueueControl<CScriptCheck> control(fScriptChecks ? &scriptcheckqueue
                                                            : nullptr);
 
     // Add all outputs
     try {
         for (const auto &ptx : block.vtx) {
             AddCoins(view, *ptx, pindex->nHeight);
         }
     } catch (const std::logic_error &e) {
         // This error will be thrown from AddCoin if we try to connect a block
         // containing duplicate transactions. Such a thing should normally be
         // caught early nowadays (due to ContextualCheckBlock's CTOR
         // enforcement) however some edge cases can escape that:
         // - ContextualCheckBlock does not get re-run after saving the block to
         // disk, and older versions may have saved a weird block.
         // - its checks are not applied to pre-CTOR chains, which we might visit
         // with checkpointing off.
         return state.DoS(
             100, error("ConnectBlock(): tried to overwrite transaction"),
             REJECT_INVALID, "tx-duplicate");
     }
 
     size_t txIndex = 0;
     for (const auto &ptx : block.vtx) {
         const CTransaction &tx = *ptx;
         const bool isCoinBase = tx.IsCoinBase();
         nInputs += tx.vin.size();
 
         Amount txfee = Amount::zero();
         if (!isCoinBase && !Consensus::CheckTxInputs(tx, state, view,
                                                      pindex->nHeight, txfee)) {
             return error("%s: Consensus::CheckTxInputs: %s, %s", __func__,
                          tx.GetId().ToString(), FormatStateMessage(state));
         }
         nFees += txfee;
         if (!MoneyRange(nFees)) {
             return state.DoS(
                 100,
                 error("%s: accumulated fee in the block out of range.",
                       __func__),
                 REJECT_INVALID, "bad-txns-accumulated-fee-outofrange");
         }
 
         // The following checks do not apply to the coinbase.
         if (isCoinBase) {
             continue;
         }
 
         // Check that transaction is BIP68 final BIP68 lock checks (as
         // opposed to nLockTime checks) must be in ConnectBlock because they
         // require the UTXO set.
         prevheights.resize(tx.vin.size());
         for (size_t j = 0; j < tx.vin.size(); j++) {
             prevheights[j] = view.AccessCoin(tx.vin[j].prevout).GetHeight();
         }
 
         if (!SequenceLocks(tx, nLockTimeFlags, &prevheights, *pindex)) {
             return state.DoS(
                 100,
                 error("%s: contains a non-BIP68-final transaction", __func__),
                 REJECT_INVALID, "bad-txns-nonfinal");
         }
 
         // Don't cache results if we're actually connecting blocks (still
         // consult the cache, though).
         bool fCacheResults = fJustCheck;
 
         std::vector<CScriptCheck> vChecks;
         // nSigChecksRet may be accurate (found in cache) or 0 (checks were
         // deferred into vChecks).
         int nSigChecksRet;
         if (!CheckInputs(tx, state, view, fScriptChecks, flags, fCacheResults,
                          fCacheResults, PrecomputedTransactionData(tx),
                          nSigChecksRet, nSigChecksTxLimiters.at(txIndex),
                          &nSigChecksBlockLimiter, &vChecks)) {
             // Parallel CheckInputs shouldn't fail except for this reason, which
             // is banworthy. Use "blk-bad-inputs" to mimic the parallel script
             // check error.
             if (!nSigChecksBlockLimiter.check()) {
                 return state.DoS(100, false, REJECT_INVALID, "blk-bad-inputs",
                                  false, "CheckInputs exceeded SigChecks limit");
             }
             return error("ConnectBlock(): CheckInputs on %s failed with %s",
                          tx.GetId().ToString(), FormatStateMessage(state));
         }
 
         control.Add(vChecks);
 
         // Note: this must execute in the same iteration as CheckTxInputs (not
         // in a separate loop) in order to detect double spends. However,
         // this does not prevent double-spending by duplicated transaction
         // inputs in the same transaction (cf. CVE-2018-17144) -- that check is
         // done in CheckBlock (CheckRegularTransaction).
         SpendCoins(view, tx, blockundo.vtxundo.at(txIndex), pindex->nHeight);
         txIndex++;
     }
 
     int64_t nTime3 = GetTimeMicros();
     nTimeConnect += nTime3 - nTime2;
     LogPrint(BCLog::BENCH,
              "      - Connect %u transactions: %.2fms (%.3fms/tx, %.3fms/txin) "
              "[%.2fs (%.2fms/blk)]\n",
              (unsigned)block.vtx.size(), MILLI * (nTime3 - nTime2),
              MILLI * (nTime3 - nTime2) / block.vtx.size(),
              nInputs <= 1 ? 0 : MILLI * (nTime3 - nTime2) / (nInputs - 1),
              nTimeConnect * MICRO, nTimeConnect * MILLI / nBlocksTotal);
 
     Amount blockReward =
         nFees + GetBlockSubsidy(pindex->nHeight, consensusParams);
     if (block.vtx[0]->GetValueOut() > blockReward) {
         return state.DoS(100,
                          error("ConnectBlock(): coinbase pays too much "
                                "(actual=%d vs limit=%d)",
                                block.vtx[0]->GetValueOut(), blockReward),
                          REJECT_INVALID, "bad-cb-amount");
     }
 
     const std::vector<CTxDestination> whitelist =
         GetMinerFundWhitelist(consensusParams, pindex->pprev);
     if (!whitelist.empty()) {
         const Amount required = blockReward / MINER_FUND_RATIO;
 
         for (auto &o : block.vtx[0]->vout) {
             if (o.nValue < required) {
                 // This output doesn't qualify because its amount is too low.
                 continue;
             }
 
             CTxDestination address;
             if (!ExtractDestination(o.scriptPubKey, address)) {
                 // Cannot decode address.
                 continue;
             }
 
             if (std::find(whitelist.begin(), whitelist.end(), address) !=
                 whitelist.end()) {
                 goto MinerFundSuccess;
             }
         }
 
         // We did not find an output that match the miner fund requirements.
         return state.DoS(100, false, REJECT_INVALID, "bad-cb-minerfund");
     }
 
 MinerFundSuccess:
 
     if (!control.Wait()) {
         return state.DoS(100, false, REJECT_INVALID, "blk-bad-inputs", false,
                          "parallel script check failed");
     }
 
     int64_t nTime4 = GetTimeMicros();
     nTimeVerify += nTime4 - nTime2;
     LogPrint(
         BCLog::BENCH,
         "    - Verify %u txins: %.2fms (%.3fms/txin) [%.2fs (%.2fms/blk)]\n",
         nInputs - 1, MILLI * (nTime4 - nTime2),
         nInputs <= 1 ? 0 : MILLI * (nTime4 - nTime2) / (nInputs - 1),
         nTimeVerify * MICRO, nTimeVerify * MILLI / nBlocksTotal);
 
     if (fJustCheck) {
         return true;
     }
 
     if (!WriteUndoDataForBlock(blockundo, state, pindex, params)) {
         return false;
     }
 
     if (!pindex->IsValid(BlockValidity::SCRIPTS)) {
         pindex->RaiseValidity(BlockValidity::SCRIPTS);
         setDirtyBlockIndex.insert(pindex);
     }
 
     assert(pindex->phashBlock);
     // add this block to the view's block chain
     view.SetBestBlock(pindex->GetBlockHash());
 
     int64_t nTime5 = GetTimeMicros();
     nTimeIndex += nTime5 - nTime4;
     LogPrint(BCLog::BENCH, "    - Index writing: %.2fms [%.2fs (%.2fms/blk)]\n",
              MILLI * (nTime5 - nTime4), nTimeIndex * MICRO,
              nTimeIndex * MILLI / nBlocksTotal);
 
     int64_t nTime6 = GetTimeMicros();
     nTimeCallbacks += nTime6 - nTime5;
     LogPrint(BCLog::BENCH, "    - Callbacks: %.2fms [%.2fs (%.2fms/blk)]\n",
              MILLI * (nTime6 - nTime5), nTimeCallbacks * MICRO,
              nTimeCallbacks * MILLI / nBlocksTotal);
 
     return true;
 }
 
 bool CChainState::FlushStateToDisk(const CChainParams &chainparams,
                                    CValidationState &state, FlushStateMode mode,
                                    int nManualPruneHeight) {
     int64_t nMempoolUsage = g_mempool.DynamicMemoryUsage();
     LOCK(cs_main);
     static int64_t nLastWrite = 0;
     static int64_t nLastFlush = 0;
     std::set<int> setFilesToPrune;
     bool full_flush_completed = false;
     try {
         {
             bool fFlushForPrune = false;
             bool fDoFullFlush = false;
             LOCK(cs_LastBlockFile);
             if (fPruneMode && (fCheckForPruning || nManualPruneHeight > 0) &&
                 !fReindex) {
                 if (nManualPruneHeight > 0) {
                     FindFilesToPruneManual(setFilesToPrune, nManualPruneHeight);
                 } else {
                     FindFilesToPrune(setFilesToPrune,
                                      chainparams.PruneAfterHeight());
                     fCheckForPruning = false;
                 }
                 if (!setFilesToPrune.empty()) {
                     fFlushForPrune = true;
                     if (!fHavePruned) {
                         pblocktree->WriteFlag("prunedblockfiles", true);
                         fHavePruned = true;
                     }
                 }
             }
             int64_t nNow = GetTimeMicros();
             // Avoid writing/flushing immediately after startup.
             if (nLastWrite == 0) {
                 nLastWrite = nNow;
             }
             if (nLastFlush == 0) {
                 nLastFlush = nNow;
             }
             int64_t nMempoolSizeMax =
                 gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000;
             int64_t cacheSize = pcoinsTip->DynamicMemoryUsage();
             int64_t nTotalSpace =
                 nCoinCacheUsage +
                 std::max<int64_t>(nMempoolSizeMax - nMempoolUsage, 0);
             // The cache is large and we're within 10% and 10 MiB of the limit,
             // but we have time now (not in the middle of a block processing).
             bool fCacheLarge =
                 mode == FlushStateMode::PERIODIC &&
                 cacheSize > std::max((9 * nTotalSpace) / 10,
                                      nTotalSpace -
                                          MAX_BLOCK_COINSDB_USAGE * 1024 * 1024);
             // The cache is over the limit, we have to write now.
             bool fCacheCritical =
                 mode == FlushStateMode::IF_NEEDED && cacheSize > nTotalSpace;
             // It's been a while since we wrote the block index to disk. Do this
             // frequently, so we don't need to redownload after a crash.
             bool fPeriodicWrite =
                 mode == FlushStateMode::PERIODIC &&
                 nNow > nLastWrite + (int64_t)DATABASE_WRITE_INTERVAL * 1000000;
             // It's been very long since we flushed the cache. Do this
             // infrequently, to optimize cache usage.
             bool fPeriodicFlush =
                 mode == FlushStateMode::PERIODIC &&
                 nNow > nLastFlush + (int64_t)DATABASE_FLUSH_INTERVAL * 1000000;
             // Combine all conditions that result in a full cache flush.
             fDoFullFlush = (mode == FlushStateMode::ALWAYS) || fCacheLarge ||
                            fCacheCritical || fPeriodicFlush || fFlushForPrune;
             // Write blocks and block index to disk.
             if (fDoFullFlush || fPeriodicWrite) {
                 // Depend on nMinDiskSpace to ensure we can write block index
                 if (!CheckDiskSpace(GetBlocksDir())) {
                     return AbortNode(state, "Disk space is low!",
                                      _("Error: Disk space is low!").translated);
                 }
 
                 // First make sure all block and undo data is flushed to disk.
                 FlushBlockFile();
                 // Then update all block file information (which may refer to
                 // block and undo files).
                 {
                     std::vector<std::pair<int, const CBlockFileInfo *>> vFiles;
                     vFiles.reserve(setDirtyFileInfo.size());
                     for (int i : setDirtyFileInfo) {
                         vFiles.push_back(std::make_pair(i, &vinfoBlockFile[i]));
                     }
 
                     setDirtyFileInfo.clear();
 
                     std::vector<const CBlockIndex *> vBlocks;
                     vBlocks.reserve(setDirtyBlockIndex.size());
                     for (const CBlockIndex *cbi : setDirtyBlockIndex) {
                         vBlocks.push_back(cbi);
                     }
 
                     setDirtyBlockIndex.clear();
 
                     if (!pblocktree->WriteBatchSync(vFiles, nLastBlockFile,
                                                     vBlocks)) {
                         return AbortNode(
                             state, "Failed to write to block index database");
                     }
                 }
 
                 // Finally remove any pruned files
                 if (fFlushForPrune) {
                     UnlinkPrunedFiles(setFilesToPrune);
                 }
                 nLastWrite = nNow;
             }
             // Flush best chain related state. This can only be done if the
             // blocks / block index write was also done.
             if (fDoFullFlush && !pcoinsTip->GetBestBlock().IsNull()) {
                 // Typical Coin structures on disk are around 48 bytes in size.
                 // Pushing a new one to the database can cause it to be written
                 // twice (once in the log, and once in the tables). This is
                 // already an overestimation, as most will delete an existing
                 // entry or overwrite one. Still, use a conservative safety
                 // factor of 2.
                 if (!CheckDiskSpace(GetDataDir(),
                                     48 * 2 * 2 * pcoinsTip->GetCacheSize())) {
                     return AbortNode(state, "Disk space is low!",
                                      _("Error: Disk space is low!").translated);
                 }
 
                 // Flush the chainstate (which may refer to block index
                 // entries).
                 if (!pcoinsTip->Flush()) {
                     return AbortNode(state, "Failed to write to coin database");
                 }
                 nLastFlush = nNow;
                 full_flush_completed = true;
             }
         }
 
         if (full_flush_completed) {
             // Update best block in wallet (so we can detect restored wallets).
             GetMainSignals().ChainStateFlushed(m_chain.GetLocator());
         }
     } catch (const std::runtime_error &e) {
         return AbortNode(state, std::string("System error while flushing: ") +
                                     e.what());
     }
     return true;
 }
 
 void CChainState::ForceFlushStateToDisk() {
     CValidationState state;
     const CChainParams &chainparams = Params();
     if (!this->FlushStateToDisk(chainparams, state, FlushStateMode::ALWAYS)) {
         LogPrintf("%s: failed to flush state (%s)\n", __func__,
                   FormatStateMessage(state));
     }
 }
 
 void CChainState::PruneAndFlush() {
     CValidationState state;
     fCheckForPruning = true;
     const CChainParams &chainparams = Params();
     if (!this->FlushStateToDisk(chainparams, state, FlushStateMode::NONE)) {
         LogPrintf("%s: failed to flush state (%s)\n", __func__,
                   FormatStateMessage(state));
     }
 }
 
 /** Check warning conditions and do some notifications on new chain tip set. */
 static void UpdateTip(const CChainParams &params, CBlockIndex *pindexNew) {
     // New best block
     g_mempool.AddTransactionsUpdated(1);
 
     {
         LOCK(g_best_block_mutex);
         g_best_block = pindexNew->GetBlockHash();
         g_best_block_cv.notify_all();
     }
 
     LogPrintf("%s: new best=%s height=%d version=0x%08x log2_work=%.8g tx=%lu "
               "date='%s' progress=%f cache=%.1fMiB(%utxo)\n",
               __func__, pindexNew->GetBlockHash().ToString(),
               pindexNew->nHeight, pindexNew->nVersion,
               log(pindexNew->nChainWork.getdouble()) / log(2.0),
               (unsigned long)pindexNew->nChainTx,
               FormatISO8601DateTime(pindexNew->GetBlockTime()),
               GuessVerificationProgress(params.TxData(), pindexNew),
               pcoinsTip->DynamicMemoryUsage() * (1.0 / (1 << 20)),
               pcoinsTip->GetCacheSize());
 }
 
 /**
  * Disconnect m_chain's tip.
  * After calling, the mempool will be in an inconsistent state, with
  * transactions from disconnected blocks being added to disconnectpool. You
  * should make the mempool consistent again by calling updateMempoolForReorg.
  * with cs_main held.
  *
  * If disconnectpool is nullptr, then no disconnected transactions are added to
  * disconnectpool (note that the caller is responsible for mempool consistency
  * in any case).
  */
 bool CChainState::DisconnectTip(const CChainParams &params,
                                 CValidationState &state,
                                 DisconnectedBlockTransactions *disconnectpool) {
     AssertLockHeld(cs_main);
     CBlockIndex *pindexDelete = m_chain.Tip();
     const Consensus::Params &consensusParams = params.GetConsensus();
 
     assert(pindexDelete);
 
     // Read block from disk.
     std::shared_ptr<CBlock> pblock = std::make_shared<CBlock>();
     CBlock &block = *pblock;
     if (!ReadBlockFromDisk(block, pindexDelete, consensusParams)) {
         return AbortNode(state, "Failed to read block");
     }
 
     // Apply the block atomically to the chain state.
     int64_t nStart = GetTimeMicros();
     {
         CCoinsViewCache view(pcoinsTip.get());
         assert(view.GetBestBlock() == pindexDelete->GetBlockHash());
         if (DisconnectBlock(block, pindexDelete, view) !=
             DisconnectResult::OK) {
             return error("DisconnectTip(): DisconnectBlock %s failed",
                          pindexDelete->GetBlockHash().ToString());
         }
 
         bool flushed = view.Flush();
         assert(flushed);
     }
 
     LogPrint(BCLog::BENCH, "- Disconnect block: %.2fms\n",
              (GetTimeMicros() - nStart) * MILLI);
 
     // Write the chain state to disk, if necessary.
     if (!FlushStateToDisk(params, state, FlushStateMode::IF_NEEDED)) {
         return false;
     }
 
     // If this block is deactivating a fork, we move all mempool transactions
     // in front of disconnectpool for reprocessing in a future
     // updateMempoolForReorg call
     if (pindexDelete->pprev != nullptr &&
         GetNextBlockScriptFlags(consensusParams, pindexDelete) !=
             GetNextBlockScriptFlags(consensusParams, pindexDelete->pprev)) {
         LogPrint(BCLog::MEMPOOL,
                  "Disconnecting mempool due to rewind of upgrade block\n");
         if (disconnectpool) {
             disconnectpool->importMempool(g_mempool);
         }
         g_mempool.clear();
     }
 
     if (disconnectpool) {
         disconnectpool->addForBlock(block.vtx);
     }
 
     // If the tip is finalized, then undo it.
     if (pindexFinalized == pindexDelete) {
         pindexFinalized = pindexDelete->pprev;
     }
 
     m_chain.SetTip(pindexDelete->pprev);
 
     // Update ::ChainActive() and related variables.
     UpdateTip(params, pindexDelete->pprev);
     // Let wallets know transactions went from 1-confirmed to
     // 0-confirmed or conflicted:
     GetMainSignals().BlockDisconnected(pblock);
     return true;
 }
 
 static int64_t nTimeReadFromDisk = 0;
 static int64_t nTimeConnectTotal = 0;
 static int64_t nTimeFlush = 0;
 static int64_t nTimeChainState = 0;
 static int64_t nTimePostConnect = 0;
 
 struct PerBlockConnectTrace {
     CBlockIndex *pindex = nullptr;
     std::shared_ptr<const CBlock> pblock;
     std::shared_ptr<std::vector<CTransactionRef>> conflictedTxs;
     PerBlockConnectTrace()
         : conflictedTxs(std::make_shared<std::vector<CTransactionRef>>()) {}
 };
 
 /**
  * Used to track blocks whose transactions were applied to the UTXO state as a
  * part of a single ActivateBestChainStep call.
  *
  * This class also tracks transactions that are removed from the mempool as
  * conflicts (per block) and can be used to pass all those transactions through
  * SyncTransaction.
  *
  * This class assumes (and asserts) that the conflicted transactions for a given
  * block are added via mempool callbacks prior to the BlockConnected()
  * associated with those transactions. If any transactions are marked
  * conflicted, it is assumed that an associated block will always be added.
  *
  * This class is single-use, once you call GetBlocksConnected() you have to
  * throw it away and make a new one.
  */
 class ConnectTrace {
 private:
     std::vector<PerBlockConnectTrace> blocksConnected;
     CTxMemPool &pool;
     boost::signals2::scoped_connection m_connNotifyEntryRemoved;
 
 public:
     explicit ConnectTrace(CTxMemPool &_pool) : blocksConnected(1), pool(_pool) {
         m_connNotifyEntryRemoved = pool.NotifyEntryRemoved.connect(
             std::bind(&ConnectTrace::NotifyEntryRemoved, this,
                       std::placeholders::_1, std::placeholders::_2));
     }
 
     void BlockConnected(CBlockIndex *pindex,
                         std::shared_ptr<const CBlock> pblock) {
         assert(!blocksConnected.back().pindex);
         assert(pindex);
         assert(pblock);
         blocksConnected.back().pindex = pindex;
         blocksConnected.back().pblock = std::move(pblock);
         blocksConnected.emplace_back();
     }
 
     std::vector<PerBlockConnectTrace> &GetBlocksConnected() {
         // We always keep one extra block at the end of our list because blocks
         // are added after all the conflicted transactions have been filled in.
         // Thus, the last entry should always be an empty one waiting for the
         // transactions from the next block. We pop the last entry here to make
         // sure the list we return is sane.
         assert(!blocksConnected.back().pindex);
         assert(blocksConnected.back().conflictedTxs->empty());
         blocksConnected.pop_back();
         return blocksConnected;
     }
 
     void NotifyEntryRemoved(CTransactionRef txRemoved,
                             MemPoolRemovalReason reason) {
         assert(!blocksConnected.back().pindex);
         if (reason == MemPoolRemovalReason::CONFLICT) {
             blocksConnected.back().conflictedTxs->emplace_back(
                 std::move(txRemoved));
         }
     }
 };
 
 static bool FinalizeBlockInternal(const Config &config, CValidationState &state,
                                   const CBlockIndex *pindex)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
     AssertLockHeld(cs_main);
     if (pindex->nStatus.isInvalid()) {
         // We try to finalize an invalid block.
         return state.DoS(100,
                          error("%s: Trying to finalize invalid block %s",
                                __func__, pindex->GetBlockHash().ToString()),
                          REJECT_INVALID, "finalize-invalid-block");
     }
 
     // Check that the request is consistent with current finalization.
     if (pindexFinalized && !AreOnTheSameFork(pindex, pindexFinalized)) {
         return state.DoS(
             20,
             error("%s: Trying to finalize block %s which conflicts "
                   "with already finalized block",
                   __func__, pindex->GetBlockHash().ToString()),
             REJECT_AGAINST_FINALIZED, "bad-fork-prior-finalized");
     }
 
     if (IsBlockFinalized(pindex)) {
         // The block is already finalized.
         return true;
     }
 
     // We have a new block to finalize.
     pindexFinalized = pindex;
     return true;
 }
 
 static const CBlockIndex *FindBlockToFinalize(const Config &config,
                                               CBlockIndex *pindexNew)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
     AssertLockHeld(cs_main);
 
     const int32_t maxreorgdepth =
         gArgs.GetArg("-maxreorgdepth", DEFAULT_MAX_REORG_DEPTH);
 
     const int64_t finalizationdelay =
         gArgs.GetArg("-finalizationdelay", DEFAULT_MIN_FINALIZATION_DELAY);
 
     // Find our candidate.
     // If maxreorgdepth is < 0 pindex will be null and auto finalization
     // disabled
     const CBlockIndex *pindex =
         pindexNew->GetAncestor(pindexNew->nHeight - maxreorgdepth);
 
     int64_t now = GetTime();
 
     // If the finalization delay is not expired since the startup time,
     // finalization should be avoided. Header receive time is not saved to disk
     // and so cannot be anterior to startup time.
     if (now < (GetStartupTime() + finalizationdelay)) {
         return nullptr;
     }
 
     // While our candidate is not eligible (finalization delay not expired), try
     // the previous one.
     while (pindex && (pindex != pindexFinalized)) {
         // Check that the block to finalize is known for a long enough time.
         // This test will ensure that an attacker could not cause a block to
         // finalize by forking the chain with a depth > maxreorgdepth.
         // If the block is loaded from disk, header receive time is 0 and the
         // block will be finalized. This is safe because the delay since the
         // node startup is already expired.
         auto headerReceivedTime = pindex->GetHeaderReceivedTime();
 
         // If finalization delay is <= 0, finalization always occurs immediately
         if (now >= (headerReceivedTime + finalizationdelay)) {
             return pindex;
         }
 
         pindex = pindex->pprev;
     }
 
     return nullptr;
 }
 
 /**
  * Connect a new block to m_chain. pblock is either nullptr or a pointer to
  * a CBlock corresponding to pindexNew, to bypass loading it again from disk.
  *
  * The block is always added to connectTrace (either after loading from disk or
  * by copying pblock) - if that is not intended, care must be taken to remove
  * the last entry in blocksConnected in case of failure.
  */
 bool CChainState::ConnectTip(const Config &config, CValidationState &state,
                              CBlockIndex *pindexNew,
                              const std::shared_ptr<const CBlock> &pblock,
                              ConnectTrace &connectTrace,
                              DisconnectedBlockTransactions &disconnectpool) {
     AssertLockHeld(cs_main);
 
     const CChainParams &params = config.GetChainParams();
     const Consensus::Params &consensusParams = params.GetConsensus();
 
     assert(pindexNew->pprev == m_chain.Tip());
     // Read block from disk.
     int64_t nTime1 = GetTimeMicros();
     std::shared_ptr<const CBlock> pthisBlock;
     if (!pblock) {
         std::shared_ptr<CBlock> pblockNew = std::make_shared<CBlock>();
         if (!ReadBlockFromDisk(*pblockNew, pindexNew, consensusParams)) {
             return AbortNode(state, "Failed to read block");
         }
         pthisBlock = pblockNew;
     } else {
         pthisBlock = pblock;
     }
 
     const CBlock &blockConnecting = *pthisBlock;
 
     // Apply the block atomically to the chain state.
     int64_t nTime2 = GetTimeMicros();
     nTimeReadFromDisk += nTime2 - nTime1;
     int64_t nTime3;
     LogPrint(BCLog::BENCH, "  - Load block from disk: %.2fms [%.2fs]\n",
              (nTime2 - nTime1) * MILLI, nTimeReadFromDisk * MICRO);
     {
         CCoinsViewCache view(pcoinsTip.get());
         bool rv = ConnectBlock(blockConnecting, state, pindexNew, view, params,
                                BlockValidationOptions(config));
         GetMainSignals().BlockChecked(blockConnecting, state);
         if (!rv) {
             if (state.IsInvalid()) {
                 InvalidBlockFound(pindexNew, state);
             }
 
             return error("%s: ConnectBlock %s failed, %s", __func__,
                          pindexNew->GetBlockHash().ToString(),
                          FormatStateMessage(state));
         }
 
         // Update the finalized block.
         const CBlockIndex *pindexToFinalize =
             FindBlockToFinalize(config, pindexNew);
         if (pindexToFinalize &&
             !FinalizeBlockInternal(config, state, pindexToFinalize)) {
             state.SetCorruptionPossible();
             return error("ConnectTip(): FinalizeBlock %s failed (%s)",
                          pindexNew->GetBlockHash().ToString(),
                          FormatStateMessage(state));
         }
 
         nTime3 = GetTimeMicros();
         nTimeConnectTotal += nTime3 - nTime2;
         LogPrint(BCLog::BENCH,
                  "  - Connect total: %.2fms [%.2fs (%.2fms/blk)]\n",
                  (nTime3 - nTime2) * MILLI, nTimeConnectTotal * MICRO,
                  nTimeConnectTotal * MILLI / nBlocksTotal);
         bool flushed = view.Flush();
         assert(flushed);
     }
 
     int64_t nTime4 = GetTimeMicros();
     nTimeFlush += nTime4 - nTime3;
     LogPrint(BCLog::BENCH, "  - Flush: %.2fms [%.2fs (%.2fms/blk)]\n",
              (nTime4 - nTime3) * MILLI, nTimeFlush * MICRO,
              nTimeFlush * MILLI / nBlocksTotal);
 
     // Write the chain state to disk, if necessary.
     if (!FlushStateToDisk(config.GetChainParams(), state,
                           FlushStateMode::IF_NEEDED)) {
         return false;
     }
 
     int64_t nTime5 = GetTimeMicros();
     nTimeChainState += nTime5 - nTime4;
     LogPrint(BCLog::BENCH,
              "  - Writing chainstate: %.2fms [%.2fs (%.2fms/blk)]\n",
              (nTime5 - nTime4) * MILLI, nTimeChainState * MICRO,
              nTimeChainState * MILLI / nBlocksTotal);
 
     // Remove conflicting transactions from the mempool.;
     g_mempool.removeForBlock(blockConnecting.vtx, pindexNew->nHeight);
     disconnectpool.removeForBlock(blockConnecting.vtx);
 
     // If this block is activating a fork, we move all mempool transactions
     // in front of disconnectpool for reprocessing in a future
     // updateMempoolForReorg call
     if (pindexNew->pprev != nullptr &&
         GetNextBlockScriptFlags(consensusParams, pindexNew) !=
             GetNextBlockScriptFlags(consensusParams, pindexNew->pprev)) {
         LogPrint(BCLog::MEMPOOL,
                  "Disconnecting mempool due to acceptance of upgrade block\n");
         disconnectpool.importMempool(g_mempool);
     }
 
     // Update m_chain & related variables.
     m_chain.SetTip(pindexNew);
     UpdateTip(params, pindexNew);
 
     int64_t nTime6 = GetTimeMicros();
     nTimePostConnect += nTime6 - nTime5;
     nTimeTotal += nTime6 - nTime1;
     LogPrint(BCLog::BENCH,
              "  - Connect postprocess: %.2fms [%.2fs (%.2fms/blk)]\n",
              (nTime6 - nTime5) * MILLI, nTimePostConnect * MICRO,
              nTimePostConnect * MILLI / nBlocksTotal);
     LogPrint(BCLog::BENCH, "- Connect block: %.2fms [%.2fs (%.2fms/blk)]\n",
              (nTime6 - nTime1) * MILLI, nTimeTotal * MICRO,
              nTimeTotal * MILLI / nBlocksTotal);
 
     connectTrace.BlockConnected(pindexNew, std::move(pthisBlock));
     return true;
 }
 
 /**
  * Return the tip of the chain with the most work in it, that isn't known to be
  * invalid (it's however far from certain to be valid).
  */
 CBlockIndex *CChainState::FindMostWorkChain() {
     AssertLockHeld(cs_main);
     do {
         CBlockIndex *pindexNew = nullptr;
 
         // Find the best candidate header.
         {
             std::set<CBlockIndex *, CBlockIndexWorkComparator>::reverse_iterator
                 it = setBlockIndexCandidates.rbegin();
             if (it == setBlockIndexCandidates.rend()) {
                 return nullptr;
             }
             pindexNew = *it;
         }
 
         // If this block will cause a finalized block to be reorged, then we
         // mark it as invalid.
         if (pindexFinalized && !AreOnTheSameFork(pindexNew, pindexFinalized)) {
             LogPrintf("Mark block %s invalid because it forks prior to the "
                       "finalization point %d.\n",
                       pindexNew->GetBlockHash().ToString(),
                       pindexFinalized->nHeight);
             pindexNew->nStatus = pindexNew->nStatus.withFailed();
             InvalidChainFound(pindexNew);
         }
 
         const CBlockIndex *pindexFork = m_chain.FindFork(pindexNew);
 
         // Check whether all blocks on the path between the currently active
         // chain and the candidate are valid. Just going until the active chain
         // is an optimization, as we know all blocks in it are valid already.
         CBlockIndex *pindexTest = pindexNew;
         bool hasValidAncestor = true;
         while (hasValidAncestor && pindexTest && pindexTest != pindexFork) {
             assert(pindexTest->HaveTxsDownloaded() || pindexTest->nHeight == 0);
 
             // If this is a parked chain, but it has enough PoW, clear the park
             // state.
             bool fParkedChain = pindexTest->nStatus.isOnParkedChain();
             if (fParkedChain && gArgs.GetBoolArg("-automaticunparking", true)) {
                 const CBlockIndex *pindexTip = m_chain.Tip();
 
                 // During initialization, pindexTip and/or pindexFork may be
                 // null. In this case, we just ignore the fact that the chain is
                 // parked.
                 if (!pindexTip || !pindexFork) {
                     UnparkBlock(pindexTest);
                     continue;
                 }
 
                 // A parked chain can be unparked if it has twice as much PoW
                 // accumulated as the main chain has since the fork block.
                 CBlockIndex const *pindexExtraPow = pindexTip;
                 arith_uint256 requiredWork = pindexTip->nChainWork;
                 switch (pindexTip->nHeight - pindexFork->nHeight) {
                     // Limit the penality for depth 1, 2 and 3 to half a block
                     // worth of work to ensure we don't fork accidentally.
                     case 3:
                     case 2:
                         pindexExtraPow = pindexExtraPow->pprev;
                     // FALLTHROUGH
                     case 1: {
                         const arith_uint256 deltaWork =
                             pindexExtraPow->nChainWork - pindexFork->nChainWork;
                         requiredWork += (deltaWork >> 1);
                         break;
                     }
                     default:
                         requiredWork +=
                             pindexExtraPow->nChainWork - pindexFork->nChainWork;
                         break;
                 }
 
                 if (pindexNew->nChainWork > requiredWork) {
                     // We have enough, clear the parked state.
                     LogPrintf("Unpark chain up to block %s as it has "
                               "accumulated enough PoW.\n",
                               pindexNew->GetBlockHash().ToString());
                     fParkedChain = false;
                     UnparkBlock(pindexTest);
                 }
             }
 
             // Pruned nodes may have entries in setBlockIndexCandidates for
             // which block files have been deleted. Remove those as candidates
             // for the most work chain if we come across them; we can't switch
             // to a chain unless we have all the non-active-chain parent blocks.
             bool fInvalidChain = pindexTest->nStatus.isInvalid();
             bool fMissingData = !pindexTest->nStatus.hasData();
             if (!(fInvalidChain || fParkedChain || fMissingData)) {
                 // The current block is acceptable, move to the parent, up to
                 // the fork point.
                 pindexTest = pindexTest->pprev;
                 continue;
             }
 
             // Candidate chain is not usable (either invalid or parked or
             // missing data)
             hasValidAncestor = false;
             setBlockIndexCandidates.erase(pindexTest);
 
             if (fInvalidChain &&
                 (pindexBestInvalid == nullptr ||
                  pindexNew->nChainWork > pindexBestInvalid->nChainWork)) {
                 pindexBestInvalid = pindexNew;
             }
 
             if (fParkedChain &&
                 (pindexBestParked == nullptr ||
                  pindexNew->nChainWork > pindexBestParked->nChainWork)) {
                 pindexBestParked = pindexNew;
             }
 
             LogPrintf("Considered switching to better tip %s but that chain "
                       "contains a%s%s%s block.\n",
                       pindexNew->GetBlockHash().ToString(),
                       fInvalidChain ? "n invalid" : "",
                       fParkedChain ? " parked" : "",
                       fMissingData ? " missing-data" : "");
 
             CBlockIndex *pindexFailed = pindexNew;
             // Remove the entire chain from the set.
             while (pindexTest != pindexFailed) {
                 if (fInvalidChain || fParkedChain) {
                     pindexFailed->nStatus =
                         pindexFailed->nStatus.withFailedParent(fInvalidChain)
                             .withParkedParent(fParkedChain);
                 } else if (fMissingData) {
                     // If we're missing data, then add back to
                     // mapBlocksUnlinked, so that if the block arrives in the
                     // future we can try adding to setBlockIndexCandidates
                     // again.
                     mapBlocksUnlinked.insert(
                         std::make_pair(pindexFailed->pprev, pindexFailed));
                 }
                 setBlockIndexCandidates.erase(pindexFailed);
                 pindexFailed = pindexFailed->pprev;
             }
 
             if (fInvalidChain || fParkedChain) {
                 // We discovered a new chain tip that is either parked or
                 // invalid, we may want to warn.
                 CheckForkWarningConditionsOnNewFork(pindexNew);
             }
         }
 
         if (g_avalanche && pindexNew->nStatus.isOnParkedChain() &&
             gArgs.GetBoolArg("-enableavalanche", AVALANCHE_DEFAULT_ENABLED)) {
             g_avalanche->addBlockToReconcile(pindexNew);
         }
 
         // We found a candidate that has valid ancestors. This is our guy.
         if (hasValidAncestor) {
             return pindexNew;
         }
     } while (true);
 }
 
 /**
  * Delete all entries in setBlockIndexCandidates that are worse than the current
  * tip.
  */
 void CChainState::PruneBlockIndexCandidates() {
     // Note that we can't delete the current block itself, as we may need to
     // return to it later in case a reorganization to a better block fails.
     auto it = setBlockIndexCandidates.begin();
     while (it != setBlockIndexCandidates.end() &&
            setBlockIndexCandidates.value_comp()(*it, m_chain.Tip())) {
         setBlockIndexCandidates.erase(it++);
     }
 
     // Either the current tip or a successor of it we're working towards is left
     // in setBlockIndexCandidates.
     assert(!setBlockIndexCandidates.empty());
 }
 
 /**
  * Try to make some progress towards making pindexMostWork the active block.
  * pblock is either nullptr or a pointer to a CBlock corresponding to
  * pindexMostWork.
  */
 bool CChainState::ActivateBestChainStep(
     const Config &config, CValidationState &state, CBlockIndex *pindexMostWork,
     const std::shared_ptr<const CBlock> &pblock, bool &fInvalidFound,
     ConnectTrace &connectTrace) {
     AssertLockHeld(cs_main);
 
     const CBlockIndex *pindexOldTip = m_chain.Tip();
     const CBlockIndex *pindexFork = m_chain.FindFork(pindexMostWork);
 
     // Disconnect active blocks which are no longer in the best chain.
     bool fBlocksDisconnected = false;
     DisconnectedBlockTransactions disconnectpool;
     while (m_chain.Tip() && m_chain.Tip() != pindexFork) {
         if (!DisconnectTip(config.GetChainParams(), state, &disconnectpool)) {
             // This is likely a fatal error, but keep the mempool consistent,
             // just in case. Only remove from the mempool in this case.
             disconnectpool.updateMempoolForReorg(config, false);
             return false;
         }
 
         fBlocksDisconnected = true;
     }
 
     // Build list of new blocks to connect.
     std::vector<CBlockIndex *> vpindexToConnect;
     bool fContinue = true;
     int nHeight = pindexFork ? pindexFork->nHeight : -1;
     while (fContinue && nHeight != pindexMostWork->nHeight) {
         // Don't iterate the entire list of potential improvements toward the
         // best tip, as we likely only need a few blocks along the way.
         int nTargetHeight = std::min(nHeight + 32, pindexMostWork->nHeight);
         vpindexToConnect.clear();
         vpindexToConnect.reserve(nTargetHeight - nHeight);
         CBlockIndex *pindexIter = pindexMostWork->GetAncestor(nTargetHeight);
         while (pindexIter && pindexIter->nHeight != nHeight) {
             vpindexToConnect.push_back(pindexIter);
             pindexIter = pindexIter->pprev;
         }
 
         nHeight = nTargetHeight;
 
         // Connect new blocks.
         for (CBlockIndex *pindexConnect : reverse_iterate(vpindexToConnect)) {
             if (!ConnectTip(config, state, pindexConnect,
                             pindexConnect == pindexMostWork
                                 ? pblock
                                 : std::shared_ptr<const CBlock>(),
                             connectTrace, disconnectpool)) {
                 if (state.IsInvalid()) {
                     // The block violates a consensus rule.
                     if (!state.CorruptionPossible()) {
                         InvalidChainFound(vpindexToConnect.back());
                     }
 
                     state = CValidationState();
                     fInvalidFound = true;
                     fContinue = false;
                     break;
                 }
 
                 // A system error occurred (disk space, database error, ...).
                 // Make the mempool consistent with the current tip, just in
                 // case any observers try to use it before shutdown.
                 disconnectpool.updateMempoolForReorg(config, false);
                 return false;
             } else {
                 PruneBlockIndexCandidates();
                 if (!pindexOldTip ||
                     m_chain.Tip()->nChainWork > pindexOldTip->nChainWork) {
                     // We're in a better position than we were. Return
                     // temporarily to release the lock.
                     fContinue = false;
                     break;
                 }
             }
         }
     }
 
     if (fBlocksDisconnected || !disconnectpool.isEmpty()) {
         // If any blocks were disconnected, we need to update the mempool even
         // if disconnectpool is empty. The disconnectpool may also be non-empty
         // if the mempool was imported due to new validation rules being in
         // effect.
         LogPrint(BCLog::MEMPOOL, "Updating mempool due to reorganization or "
                                  "rules upgrade/downgrade\n");
         disconnectpool.updateMempoolForReorg(config, true);
     }
 
     g_mempool.check(pcoinsTip.get());
 
     // Callbacks/notifications for a new best chain.
     if (fInvalidFound) {
         CheckForkWarningConditionsOnNewFork(pindexMostWork);
     } else {
         CheckForkWarningConditions();
     }
 
     return true;
 }
 
 static void NotifyHeaderTip() LOCKS_EXCLUDED(cs_main) {
     bool fNotify = false;
     bool fInitialBlockDownload = false;
     static CBlockIndex *pindexHeaderOld = nullptr;
     CBlockIndex *pindexHeader = nullptr;
     {
         LOCK(cs_main);
         pindexHeader = pindexBestHeader;
 
         if (pindexHeader != pindexHeaderOld) {
             fNotify = true;
             fInitialBlockDownload =
                 ::ChainstateActive().IsInitialBlockDownload();
             pindexHeaderOld = pindexHeader;
         }
     }
 
     // Send block tip changed notifications without cs_main
     if (fNotify) {
         uiInterface.NotifyHeaderTip(fInitialBlockDownload, pindexHeader);
     }
 }
 
 /**
  * Make the best chain active, in multiple steps. The result is either failure
  * or an activated best chain. pblock is either nullptr or a pointer to a block
  * that is already loaded (to avoid loading it again from disk).
  *
  * ActivateBestChain is split into steps (see ActivateBestChainStep) so that
  * we avoid holding cs_main for an extended period of time; the length of this
  * call may be quite long during reindexing or a substantial reorg.
  */
 bool CChainState::ActivateBestChain(const Config &config,
                                     CValidationState &state,
                                     std::shared_ptr<const CBlock> pblock) {
     // Note that while we're often called here from ProcessNewBlock, this is
     // far from a guarantee. Things in the P2P/RPC will often end up calling
     // us in the middle of ProcessNewBlock - do not assume pblock is set
     // sanely for performance or correctness!
     AssertLockNotHeld(cs_main);
 
     const CChainParams &params = config.GetChainParams();
 
     // ABC maintains a fair degree of expensive-to-calculate internal state
     // because this function periodically releases cs_main so that it does not
     // lock up other threads for too long during large connects - and to allow
     // for e.g. the callback queue to drain we use m_cs_chainstate to enforce
     // mutual exclusion so that only one caller may execute this function at a
     // time
     LOCK(m_cs_chainstate);
 
     CBlockIndex *pindexMostWork = nullptr;
     CBlockIndex *pindexNewTip = nullptr;
     int nStopAtHeight = gArgs.GetArg("-stopatheight", DEFAULT_STOPATHEIGHT);
     do {
         boost::this_thread::interruption_point();
 
         if (GetMainSignals().CallbacksPending() > 10) {
             // Block until the validation queue drains. This should largely
             // never happen in normal operation, however may happen during
             // reindex, causing memory blowup if we run too far ahead.
             // Note that if a validationinterface callback ends up calling
             // ActivateBestChain this may lead to a deadlock! We should
             // probably have a DEBUG_LOCKORDER test for this in the future.
             SyncWithValidationInterfaceQueue();
         }
 
         {
             LOCK(cs_main);
             CBlockIndex *starting_tip = m_chain.Tip();
             bool blocks_connected = false;
             do {
                 // We absolutely may not unlock cs_main until we've made forward
                 // progress (with the exception of shutdown due to hardware
                 // issues, low disk space, etc).
 
                 // Destructed before cs_main is unlocked
                 ConnectTrace connectTrace(g_mempool);
 
                 if (pindexMostWork == nullptr) {
                     pindexMostWork = FindMostWorkChain();
                 }
 
                 // Whether we have anything to do at all.
                 if (pindexMostWork == nullptr ||
                     pindexMostWork == m_chain.Tip()) {
                     break;
                 }
 
                 bool fInvalidFound = false;
                 std::shared_ptr<const CBlock> nullBlockPtr;
                 if (!ActivateBestChainStep(
                         config, state, pindexMostWork,
                         pblock && pblock->GetHash() ==
                                       pindexMostWork->GetBlockHash()
                             ? pblock
                             : nullBlockPtr,
                         fInvalidFound, connectTrace)) {
                     return false;
                 }
                 blocks_connected = true;
 
                 if (fInvalidFound) {
                     // Wipe cache, we may need another branch now.
                     pindexMostWork = nullptr;
                 }
 
                 pindexNewTip = m_chain.Tip();
                 for (const PerBlockConnectTrace &trace :
                      connectTrace.GetBlocksConnected()) {
                     assert(trace.pblock && trace.pindex);
                     GetMainSignals().BlockConnected(trace.pblock, trace.pindex,
                                                     trace.conflictedTxs);
                 }
             } while (!m_chain.Tip() ||
                      (starting_tip && CBlockIndexWorkComparator()(
                                           m_chain.Tip(), starting_tip)));
 
             // Check the index once we're done with the above loop, since
             // we're going to release cs_main soon. If the index is in a bad
             // state now, then it's better to know immediately rather than
             // randomly have it cause a problem in a race.
             CheckBlockIndex(params.GetConsensus());
 
             if (!blocks_connected) {
                 return true;
             }
 
             const CBlockIndex *pindexFork = m_chain.FindFork(starting_tip);
             bool fInitialDownload = IsInitialBlockDownload();
 
             // Notify external listeners about the new tip.
             // Enqueue while holding cs_main to ensure that UpdatedBlockTip is
             // called in the order in which blocks are connected
             if (pindexFork != pindexNewTip) {
                 // Notify ValidationInterface subscribers
                 GetMainSignals().UpdatedBlockTip(pindexNewTip, pindexFork,
                                                  fInitialDownload);
 
                 // Always notify the UI if a new block tip was connected
                 uiInterface.NotifyBlockTip(fInitialDownload, pindexNewTip);
             }
         }
         // When we reach this point, we switched to a new tip (stored in
         // pindexNewTip).
 
         if (nStopAtHeight && pindexNewTip &&
             pindexNewTip->nHeight >= nStopAtHeight) {
             StartShutdown();
         }
 
         // We check shutdown only after giving ActivateBestChainStep a chance to
         // run once so that we never shutdown before connecting the genesis
         // block during LoadChainTip(). Previously this caused an assert()
         // failure during shutdown in such cases as the UTXO DB flushing checks
         // that the best block hash is non-null.
         if (ShutdownRequested()) {
             break;
         }
     } while (pindexNewTip != pindexMostWork);
 
     // Write changes periodically to disk, after relay.
     if (!FlushStateToDisk(params, state, FlushStateMode::PERIODIC)) {
         return false;
     }
 
     return true;
 }
 
 bool ActivateBestChain(const Config &config, CValidationState &state,
                        std::shared_ptr<const CBlock> pblock) {
     return ::ChainstateActive().ActivateBestChain(config, state,
                                                   std::move(pblock));
 }
 
 bool CChainState::PreciousBlock(const Config &config, CValidationState &state,
                                 CBlockIndex *pindex) {
     {
         LOCK(cs_main);
         if (pindex->nChainWork < m_chain.Tip()->nChainWork) {
             // Nothing to do, this block is not at the tip.
             return true;
         }
 
         if (m_chain.Tip()->nChainWork > nLastPreciousChainwork) {
             // The chain has been extended since the last call, reset the
             // counter.
             nBlockReverseSequenceId = -1;
         }
 
         nLastPreciousChainwork = m_chain.Tip()->nChainWork;
         setBlockIndexCandidates.erase(pindex);
         pindex->nSequenceId = nBlockReverseSequenceId;
         if (nBlockReverseSequenceId > std::numeric_limits<int32_t>::min()) {
             // We can't keep reducing the counter if somebody really wants to
             // call preciousblock 2**31-1 times on the same set of tips...
             nBlockReverseSequenceId--;
         }
 
         // In case this was parked, unpark it.
         UnparkBlock(pindex);
 
         // Make sure it is added to the candidate list if appropriate.
         if (pindex->IsValid(BlockValidity::TRANSACTIONS) &&
             pindex->HaveTxsDownloaded()) {
             setBlockIndexCandidates.insert(pindex);
             PruneBlockIndexCandidates();
         }
     }
 
     return ActivateBestChain(config, state);
 }
 
 bool PreciousBlock(const Config &config, CValidationState &state,
                    CBlockIndex *pindex) {
     return ::ChainstateActive().PreciousBlock(config, state, pindex);
 }
 
 bool CChainState::UnwindBlock(const Config &config, CValidationState &state,
                               CBlockIndex *pindex, bool invalidate) {
     CBlockIndex *to_mark_failed_or_parked = pindex;
     bool pindex_was_in_chain = false;
     int disconnected = 0;
 
     // Disconnect (descendants of) pindex, and mark them invalid.
     while (true) {
         if (ShutdownRequested()) {
             break;
         }
 
         LOCK(cs_main);
 
         if (!m_chain.Contains(pindex)) {
             break;
         }
 
         pindex_was_in_chain = true;
         CBlockIndex *invalid_walk_tip = m_chain.Tip();
 
         // ActivateBestChain considers blocks already in m_chain
         // unconditionally valid already, so force disconnect away from it.
 
         DisconnectedBlockTransactions disconnectpool;
 
         bool ret =
             DisconnectTip(config.GetChainParams(), state, &disconnectpool);
 
         // DisconnectTip will add transactions to disconnectpool.
         // Adjust the mempool to be consistent with the new tip, adding
         // transactions back to the mempool if disconnecting was successful,
         // and we're not doing a very deep invalidation (in which case
         // keeping the mempool up to date is probably futile anyway).
         disconnectpool.updateMempoolForReorg(
             config, /* fAddToMempool = */ (++disconnected <= 10) && ret);
 
         if (!ret) {
             return false;
         }
 
         assert(invalid_walk_tip->pprev == m_chain.Tip());
 
         // We immediately mark the disconnected blocks as invalid.
         // This prevents a case where pruned nodes may fail to invalidateblock
         // and be left unable to start as they have no tip candidates (as there
         // are no blocks that meet the "have data and are not invalid per
         // nStatus" criteria for inclusion in setBlockIndexCandidates).
 
         invalid_walk_tip->nStatus =
             invalidate ? invalid_walk_tip->nStatus.withFailed()
                        : invalid_walk_tip->nStatus.withParked();
 
         setDirtyBlockIndex.insert(invalid_walk_tip);
         setBlockIndexCandidates.insert(invalid_walk_tip->pprev);
 
         if (invalid_walk_tip == to_mark_failed_or_parked->pprev &&
             (invalidate ? to_mark_failed_or_parked->nStatus.hasFailed()
                         : to_mark_failed_or_parked->nStatus.isParked())) {
             // We only want to mark the last disconnected block as
             // Failed (or Parked); its children need to be FailedParent (or
             // ParkedParent) instead.
             to_mark_failed_or_parked->nStatus =
                 (invalidate
                      ? to_mark_failed_or_parked->nStatus.withFailed(false)
                            .withFailedParent()
                      : to_mark_failed_or_parked->nStatus.withParked(false)
                            .withParkedParent());
 
             setDirtyBlockIndex.insert(to_mark_failed_or_parked);
         }
 
         // Track the last disconnected block, so we can correct its
         // FailedParent (or ParkedParent) status in future iterations, or, if
         // it's the last one, call InvalidChainFound on it.
         to_mark_failed_or_parked = invalid_walk_tip;
     }
 
     {
         LOCK(cs_main);
         if (m_chain.Contains(to_mark_failed_or_parked)) {
             // If the to-be-marked invalid block is in the active chain,
             // something is interfering and we can't proceed.
             return false;
         }
 
         // Mark pindex (or the last disconnected block) as invalid (or parked),
         // even when it never was in the main chain.
         to_mark_failed_or_parked->nStatus =
             invalidate ? to_mark_failed_or_parked->nStatus.withFailed()
                        : to_mark_failed_or_parked->nStatus.withParked();
         setDirtyBlockIndex.insert(to_mark_failed_or_parked);
         if (invalidate) {
             m_failed_blocks.insert(to_mark_failed_or_parked);
         }
 
         // The resulting new best tip may not be in setBlockIndexCandidates
         // anymore, so add it again.
         for (const std::pair<const BlockHash, CBlockIndex *> &it :
              mapBlockIndex) {
             CBlockIndex *i = it.second;
             if (i->IsValid(BlockValidity::TRANSACTIONS) &&
                 i->HaveTxsDownloaded() &&
                 !setBlockIndexCandidates.value_comp()(i, m_chain.Tip())) {
                 setBlockIndexCandidates.insert(i);
             }
         }
 
         if (invalidate) {
             InvalidChainFound(to_mark_failed_or_parked);
         }
     }
 
     // Only notify about a new block tip if the active chain was modified.
     if (pindex_was_in_chain) {
         uiInterface.NotifyBlockTip(IsInitialBlockDownload(),
                                    to_mark_failed_or_parked->pprev);
     }
     return true;
 }
 
 bool FinalizeBlockAndInvalidate(const Config &config, CValidationState &state,
                                 CBlockIndex *pindex) {
     AssertLockHeld(cs_main);
     if (!FinalizeBlockInternal(config, state, pindex)) {
         // state is set by FinalizeBlockInternal.
         return false;
     }
 
     // We have a valid candidate, make sure it is not parked.
     if (pindex->nStatus.isOnParkedChain()) {
         UnparkBlock(pindex);
     }
 
     // If the finalized block is not on the active chain, we may need to rewind.
     if (!::ChainActive().Contains(pindex)) {
         const CBlockIndex *pindexFork = ::ChainActive().FindFork(pindex);
         CBlockIndex *pindexToInvalidate = ::ChainActive().Next(pindexFork);
         if (pindexToInvalidate) {
             return InvalidateBlock(config, state, pindexToInvalidate);
         }
     }
 
     return true;
 }
 
 bool InvalidateBlock(const Config &config, CValidationState &state,
                      CBlockIndex *pindex) {
     return ::ChainstateActive().UnwindBlock(config, state, pindex, true);
 }
 
 bool ParkBlock(const Config &config, CValidationState &state,
                CBlockIndex *pindex) {
     return ::ChainstateActive().UnwindBlock(config, state, pindex, false);
 }
 
 template <typename F>
 bool CChainState::UpdateFlagsForBlock(CBlockIndex *pindexBase,
                                       CBlockIndex *pindex, F f) {
     BlockStatus newStatus = f(pindex->nStatus);
     if (pindex->nStatus != newStatus &&
         (!pindexBase ||
          pindex->GetAncestor(pindexBase->nHeight) == pindexBase)) {
         pindex->nStatus = newStatus;
         setDirtyBlockIndex.insert(pindex);
         if (newStatus.isValid()) {
             m_failed_blocks.erase(pindex);
         }
 
         if (pindex->IsValid(BlockValidity::TRANSACTIONS) &&
             pindex->HaveTxsDownloaded() &&
             setBlockIndexCandidates.value_comp()(::ChainActive().Tip(),
                                                  pindex)) {
             setBlockIndexCandidates.insert(pindex);
         }
         return true;
     }
     return false;
 }
 
 template <typename F, typename C, typename AC>
 void CChainState::UpdateFlags(CBlockIndex *pindex, CBlockIndex *&pindexReset,
                               F f, C fChild, AC fAncestorWasChanged) {
     AssertLockHeld(cs_main);
 
     // Update the current block and ancestors; while we're doing this, identify
     // which was the deepest ancestor we changed.
     CBlockIndex *pindexDeepestChanged = pindex;
     for (auto pindexAncestor = pindex; pindexAncestor != nullptr;
          pindexAncestor = pindexAncestor->pprev) {
         if (UpdateFlagsForBlock(nullptr, pindexAncestor, f)) {
             pindexDeepestChanged = pindexAncestor;
         }
     }
 
     if (pindexReset &&
         pindexReset->GetAncestor(pindexDeepestChanged->nHeight) ==
             pindexDeepestChanged) {
         // reset pindexReset if it had a modified ancestor.
         pindexReset = nullptr;
     }
 
     // Update all blocks under modified blocks.
     BlockMap::iterator it = mapBlockIndex.begin();
     while (it != mapBlockIndex.end()) {
         UpdateFlagsForBlock(pindex, it->second, fChild);
         UpdateFlagsForBlock(pindexDeepestChanged, it->second,
                             fAncestorWasChanged);
         it++;
     }
 }
 
 void CChainState::ResetBlockFailureFlags(CBlockIndex *pindex) {
     AssertLockHeld(cs_main);
 
     // In case we are reconsidering something before the finalization point,
     // move the finalization point to the last common ancestor.
     if (pindexFinalized) {
         pindexFinalized = LastCommonAncestor(pindex, pindexFinalized);
     }
 
     UpdateFlags(
         pindex, pindexBestInvalid,
         [](const BlockStatus status) {
             return status.withClearedFailureFlags();
         },
         [](const BlockStatus status) {
             return status.withClearedFailureFlags();
         },
         [](const BlockStatus status) {
             return status.withFailedParent(false);
         });
 }
 
 void ResetBlockFailureFlags(CBlockIndex *pindex) {
     return ::ChainstateActive().ResetBlockFailureFlags(pindex);
 }
 
 void CChainState::UnparkBlockImpl(CBlockIndex *pindex, bool fClearChildren) {
     AssertLockHeld(cs_main);
 
     UpdateFlags(
         pindex, pindexBestParked,
         [](const BlockStatus status) {
             return status.withClearedParkedFlags();
         },
         [fClearChildren](const BlockStatus status) {
             return fClearChildren ? status.withClearedParkedFlags()
                                   : status.withParkedParent(false);
         },
         [](const BlockStatus status) {
             return status.withParkedParent(false);
         });
 }
 
 void UnparkBlockAndChildren(CBlockIndex *pindex) {
     return ::ChainstateActive().UnparkBlockImpl(pindex, true);
 }
 
 void UnparkBlock(CBlockIndex *pindex) {
     return ::ChainstateActive().UnparkBlockImpl(pindex, false);
 }
 
 const CBlockIndex *GetFinalizedBlock() {
     AssertLockHeld(cs_main);
     return pindexFinalized;
 }
 
 bool IsBlockFinalized(const CBlockIndex *pindex) {
     AssertLockHeld(cs_main);
     return pindexFinalized &&
            pindexFinalized->GetAncestor(pindex->nHeight) == pindex;
 }
 
 CBlockIndex *CChainState::AddToBlockIndex(const CBlockHeader &block) {
     AssertLockHeld(cs_main);
 
     // Check for duplicate
     BlockHash hash = block.GetHash();
     BlockMap::iterator it = mapBlockIndex.find(hash);
     if (it != mapBlockIndex.end()) {
         return it->second;
     }
 
     // Construct new block index object
     CBlockIndex *pindexNew = new CBlockIndex(block);
     // We assign the sequence id to blocks only when the full data is available,
     // to avoid miners withholding blocks but broadcasting headers, to get a
     // competitive advantage.
     pindexNew->nSequenceId = 0;
     BlockMap::iterator mi =
         mapBlockIndex.insert(std::make_pair(hash, pindexNew)).first;
     pindexNew->phashBlock = &((*mi).first);
     BlockMap::iterator miPrev = mapBlockIndex.find(block.hashPrevBlock);
     if (miPrev != mapBlockIndex.end()) {
         pindexNew->pprev = (*miPrev).second;
         pindexNew->nHeight = pindexNew->pprev->nHeight + 1;
         pindexNew->BuildSkip();
     }
     pindexNew->nTimeReceived = GetTime();
     pindexNew->nTimeMax =
         (pindexNew->pprev
              ? std::max(pindexNew->pprev->nTimeMax, pindexNew->nTime)
              : pindexNew->nTime);
     pindexNew->nChainWork =
         (pindexNew->pprev ? pindexNew->pprev->nChainWork : 0) +
         GetBlockProof(*pindexNew);
     pindexNew->RaiseValidity(BlockValidity::TREE);
     if (pindexBestHeader == nullptr ||
         pindexBestHeader->nChainWork < pindexNew->nChainWork) {
         pindexBestHeader = pindexNew;
     }
 
     setDirtyBlockIndex.insert(pindexNew);
     return pindexNew;
 }
 
 /**
  * Mark a block as having its data received and checked (up to
  * BLOCK_VALID_TRANSACTIONS).
  */
 void CChainState::ReceivedBlockTransactions(const CBlock &block,
                                             CBlockIndex *pindexNew,
                                             const FlatFilePos &pos) {
     pindexNew->nTx = block.vtx.size();
     pindexNew->nChainTx = 0;
     pindexNew->nFile = pos.nFile;
     pindexNew->nDataPos = pos.nPos;
     pindexNew->nUndoPos = 0;
     pindexNew->nStatus = pindexNew->nStatus.withData();
     pindexNew->RaiseValidity(BlockValidity::TRANSACTIONS);
     setDirtyBlockIndex.insert(pindexNew);
 
     if (pindexNew->pprev == nullptr || pindexNew->pprev->HaveTxsDownloaded()) {
         // If pindexNew is the genesis block or all parents are
         // BLOCK_VALID_TRANSACTIONS.
         std::deque<CBlockIndex *> queue;
         queue.push_back(pindexNew);
 
         // Recursively process any descendant blocks that now may be eligible to
         // be connected.
         while (!queue.empty()) {
             CBlockIndex *pindex = queue.front();
             queue.pop_front();
             pindex->nChainTx =
                 (pindex->pprev ? pindex->pprev->nChainTx : 0) + pindex->nTx;
             if (pindex->nSequenceId == 0) {
                 // We assign a sequence is when transaction are received to
                 // prevent a miner from being able to broadcast a block but not
                 // its content. However, a sequence id may have been set
                 // manually, for instance via PreciousBlock, in which case, we
                 // don't need to assign one.
                 pindex->nSequenceId = nBlockSequenceId++;
             }
 
             if (m_chain.Tip() == nullptr ||
                 !setBlockIndexCandidates.value_comp()(pindex, m_chain.Tip())) {
                 setBlockIndexCandidates.insert(pindex);
             }
 
             std::pair<std::multimap<CBlockIndex *, CBlockIndex *>::iterator,
                       std::multimap<CBlockIndex *, CBlockIndex *>::iterator>
                 range = mapBlocksUnlinked.equal_range(pindex);
             while (range.first != range.second) {
                 std::multimap<CBlockIndex *, CBlockIndex *>::iterator it =
                     range.first;
                 queue.push_back(it->second);
                 range.first++;
                 mapBlocksUnlinked.erase(it);
             }
         }
     } else if (pindexNew->pprev &&
                pindexNew->pprev->IsValid(BlockValidity::TREE)) {
         mapBlocksUnlinked.insert(std::make_pair(pindexNew->pprev, pindexNew));
     }
 }
 
 static bool FindBlockPos(FlatFilePos &pos, unsigned int nAddSize,
                          unsigned int nHeight, uint64_t nTime,
                          bool fKnown = false) {
     LOCK(cs_LastBlockFile);
 
     unsigned int nFile = fKnown ? pos.nFile : nLastBlockFile;
     if (vinfoBlockFile.size() <= nFile) {
         vinfoBlockFile.resize(nFile + 1);
     }
 
     if (!fKnown) {
         while (vinfoBlockFile[nFile].nSize + nAddSize >= MAX_BLOCKFILE_SIZE) {
             nFile++;
             if (vinfoBlockFile.size() <= nFile) {
                 vinfoBlockFile.resize(nFile + 1);
             }
         }
         pos.nFile = nFile;
         pos.nPos = vinfoBlockFile[nFile].nSize;
     }
 
     if ((int)nFile != nLastBlockFile) {
         if (!fKnown) {
             LogPrintf("Leaving block file %i: %s\n", nLastBlockFile,
                       vinfoBlockFile[nLastBlockFile].ToString());
         }
         FlushBlockFile(!fKnown);
         nLastBlockFile = nFile;
     }
 
     vinfoBlockFile[nFile].AddBlock(nHeight, nTime);
     if (fKnown) {
         vinfoBlockFile[nFile].nSize =
             std::max(pos.nPos + nAddSize, vinfoBlockFile[nFile].nSize);
     } else {
         vinfoBlockFile[nFile].nSize += nAddSize;
     }
 
     if (!fKnown) {
         bool out_of_space;
         size_t bytes_allocated =
             BlockFileSeq().Allocate(pos, nAddSize, out_of_space);
         if (out_of_space) {
             return AbortNode("Disk space is low!",
                              _("Error: Disk space is low!").translated);
         }
         if (bytes_allocated != 0 && fPruneMode) {
             fCheckForPruning = true;
         }
     }
 
     setDirtyFileInfo.insert(nFile);
     return true;
 }
 
 static bool FindUndoPos(CValidationState &state, int nFile, FlatFilePos &pos,
                         unsigned int nAddSize) {
     pos.nFile = nFile;
 
     LOCK(cs_LastBlockFile);
 
     pos.nPos = vinfoBlockFile[nFile].nUndoSize;
     vinfoBlockFile[nFile].nUndoSize += nAddSize;
     setDirtyFileInfo.insert(nFile);
 
     bool out_of_space;
     size_t bytes_allocated =
         UndoFileSeq().Allocate(pos, nAddSize, out_of_space);
     if (out_of_space) {
         return AbortNode(state, "Disk space is low!",
                          _("Error: Disk space is low!").translated);
     }
     if (bytes_allocated != 0 && fPruneMode) {
         fCheckForPruning = true;
     }
 
     return true;
 }
 
 /**
  * Return true if the provided block header is valid.
  * Only verify PoW if blockValidationOptions is configured to do so.
  * This allows validation of headers on which the PoW hasn't been done.
  * For example: to validate template handed to mining software.
  * Do not call this for any check that depends on the context.
  * For context-dependent calls, see ContextualCheckBlockHeader.
  */
 static bool CheckBlockHeader(const CBlockHeader &block, CValidationState &state,
                              const Consensus::Params &params,
                              BlockValidationOptions validationOptions) {
     // Check proof of work matches claimed amount
     if (validationOptions.shouldValidatePoW() &&
         !CheckProofOfWork(block.GetHash(), block.nBits, params)) {
         return state.DoS(50, false, REJECT_INVALID, "high-hash", false,
                          "proof of work failed");
     }
 
     return true;
 }
 
 bool CheckBlock(const CBlock &block, CValidationState &state,
                 const Consensus::Params &params,
                 BlockValidationOptions validationOptions) {
     // These are checks that are independent of context.
     if (block.fChecked) {
         return true;
     }
 
     // Check that the header is valid (particularly PoW).  This is mostly
     // redundant with the call in AcceptBlockHeader.
     if (!CheckBlockHeader(block, state, params, validationOptions)) {
         return false;
     }
 
     // Check the merkle root.
     if (validationOptions.shouldValidateMerkleRoot()) {
         bool mutated;
         uint256 hashMerkleRoot2 = BlockMerkleRoot(block, &mutated);
         if (block.hashMerkleRoot != hashMerkleRoot2) {
             return state.DoS(100, false, REJECT_INVALID, "bad-txnmrklroot",
                              true, "hashMerkleRoot mismatch");
         }
 
         // Check for merkle tree malleability (CVE-2012-2459): repeating
         // sequences of transactions in a block without affecting the merkle
         // root of a block, while still invalidating it.
         if (mutated) {
             return state.DoS(100, false, REJECT_INVALID, "bad-txns-duplicate",
                              true, "duplicate transaction");
         }
     }
 
     // All potential-corruption validation must be done before we do any
     // transaction validation, as otherwise we may mark the header as invalid
     // because we receive the wrong transactions for it.
 
     // First transaction must be coinbase.
     if (block.vtx.empty()) {
         return state.DoS(100, false, REJECT_INVALID, "bad-cb-missing", false,
                          "first tx is not coinbase");
     }
 
     // Size limits.
     auto nMaxBlockSize = validationOptions.getExcessiveBlockSize();
 
     // Bail early if there is no way this block is of reasonable size.
     if ((block.vtx.size() * MIN_TRANSACTION_SIZE) > nMaxBlockSize) {
         return state.DoS(100, false, REJECT_INVALID, "bad-blk-length", false,
                          "size limits failed");
     }
 
     auto currentBlockSize = ::GetSerializeSize(block, PROTOCOL_VERSION);
     if (currentBlockSize > nMaxBlockSize) {
         return state.DoS(100, false, REJECT_INVALID, "bad-blk-length", false,
                          "size limits failed");
     }
 
     // And a valid coinbase.
     if (!CheckCoinbase(*block.vtx[0], state)) {
         return state.Invalid(false, state.GetRejectCode(),
                              state.GetRejectReason(),
                              strprintf("Coinbase check failed (txid %s) %s",
                                        block.vtx[0]->GetId().ToString(),
                                        state.GetDebugMessage()));
     }
 
     // Check transactions for regularity, skipping the first. Note that this
     // is the first time we check that all after the first are !IsCoinBase.
     for (size_t i = 1; i < block.vtx.size(); i++) {
         auto *tx = block.vtx[i].get();
         if (!CheckRegularTransaction(*tx, state)) {
             return state.Invalid(
                 false, state.GetRejectCode(), state.GetRejectReason(),
                 strprintf("Transaction check failed (txid %s) %s",
                           tx->GetId().ToString(), state.GetDebugMessage()));
         }
     }
 
     if (validationOptions.shouldValidatePoW() &&
         validationOptions.shouldValidateMerkleRoot()) {
         block.fChecked = true;
     }
 
     return true;
 }
 
 /**
  * Context-dependent validity checks.
  * By "context", we mean only the previous block headers, but not the UTXO
  * set; UTXO-related validity checks are done in ConnectBlock().
  * NOTE: This function is not currently invoked by ConnectBlock(), so we
  * should consider upgrade issues if we change which consensus rules are
  * enforced in this function (eg by adding a new consensus rule). See comment
  * in ConnectBlock().
  * Note that -reindex-chainstate skips the validation that happens here!
  */
 static bool ContextualCheckBlockHeader(const CChainParams &params,
                                        const CBlockHeader &block,
                                        CValidationState &state,
                                        const CBlockIndex *pindexPrev,
                                        int64_t nAdjustedTime) {
     assert(pindexPrev != nullptr);
     const int nHeight = pindexPrev->nHeight + 1;
 
     // Check proof of work
     const Consensus::Params &consensusParams = params.GetConsensus();
     if (block.nBits !=
         GetNextWorkRequired(pindexPrev, &block, consensusParams)) {
         LogPrintf("bad bits after height: %d\n", pindexPrev->nHeight);
         return state.DoS(100, false, REJECT_INVALID, "bad-diffbits", false,
                          "incorrect proof of work");
     }
 
     // Check against checkpoints
     if (fCheckpointsEnabled) {
         const CCheckpointData &checkpoints = params.Checkpoints();
 
         // Check that the block chain matches the known block chain up to a
         // checkpoint.
         if (!Checkpoints::CheckBlock(checkpoints, nHeight, block.GetHash())) {
             return state.DoS(100,
                              error("%s: rejected by checkpoint lock-in at %d",
                                    __func__, nHeight),
                              REJECT_CHECKPOINT, "checkpoint mismatch");
         }
 
         // Don't accept any forks from the main chain prior to last checkpoint.
         // GetLastCheckpoint finds the last checkpoint in MapCheckpoints that's
         // in our MapBlockIndex.
         CBlockIndex *pcheckpoint = Checkpoints::GetLastCheckpoint(checkpoints);
         if (pcheckpoint && nHeight < pcheckpoint->nHeight) {
             return state.DoS(
                 100,
                 error("%s: forked chain older than last checkpoint (height %d)",
                       __func__, nHeight),
                 REJECT_CHECKPOINT, "bad-fork-prior-to-checkpoint");
         }
     }
 
     // Check timestamp against prev
     if (block.GetBlockTime() <= pindexPrev->GetMedianTimePast()) {
         return state.Invalid(false, REJECT_INVALID, "time-too-old",
                              "block's timestamp is too early");
     }
 
     // Check timestamp
     if (block.GetBlockTime() > nAdjustedTime + MAX_FUTURE_BLOCK_TIME) {
         return state.Invalid(false, REJECT_INVALID, "time-too-new",
                              "block timestamp too far in the future");
     }
 
     // Reject outdated version blocks when 95% (75% on testnet) of the network
     // has upgraded:
     // check for version 2, 3 and 4 upgrades
     if ((block.nVersion < 2 && nHeight >= consensusParams.BIP34Height) ||
         (block.nVersion < 3 && nHeight >= consensusParams.BIP66Height) ||
         (block.nVersion < 4 && nHeight >= consensusParams.BIP65Height)) {
         return state.Invalid(
             false, REJECT_OBSOLETE,
             strprintf("bad-version(0x%08x)", block.nVersion),
             strprintf("rejected nVersion=0x%08x block", block.nVersion));
     }
 
     return true;
 }
 
 bool ContextualCheckTransactionForCurrentBlock(const Consensus::Params &params,
                                                const CTransaction &tx,
                                                CValidationState &state,
                                                int flags) {
     AssertLockHeld(cs_main);
 
     // By convention a negative value for flags indicates that the current
     // network-enforced consensus rules should be used. In a future soft-fork
     // scenario that would mean checking which rules would be enforced for the
     // next block and setting the appropriate flags. At the present time no
     // soft-forks are scheduled, so no flags are set.
     flags = std::max(flags, 0);
 
     // ContextualCheckTransactionForCurrentBlock() uses
     // ::ChainActive().Height()+1 to evaluate nLockTime because when IsFinalTx()
     // is called within CBlock::AcceptBlock(), the height of the block *being*
     // evaluated is what is used. Thus if we want to know if a transaction can
     // be part of the *next* block, we need to call ContextualCheckTransaction()
     // with one more than ::ChainActive().Height().
     const int nBlockHeight = ::ChainActive().Height() + 1;
 
     // BIP113 will require that time-locked transactions have nLockTime set to
     // less than the median time of the previous block they're contained in.
     // When the next block is created its previous block will be the current
     // chain tip, so we use that to calculate the median time passed to
     // ContextualCheckTransaction() if LOCKTIME_MEDIAN_TIME_PAST is set.
     const int64_t nMedianTimePast =
         ::ChainActive().Tip() == nullptr
             ? 0
             : ::ChainActive().Tip()->GetMedianTimePast();
     const int64_t nLockTimeCutoff = (flags & LOCKTIME_MEDIAN_TIME_PAST)
                                         ? nMedianTimePast
                                         : GetAdjustedTime();
 
     return ContextualCheckTransaction(params, tx, state, nBlockHeight,
                                       nLockTimeCutoff, nMedianTimePast);
 }
 
 /**
  * NOTE: This function is not currently invoked by ConnectBlock(), so we
  * should consider upgrade issues if we change which consensus rules are
  * enforced in this function (eg by adding a new consensus rule). See comment
  * in ConnectBlock().
  * Note that -reindex-chainstate skips the validation that happens here!
  */
 static bool ContextualCheckBlock(const CBlock &block, CValidationState &state,
                                  const Consensus::Params &params,
                                  const CBlockIndex *pindexPrev) {
     const int nHeight = pindexPrev == nullptr ? 0 : pindexPrev->nHeight + 1;
 
     // Start enforcing BIP113 (Median Time Past).
     int nLockTimeFlags = 0;
     if (nHeight >= params.CSVHeight) {
         assert(pindexPrev != nullptr);
         nLockTimeFlags |= LOCKTIME_MEDIAN_TIME_PAST;
     }
 
     const int64_t nMedianTimePast =
         pindexPrev == nullptr ? 0 : pindexPrev->GetMedianTimePast();
 
     const int64_t nLockTimeCutoff = (nLockTimeFlags & LOCKTIME_MEDIAN_TIME_PAST)
                                         ? nMedianTimePast
                                         : block.GetBlockTime();
 
     const bool fIsMagneticAnomalyEnabled =
         IsMagneticAnomalyEnabled(params, pindexPrev);
 
     // Check transactions:
     // - canonical ordering
     // - ensure they are finalized
     // - perform a preliminary block-sigops count (they will be recounted more
     // strictly during ConnectBlock).
     // - perform a transaction-sigops check (again, a more strict check will
     // happen in ConnectBlock).
     const CTransaction *prevTx = nullptr;
     for (const auto &ptx : block.vtx) {
         const CTransaction &tx = *ptx;
         if (fIsMagneticAnomalyEnabled) {
             if (prevTx && (tx.GetId() <= prevTx->GetId())) {
                 if (tx.GetId() == prevTx->GetId()) {
                     return state.DoS(100, false, REJECT_INVALID, "tx-duplicate",
                                      false,
                                      strprintf("Duplicated transaction %s",
                                                tx.GetId().ToString()));
                 }
 
                 return state.DoS(
                     100, false, REJECT_INVALID, "tx-ordering", false,
                     strprintf("Transaction order is invalid (%s < %s)",
                               tx.GetId().ToString(),
                               prevTx->GetId().ToString()));
             }
 
             if (prevTx || !tx.IsCoinBase()) {
                 prevTx = &tx;
             }
         }
 
         if (!ContextualCheckTransaction(params, tx, state, nHeight,
                                         nLockTimeCutoff, nMedianTimePast)) {
             // state set by ContextualCheckTransaction.
             return false;
         }
     }
 
     // Enforce rule that the coinbase starts with serialized block height
     if (nHeight >= params.BIP34Height) {
         CScript expect = CScript() << nHeight;
         if (block.vtx[0]->vin[0].scriptSig.size() < expect.size() ||
             !std::equal(expect.begin(), expect.end(),
                         block.vtx[0]->vin[0].scriptSig.begin())) {
             return state.DoS(100, false, REJECT_INVALID, "bad-cb-height", false,
                              "block height mismatch in coinbase");
         }
     }
 
     return true;
 }
 
 /**
  * If the provided block header is valid, add it to the block index.
  *
  * Returns true if the block is successfully added to the block index.
  */
 bool CChainState::AcceptBlockHeader(const Config &config,
                                     const CBlockHeader &block,
                                     CValidationState &state,
                                     CBlockIndex **ppindex) {
     AssertLockHeld(cs_main);
     const CChainParams &chainparams = config.GetChainParams();
 
     // Check for duplicate
     BlockHash hash = block.GetHash();
     BlockMap::iterator miSelf = mapBlockIndex.find(hash);
     CBlockIndex *pindex = nullptr;
     if (hash != chainparams.GetConsensus().hashGenesisBlock) {
         if (miSelf != mapBlockIndex.end()) {
             // Block header is already known.
             pindex = miSelf->second;
             if (ppindex) {
                 *ppindex = pindex;
             }
 
             if (pindex->nStatus.isInvalid()) {
                 return state.Invalid(error("%s: block %s is marked invalid",
                                            __func__, hash.ToString()),
                                      0, "duplicate");
             }
 
             return true;
         }
 
         if (!CheckBlockHeader(block, state, chainparams.GetConsensus(),
                               BlockValidationOptions(config))) {
             return error("%s: Consensus::CheckBlockHeader: %s, %s", __func__,
                          hash.ToString(), FormatStateMessage(state));
         }
 
         // Get prev block index
         BlockMap::iterator mi = mapBlockIndex.find(block.hashPrevBlock);
         if (mi == mapBlockIndex.end()) {
             return state.DoS(10, error("%s: prev block not found", __func__), 0,
                              "prev-blk-not-found");
         }
 
         CBlockIndex *pindexPrev = (*mi).second;
         assert(pindexPrev);
         if (pindexPrev->nStatus.isInvalid()) {
             return state.DoS(100, error("%s: prev block invalid", __func__),
                              REJECT_INVALID, "bad-prevblk");
         }
 
         if (!ContextualCheckBlockHeader(chainparams, block, state, pindexPrev,
                                         GetAdjustedTime())) {
             return error("%s: Consensus::ContextualCheckBlockHeader: %s, %s",
                          __func__, hash.ToString(), FormatStateMessage(state));
         }
 
         /* Determine if this block descends from any block which has been found
          * invalid (m_failed_blocks), then mark pindexPrev and any blocks
          * between them as failed. For example:
          *
          *                D3
          *              /
          *      B2 - C2
          *    /         \
          *  A             D2 - E2 - F2
          *    \
          *      B1 - C1 - D1 - E1
          *
          * In the case that we attempted to reorg from E1 to F2, only to find
          * C2 to be invalid, we would mark D2, E2, and F2 as BLOCK_FAILED_CHILD
          * but NOT D3 (it was not in any of our candidate sets at the time).
          *
          * In any case D3 will also be marked as BLOCK_FAILED_CHILD at restart
          * in LoadBlockIndex.
          */
         if (!pindexPrev->IsValid(BlockValidity::SCRIPTS)) {
             // The above does not mean "invalid": it checks if the previous
             // block hasn't been validated up to BLOCK_VALID_SCRIPTS. This is a
             // performance optimization, in the common case of adding a new
             // block to the tip, we don't need to iterate over the failed blocks
             // list.
             for (const CBlockIndex *failedit : m_failed_blocks) {
                 if (pindexPrev->GetAncestor(failedit->nHeight) == failedit) {
                     assert(failedit->nStatus.hasFailed());
                     CBlockIndex *invalid_walk = pindexPrev;
                     while (invalid_walk != failedit) {
                         invalid_walk->nStatus =
                             invalid_walk->nStatus.withFailedParent();
                         setDirtyBlockIndex.insert(invalid_walk);
                         invalid_walk = invalid_walk->pprev;
                     }
                     return state.DoS(100,
                                      error("%s: prev block invalid", __func__),
                                      REJECT_INVALID, "bad-prevblk");
                 }
             }
         }
     }
 
     if (pindex == nullptr) {
         pindex = AddToBlockIndex(block);
     }
 
     if (ppindex) {
         *ppindex = pindex;
     }
 
     CheckBlockIndex(chainparams.GetConsensus());
     return true;
 }
 
 // Exposed wrapper for AcceptBlockHeader
 bool ProcessNewBlockHeaders(const Config &config,
                             const std::vector<CBlockHeader> &headers,
                             CValidationState &state,
                             const CBlockIndex **ppindex,
                             CBlockHeader *first_invalid) {
     if (first_invalid != nullptr) {
         first_invalid->SetNull();
     }
 
     {
         LOCK(cs_main);
         for (const CBlockHeader &header : headers) {
             // Use a temp pindex instead of ppindex to avoid a const_cast
             CBlockIndex *pindex = nullptr;
             if (!::ChainstateActive().AcceptBlockHeader(config, header, state,
                                                         &pindex)) {
                 if (first_invalid) {
                     *first_invalid = header;
                 }
                 return false;
             }
 
             if (ppindex) {
                 *ppindex = pindex;
             }
         }
     }
 
     NotifyHeaderTip();
     return true;
 }
 
 /**
  * Store block on disk. If dbp is non-nullptr, the file is known to already
  * reside on disk.
  */
 static FlatFilePos SaveBlockToDisk(const CBlock &block, int nHeight,
                                    const CChainParams &chainparams,
                                    const FlatFilePos *dbp) {
     unsigned int nBlockSize = ::GetSerializeSize(block, CLIENT_VERSION);
     FlatFilePos blockPos;
     if (dbp != nullptr) {
         blockPos = *dbp;
     }
     if (!FindBlockPos(blockPos, nBlockSize + 8, nHeight, block.GetBlockTime(),
                       dbp != nullptr)) {
         error("%s: FindBlockPos failed", __func__);
         return FlatFilePos();
     }
     if (dbp == nullptr) {
         if (!WriteBlockToDisk(block, blockPos, chainparams.DiskMagic())) {
             AbortNode("Failed to write block");
             return FlatFilePos();
         }
     }
     return blockPos;
 }
 
 /**
  * Store a block on disk.
  *
  * @param[in]     config     The global config.
  * @param[in-out] pblock     The block we want to accept.
  * @param[in]     fRequested A boolean to indicate if this block was requested
  *                           from our peers.
  * @param[in]     dbp        If non-null, the disk position of the block.
  * @param[in-out] fNewBlock  True if block was first received via this call.
  * @return True if the block is accepted as a valid block and written to disk.
  */
 bool CChainState::AcceptBlock(const Config &config,
                               const std::shared_ptr<const CBlock> &pblock,
                               CValidationState &state, bool fRequested,
                               const FlatFilePos *dbp, bool *fNewBlock) {
     AssertLockHeld(cs_main);
 
     const CBlock &block = *pblock;
     if (fNewBlock) {
         *fNewBlock = false;
     }
 
     CBlockIndex *pindex = nullptr;
     if (!AcceptBlockHeader(config, block, state, &pindex)) {
         return false;
     }
 
     // Try to process all requested blocks that we don't have, but only
     // process an unrequested block if it's new and has enough work to
     // advance our tip, and isn't too many blocks ahead.
     bool fAlreadyHave = pindex->nStatus.hasData();
 
     // TODO: deal better with return value and error conditions for duplicate
     // and unrequested blocks.
     if (fAlreadyHave) {
         return true;
     }
 
     // Compare block header timestamps and received times of the block and the
     // chaintip.  If they have the same chain height, use these diffs as a
     // tie-breaker, attempting to pick the more honestly-mined block.
     int64_t newBlockTimeDiff = std::llabs(pindex->GetReceivedTimeDiff());
     int64_t chainTipTimeDiff =
         m_chain.Tip() ? std::llabs(m_chain.Tip()->GetReceivedTimeDiff()) : 0;
 
     bool isSameHeight =
         m_chain.Tip() && (pindex->nChainWork == m_chain.Tip()->nChainWork);
     if (isSameHeight) {
         LogPrintf("Chain tip timestamp-to-received-time difference: hash=%s, "
                   "diff=%d\n",
                   m_chain.Tip()->GetBlockHash().ToString(), chainTipTimeDiff);
         LogPrintf("New block timestamp-to-received-time difference: hash=%s, "
                   "diff=%d\n",
                   pindex->GetBlockHash().ToString(), newBlockTimeDiff);
     }
 
     bool fHasMoreOrSameWork =
         (m_chain.Tip() ? pindex->nChainWork >= m_chain.Tip()->nChainWork
                        : true);
 
     // Blocks that are too out-of-order needlessly limit the effectiveness of
     // pruning, because pruning will not delete block files that contain any
     // blocks which are too close in height to the tip.  Apply this test
     // regardless of whether pruning is enabled; it should generally be safe to
     // not process unrequested blocks.
     bool fTooFarAhead =
         (pindex->nHeight > int(m_chain.Height() + MIN_BLOCKS_TO_KEEP));
 
     // TODO: Decouple this function from the block download logic by removing
     // fRequested
     // This requires some new chain data structure to efficiently look up if a
     // block is in a chain leading to a candidate for best tip, despite not
     // being such a candidate itself.
 
     // If we didn't ask for it:
     if (!fRequested) {
         // This is a previously-processed block that was pruned.
         if (pindex->nTx != 0) {
             return true;
         }
 
         // Don't process less-work chains.
         if (!fHasMoreOrSameWork) {
             return true;
         }
 
         // Block height is too high.
         if (fTooFarAhead) {
             return true;
         }
 
         // Protect against DoS attacks from low-work chains.
         // If our tip is behind, a peer could try to send us
         // low-work blocks on a fake chain that we would never
         // request; don't process these.
         if (pindex->nChainWork < nMinimumChainWork) {
             return true;
         }
     }
 
     const CChainParams &chainparams = config.GetChainParams();
     const Consensus::Params &consensusParams = chainparams.GetConsensus();
 
     if (!CheckBlock(block, state, consensusParams,
                     BlockValidationOptions(config)) ||
         !ContextualCheckBlock(block, state, consensusParams, pindex->pprev)) {
         if (state.IsInvalid() && !state.CorruptionPossible()) {
             pindex->nStatus = pindex->nStatus.withFailed();
             setDirtyBlockIndex.insert(pindex);
         }
 
         return error("%s: %s (block %s)", __func__, FormatStateMessage(state),
                      block.GetHash().ToString());
     }
 
     // If connecting the new block would require rewinding more than one block
     // from the active chain (i.e., a "deep reorg"), then mark the new block as
     // parked. If it has enough work then it will be automatically unparked
     // later, during FindMostWorkChain. We mark the block as parked at the very
     // last minute so we can make sure everything is ready to be reorged if
     // needed.
     if (gArgs.GetBoolArg("-parkdeepreorg", true)) {
         const CBlockIndex *pindexFork = m_chain.FindFork(pindex);
         if (pindexFork && pindexFork->nHeight + 1 < m_chain.Height()) {
             LogPrintf("Park block %s as it would cause a deep reorg.\n",
                       pindex->GetBlockHash().ToString());
             pindex->nStatus = pindex->nStatus.withParked();
             setDirtyBlockIndex.insert(pindex);
         }
     }
 
     // Header is valid/has work and the merkle tree is good.
     // Relay now, but if it does not build on our best tip, let the
     // SendMessages loop relay it.
     if (!IsInitialBlockDownload() && m_chain.Tip() == pindex->pprev) {
         GetMainSignals().NewPoWValidBlock(pindex, pblock);
     }
 
     // Write block to history file
     if (fNewBlock) {
         *fNewBlock = true;
     }
     try {
         FlatFilePos blockPos =
             SaveBlockToDisk(block, pindex->nHeight, chainparams, dbp);
         if (blockPos.IsNull()) {
             state.Error(strprintf(
                 "%s: Failed to find position to write new block to disk",
                 __func__));
             return false;
         }
         ReceivedBlockTransactions(block, pindex, blockPos);
     } catch (const std::runtime_error &e) {
         return AbortNode(state, std::string("System error: ") + e.what());
     }
 
     FlushStateToDisk(chainparams, state, FlushStateMode::NONE);
 
     CheckBlockIndex(consensusParams);
 
     return true;
 }
 
 bool ProcessNewBlock(const Config &config,
                      const std::shared_ptr<const CBlock> pblock,
                      bool fForceProcessing, bool *fNewBlock) {
     AssertLockNotHeld(cs_main);
 
     {
         if (fNewBlock) {
             *fNewBlock = false;
         }
 
         CValidationState state;
 
         // CheckBlock() does not support multi-threaded block validation
         // because CBlock::fChecked can cause data race.
         // Therefore, the following critical section must include the
         // CheckBlock() call as well.
         LOCK(cs_main);
 
         // Ensure that CheckBlock() passes before calling AcceptBlock, as
         // belt-and-suspenders.
         bool ret =
             CheckBlock(*pblock, state, config.GetChainParams().GetConsensus(),
                        BlockValidationOptions(config));
         if (ret) {
             // Store to disk
             ret = ::ChainstateActive().AcceptBlock(
                 config, pblock, state, fForceProcessing, nullptr, fNewBlock);
         }
 
         if (!ret) {
             GetMainSignals().BlockChecked(*pblock, state);
             return error("%s: AcceptBlock FAILED (%s)", __func__,
                          FormatStateMessage(state));
         }
     }
 
     NotifyHeaderTip();
 
     // Only used to report errors, not invalidity - ignore it
     CValidationState state;
     if (!::ChainstateActive().ActivateBestChain(config, state, pblock)) {
         return error("%s: ActivateBestChain failed (%s)", __func__,
                      FormatStateMessage(state));
     }
 
     return true;
 }
 
 bool TestBlockValidity(CValidationState &state, const CChainParams &params,
                        const CBlock &block, CBlockIndex *pindexPrev,
                        BlockValidationOptions validationOptions) {
     AssertLockHeld(cs_main);
     assert(pindexPrev && pindexPrev == ::ChainActive().Tip());
     CCoinsViewCache viewNew(pcoinsTip.get());
     BlockHash block_hash(block.GetHash());
     CBlockIndex indexDummy(block);
     indexDummy.pprev = pindexPrev;
     indexDummy.nHeight = pindexPrev->nHeight + 1;
     indexDummy.phashBlock = &block_hash;
 
     // NOTE: CheckBlockHeader is called by CheckBlock
     if (!ContextualCheckBlockHeader(params, block, state, pindexPrev,
                                     GetAdjustedTime())) {
         return error("%s: Consensus::ContextualCheckBlockHeader: %s", __func__,
                      FormatStateMessage(state));
     }
 
     if (!CheckBlock(block, state, params.GetConsensus(), validationOptions)) {
         return error("%s: Consensus::CheckBlock: %s", __func__,
                      FormatStateMessage(state));
     }
 
     if (!ContextualCheckBlock(block, state, params.GetConsensus(),
                               pindexPrev)) {
         return error("%s: Consensus::ContextualCheckBlock: %s", __func__,
                      FormatStateMessage(state));
     }
 
     if (!::ChainstateActive().ConnectBlock(block, state, &indexDummy, viewNew,
                                            params, validationOptions, true)) {
         return false;
     }
 
     assert(state.IsValid());
     return true;
 }
 
 /**
  * BLOCK PRUNING CODE
  */
 
 /**
  * Calculate the amount of disk space the block & undo files currently use.
  */
 uint64_t CalculateCurrentUsage() {
     LOCK(cs_LastBlockFile);
 
     uint64_t retval = 0;
     for (const CBlockFileInfo &file : vinfoBlockFile) {
         retval += file.nSize + file.nUndoSize;
     }
 
     return retval;
 }
 
 /**
  * Prune a block file (modify associated database entries)
  */
 void PruneOneBlockFile(const int fileNumber) {
     LOCK(cs_LastBlockFile);
 
     for (const auto &entry : mapBlockIndex) {
         CBlockIndex *pindex = entry.second;
         if (pindex->nFile == fileNumber) {
             pindex->nStatus = pindex->nStatus.withData(false).withUndo(false);
             pindex->nFile = 0;
             pindex->nDataPos = 0;
             pindex->nUndoPos = 0;
             setDirtyBlockIndex.insert(pindex);
 
             // Prune from mapBlocksUnlinked -- any block we prune would have
             // to be downloaded again in order to consider its chain, at which
             // point it would be considered as a candidate for
             // mapBlocksUnlinked or setBlockIndexCandidates.
             std::pair<std::multimap<CBlockIndex *, CBlockIndex *>::iterator,
                       std::multimap<CBlockIndex *, CBlockIndex *>::iterator>
                 range = mapBlocksUnlinked.equal_range(pindex->pprev);
             while (range.first != range.second) {
                 std::multimap<CBlockIndex *, CBlockIndex *>::iterator _it =
                     range.first;
                 range.first++;
                 if (_it->second == pindex) {
                     mapBlocksUnlinked.erase(_it);
                 }
             }
         }
     }
 
     vinfoBlockFile[fileNumber].SetNull();
     setDirtyFileInfo.insert(fileNumber);
 }
 
 void UnlinkPrunedFiles(const std::set<int> &setFilesToPrune) {
     for (const int i : setFilesToPrune) {
         FlatFilePos pos(i, 0);
         fs::remove(BlockFileSeq().FileName(pos));
         fs::remove(UndoFileSeq().FileName(pos));
         LogPrintf("Prune: %s deleted blk/rev (%05u)\n", __func__, i);
     }
 }
 
 /**
  * Calculate the block/rev files to delete based on height specified by user
  * with RPC command pruneblockchain
  */
 static void FindFilesToPruneManual(std::set<int> &setFilesToPrune,
                                    int nManualPruneHeight) {
     assert(fPruneMode && nManualPruneHeight > 0);
 
     LOCK2(cs_main, cs_LastBlockFile);
     if (::ChainActive().Tip() == nullptr) {
         return;
     }
 
     // last block to prune is the lesser of (user-specified height,
     // MIN_BLOCKS_TO_KEEP from the tip)
     unsigned int nLastBlockWeCanPrune =
         std::min((unsigned)nManualPruneHeight,
                  ::ChainActive().Tip()->nHeight - MIN_BLOCKS_TO_KEEP);
     int count = 0;
     for (int fileNumber = 0; fileNumber < nLastBlockFile; fileNumber++) {
         if (vinfoBlockFile[fileNumber].nSize == 0 ||
             vinfoBlockFile[fileNumber].nHeightLast > nLastBlockWeCanPrune) {
             continue;
         }
         PruneOneBlockFile(fileNumber);
         setFilesToPrune.insert(fileNumber);
         count++;
     }
     LogPrintf("Prune (Manual): prune_height=%d removed %d blk/rev pairs\n",
               nLastBlockWeCanPrune, count);
 }
 
 /* This function is called from the RPC code for pruneblockchain */
 void PruneBlockFilesManual(int nManualPruneHeight) {
     CValidationState state;
     const CChainParams &chainparams = Params();
     if (!::ChainstateActive().FlushStateToDisk(
             chainparams, state, FlushStateMode::NONE, nManualPruneHeight)) {
         LogPrintf("%s: failed to flush state (%s)\n", __func__,
                   FormatStateMessage(state));
     }
 }
 
 /**
  * Prune block and undo files (blk???.dat and undo???.dat) so that the disk
  * space used is less than a user-defined target. The user sets the target (in
  * MB) on the command line or in config file.  This will be run on startup and
  * whenever new space is allocated in a block or undo file, staying below the
  * target. Changing back to unpruned requires a reindex (which in this case
  * means the blockchain must be re-downloaded.)
  *
  * Pruning functions are called from FlushStateToDisk when the global
  * fCheckForPruning flag has been set. Block and undo files are deleted in
  * lock-step (when blk00003.dat is deleted, so is rev00003.dat.). Pruning cannot
  * take place until the longest chain is at least a certain length (100000 on
  * mainnet, 1000 on testnet, 1000 on regtest). Pruning will never delete a block
  * within a defined distance (currently 288) from the active chain's tip. The
  * block index is updated by unsetting HAVE_DATA and HAVE_UNDO for any blocks
  * that were stored in the deleted files. A db flag records the fact that at
  * least some block files have been pruned.
  *
  * @param[out]   setFilesToPrune   The set of file indices that can be unlinked
  * will be returned
  */
 static void FindFilesToPrune(std::set<int> &setFilesToPrune,
                              uint64_t nPruneAfterHeight) {
     LOCK2(cs_main, cs_LastBlockFile);
     if (::ChainActive().Tip() == nullptr || nPruneTarget == 0) {
         return;
     }
     if (uint64_t(::ChainActive().Tip()->nHeight) <= nPruneAfterHeight) {
         return;
     }
 
     unsigned int nLastBlockWeCanPrune =
         ::ChainActive().Tip()->nHeight - MIN_BLOCKS_TO_KEEP;
     uint64_t nCurrentUsage = CalculateCurrentUsage();
     // We don't check to prune until after we've allocated new space for files,
     // so we should leave a buffer under our target to account for another
     // allocation before the next pruning.
     uint64_t nBuffer = BLOCKFILE_CHUNK_SIZE + UNDOFILE_CHUNK_SIZE;
     uint64_t nBytesToPrune;
     int count = 0;
 
     if (nCurrentUsage + nBuffer >= nPruneTarget) {
         // On a prune event, the chainstate DB is flushed.
         // To avoid excessive prune events negating the benefit of high dbcache
         // values, we should not prune too rapidly.
         // So when pruning in IBD, increase the buffer a bit to avoid a re-prune
         // too soon.
         if (::ChainstateActive().IsInitialBlockDownload()) {
             // Since this is only relevant during IBD, we use a fixed 10%
             nBuffer += nPruneTarget / 10;
         }
 
         for (int fileNumber = 0; fileNumber < nLastBlockFile; fileNumber++) {
             nBytesToPrune = vinfoBlockFile[fileNumber].nSize +
                             vinfoBlockFile[fileNumber].nUndoSize;
 
             if (vinfoBlockFile[fileNumber].nSize == 0) {
                 continue;
             }
 
             // are we below our target?
             if (nCurrentUsage + nBuffer < nPruneTarget) {
                 break;
             }
 
             // don't prune files that could have a block within
             // MIN_BLOCKS_TO_KEEP of the main chain's tip but keep scanning
             if (vinfoBlockFile[fileNumber].nHeightLast > nLastBlockWeCanPrune) {
                 continue;
             }
 
             PruneOneBlockFile(fileNumber);
             // Queue up the files for removal
             setFilesToPrune.insert(fileNumber);
             nCurrentUsage -= nBytesToPrune;
             count++;
         }
     }
 
     LogPrint(BCLog::PRUNE,
              "Prune: target=%dMiB actual=%dMiB diff=%dMiB "
              "max_prune_height=%d removed %d blk/rev pairs\n",
              nPruneTarget / 1024 / 1024, nCurrentUsage / 1024 / 1024,
              ((int64_t)nPruneTarget - (int64_t)nCurrentUsage) / 1024 / 1024,
              nLastBlockWeCanPrune, count);
 }
 
 static FlatFileSeq BlockFileSeq() {
     return FlatFileSeq(GetBlocksDir(), "blk", BLOCKFILE_CHUNK_SIZE);
 }
 
 static FlatFileSeq UndoFileSeq() {
     return FlatFileSeq(GetBlocksDir(), "rev", UNDOFILE_CHUNK_SIZE);
 }
 
 FILE *OpenBlockFile(const FlatFilePos &pos, bool fReadOnly) {
     return BlockFileSeq().Open(pos, fReadOnly);
 }
 
 /** Open an undo file (rev?????.dat) */
 static FILE *OpenUndoFile(const FlatFilePos &pos, bool fReadOnly) {
     return UndoFileSeq().Open(pos, fReadOnly);
 }
 
 fs::path GetBlockPosFilename(const FlatFilePos &pos) {
     return BlockFileSeq().FileName(pos);
 }
 
 CBlockIndex *CChainState::InsertBlockIndex(const BlockHash &hash) {
     AssertLockHeld(cs_main);
 
     if (hash.IsNull()) {
         return nullptr;
     }
 
     // Return existing
     BlockMap::iterator mi = mapBlockIndex.find(hash);
     if (mi != mapBlockIndex.end()) {
         return (*mi).second;
     }
 
     // Create new
     CBlockIndex *pindexNew = new CBlockIndex();
     mi = mapBlockIndex.insert(std::make_pair(hash, pindexNew)).first;
     pindexNew->phashBlock = &((*mi).first);
 
     return pindexNew;
 }
 
 bool CChainState::LoadBlockIndex(const Config &config,
                                  CBlockTreeDB &blocktree) {
     AssertLockHeld(cs_main);
     if (!blocktree.LoadBlockIndexGuts(
             config.GetChainParams().GetConsensus(),
             [this](const BlockHash &hash) EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
                 return this->InsertBlockIndex(hash);
             })) {
         return false;
     }
 
     // Calculate nChainWork
     std::vector<std::pair<int, CBlockIndex *>> vSortedByHeight;
     vSortedByHeight.reserve(mapBlockIndex.size());
     for (const std::pair<const BlockHash, CBlockIndex *> &item :
          mapBlockIndex) {
         CBlockIndex *pindex = item.second;
         vSortedByHeight.push_back(std::make_pair(pindex->nHeight, pindex));
     }
 
     sort(vSortedByHeight.begin(), vSortedByHeight.end());
     for (const std::pair<int, CBlockIndex *> &item : vSortedByHeight) {
         CBlockIndex *pindex = item.second;
         pindex->nChainWork = (pindex->pprev ? pindex->pprev->nChainWork : 0) +
                              GetBlockProof(*pindex);
         pindex->nTimeMax =
             (pindex->pprev ? std::max(pindex->pprev->nTimeMax, pindex->nTime)
                            : pindex->nTime);
         // We can link the chain of blocks for which we've received transactions
         // at some point. Pruned nodes may have deleted the block.
         if (pindex->nTx > 0) {
             if (pindex->pprev) {
                 if (pindex->pprev->HaveTxsDownloaded()) {
                     pindex->nChainTx = pindex->pprev->nChainTx + pindex->nTx;
                 } else {
                     pindex->nChainTx = 0;
                     mapBlocksUnlinked.insert(
                         std::make_pair(pindex->pprev, pindex));
                 }
             } else {
                 pindex->nChainTx = pindex->nTx;
             }
         }
 
         if (!pindex->nStatus.hasFailed() && pindex->pprev &&
             pindex->pprev->nStatus.hasFailed()) {
             pindex->nStatus = pindex->nStatus.withFailedParent();
             setDirtyBlockIndex.insert(pindex);
         }
         if (pindex->IsValid(BlockValidity::TRANSACTIONS) &&
             (pindex->HaveTxsDownloaded() || pindex->pprev == nullptr)) {
             setBlockIndexCandidates.insert(pindex);
         }
 
         if (pindex->nStatus.isInvalid() &&
             (!pindexBestInvalid ||
              pindex->nChainWork > pindexBestInvalid->nChainWork)) {
             pindexBestInvalid = pindex;
         }
 
         if (pindex->nStatus.isOnParkedChain() &&
             (!pindexBestParked ||
              pindex->nChainWork > pindexBestParked->nChainWork)) {
             pindexBestParked = pindex;
         }
 
         if (pindex->pprev) {
             pindex->BuildSkip();
         }
 
         if (pindex->IsValid(BlockValidity::TREE) &&
             (pindexBestHeader == nullptr ||
              CBlockIndexWorkComparator()(pindexBestHeader, pindex))) {
             pindexBestHeader = pindex;
         }
     }
 
     return true;
 }
 
 static bool LoadBlockIndexDB(const Config &config)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
     if (!::ChainstateActive().LoadBlockIndex(config, *pblocktree)) {
         return false;
     }
 
     // Load block file info
     pblocktree->ReadLastBlockFile(nLastBlockFile);
     vinfoBlockFile.resize(nLastBlockFile + 1);
     LogPrintf("%s: last block file = %i\n", __func__, nLastBlockFile);
     for (int nFile = 0; nFile <= nLastBlockFile; nFile++) {
         pblocktree->ReadBlockFileInfo(nFile, vinfoBlockFile[nFile]);
     }
 
     LogPrintf("%s: last block file info: %s\n", __func__,
               vinfoBlockFile[nLastBlockFile].ToString());
 
     for (int nFile = nLastBlockFile + 1; true; nFile++) {
         CBlockFileInfo info;
         if (pblocktree->ReadBlockFileInfo(nFile, info)) {
             vinfoBlockFile.push_back(info);
         } else {
             break;
         }
     }
 
     // Check presence of blk files
     LogPrintf("Checking all blk files are present...\n");
     std::set<int> setBlkDataFiles;
     for (const std::pair<const BlockHash, CBlockIndex *> &item :
          mapBlockIndex) {
         CBlockIndex *pindex = item.second;
         if (pindex->nStatus.hasData()) {
             setBlkDataFiles.insert(pindex->nFile);
         }
     }
 
     for (const int i : setBlkDataFiles) {
         FlatFilePos pos(i, 0);
         if (CAutoFile(OpenBlockFile(pos, true), SER_DISK, CLIENT_VERSION)
                 .IsNull()) {
             return false;
         }
     }
 
     // Check whether we have ever pruned block & undo files
     pblocktree->ReadFlag("prunedblockfiles", fHavePruned);
     if (fHavePruned) {
         LogPrintf(
             "LoadBlockIndexDB(): Block files have previously been pruned\n");
     }
 
     // Check whether we need to continue reindexing
     bool fReindexing = false;
     pblocktree->ReadReindexing(fReindexing);
     if (fReindexing) {
         fReindex = true;
     }
 
     return true;
 }
 
 bool LoadChainTip(const Config &config) {
     AssertLockHeld(cs_main);
 
     if (::ChainActive().Tip() &&
         ::ChainActive().Tip()->GetBlockHash() == pcoinsTip->GetBestBlock()) {
         return true;
     }
 
     if (pcoinsTip->GetBestBlock().IsNull() && mapBlockIndex.size() == 1) {
         // In case we just added the genesis block, connect it now, so
         // that we always have a ::ChainActive().Tip() when we return.
         LogPrintf("%s: Connecting genesis block...\n", __func__);
         CValidationState state;
         if (!ActivateBestChain(config, state)) {
             LogPrintf("%s: failed to activate chain (%s)\n", __func__,
                       FormatStateMessage(state));
             return false;
         }
     }
 
     // Load pointer to end of best chain
     CBlockIndex *pindex = LookupBlockIndex(pcoinsTip->GetBestBlock());
     if (!pindex) {
         return false;
     }
     ::ChainActive().SetTip(pindex);
 
     ::ChainstateActive().PruneBlockIndexCandidates();
 
     LogPrintf(
         "Loaded best chain: hashBestChain=%s height=%d date=%s progress=%f\n",
         ::ChainActive().Tip()->GetBlockHash().ToString(),
         ::ChainActive().Height(),
         FormatISO8601DateTime(::ChainActive().Tip()->GetBlockTime()),
         GuessVerificationProgress(config.GetChainParams().TxData(),
                                   ::ChainActive().Tip()));
     return true;
 }
 
 CVerifyDB::CVerifyDB() {
     uiInterface.ShowProgress(_("Verifying blocks...").translated, 0, false);
 }
 
 CVerifyDB::~CVerifyDB() {
     uiInterface.ShowProgress("", 100, false);
 }
 
 bool CVerifyDB::VerifyDB(const Config &config, CCoinsView *coinsview,
                          int nCheckLevel, int nCheckDepth) {
     LOCK(cs_main);
 
     const CChainParams &params = config.GetChainParams();
     const Consensus::Params &consensusParams = params.GetConsensus();
 
     if (::ChainActive().Tip() == nullptr ||
         ::ChainActive().Tip()->pprev == nullptr) {
         return true;
     }
 
     // Verify blocks in the best chain
     if (nCheckDepth <= 0 || nCheckDepth > ::ChainActive().Height()) {
         nCheckDepth = ::ChainActive().Height();
     }
 
     nCheckLevel = std::max(0, std::min(4, nCheckLevel));
     LogPrintf("Verifying last %i blocks at level %i\n", nCheckDepth,
               nCheckLevel);
 
     CCoinsViewCache coins(coinsview);
     CBlockIndex *pindex;
     CBlockIndex *pindexFailure = nullptr;
     int nGoodTransactions = 0;
     CValidationState state;
     int reportDone = 0;
     LogPrintfToBeContinued("[0%%]...");
     for (pindex = ::ChainActive().Tip(); pindex && pindex->pprev;
          pindex = pindex->pprev) {
         boost::this_thread::interruption_point();
         int percentageDone =
             std::max(1, std::min(99, (int)(((double)(::ChainActive().Height() -
                                                      pindex->nHeight)) /
                                            (double)nCheckDepth *
                                            (nCheckLevel >= 4 ? 50 : 100))));
 
         if (reportDone < percentageDone / 10) {
             // report every 10% step
             LogPrintfToBeContinued("[%d%%]...", percentageDone);
             reportDone = percentageDone / 10;
         }
 
         uiInterface.ShowProgress(_("Verifying blocks...").translated,
                                  percentageDone, false);
         if (pindex->nHeight <= ::ChainActive().Height() - nCheckDepth) {
             break;
         }
 
         if (fPruneMode && !pindex->nStatus.hasData()) {
             // If pruning, only go back as far as we have data.
             LogPrintf("VerifyDB(): block verification stopping at height %d "
                       "(pruning, no data)\n",
                       pindex->nHeight);
             break;
         }
 
         CBlock block;
 
         // check level 0: read from disk
         if (!ReadBlockFromDisk(block, pindex, consensusParams)) {
             return error(
                 "VerifyDB(): *** ReadBlockFromDisk failed at %d, hash=%s",
                 pindex->nHeight, pindex->GetBlockHash().ToString());
         }
 
         // check level 1: verify block validity
         if (nCheckLevel >= 1 && !CheckBlock(block, state, consensusParams,
                                             BlockValidationOptions(config))) {
             return error("%s: *** found bad block at %d, hash=%s (%s)\n",
                          __func__, pindex->nHeight,
                          pindex->GetBlockHash().ToString(),
                          FormatStateMessage(state));
         }
 
         // check level 2: verify undo validity
         if (nCheckLevel >= 2 && pindex) {
             CBlockUndo undo;
             if (!pindex->GetUndoPos().IsNull()) {
                 if (!UndoReadFromDisk(undo, pindex)) {
                     return error(
                         "VerifyDB(): *** found bad undo data at %d, hash=%s\n",
                         pindex->nHeight, pindex->GetBlockHash().ToString());
                 }
             }
         }
 
         // check level 3: check for inconsistencies during memory-only
         // disconnect of tip blocks
         if (nCheckLevel >= 3 &&
             (coins.DynamicMemoryUsage() + pcoinsTip->DynamicMemoryUsage()) <=
                 nCoinCacheUsage) {
             assert(coins.GetBestBlock() == pindex->GetBlockHash());
             DisconnectResult res =
                 ::ChainstateActive().DisconnectBlock(block, pindex, coins);
             if (res == DisconnectResult::FAILED) {
                 return error("VerifyDB(): *** irrecoverable inconsistency in "
                              "block data at %d, hash=%s",
                              pindex->nHeight,
                              pindex->GetBlockHash().ToString());
             }
 
             if (res == DisconnectResult::UNCLEAN) {
                 nGoodTransactions = 0;
                 pindexFailure = pindex;
             } else {
                 nGoodTransactions += block.vtx.size();
             }
         }
 
         if (ShutdownRequested()) {
             return true;
         }
     }
 
     if (pindexFailure) {
         return error("VerifyDB(): *** coin database inconsistencies found "
                      "(last %i blocks, %i good transactions before that)\n",
                      ::ChainActive().Height() - pindexFailure->nHeight + 1,
                      nGoodTransactions);
     }
 
     // store block count as we move pindex at check level >= 4
     int block_count = ::ChainActive().Height() - pindex->nHeight;
 
     // check level 4: try reconnecting blocks
     if (nCheckLevel >= 4) {
         while (pindex != ::ChainActive().Tip()) {
             boost::this_thread::interruption_point();
             uiInterface.ShowProgress(
                 _("Verifying blocks...").translated,
                 std::max(
                     1, std::min(99,
                                 100 - (int)(((double)(::ChainActive().Height() -
                                                       pindex->nHeight)) /
                                             (double)nCheckDepth * 50))),
                 false);
             pindex = ::ChainActive().Next(pindex);
             CBlock block;
             if (!ReadBlockFromDisk(block, pindex, consensusParams)) {
                 return error(
                     "VerifyDB(): *** ReadBlockFromDisk failed at %d, hash=%s",
                     pindex->nHeight, pindex->GetBlockHash().ToString());
             }
             if (!::ChainstateActive().ConnectBlock(
                     block, state, pindex, coins, params,
                     BlockValidationOptions(config))) {
                 return error("VerifyDB(): *** found unconnectable block at %d, "
                              "hash=%s (%s)",
                              pindex->nHeight, pindex->GetBlockHash().ToString(),
                              FormatStateMessage(state));
             }
         }
     }
 
     LogPrintf("[DONE].\n");
     LogPrintf("No coin database inconsistencies in last %i blocks (%i "
               "transactions)\n",
               block_count, nGoodTransactions);
 
     return true;
 }
 
 /**
  * Apply the effects of a block on the utxo cache, ignoring that it may already
  * have been applied.
  */
 bool CChainState::RollforwardBlock(const CBlockIndex *pindex,
                                    CCoinsViewCache &view,
                                    const Consensus::Params &params) {
     // TODO: merge with ConnectBlock
     CBlock block;
     if (!ReadBlockFromDisk(block, pindex, params)) {
         return error("ReplayBlock(): ReadBlockFromDisk failed at %d, hash=%s",
                      pindex->nHeight, pindex->GetBlockHash().ToString());
     }
 
     for (const CTransactionRef &tx : block.vtx) {
         // Pass check = true as every addition may be an overwrite.
         AddCoins(view, *tx, pindex->nHeight, true);
     }
 
     for (const CTransactionRef &tx : block.vtx) {
         if (tx->IsCoinBase()) {
             continue;
         }
 
         for (const CTxIn &txin : tx->vin) {
             view.SpendCoin(txin.prevout);
         }
     }
 
     return true;
 }
 
 bool CChainState::ReplayBlocks(const Consensus::Params &params,
                                CCoinsView *view) {
     LOCK(cs_main);
 
     CCoinsViewCache cache(view);
 
     std::vector<BlockHash> hashHeads = view->GetHeadBlocks();
     if (hashHeads.empty()) {
         // We're already in a consistent state.
         return true;
     }
 
     if (hashHeads.size() != 2) {
         return error("ReplayBlocks(): unknown inconsistent state");
     }
 
     uiInterface.ShowProgress(_("Replaying blocks...").translated, 0, false);
     LogPrintf("Replaying blocks\n");
 
     // Old tip during the interrupted flush.
     const CBlockIndex *pindexOld = nullptr;
     // New tip during the interrupted flush.
     const CBlockIndex *pindexNew;
     // Latest block common to both the old and the new tip.
     const CBlockIndex *pindexFork = nullptr;
 
     if (mapBlockIndex.count(hashHeads[0]) == 0) {
         return error(
             "ReplayBlocks(): reorganization to unknown block requested");
     }
 
     pindexNew = mapBlockIndex[hashHeads[0]];
 
     if (!hashHeads[1].IsNull()) {
         // The old tip is allowed to be 0, indicating it's the first flush.
         if (mapBlockIndex.count(hashHeads[1]) == 0) {
             return error(
                 "ReplayBlocks(): reorganization from unknown block requested");
         }
 
         pindexOld = mapBlockIndex[hashHeads[1]];
         pindexFork = LastCommonAncestor(pindexOld, pindexNew);
         assert(pindexFork != nullptr);
     }
 
     // Rollback along the old branch.
     while (pindexOld != pindexFork) {
         if (pindexOld->nHeight > 0) {
             // Never disconnect the genesis block.
             CBlock block;
             if (!ReadBlockFromDisk(block, pindexOld, params)) {
                 return error("RollbackBlock(): ReadBlockFromDisk() failed at "
                              "%d, hash=%s",
                              pindexOld->nHeight,
                              pindexOld->GetBlockHash().ToString());
             }
 
             LogPrintf("Rolling back %s (%i)\n",
                       pindexOld->GetBlockHash().ToString(), pindexOld->nHeight);
             DisconnectResult res = DisconnectBlock(block, pindexOld, cache);
             if (res == DisconnectResult::FAILED) {
                 return error(
                     "RollbackBlock(): DisconnectBlock failed at %d, hash=%s",
                     pindexOld->nHeight, pindexOld->GetBlockHash().ToString());
             }
 
             // If DisconnectResult::UNCLEAN is returned, it means a non-existing
             // UTXO was deleted, or an existing UTXO was overwritten. It
             // corresponds to cases where the block-to-be-disconnect never had
             // all its operations applied to the UTXO set. However, as both
             // writing a UTXO and deleting a UTXO are idempotent operations, the
             // result is still a version of the UTXO set with the effects of
             // that block undone.
         }
         pindexOld = pindexOld->pprev;
     }
 
     // Roll forward from the forking point to the new tip.
     int nForkHeight = pindexFork ? pindexFork->nHeight : 0;
     for (int nHeight = nForkHeight + 1; nHeight <= pindexNew->nHeight;
          ++nHeight) {
         const CBlockIndex *pindex = pindexNew->GetAncestor(nHeight);
         LogPrintf("Rolling forward %s (%i)\n",
                   pindex->GetBlockHash().ToString(), nHeight);
         if (!RollforwardBlock(pindex, cache, params)) {
             return false;
         }
     }
 
     cache.SetBestBlock(pindexNew->GetBlockHash());
     cache.Flush();
     uiInterface.ShowProgress("", 100, false);
     return true;
 }
 
 bool ReplayBlocks(const Consensus::Params &params, CCoinsView *view) {
     return ::ChainstateActive().ReplayBlocks(params, view);
 }
 
 // May NOT be used after any connections are up as much of the peer-processing
 // logic assumes a consistent block index state
 void CChainState::UnloadBlockIndex() {
     nBlockSequenceId = 1;
     m_failed_blocks.clear();
     setBlockIndexCandidates.clear();
 }
 
 // May NOT be used after any connections are up as much
 // of the peer-processing logic assumes a consistent
 // block index state
 void UnloadBlockIndex() {
     LOCK(cs_main);
     ::ChainActive().SetTip(nullptr);
     pindexFinalized = nullptr;
     pindexBestInvalid = nullptr;
     pindexBestParked = nullptr;
     pindexBestHeader = nullptr;
     pindexBestForkTip = nullptr;
     pindexBestForkBase = nullptr;
     g_mempool.clear();
     mapBlocksUnlinked.clear();
     vinfoBlockFile.clear();
     nLastBlockFile = 0;
     setDirtyBlockIndex.clear();
     setDirtyFileInfo.clear();
 
     for (const BlockMap::value_type &entry : mapBlockIndex) {
         delete entry.second;
     }
 
     mapBlockIndex.clear();
     fHavePruned = false;
 
     ::ChainstateActive().UnloadBlockIndex();
 }
 
 bool LoadBlockIndex(const Config &config) {
     // Load block index from databases
     bool needs_init = fReindex;
     if (!fReindex) {
         bool ret = LoadBlockIndexDB(config);
         if (!ret) {
             return false;
         }
 
         needs_init = mapBlockIndex.empty();
     }
 
     if (needs_init) {
         // Everything here is for *new* reindex/DBs. Thus, though
         // LoadBlockIndexDB may have set fReindex if we shut down
         // mid-reindex previously, we don't check fReindex and
         // instead only check it prior to LoadBlockIndexDB to set
         // needs_init.
 
         LogPrintf("Initializing databases...\n");
     }
     return true;
 }
 
 bool CChainState::LoadGenesisBlock(const CChainParams &chainparams) {
     LOCK(cs_main);
 
     // Check whether we're already initialized by checking for genesis in
     // mapBlockIndex. Note that we can't use m_chain here, since it is
     // set based on the coins db, not the block index db, which is the only
     // thing loaded at this point.
     if (mapBlockIndex.count(chainparams.GenesisBlock().GetHash())) {
         return true;
     }
 
     try {
         const CBlock &block = chainparams.GenesisBlock();
         FlatFilePos blockPos = SaveBlockToDisk(block, 0, chainparams, nullptr);
         if (blockPos.IsNull()) {
             return error("%s: writing genesis block to disk failed", __func__);
         }
         CBlockIndex *pindex = AddToBlockIndex(block);
         ReceivedBlockTransactions(block, pindex, blockPos);
     } catch (const std::runtime_error &e) {
         return error("%s: failed to write genesis block: %s", __func__,
                      e.what());
     }
 
     return true;
 }
 
 bool LoadGenesisBlock(const CChainParams &chainparams) {
     return ::ChainstateActive().LoadGenesisBlock(chainparams);
 }
 
 bool LoadExternalBlockFile(const Config &config, FILE *fileIn,
                            FlatFilePos *dbp) {
     // Map of disk positions for blocks with unknown parent (only used for
     // reindex)
     static std::multimap<uint256, FlatFilePos> mapBlocksUnknownParent;
     int64_t nStart = GetTimeMillis();
 
     const CChainParams &chainparams = config.GetChainParams();
 
     int nLoaded = 0;
     try {
         // This takes over fileIn and calls fclose() on it in the CBufferedFile
         // destructor. Make sure we have at least 2*MAX_TX_SIZE space in there
         // so any transaction can fit in the buffer.
         CBufferedFile blkdat(fileIn, 2 * MAX_TX_SIZE, MAX_TX_SIZE + 8, SER_DISK,
                              CLIENT_VERSION);
         uint64_t nRewind = blkdat.GetPos();
         while (!blkdat.eof()) {
             boost::this_thread::interruption_point();
 
             blkdat.SetPos(nRewind);
             // Start one byte further next time, in case of failure.
             nRewind++;
             // Remove former limit.
             blkdat.SetLimit();
             unsigned int nSize = 0;
             try {
                 // Locate a header.
                 uint8_t buf[CMessageHeader::MESSAGE_START_SIZE];
                 blkdat.FindByte(chainparams.DiskMagic()[0]);
                 nRewind = blkdat.GetPos() + 1;
                 blkdat >> buf;
                 if (memcmp(buf, chainparams.DiskMagic().data(),
                            CMessageHeader::MESSAGE_START_SIZE)) {
                     continue;
                 }
 
                 // Read size.
                 blkdat >> nSize;
                 if (nSize < 80) {
                     continue;
                 }
             } catch (const std::exception &) {
                 // No valid block header found; don't complain.
                 break;
             }
 
             try {
                 // read block
                 uint64_t nBlockPos = blkdat.GetPos();
                 if (dbp) {
                     dbp->nPos = nBlockPos;
                 }
                 blkdat.SetLimit(nBlockPos + nSize);
                 blkdat.SetPos(nBlockPos);
                 std::shared_ptr<CBlock> pblock = std::make_shared<CBlock>();
                 CBlock &block = *pblock;
                 blkdat >> block;
                 nRewind = blkdat.GetPos();
 
                 const BlockHash hash = block.GetHash();
                 {
                     LOCK(cs_main);
                     // detect out of order blocks, and store them for later
                     if (hash != chainparams.GetConsensus().hashGenesisBlock &&
                         !LookupBlockIndex(block.hashPrevBlock)) {
                         LogPrint(
                             BCLog::REINDEX,
                             "%s: Out of order block %s, parent %s not known\n",
                             __func__, hash.ToString(),
                             block.hashPrevBlock.ToString());
                         if (dbp) {
                             mapBlocksUnknownParent.insert(
                                 std::make_pair(block.hashPrevBlock, *dbp));
                         }
                         continue;
                     }
 
                     // process in case the block isn't known yet
                     CBlockIndex *pindex = LookupBlockIndex(hash);
                     if (!pindex || !pindex->nStatus.hasData()) {
                         CValidationState state;
                         if (::ChainstateActive().AcceptBlock(
                                 config, pblock, state, true, dbp, nullptr)) {
                             nLoaded++;
                         }
                         if (state.IsError()) {
                             break;
                         }
                     } else if (hash != chainparams.GetConsensus()
                                            .hashGenesisBlock &&
                                pindex->nHeight % 1000 == 0) {
                         LogPrint(
                             BCLog::REINDEX,
                             "Block Import: already had block %s at height %d\n",
                             hash.ToString(), pindex->nHeight);
                     }
                 }
 
                 // Activate the genesis block so normal node progress can
                 // continue
                 if (hash == chainparams.GetConsensus().hashGenesisBlock) {
                     CValidationState state;
                     if (!ActivateBestChain(config, state)) {
                         break;
                     }
                 }
 
                 NotifyHeaderTip();
 
                 // Recursively process earlier encountered successors of this
                 // block
                 std::deque<uint256> queue;
                 queue.push_back(hash);
                 while (!queue.empty()) {
                     uint256 head = queue.front();
                     queue.pop_front();
                     std::pair<std::multimap<uint256, FlatFilePos>::iterator,
                               std::multimap<uint256, FlatFilePos>::iterator>
                         range = mapBlocksUnknownParent.equal_range(head);
                     while (range.first != range.second) {
                         std::multimap<uint256, FlatFilePos>::iterator it =
                             range.first;
                         std::shared_ptr<CBlock> pblockrecursive =
                             std::make_shared<CBlock>();
                         if (ReadBlockFromDisk(*pblockrecursive, it->second,
                                               chainparams.GetConsensus())) {
                             LogPrint(
                                 BCLog::REINDEX,
                                 "%s: Processing out of order child %s of %s\n",
                                 __func__, pblockrecursive->GetHash().ToString(),
                                 head.ToString());
                             LOCK(cs_main);
                             CValidationState dummy;
                             if (::ChainstateActive().AcceptBlock(
                                     config, pblockrecursive, dummy, true,
                                     &it->second, nullptr)) {
                                 nLoaded++;
                                 queue.push_back(pblockrecursive->GetHash());
                             }
                         }
                         range.first++;
                         mapBlocksUnknownParent.erase(it);
                         NotifyHeaderTip();
                     }
                 }
             } catch (const std::exception &e) {
                 LogPrintf("%s: Deserialize or I/O error - %s\n", __func__,
                           e.what());
             }
         }
     } catch (const std::runtime_error &e) {
         AbortNode(std::string("System error: ") + e.what());
     }
 
     if (nLoaded > 0) {
         LogPrintf("Loaded %i blocks from external file in %dms\n", nLoaded,
                   GetTimeMillis() - nStart);
     }
 
     return nLoaded > 0;
 }
 
 void CChainState::CheckBlockIndex(const Consensus::Params &consensusParams) {
     if (!fCheckBlockIndex) {
         return;
     }
 
     LOCK(cs_main);
 
     // During a reindex, we read the genesis block and call CheckBlockIndex
     // before ActivateBestChain, so we have the genesis block in mapBlockIndex
     // but no active chain. (A few of the tests when iterating the block tree
     // require that m_chain has been initialized.)
     if (m_chain.Height() < 0) {
         assert(mapBlockIndex.size() <= 1);
         return;
     }
 
     // Build forward-pointing map of the entire block tree.
     std::multimap<CBlockIndex *, CBlockIndex *> forward;
     for (const auto &entry : mapBlockIndex) {
         forward.emplace(entry.second->pprev, entry.second);
     }
 
     assert(forward.size() == mapBlockIndex.size());
 
     std::pair<std::multimap<CBlockIndex *, CBlockIndex *>::iterator,
               std::multimap<CBlockIndex *, CBlockIndex *>::iterator>
         rangeGenesis = forward.equal_range(nullptr);
     CBlockIndex *pindex = rangeGenesis.first->second;
     rangeGenesis.first++;
     // There is only one index entry with parent nullptr.
     assert(rangeGenesis.first == rangeGenesis.second);
 
     // Iterate over the entire block tree, using depth-first search.
     // Along the way, remember whether there are blocks on the path from genesis
     // block being explored which are the first to have certain properties.
     size_t nNodes = 0;
     int nHeight = 0;
     // Oldest ancestor of pindex which is invalid.
     CBlockIndex *pindexFirstInvalid = nullptr;
     // Oldest ancestor of pindex which is parked.
     CBlockIndex *pindexFirstParked = nullptr;
     // Oldest ancestor of pindex which does not have data available.
     CBlockIndex *pindexFirstMissing = nullptr;
     // Oldest ancestor of pindex for which nTx == 0.
     CBlockIndex *pindexFirstNeverProcessed = nullptr;
     // Oldest ancestor of pindex which does not have BLOCK_VALID_TREE
     // (regardless of being valid or not).
     CBlockIndex *pindexFirstNotTreeValid = nullptr;
     // Oldest ancestor of pindex which does not have BLOCK_VALID_TRANSACTIONS
     // (regardless of being valid or not).
     CBlockIndex *pindexFirstNotTransactionsValid = nullptr;
     // Oldest ancestor of pindex which does not have BLOCK_VALID_CHAIN
     // (regardless of being valid or not).
     CBlockIndex *pindexFirstNotChainValid = nullptr;
     // Oldest ancestor of pindex which does not have BLOCK_VALID_SCRIPTS
     // (regardless of being valid or not).
     CBlockIndex *pindexFirstNotScriptsValid = nullptr;
     while (pindex != nullptr) {
         nNodes++;
         if (pindexFirstInvalid == nullptr && pindex->nStatus.hasFailed()) {
             pindexFirstInvalid = pindex;
         }
         if (pindexFirstParked == nullptr && pindex->nStatus.isParked()) {
             pindexFirstParked = pindex;
         }
         if (pindexFirstMissing == nullptr && !pindex->nStatus.hasData()) {
             pindexFirstMissing = pindex;
         }
         if (pindexFirstNeverProcessed == nullptr && pindex->nTx == 0) {
             pindexFirstNeverProcessed = pindex;
         }
         if (pindex->pprev != nullptr && pindexFirstNotTreeValid == nullptr &&
             pindex->nStatus.getValidity() < BlockValidity::TREE) {
             pindexFirstNotTreeValid = pindex;
         }
         if (pindex->pprev != nullptr &&
             pindexFirstNotTransactionsValid == nullptr &&
             pindex->nStatus.getValidity() < BlockValidity::TRANSACTIONS) {
             pindexFirstNotTransactionsValid = pindex;
         }
         if (pindex->pprev != nullptr && pindexFirstNotChainValid == nullptr &&
             pindex->nStatus.getValidity() < BlockValidity::CHAIN) {
             pindexFirstNotChainValid = pindex;
         }
         if (pindex->pprev != nullptr && pindexFirstNotScriptsValid == nullptr &&
             pindex->nStatus.getValidity() < BlockValidity::SCRIPTS) {
             pindexFirstNotScriptsValid = pindex;
         }
 
         // Begin: actual consistency checks.
         if (pindex->pprev == nullptr) {
             // Genesis block checks.
             // Genesis block's hash must match.
             assert(pindex->GetBlockHash() == consensusParams.hashGenesisBlock);
             // The current active chain's genesis block must be this block.
             assert(pindex == m_chain.Genesis());
         }
         if (!pindex->HaveTxsDownloaded()) {
             // nSequenceId can't be set positive for blocks that aren't linked
             // (negative is used for preciousblock)
             assert(pindex->nSequenceId <= 0);
         }
         // VALID_TRANSACTIONS is equivalent to nTx > 0 for all nodes (whether or
         // not pruning has occurred). HAVE_DATA is only equivalent to nTx > 0
         // (or VALID_TRANSACTIONS) if no pruning has occurred.
         if (!fHavePruned) {
             // If we've never pruned, then HAVE_DATA should be equivalent to nTx
             // > 0
             assert(pindex->nStatus.hasData() == (pindex->nTx > 0));
             assert(pindexFirstMissing == pindexFirstNeverProcessed);
         } else if (pindex->nStatus.hasData()) {
             // If we have pruned, then we can only say that HAVE_DATA implies
             // nTx > 0
             assert(pindex->nTx > 0);
         }
         if (pindex->nStatus.hasUndo()) {
             assert(pindex->nStatus.hasData());
         }
         // This is pruning-independent.
         assert((pindex->nStatus.getValidity() >= BlockValidity::TRANSACTIONS) ==
                (pindex->nTx > 0));
         // All parents having had data (at some point) is equivalent to all
         // parents being VALID_TRANSACTIONS, which is equivalent to
         // HaveTxsDownloaded(). All parents having had data (at some point) is
         // equivalent to all parents being VALID_TRANSACTIONS, which is
         // equivalent to HaveTxsDownloaded().
         assert((pindexFirstNeverProcessed == nullptr) ==
                (pindex->HaveTxsDownloaded()));
         assert((pindexFirstNotTransactionsValid == nullptr) ==
                (pindex->HaveTxsDownloaded()));
         // nHeight must be consistent.
         assert(pindex->nHeight == nHeight);
         // For every block except the genesis block, the chainwork must be
         // larger than the parent's.
         assert(pindex->pprev == nullptr ||
                pindex->nChainWork >= pindex->pprev->nChainWork);
         // The pskip pointer must point back for all but the first 2 blocks.
         assert(nHeight < 2 ||
                (pindex->pskip && (pindex->pskip->nHeight < nHeight)));
         // All mapBlockIndex entries must at least be TREE valid
         assert(pindexFirstNotTreeValid == nullptr);
         if (pindex->nStatus.getValidity() >= BlockValidity::TREE) {
             // TREE valid implies all parents are TREE valid
             assert(pindexFirstNotTreeValid == nullptr);
         }
         if (pindex->nStatus.getValidity() >= BlockValidity::CHAIN) {
             // CHAIN valid implies all parents are CHAIN valid
             assert(pindexFirstNotChainValid == nullptr);
         }
         if (pindex->nStatus.getValidity() >= BlockValidity::SCRIPTS) {
             // SCRIPTS valid implies all parents are SCRIPTS valid
             assert(pindexFirstNotScriptsValid == nullptr);
         }
         if (pindexFirstInvalid == nullptr) {
             // Checks for not-invalid blocks.
             // The failed mask cannot be set for blocks without invalid parents.
             assert(!pindex->nStatus.isInvalid());
         }
         if (pindexFirstParked == nullptr) {
             // Checks for not-parked blocks.
             // The parked mask cannot be set for blocks without parked parents.
             // (i.e., hasParkedParent only if an ancestor is properly parked).
             assert(!pindex->nStatus.isOnParkedChain());
         }
         if (!CBlockIndexWorkComparator()(pindex, m_chain.Tip()) &&
             pindexFirstNeverProcessed == nullptr) {
             if (pindexFirstInvalid == nullptr) {
                 // If this block sorts at least as good as the current tip and
                 // is valid and we have all data for its parents, it must be in
                 // setBlockIndexCandidates or be parked.
                 if (pindexFirstMissing == nullptr) {
                     assert(pindex->nStatus.isOnParkedChain() ||
                            setBlockIndexCandidates.count(pindex));
                 }
                 // m_chain.Tip() must also be there even if some data has
                 // been pruned.
                 if (pindex == m_chain.Tip()) {
                     assert(setBlockIndexCandidates.count(pindex));
                 }
                 // If some parent is missing, then it could be that this block
                 // was in setBlockIndexCandidates but had to be removed because
                 // of the missing data. In this case it must be in
                 // mapBlocksUnlinked -- see test below.
             }
         } else {
             // If this block sorts worse than the current tip or some ancestor's
             // block has never been seen, it cannot be in
             // setBlockIndexCandidates.
             assert(setBlockIndexCandidates.count(pindex) == 0);
         }
         // Check whether this block is in mapBlocksUnlinked.
         std::pair<std::multimap<CBlockIndex *, CBlockIndex *>::iterator,
                   std::multimap<CBlockIndex *, CBlockIndex *>::iterator>
             rangeUnlinked = mapBlocksUnlinked.equal_range(pindex->pprev);
         bool foundInUnlinked = false;
         while (rangeUnlinked.first != rangeUnlinked.second) {
             assert(rangeUnlinked.first->first == pindex->pprev);
             if (rangeUnlinked.first->second == pindex) {
                 foundInUnlinked = true;
                 break;
             }
             rangeUnlinked.first++;
         }
         if (pindex->pprev && pindex->nStatus.hasData() &&
             pindexFirstNeverProcessed != nullptr &&
             pindexFirstInvalid == nullptr) {
             // If this block has block data available, some parent was never
             // received, and has no invalid parents, it must be in
             // mapBlocksUnlinked.
             assert(foundInUnlinked);
         }
         if (!pindex->nStatus.hasData()) {
             // Can't be in mapBlocksUnlinked if we don't HAVE_DATA
             assert(!foundInUnlinked);
         }
         if (pindexFirstMissing == nullptr) {
             // We aren't missing data for any parent -- cannot be in
             // mapBlocksUnlinked.
             assert(!foundInUnlinked);
         }
         if (pindex->pprev && pindex->nStatus.hasData() &&
             pindexFirstNeverProcessed == nullptr &&
             pindexFirstMissing != nullptr) {
             // We HAVE_DATA for this block, have received data for all parents
             // at some point, but we're currently missing data for some parent.
             // We must have pruned.
             assert(fHavePruned);
             // This block may have entered mapBlocksUnlinked if:
             //  - it has a descendant that at some point had more work than the
             //    tip, and
             //  - we tried switching to that descendant but were missing
             //    data for some intermediate block between m_chain and the
             //    tip.
             // So if this block is itself better than m_chain.Tip() and it
             // wasn't in
             // setBlockIndexCandidates, then it must be in mapBlocksUnlinked.
             if (!CBlockIndexWorkComparator()(pindex, m_chain.Tip()) &&
                 setBlockIndexCandidates.count(pindex) == 0) {
                 if (pindexFirstInvalid == nullptr) {
                     assert(foundInUnlinked);
                 }
             }
         }
         // Perhaps too slow
         // assert(pindex->GetBlockHash() == pindex->GetBlockHeader().GetHash());
         // End: actual consistency checks.
 
         // Try descending into the first subnode.
         std::pair<std::multimap<CBlockIndex *, CBlockIndex *>::iterator,
                   std::multimap<CBlockIndex *, CBlockIndex *>::iterator>
             range = forward.equal_range(pindex);
         if (range.first != range.second) {
             // A subnode was found.
             pindex = range.first->second;
             nHeight++;
             continue;
         }
         // This is a leaf node. Move upwards until we reach a node of which we
         // have not yet visited the last child.
         while (pindex) {
             // We are going to either move to a parent or a sibling of pindex.
             // If pindex was the first with a certain property, unset the
             // corresponding variable.
             if (pindex == pindexFirstInvalid) {
                 pindexFirstInvalid = nullptr;
             }
             if (pindex == pindexFirstParked) {
                 pindexFirstParked = nullptr;
             }
             if (pindex == pindexFirstMissing) {
                 pindexFirstMissing = nullptr;
             }
             if (pindex == pindexFirstNeverProcessed) {
                 pindexFirstNeverProcessed = nullptr;
             }
             if (pindex == pindexFirstNotTreeValid) {
                 pindexFirstNotTreeValid = nullptr;
             }
             if (pindex == pindexFirstNotTransactionsValid) {
                 pindexFirstNotTransactionsValid = nullptr;
             }
             if (pindex == pindexFirstNotChainValid) {
                 pindexFirstNotChainValid = nullptr;
             }
             if (pindex == pindexFirstNotScriptsValid) {
                 pindexFirstNotScriptsValid = nullptr;
             }
             // Find our parent.
             CBlockIndex *pindexPar = pindex->pprev;
             // Find which child we just visited.
             std::pair<std::multimap<CBlockIndex *, CBlockIndex *>::iterator,
                       std::multimap<CBlockIndex *, CBlockIndex *>::iterator>
                 rangePar = forward.equal_range(pindexPar);
             while (rangePar.first->second != pindex) {
                 // Our parent must have at least the node we're coming from as
                 // child.
                 assert(rangePar.first != rangePar.second);
                 rangePar.first++;
             }
             // Proceed to the next one.
             rangePar.first++;
             if (rangePar.first != rangePar.second) {
                 // Move to the sibling.
                 pindex = rangePar.first->second;
                 break;
             } else {
                 // Move up further.
                 pindex = pindexPar;
                 nHeight--;
                 continue;
             }
         }
     }
 
     // Check that we actually traversed the entire map.
     assert(nNodes == forward.size());
 }
 
 std::string CBlockFileInfo::ToString() const {
     return strprintf(
         "CBlockFileInfo(blocks=%u, size=%u, heights=%u...%u, time=%s...%s)",
         nBlocks, nSize, nHeightFirst, nHeightLast,
         FormatISO8601DateTime(nTimeFirst), FormatISO8601DateTime(nTimeLast));
 }
 
 CBlockFileInfo *GetBlockFileInfo(size_t n) {
     LOCK(cs_LastBlockFile);
 
     return &vinfoBlockFile.at(n);
 }
 
 static ThresholdState VersionBitsStateImpl(const Consensus::Params &params,
                                            Consensus::DeploymentPos pos,
                                            const CBlockIndex *pindex)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
     return VersionBitsState(pindex, params, pos, versionbitscache);
 }
 
 ThresholdState VersionBitsTipState(const Consensus::Params &params,
                                    Consensus::DeploymentPos pos) {
     LOCK(cs_main);
     return VersionBitsStateImpl(params, pos, ::ChainActive().Tip());
 }
 
 ThresholdState VersionBitsBlockState(const Consensus::Params &params,
                                      Consensus::DeploymentPos pos,
                                      const CBlockIndex *pindex) {
     LOCK(cs_main);
     return VersionBitsStateImpl(params, pos, pindex);
 }
 
 BIP9Stats VersionBitsTipStatistics(const Consensus::Params &params,
                                    Consensus::DeploymentPos pos) {
     LOCK(cs_main);
     return VersionBitsStatistics(::ChainActive().Tip(), params, pos);
 }
 
 int VersionBitsTipStateSinceHeight(const Consensus::Params &params,
                                    Consensus::DeploymentPos pos) {
     LOCK(cs_main);
     return VersionBitsStateSinceHeight(::ChainActive().Tip(), params, pos,
                                        versionbitscache);
 }
 
 static const uint64_t MEMPOOL_DUMP_VERSION = 1;
 
 bool LoadMempool(const Config &config, CTxMemPool &pool) {
     int64_t nExpiryTimeout =
         gArgs.GetArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY) * 60 * 60;
     FILE *filestr = fsbridge::fopen(GetDataDir() / "mempool.dat", "rb");
     CAutoFile file(filestr, SER_DISK, CLIENT_VERSION);
     if (file.IsNull()) {
         LogPrintf(
             "Failed to open mempool file from disk. Continuing anyway.\n");
         return false;
     }
 
     int64_t count = 0;
     int64_t expired = 0;
     int64_t failed = 0;
     int64_t already_there = 0;
     int64_t nNow = GetTime();
 
     try {
         uint64_t version;
         file >> version;
         if (version != MEMPOOL_DUMP_VERSION) {
             return false;
         }
 
         uint64_t num;
         file >> num;
         while (num--) {
             CTransactionRef tx;
             int64_t nTime;
             int64_t nFeeDelta;
             file >> tx;
             file >> nTime;
             file >> nFeeDelta;
 
             Amount amountdelta = nFeeDelta * SATOSHI;
             if (amountdelta != Amount::zero()) {
                 pool.PrioritiseTransaction(tx->GetId(), amountdelta);
             }
             CValidationState state;
             if (nTime + nExpiryTimeout > nNow) {
                 LOCK(cs_main);
                 AcceptToMemoryPoolWithTime(
                     config, pool, state, tx, nullptr /* pfMissingInputs */,
                     nTime, false /* bypass_limits */,
                     Amount::zero() /* nAbsurdFee */, false /* test_accept */);
                 if (state.IsValid()) {
                     ++count;
                 } else {
                     // mempool may contain the transaction already, e.g. from
                     // wallet(s) having loaded it while we were processing
                     // mempool transactions; consider these as valid, instead of
                     // failed, but mark them as 'already there'
                     if (pool.exists(tx->GetId())) {
                         ++already_there;
                     } else {
                         ++failed;
                     }
                 }
             } else {
                 ++expired;
             }
 
             if (ShutdownRequested()) {
                 return false;
             }
         }
         std::map<TxId, Amount> mapDeltas;
         file >> mapDeltas;
 
         for (const auto &i : mapDeltas) {
             pool.PrioritiseTransaction(i.first, i.second);
         }
     } catch (const std::exception &e) {
         LogPrintf("Failed to deserialize mempool data on disk: %s. Continuing "
                   "anyway.\n",
                   e.what());
         return false;
     }
 
     LogPrintf("Imported mempool transactions from disk: %i succeeded, %i "
               "failed, %i expired, %i already there\n",
               count, failed, expired, already_there);
     return true;
 }
 
 bool DumpMempool(const CTxMemPool &pool) {
     int64_t start = GetTimeMicros();
 
     std::map<uint256, Amount> mapDeltas;
     std::vector<TxMempoolInfo> vinfo;
 
     static Mutex dump_mutex;
     LOCK(dump_mutex);
 
     {
         LOCK(pool.cs);
         for (const auto &i : pool.mapDeltas) {
             mapDeltas[i.first] = i.second;
         }
 
         vinfo = pool.infoAll();
     }
 
     int64_t mid = GetTimeMicros();
 
     try {
         FILE *filestr = fsbridge::fopen(GetDataDir() / "mempool.dat.new", "wb");
         if (!filestr) {
             return false;
         }
 
         CAutoFile file(filestr, SER_DISK, CLIENT_VERSION);
 
         uint64_t version = MEMPOOL_DUMP_VERSION;
         file << version;
 
         file << uint64_t(vinfo.size());
         for (const auto &i : vinfo) {
             file << *(i.tx);
             file << int64_t(i.nTime);
             file << i.nFeeDelta;
             mapDeltas.erase(i.tx->GetId());
         }
 
         file << mapDeltas;
         if (!FileCommit(file.Get())) {
             throw std::runtime_error("FileCommit failed");
         }
         file.fclose();
         RenameOver(GetDataDir() / "mempool.dat.new",
                    GetDataDir() / "mempool.dat");
         int64_t last = GetTimeMicros();
         LogPrintf("Dumped mempool: %gs to copy, %gs to dump\n",
                   (mid - start) * MICRO, (last - mid) * MICRO);
     } catch (const std::exception &e) {
         LogPrintf("Failed to dump mempool: %s. Continuing anyway.\n", e.what());
         return false;
     }
     return true;
 }
 
 bool IsBlockPruned(const CBlockIndex *pblockindex) {
     return (fHavePruned && !pblockindex->nStatus.hasData() &&
             pblockindex->nTx > 0);
 }
 
 //! Guess how far we are in the verification process at the given block index
 //! require cs_main if pindex has not been validated yet (because nChainTx might
 //! be unset)
 //! This conditional lock requirement might be confusing, see:
 //! https://github.com/bitcoin/bitcoin/issues/15994
 double GuessVerificationProgress(const ChainTxData &data,
                                  const CBlockIndex *pindex) {
     if (pindex == nullptr) {
         return 0.0;
     }
 
     int64_t nNow = time(nullptr);
 
     double fTxTotal;
     if (pindex->nChainTx <= data.nTxCount) {
         fTxTotal = data.nTxCount + (nNow - data.nTime) * data.dTxRate;
     } else {
         fTxTotal =
             pindex->nChainTx + (nNow - pindex->GetBlockTime()) * data.dTxRate;
     }
 
     return pindex->nChainTx / fTxTotal;
 }
 
 class CMainCleanup {
 public:
     CMainCleanup() {}
     ~CMainCleanup() {
         // block headers
         for (const std::pair<const BlockHash, CBlockIndex *> &it :
              mapBlockIndex) {
             delete it.second;
         }
         mapBlockIndex.clear();
     }
 } instance_of_cmaincleanup;
diff --git a/src/validation.h b/src/validation.h
index 31d8a2ba7..b2f2f5bad 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -1,1008 +1,995 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2019 The Bitcoin Core developers
 // Copyright (c) 2017-2020 The Bitcoin developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_VALIDATION_H
 #define BITCOIN_VALIDATION_H
 
 #if defined(HAVE_CONFIG_H)
 #include <config/bitcoin-config.h>
 #endif
 
 #include <amount.h>
 #include <blockfileinfo.h>
 #include <blockindexworkcomparator.h>
 #include <coins.h>
 #include <consensus/consensus.h>
 #include <disconnectresult.h>
 #include <flatfile.h>
 #include <fs.h>
 #include <protocol.h> // For CMessageHeader::MessageMagic
 #include <script/script_error.h>
 #include <script/script_metrics.h>
 #include <sync.h>
 #include <versionbits.h>
 
 #include <algorithm>
 #include <atomic>
 #include <cstdint>
 #include <exception>
 #include <map>
 #include <memory>
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
 
 class CBlockIndex;
 class CBlockTreeDB;
 class CChainParams;
 class CChain;
 class CCoinsViewDB;
 class CConnman;
 class CInv;
 class Config;
 class CScriptCheck;
 class CTxMemPool;
 class CTxUndo;
 class CValidationState;
 class DisconnectedBlockTransactions;
 
 struct ChainTxData;
 struct FlatFilePos;
 struct PrecomputedTransactionData;
 struct LockPoints;
 
 namespace Consensus {
 struct Params;
 }
 
 #define MIN_TRANSACTION_SIZE                                                   \
     (::GetSerializeSize(CTransaction(), PROTOCOL_VERSION))
 
 /** Default for -minrelaytxfee, minimum relay fee for transactions */
 static const Amount DEFAULT_MIN_RELAY_TX_FEE_PER_KB(1000 * SATOSHI);
 /** Default for -excessutxocharge for transactions transactions */
 static const Amount DEFAULT_UTXO_FEE = Amount::zero();
-//! -maxtxfee default
-static const Amount DEFAULT_TRANSACTION_MAXFEE(COIN / 10);
-//! Discourage users to set fees higher than this amount (in satoshis) per kB
-static const Amount HIGH_TX_FEE_PER_KB(COIN / 100);
-/**
- * -maxtxfee will warn if called with a higher fee than this amount (in satoshis
- */
-static const Amount HIGH_MAX_TX_FEE(100 * HIGH_TX_FEE_PER_KB);
 /**
  * Default for -mempoolexpiry, expiration time for mempool transactions in
  * hours.
  */
 static const unsigned int DEFAULT_MEMPOOL_EXPIRY = 336;
 /** The maximum size of a blk?????.dat file (since 0.8) */
 static const unsigned int MAX_BLOCKFILE_SIZE = 0x8000000; // 128 MiB
 /** The pre-allocation chunk size for blk?????.dat files (since 0.8) */
 static const unsigned int BLOCKFILE_CHUNK_SIZE = 0x1000000; // 16 MiB
 /** The pre-allocation chunk size for rev?????.dat files (since 0.8) */
 static const unsigned int UNDOFILE_CHUNK_SIZE = 0x100000; // 1 MiB
 
 /** Maximum number of script-checking threads allowed */
 static const int MAX_SCRIPTCHECK_THREADS = 16;
 /** -par default (number of script-checking threads, 0 = auto) */
 static const int DEFAULT_SCRIPTCHECK_THREADS = 0;
 /**
  * Number of blocks that can be requested at any given time from a single peer.
  */
 static const int MAX_BLOCKS_IN_TRANSIT_PER_PEER = 16;
 /**
  * Timeout in seconds during which a peer must stall block download progress
  * before being disconnected.
  */
 static const unsigned int BLOCK_STALLING_TIMEOUT = 2;
 /**
  * Number of headers sent in one getheaders result. We rely on the assumption
  * that if a peer sends less than this number, we reached its tip. Changing this
  * value is a protocol upgrade.
  */
 static const unsigned int MAX_HEADERS_RESULTS = 2000;
 /**
  * Maximum depth of blocks we're willing to serve as compact blocks to peers
  * when requested. For older blocks, a regular BLOCK response will be sent.
  */
 static const int MAX_CMPCTBLOCK_DEPTH = 5;
 /**
  * Maximum depth of blocks we're willing to respond to GETBLOCKTXN requests for.
  */
 static const int MAX_BLOCKTXN_DEPTH = 10;
 /**
  * Size of the "block download window": how far ahead of our current height do
  * we fetch ? Larger windows tolerate larger download speed differences between
  * peer, but increase the potential degree of disordering of blocks on disk
  * (which make reindexing and in the future perhaps pruning harder). We'll
  * probably want to make this a per-peer adaptive value at some point.
  */
 static const unsigned int BLOCK_DOWNLOAD_WINDOW = 1024;
 /** Time to wait (in seconds) between writing blocks/block index to disk. */
 static const unsigned int DATABASE_WRITE_INTERVAL = 60 * 60;
 /** Time to wait (in seconds) between flushing chainstate to disk. */
 static const unsigned int DATABASE_FLUSH_INTERVAL = 24 * 60 * 60;
 /** Maximum length of reject messages. */
 static const unsigned int MAX_REJECT_MESSAGE_LENGTH = 111;
 /** Block download timeout base, expressed in millionths of the block interval
  * (i.e. 10 min) */
 static const int64_t BLOCK_DOWNLOAD_TIMEOUT_BASE = 1000000;
 /**
  * Additional block download timeout per parallel downloading peer (i.e. 5 min)
  */
 static const int64_t BLOCK_DOWNLOAD_TIMEOUT_PER_PEER = 500000;
 
 static const int64_t DEFAULT_MAX_TIP_AGE = 24 * 60 * 60;
 /**
  * Maximum age of our tip in seconds for us to be considered current for fee
  * estimation.
  */
 static const int64_t MAX_FEE_ESTIMATION_TIP_AGE = 3 * 60 * 60;
 
 static const bool DEFAULT_CHECKPOINTS_ENABLED = true;
 static const bool DEFAULT_TXINDEX = false;
 static const unsigned int DEFAULT_BANSCORE_THRESHOLD = 100;
 
 /** Default for -persistmempool */
 static const bool DEFAULT_PERSIST_MEMPOOL = true;
 /** Default for using fee filter */
 static const bool DEFAULT_FEEFILTER = true;
 
 /**
  * Maximum number of headers to announce when relaying blocks with headers
  * message.
  */
 static const unsigned int MAX_BLOCKS_TO_ANNOUNCE = 8;
 
 /** Maximum number of unconnecting headers announcements before DoS score */
 static const int MAX_UNCONNECTING_HEADERS = 10;
 
 static const bool DEFAULT_PEERBLOOMFILTERS = true;
 
 /** Default for -stopatheight */
 static const int DEFAULT_STOPATHEIGHT = 0;
 /** Default for -maxreorgdepth */
 static const int DEFAULT_MAX_REORG_DEPTH = 10;
 /**
  * Default for -finalizationdelay
  * This is the minimum time between a block header reception and the block
  * finalization.
  * This value should be >> block propagation and validation time
  */
 static const int64_t DEFAULT_MIN_FINALIZATION_DELAY = 2 * 60 * 60;
 
 extern CScript COINBASE_FLAGS;
 extern RecursiveMutex cs_main;
 extern CTxMemPool g_mempool;
 extern Mutex g_best_block_mutex;
 extern std::condition_variable g_best_block_cv;
 extern uint256 g_best_block;
 extern std::atomic_bool fImporting;
 extern std::atomic_bool fReindex;
 extern int nScriptCheckThreads;
 extern bool fRequireStandard;
 extern bool fCheckBlockIndex;
 extern bool fCheckpointsEnabled;
 extern size_t nCoinCacheUsage;
 
 /**
  * A fee rate smaller than this is considered zero fee (for relaying, mining and
  * transaction creation)
  */
 extern CFeeRate minRelayTxFee;
-/**
- * Absolute maximum transaction fee (in satoshis) used by wallet and mempool
- * (rejects high fee in sendrawtransaction)
- */
-extern Amount maxTxFee;
 /**
  * If the tip is older than this (in seconds), the node is considered to be in
  * initial block download.
  */
 extern int64_t nMaxTipAge;
 
 /**
  * Block hash whose ancestors we will assume to have valid scripts without
  * checking them.
  */
 extern BlockHash hashAssumeValid;
 
 /**
  * Minimum work we will assume exists on some valid chain.
  */
 extern arith_uint256 nMinimumChainWork;
 
 /**
  * Best header we've seen so far (used for getheaders queries' starting points).
  */
 extern CBlockIndex *pindexBestHeader;
 
 /** Pruning-related variables and constants */
 /** True if any block files have ever been pruned. */
 extern bool fHavePruned;
 /** True if we're running in -prune mode. */
 extern bool fPruneMode;
 /** Number of MiB of block files that we're trying to stay below. */
 extern uint64_t nPruneTarget;
 /**
  * Block files containing a block-height within MIN_BLOCKS_TO_KEEP of
  * ::ChainActive().Tip() will not be pruned.
  */
 static const unsigned int MIN_BLOCKS_TO_KEEP = 288;
 /** Minimum blocks required to signal NODE_NETWORK_LIMITED */
 static const unsigned int NODE_NETWORK_LIMITED_MIN_BLOCKS = 288;
 
 static const signed int DEFAULT_CHECKBLOCKS = 6;
 static const unsigned int DEFAULT_CHECKLEVEL = 3;
 
 /**
  * Require that user allocate at least 550MB for block & undo files (blk???.dat
  * and rev???.dat)
  * At 1MB per block, 288 blocks = 288MB.
  * Add 15% for Undo data = 331MB
  * Add 20% for Orphan block rate = 397MB
  * We want the low water mark after pruning to be at least 397 MB and since we
  * prune in full block file chunks, we need the high water mark which triggers
  * the prune to be one 128MB block file + added 15% undo data = 147MB greater
  * for a total of 545MB. Setting the target to > than 550MB will make it likely
  * we can respect the target.
  */
 static const uint64_t MIN_DISK_SPACE_FOR_BLOCK_FILES = 550 * 1024 * 1024;
 
 class BlockValidationOptions {
 private:
     uint64_t excessiveBlockSize;
     bool checkPoW : 1;
     bool checkMerkleRoot : 1;
 
 public:
     // Do full validation by default
     BlockValidationOptions(const Config &config);
     BlockValidationOptions(uint64_t _excessiveBlockSize, bool _checkPow = true,
                            bool _checkMerkleRoot = true)
         : excessiveBlockSize(_excessiveBlockSize), checkPoW(_checkPow),
           checkMerkleRoot(_checkMerkleRoot) {}
 
     BlockValidationOptions withCheckPoW(bool _checkPoW = true) const {
         BlockValidationOptions ret = *this;
         ret.checkPoW = _checkPoW;
         return ret;
     }
 
     BlockValidationOptions
     withCheckMerkleRoot(bool _checkMerkleRoot = true) const {
         BlockValidationOptions ret = *this;
         ret.checkMerkleRoot = _checkMerkleRoot;
         return ret;
     }
 
     bool shouldValidatePoW() const { return checkPoW; }
     bool shouldValidateMerkleRoot() const { return checkMerkleRoot; }
     uint64_t getExcessiveBlockSize() const { return excessiveBlockSize; }
 };
 
 /**
  * Process an incoming block. This only returns after the best known valid
  * block is made active. Note that it does not, however, guarantee that the
  * specific block passed to it has been checked for validity!
  *
  * If you want to *possibly* get feedback on whether pblock is valid, you must
  * install a CValidationInterface (see validationinterface.h) - this will have
  * its BlockChecked method called whenever *any* block completes validation.
  *
  * Note that we guarantee that either the proof-of-work is valid on pblock, or
  * (and possibly also) BlockChecked will have been called.
  *
  * May not be called in a validationinterface callback.
  *
  * @param[in]   config  The global config.
  * @param[in]   pblock  The block we want to process.
  * @param[in]   fForceProcessing Process this block even if unrequested; used
  * for non-network block sources and whitelisted peers.
  * @param[out]  fNewBlock A boolean which is set to indicate if the block was
  *                        first received via this call.
  * @return True if the block is accepted as a valid block.
  */
 bool ProcessNewBlock(const Config &config,
                      const std::shared_ptr<const CBlock> pblock,
                      bool fForceProcessing, bool *fNewBlock)
     LOCKS_EXCLUDED(cs_main);
 
 /**
  * Process incoming block headers.
  *
  * May not be called in a validationinterface callback.
  *
  * @param[in]  config        The config.
  * @param[in]  block         The block headers themselves.
  * @param[out] state         This may be set to an Error state if any error
  *                           occurred processing them.
  * @param[out] ppindex       If set, the pointer will be set to point to the
  *                           last new block index object for the given headers.
  * @param[out] first_invalid First header that fails validation, if one exists.
  * @return True if block headers were accepted as valid.
  */
 bool ProcessNewBlockHeaders(const Config &config,
                             const std::vector<CBlockHeader> &block,
                             CValidationState &state,
                             const CBlockIndex **ppindex = nullptr,
                             CBlockHeader *first_invalid = nullptr)
     LOCKS_EXCLUDED(cs_main);
 
 /**
  * Open a block file (blk?????.dat).
  */
 FILE *OpenBlockFile(const FlatFilePos &pos, bool fReadOnly = false);
 
 /**
  * Translation to a filesystem path.
  */
 fs::path GetBlockPosFilename(const FlatFilePos &pos);
 
 /**
  * Import blocks from an external file.
  */
 bool LoadExternalBlockFile(const Config &config, FILE *fileIn,
                            FlatFilePos *dbp = nullptr);
 
 /**
  * Ensures we have a genesis block in the block tree, possibly writing one to
  * disk.
  */
 bool LoadGenesisBlock(const CChainParams &chainparams);
 
 /**
  * Load the block tree and coins database from disk, initializing state if we're
  * running with -reindex.
  */
 bool LoadBlockIndex(const Config &config) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /**
  * Update the chain tip based on database information.
  */
 bool LoadChainTip(const Config &config) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /**
  * Unload database information.
  */
 void UnloadBlockIndex();
 
 /**
  * Run an instance of the script checking thread.
  */
 void ThreadScriptCheck(int worker_num);
 
 /**
  * Retrieve a transaction (from memory pool, or from disk, if possible).
  */
 bool GetTransaction(const TxId &txid, CTransactionRef &txOut,
                     const Consensus::Params &params, BlockHash &hashBlock,
                     const CBlockIndex *const blockIndex = nullptr);
 
 /**
  * Find the best known block, and make it the tip of the block chain
  *
  * May not be called with cs_main held. May not be called in a
  * validationinterface callback.
  */
 bool ActivateBestChain(
     const Config &config, CValidationState &state,
     std::shared_ptr<const CBlock> pblock = std::shared_ptr<const CBlock>());
 Amount GetBlockSubsidy(int nHeight, const Consensus::Params &consensusParams);
 
 /**
  * Guess verification progress (as a fraction between 0.0=genesis and
  * 1.0=current tip).
  */
 double GuessVerificationProgress(const ChainTxData &data,
                                  const CBlockIndex *pindex);
 
 /**
  * Calculate the amount of disk space the block & undo files currently use.
  */
 uint64_t CalculateCurrentUsage();
 
 /**
  * Mark one block file as pruned.
  */
 void PruneOneBlockFile(const int fileNumber) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /**
  * Actually unlink the specified files
  */
 void UnlinkPrunedFiles(const std::set<int> &setFilesToPrune);
 
 /** Prune block files up to a given height */
 void PruneBlockFilesManual(int nManualPruneHeight);
 
 /**
  * (try to) add transaction to memory pool
  */
 bool AcceptToMemoryPool(const Config &config, CTxMemPool &pool,
                         CValidationState &state, const CTransactionRef &tx,
                         bool *pfMissingInputs, bool bypass_limits,
                         const Amount nAbsurdFee, bool test_accept = false)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /**
  * Simple class for regulating resource usage during CheckInputs (and
  * CScriptCheck), atomic so as to be compatible with parallel validation.
  */
 class CheckInputsLimiter {
 protected:
     std::atomic<int64_t> remaining;
 
 public:
     CheckInputsLimiter(int64_t limit) : remaining(limit) {}
 
     bool consume_and_check(int consumed) {
         auto newvalue = (remaining -= consumed);
         return newvalue >= 0;
     }
 
     bool check() { return remaining >= 0; }
 };
 
 class TxSigCheckLimiter : public CheckInputsLimiter {
 public:
     TxSigCheckLimiter() : CheckInputsLimiter(MAX_TX_SIGCHECKS) {}
 
     // Let's make this bad boy copiable.
     TxSigCheckLimiter(const TxSigCheckLimiter &rhs)
         : CheckInputsLimiter(rhs.remaining.load()) {}
 
     TxSigCheckLimiter &operator=(const TxSigCheckLimiter &rhs) {
         remaining = rhs.remaining.load();
         return *this;
     }
 };
 
 class ConnectTrace;
 
 /**
  * Check whether all inputs of this transaction are valid (no double spends,
  * scripts & sigs, amounts). This does not modify the UTXO set.
  *
  * If pvChecks is not nullptr, script checks are pushed onto it instead of being
  * performed inline. Any script checks which are not necessary (eg due to script
  * execution cache hits) are, obviously, not pushed onto pvChecks/run.
  *
  * Upon success nSigChecksOut will be filled in with either:
  * - correct total for all inputs, or,
  * - 0, in the case when checks were pushed onto pvChecks (i.e., a cache miss
  * with pvChecks non-null), in which case the total can be found by executing
  * pvChecks and adding the results.
  *
  * Setting sigCacheStore/scriptCacheStore to false will remove elements from the
  * corresponding cache which are matched. This is useful for checking blocks
  * where we will likely never need the cache entry again.
  *
  * pLimitSigChecks can be passed to limit the sigchecks count either in parallel
  * or serial validation. With pvChecks null (serial validation), breaking the
  * pLimitSigChecks limit will abort evaluation early and return false. With
  * pvChecks not-null (parallel validation): the cached nSigChecks may itself
  * break the limit in which case false is returned, OR, each entry in the
  * returned pvChecks must be executed exactly once in order to probe the limit
  * accurately.
  */
 bool CheckInputs(const CTransaction &tx, CValidationState &state,
                  const CCoinsViewCache &view, bool fScriptChecks,
                  const uint32_t flags, bool sigCacheStore,
                  bool scriptCacheStore,
                  const PrecomputedTransactionData &txdata, int &nSigChecksOut,
                  TxSigCheckLimiter &txLimitSigChecks,
                  CheckInputsLimiter *pBlockLimitSigChecks,
                  std::vector<CScriptCheck> *pvChecks)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /**
  * Handy shortcut to full fledged CheckInputs call.
  */
 static inline bool
 CheckInputs(const CTransaction &tx, CValidationState &state,
             const CCoinsViewCache &view, bool fScriptChecks,
             const uint32_t flags, bool sigCacheStore, bool scriptCacheStore,
             const PrecomputedTransactionData &txdata, int &nSigChecksOut)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
     TxSigCheckLimiter nSigChecksTxLimiter;
     return CheckInputs(tx, state, view, fScriptChecks, flags, sigCacheStore,
                        scriptCacheStore, txdata, nSigChecksOut,
                        nSigChecksTxLimiter, nullptr, nullptr);
 }
 
 /** Get the BIP9 state for a given deployment at the current tip. */
 ThresholdState VersionBitsTipState(const Consensus::Params &params,
                                    Consensus::DeploymentPos pos);
 
 /** Get the BIP9 state for a given deployment at a given block. */
 ThresholdState VersionBitsBlockState(const Consensus::Params &params,
                                      Consensus::DeploymentPos pos,
                                      const CBlockIndex *pindex);
 
 /**
  * Get the numerical statistics for the BIP9 state for a given deployment at the
  * current tip.
  */
 BIP9Stats VersionBitsTipStatistics(const Consensus::Params &params,
                                    Consensus::DeploymentPos pos);
 
 /**
  * Get the block height at which the BIP9 deployment switched into the state for
  * the block building on the current tip.
  */
 int VersionBitsTipStateSinceHeight(const Consensus::Params &params,
                                    Consensus::DeploymentPos pos);
 
 /** Apply the effects of this transaction on the UTXO set represented by view */
 void UpdateCoins(const CTransaction &tx, CCoinsViewCache &inputs, int nHeight);
 
 /**
  * Mark all the coins corresponding to a given transaction inputs as spent.
  */
 void SpendCoins(CCoinsViewCache &view, const CTransaction &tx, CTxUndo &txundo,
                 int nHeight);
 
 /**
  * Apply the effects of this transaction on the UTXO set represented by view.
  */
 void UpdateCoins(CCoinsViewCache &view, const CTransaction &tx, int nHeight);
 void UpdateCoins(CCoinsViewCache &view, const CTransaction &tx, CTxUndo &txundo,
                  int nHeight);
 
 /**
  * Test whether the LockPoints height and time are still valid on the current
  * chain.
  */
 bool TestLockPointValidity(const LockPoints *lp)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /**
  * Check if transaction will be BIP 68 final in the next block to be created.
  *
  * Simulates calling SequenceLocks() with data from the tip of the current
  * active chain. Optionally stores in LockPoints the resulting height and time
  * calculated and the hash of the block needed for calculation or skips the
  * calculation and uses the LockPoints passed in for evaluation. The LockPoints
  * should not be considered valid if CheckSequenceLocks returns false.
  *
  * See consensus/consensus.h for flag definitions.
  */
 bool CheckSequenceLocks(const CTxMemPool &pool, const CTransaction &tx,
                         int flags, LockPoints *lp = nullptr,
                         bool useExistingLockPoints = false)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /**
  * Closure representing one script verification.
  * Note that this stores references to the spending transaction.
  *
  * Note that if pLimitSigChecks is passed, then failure does not imply that
  * scripts have failed.
  */
 class CScriptCheck {
 private:
     CScript scriptPubKey;
     Amount amount;
     const CTransaction *ptxTo;
     unsigned int nIn;
     uint32_t nFlags;
     bool cacheStore;
     ScriptError error;
     ScriptExecutionMetrics metrics;
     PrecomputedTransactionData txdata;
     TxSigCheckLimiter *pTxLimitSigChecks;
     CheckInputsLimiter *pBlockLimitSigChecks;
 
 public:
     CScriptCheck()
         : amount(), ptxTo(nullptr), nIn(0), nFlags(0), cacheStore(false),
           error(ScriptError::UNKNOWN), txdata(), pTxLimitSigChecks(nullptr),
           pBlockLimitSigChecks(nullptr) {}
 
     CScriptCheck(const CScript &scriptPubKeyIn, const Amount amountIn,
                  const CTransaction &txToIn, unsigned int nInIn,
                  uint32_t nFlagsIn, bool cacheIn,
                  const PrecomputedTransactionData &txdataIn,
                  TxSigCheckLimiter *pTxLimitSigChecksIn = nullptr,
                  CheckInputsLimiter *pBlockLimitSigChecksIn = nullptr)
         : scriptPubKey(scriptPubKeyIn), amount(amountIn), ptxTo(&txToIn),
           nIn(nInIn), nFlags(nFlagsIn), cacheStore(cacheIn),
           error(ScriptError::UNKNOWN), txdata(txdataIn),
           pTxLimitSigChecks(pTxLimitSigChecksIn),
           pBlockLimitSigChecks(pBlockLimitSigChecksIn) {}
 
     bool operator()();
 
     void swap(CScriptCheck &check) {
         scriptPubKey.swap(check.scriptPubKey);
         std::swap(ptxTo, check.ptxTo);
         std::swap(amount, check.amount);
         std::swap(nIn, check.nIn);
         std::swap(nFlags, check.nFlags);
         std::swap(cacheStore, check.cacheStore);
         std::swap(error, check.error);
         std::swap(metrics, check.metrics);
         std::swap(txdata, check.txdata);
         std::swap(pTxLimitSigChecks, check.pTxLimitSigChecks);
         std::swap(pBlockLimitSigChecks, check.pBlockLimitSigChecks);
     }
 
     ScriptError GetScriptError() const { return error; }
 
     ScriptExecutionMetrics GetScriptExecutionMetrics() const { return metrics; }
 };
 
 /** Functions for disk access for blocks */
 bool ReadBlockFromDisk(CBlock &block, const FlatFilePos &pos,
                        const Consensus::Params &params);
 bool ReadBlockFromDisk(CBlock &block, const CBlockIndex *pindex,
                        const Consensus::Params &params);
 
 /** Functions for validating blocks and updating the block tree */
 
 /**
  * Context-independent validity checks.
  *
  * Returns true if the provided block is valid (has valid header,
  * transactions are valid, block is a valid size, etc.)
  */
 bool CheckBlock(const CBlock &block, CValidationState &state,
                 const Consensus::Params &params,
                 BlockValidationOptions validationOptions);
 
 /**
  * This is a variant of ContextualCheckTransaction which computes the contextual
  * check for a transaction based on the chain tip.
  *
  * See consensus/consensus.h for flag definitions.
  */
 bool ContextualCheckTransactionForCurrentBlock(const Consensus::Params &params,
                                                const CTransaction &tx,
                                                CValidationState &state,
                                                int flags = -1);
 
 /**
  * Check a block is completely valid from start to finish (only works on top of
  * our current best block)
  */
 bool TestBlockValidity(CValidationState &state, const CChainParams &params,
                        const CBlock &block, CBlockIndex *pindexPrev,
                        BlockValidationOptions validationOptions)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /**
  * RAII wrapper for VerifyDB: Verify consistency of the block and coin
  * databases.
  */
 class CVerifyDB {
 public:
     CVerifyDB();
     ~CVerifyDB();
     bool VerifyDB(const Config &config, CCoinsView *coinsview, int nCheckLevel,
                   int nCheckDepth);
 };
 
 /** Replay blocks that aren't fully applied to the database. */
 bool ReplayBlocks(const Consensus::Params &params, CCoinsView *view);
 
 /** Find the last common block between the parameter chain and a locator. */
 CBlockIndex *FindForkInGlobalIndex(const CChain &chain,
                                    const CBlockLocator &locator)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /** @see CChainState::FlushStateToDisk */
 enum class FlushStateMode { NONE, IF_NEEDED, PERIODIC, ALWAYS };
 
 /**
  * CChainState stores and provides an API to update our local knowledge of the
  * current best chain and header tree.
  *
  * It generally provides access to the current block tree, as well as functions
  * to provide new data, which it will appropriately validate and incorporate in
  * its state as necessary.
  *
  * Eventually, the API here is targeted at being exposed externally as a
  * consumable libconsensus library, so any functions added must only call
  * other class member functions, pure functions in other parts of the consensus
  * library, callbacks via the validation interface, or read/write-to-disk
  * functions (eventually this will also be via callbacks).
  */
 class CChainState {
 private:
     /**
      * The set of all CBlockIndex entries with BLOCK_VALID_TRANSACTIONS (for
      * itself and all ancestors) and as good as our current tip or better.
      * Entries may be failed or parked though, and pruning nodes may be missing
      * the data for the block; these will get cleaned during FindMostWorkChain.
      */
     std::set<CBlockIndex *, CBlockIndexWorkComparator> setBlockIndexCandidates;
 
     /**
      * the ChainState CriticalSection
      * A lock that must be held when modifying this ChainState - held in
      * ActivateBestChain()
      */
     RecursiveMutex m_cs_chainstate;
 
     /**
      * Every received block is assigned a unique and increasing identifier, so
      * we know which one to give priority in case of a fork.
      * Blocks loaded from disk are assigned id 0, so start the counter at 1.
      */
     std::atomic<int32_t> nBlockSequenceId{1};
     /** Decreasing counter (used by subsequent preciousblock calls). */
     int32_t nBlockReverseSequenceId = -1;
     /** chainwork for the last block that preciousblock has been applied to. */
     arith_uint256 nLastPreciousChainwork = 0;
 
     /**
      * In order to efficiently track invalidity of headers, we keep the set of
      * blocks which we tried to connect and found to be invalid here (ie which
      * were set to BLOCK_FAILED_VALID since the last restart). We can then
      * walk this set and check if a new header is a descendant of something in
      * this set, preventing us from having to walk mapBlockIndex when we try
      * to connect a bad block and fail.
      *
      * While this is more complicated than marking everything which descends
      * from an invalid block as invalid at the time we discover it to be
      * invalid, doing so would require walking all of mapBlockIndex to find all
      * descendants. Since this case should be very rare, keeping track of all
      * BLOCK_FAILED_VALID blocks in a set should be just fine and work just as
      * well.
      *
      * Because we already walk mapBlockIndex in height-order at startup, we go
      * ahead and mark descendants of invalid blocks as FAILED_CHILD at that
      * time, instead of putting things in this set.
      */
     std::set<CBlockIndex *> m_failed_blocks;
 
     /**
      * Whether this chainstate is undergoing initial block download.
      *
      * Mutable because we need to be able to mark IsInitialBlockDownload()
      * const, which latches this for caching purposes.
      */
     mutable std::atomic<bool> m_cached_finished_ibd{false};
 
 public:
     CChain m_chain;
     BlockMap mapBlockIndex GUARDED_BY(cs_main);
     std::multimap<CBlockIndex *, CBlockIndex *> mapBlocksUnlinked;
     CBlockIndex *pindexBestInvalid = nullptr;
     CBlockIndex *pindexBestParked = nullptr;
     CBlockIndex const *pindexFinalized = nullptr;
 
     bool LoadBlockIndex(const Config &config, CBlockTreeDB &blocktree)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
     /**
      * Update the on-disk chain state.
      * The caches and indexes are flushed depending on the mode we're called
      * with if they're too large, if it's been a while since the last write, or
      * always and in all cases if we're in prune mode and are deleting files.
      *
      * If FlushStateMode::NONE is used, then FlushStateToDisk(...) won't do
      * anything besides checking if we need to prune.
      */
     bool FlushStateToDisk(const CChainParams &chainparams,
                           CValidationState &state, FlushStateMode mode,
                           int nManualPruneHeight = 0);
 
     //! Unconditionally flush all changes to disk.
     void ForceFlushStateToDisk();
 
     //! Prune blockfiles from the disk if necessary and then flush chainstate
     //! changes if we pruned.
     void PruneAndFlush();
 
     bool ActivateBestChain(
         const Config &config, CValidationState &state,
         std::shared_ptr<const CBlock> pblock = std::shared_ptr<const CBlock>());
 
     /**
      * If a block header hasn't already been seen, call CheckBlockHeader on it,
      * ensure that it doesn't descend from an invalid block, and then add it to
      * mapBlockIndex.
      */
     bool AcceptBlockHeader(const Config &config, const CBlockHeader &block,
                            CValidationState &state, CBlockIndex **ppindex)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
     bool AcceptBlock(const Config &config,
                      const std::shared_ptr<const CBlock> &pblock,
                      CValidationState &state, bool fRequested,
                      const FlatFilePos *dbp, bool *fNewBlock)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
     // Block (dis)connection on a given view:
     DisconnectResult DisconnectBlock(const CBlock &block,
                                      const CBlockIndex *pindex,
                                      CCoinsViewCache &view);
     bool ConnectBlock(const CBlock &block, CValidationState &state,
                       CBlockIndex *pindex, CCoinsViewCache &view,
                       const CChainParams &params,
                       BlockValidationOptions options, bool fJustCheck = false)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
     // Block disconnection on our pcoinsTip:
     bool DisconnectTip(const CChainParams &params, CValidationState &state,
                        DisconnectedBlockTransactions *disconnectpool)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
     // Manual block validity manipulation:
     bool PreciousBlock(const Config &config, CValidationState &state,
                        CBlockIndex *pindex) LOCKS_EXCLUDED(cs_main);
     bool UnwindBlock(const Config &config, CValidationState &state,
                      CBlockIndex *pindex, bool invalidate);
     void ResetBlockFailureFlags(CBlockIndex *pindex)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
     template <typename F>
     bool UpdateFlagsForBlock(CBlockIndex *pindexBase, CBlockIndex *pindex, F f)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
     template <typename F, typename C, typename AC>
     void UpdateFlags(CBlockIndex *pindex, CBlockIndex *&pindexReset, F f,
                      C fChild, AC fAncestorWasChanged)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
     /** Remove parked status from a block and its descendants. */
     void UnparkBlockImpl(CBlockIndex *pindex, bool fClearChildren)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
     bool ReplayBlocks(const Consensus::Params &params, CCoinsView *view);
     bool LoadGenesisBlock(const CChainParams &chainparams);
 
     void PruneBlockIndexCandidates();
 
     void UnloadBlockIndex();
 
     /**
      * Check whether we are doing an initial block download (synchronizing from
      * disk or network)
      */
     bool IsInitialBlockDownload() const;
 
 private:
     bool ActivateBestChainStep(const Config &config, CValidationState &state,
                                CBlockIndex *pindexMostWork,
                                const std::shared_ptr<const CBlock> &pblock,
                                bool &fInvalidFound, ConnectTrace &connectTrace)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
     bool ConnectTip(const Config &config, CValidationState &state,
                     CBlockIndex *pindexNew,
                     const std::shared_ptr<const CBlock> &pblock,
                     ConnectTrace &connectTrace,
                     DisconnectedBlockTransactions &disconnectpool)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
     CBlockIndex *AddToBlockIndex(const CBlockHeader &block)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
     /** Create a new block index entry for a given block hash */
     CBlockIndex *InsertBlockIndex(const BlockHash &hash)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
     /**
      * Make various assertions about the state of the block index.
      *
      * By default this only executes fully when using the Regtest chain; see:
      * fCheckBlockIndex.
      */
     void CheckBlockIndex(const Consensus::Params &consensusParams);
 
     void InvalidBlockFound(CBlockIndex *pindex, const CValidationState &state)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
     CBlockIndex *FindMostWorkChain() EXCLUSIVE_LOCKS_REQUIRED(cs_main);
     void ReceivedBlockTransactions(const CBlock &block, CBlockIndex *pindexNew,
                                    const FlatFilePos &pos)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
     bool RollforwardBlock(const CBlockIndex *pindex, CCoinsViewCache &inputs,
                           const Consensus::Params &params)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 };
 
 /**
  * Mark a block as precious and reorganize.
  *
  * May not be called in a validationinterface callback.
  */
 bool PreciousBlock(const Config &config, CValidationState &state,
                    CBlockIndex *pindex) LOCKS_EXCLUDED(cs_main);
 
 /**
  * Mark a block as finalized.
  * A finalized block can not be reorged in any way.
  */
 bool FinalizeBlockAndInvalidate(const Config &config, CValidationState &state,
                                 CBlockIndex *pindex)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /** Mark a block as invalid. */
 bool InvalidateBlock(const Config &config, CValidationState &state,
                      CBlockIndex *pindex);
 
 /** Park a block. */
 bool ParkBlock(const Config &config, CValidationState &state,
                CBlockIndex *pindex);
 
 /** Remove invalidity status from a block and its descendants. */
 void ResetBlockFailureFlags(CBlockIndex *pindex)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /** Remove parked status from a block and its descendants. */
 void UnparkBlockAndChildren(CBlockIndex *pindex)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /** Remove parked status from a block. */
 void UnparkBlock(CBlockIndex *pindex) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /**
  * Retrieve the topmost finalized block.
  */
 const CBlockIndex *GetFinalizedBlock() EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /**
  * Checks if a block is finalized.
  */
 bool IsBlockFinalized(const CBlockIndex *pindex)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /** @returns the most-work valid chainstate. */
 CChainState &ChainstateActive();
 
 /** @returns the most-work chain. */
 CChain &ChainActive();
 
 /**
  * Global variable that points to the coins database (protected by cs_main)
  */
 extern std::unique_ptr<CCoinsViewDB> pcoinsdbview;
 
 /**
  * Global variable that points to the active CCoinsView (protected by cs_main)
  */
 extern std::unique_ptr<CCoinsViewCache> pcoinsTip;
 
 /**
  * Global variable that points to the active block tree (protected by cs_main)
  */
 extern std::unique_ptr<CBlockTreeDB> pblocktree;
 
 /**
  * Return the spend height, which is one more than the inputs.GetBestBlock().
  * While checking, GetBestBlock() refers to the parent block. (protected by
  * cs_main)
  * This is also true for mempool checks.
  */
 int GetSpendHeight(const CCoinsViewCache &inputs);
 
 /**
  * Determine what nVersion a new block should use.
  */
 int32_t ComputeBlockVersion(const CBlockIndex *pindexPrev,
                             const Consensus::Params &params);
 
 /**
  * Reject codes greater or equal to this can be returned by AcceptToMemPool or
  * AcceptBlock for blocks/transactions, to signal internal conditions. They
  * cannot and should not be sent over the P2P network.
  */
 static const unsigned int REJECT_INTERNAL = 0x100;
 /** Too high fee. Can not be triggered by P2P transactions */
 static const unsigned int REJECT_HIGHFEE = 0x100;
 /** Block conflicts with a transaction already known */
 static const unsigned int REJECT_AGAINST_FINALIZED = 0x103;
 
 /** Get block file info entry for one block file */
 CBlockFileInfo *GetBlockFileInfo(size_t n);
 
 /** Dump the mempool to disk. */
 bool DumpMempool(const CTxMemPool &pool);
 
 /** Load the mempool from disk. */
 bool LoadMempool(const Config &config, CTxMemPool &pool);
 
 //! Check whether the block associated with this index entry is pruned or not.
 bool IsBlockPruned(const CBlockIndex *pblockindex);
 
 #endif // BITCOIN_VALIDATION_H
diff --git a/src/wallet/fees.cpp b/src/wallet/fees.cpp
index 8a503c703..997886579 100644
--- a/src/wallet/fees.cpp
+++ b/src/wallet/fees.cpp
@@ -1,56 +1,56 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2017 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <wallet/fees.h>
 
 #include <config.h>
 #include <policy/policy.h>
 #include <txmempool.h>
 #include <util/system.h>
 #include <validation.h>
 #include <wallet/coincontrol.h>
 #include <wallet/wallet.h>
 
 Amount GetRequiredFee(const CWallet &wallet, unsigned int nTxBytes) {
     return GetRequiredFeeRate(wallet).GetFeeCeiling(nTxBytes);
 }
 
 Amount GetMinimumFee(const CWallet &wallet, unsigned int nTxBytes,
                      const CCoinControl &coin_control) {
     Amount nFeeNeeded =
         GetMinimumFeeRate(wallet, coin_control).GetFeeCeiling(nTxBytes);
 
     // But always obey the maximum.
-    const Amount max_tx_fee = wallet.chain().maxTxFee();
+    const Amount max_tx_fee = wallet.m_default_max_tx_fee;
     if (nFeeNeeded > max_tx_fee) {
         nFeeNeeded = max_tx_fee;
     }
 
     return nFeeNeeded;
 }
 
 CFeeRate GetRequiredFeeRate(const CWallet &wallet) {
     return std::max(wallet.m_min_fee, wallet.chain().relayMinFee());
 }
 
 CFeeRate GetMinimumFeeRate(const CWallet &wallet,
                            const CCoinControl &coin_control) {
     CFeeRate neededFeeRate =
         (coin_control.fOverrideFeeRate && coin_control.m_feerate)
             ? *coin_control.m_feerate
             : wallet.m_pay_tx_fee;
 
     if (neededFeeRate == CFeeRate()) {
         neededFeeRate = wallet.chain().estimateFee();
         // ... unless we don't have enough mempool data for estimatefee, then
         // use fallback fee.
         if (neededFeeRate == CFeeRate()) {
             neededFeeRate = wallet.m_fallback_fee;
         }
     }
 
     // Prevent user from paying a fee below minRelayTxFee or minTxFee.
     return std::max(neededFeeRate, GetRequiredFeeRate(wallet));
 }
diff --git a/src/wallet/init.cpp b/src/wallet/init.cpp
index fa954c61b..c0b6c0f14 100644
--- a/src/wallet/init.cpp
+++ b/src/wallet/init.cpp
@@ -1,268 +1,237 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2017 The Bitcoin Core developers
 // Copyright (c) 2018-2019 The Bitcoin developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <config.h>
 #include <init.h>
 #include <interfaces/chain.h>
 #include <net.h>
 #include <scheduler.h>
 #include <util/error.h>
 #include <util/moneystr.h>
 #include <util/system.h>
 #include <util/translation.h>
 #include <validation.h>
 #include <wallet/rpcdump.h>
 #include <wallet/rpcwallet.h>
 #include <wallet/wallet.h>
 #include <wallet/walletutil.h>
 #include <walletinitinterface.h>
 
 class WalletInit : public WalletInitInterface {
 public:
     //! Was the wallet component compiled in.
     bool HasWalletSupport() const override { return true; }
 
     //! Return the wallets help message.
     void AddWalletOptions() const override;
 
     //! Wallets parameter interaction
     bool ParameterInteraction() const override;
 
     //! Add wallets that should be opened to list of chain clients.
     void Construct(NodeContext &node) const override;
 };
 
 const WalletInitInterface &g_wallet_init_interface = WalletInit();
 
 void WalletInit::AddWalletOptions() const {
     gArgs.AddArg(
         "-avoidpartialspends",
         strprintf("Group outputs by address, selecting all or none, instead of "
                   "selecting on a per-output basis. Privacy is improved as an "
                   "address is only used once (unless someone sends to it after "
                   "spending from it), but may result in slightly higher fees "
                   "as suboptimal coin selection may result due to the added "
                   "limitation (default: %u)",
                   DEFAULT_AVOIDPARTIALSPENDS),
         ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
 
     gArgs.AddArg("-disablewallet",
                  "Do not load the wallet and disable wallet RPC calls",
                  ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
     gArgs.AddArg("-fallbackfee=<amt>",
                  strprintf("A fee rate (in %s/kB) that will be used when fee "
                            "estimation has insufficient data (default: %s)",
                            CURRENCY_UNIT, FormatMoney(DEFAULT_FALLBACK_FEE)),
                  ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
     gArgs.AddArg("-keypool=<n>",
                  strprintf("Set key pool size to <n> (default: %u)",
                            DEFAULT_KEYPOOL_SIZE),
                  ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
     gArgs.AddArg(
         "-maxtxfee=<amt>",
         strprintf("Maximum total fees (in %s) to use in a single wallet "
                   "transaction or raw transaction; setting this too low may "
                   "abort large transactions (default: %s)",
                   CURRENCY_UNIT, FormatMoney(DEFAULT_TRANSACTION_MAXFEE)),
         ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-mintxfee=<amt>",
                  strprintf("Fees (in %s/kB) smaller than this are considered "
                            "zero fee for transaction creation (default: %s)",
                            CURRENCY_UNIT,
                            FormatMoney(DEFAULT_TRANSACTION_MINFEE_PER_KB)),
                  ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
     gArgs.AddArg(
         "-paytxfee=<amt>",
         strprintf(
             "Fee (in %s/kB) to add to transactions you send (default: %s)",
             CURRENCY_UNIT,
             FormatMoney(CFeeRate{DEFAULT_PAY_TX_FEE}.GetFeePerK())),
         ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
     gArgs.AddArg(
         "-rescan",
         "Rescan the block chain for missing wallet transactions on startup",
         ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
     gArgs.AddArg(
         "-salvagewallet",
         "Attempt to recover private keys from a corrupt wallet on startup",
         ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
 
     gArgs.AddArg(
         "-spendzeroconfchange",
         strprintf(
             "Spend unconfirmed change when sending transactions (default: %d)",
             DEFAULT_SPEND_ZEROCONF_CHANGE),
         ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
     gArgs.AddArg("-upgradewallet", "Upgrade wallet to latest format on startup",
                  ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
     gArgs.AddArg("-wallet=<path>",
                  "Specify wallet database path. Can be specified multiple "
                  "times to load multiple wallets. Path is interpreted relative "
                  "to <walletdir> if it is not absolute, and will be created if "
                  "it does not exist (as a directory containing a wallet.dat "
                  "file and log files). For backwards compatibility this will "
                  "also accept names of existing data files in <walletdir>.)",
                  ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY,
                  OptionsCategory::WALLET);
     gArgs.AddArg(
         "-walletbroadcast",
         strprintf("Make the wallet broadcast transactions (default: %d)",
                   DEFAULT_WALLETBROADCAST),
         ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
     gArgs.AddArg("-walletdir=<dir>",
                  "Specify directory to hold wallets (default: "
                  "<datadir>/wallets if it exists, otherwise <datadir>)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
     gArgs.AddArg("-walletnotify=<cmd>",
                  "Execute command when a wallet transaction changes (%s in cmd "
                  "is replaced by TxID)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
     gArgs.AddArg(
         "-zapwallettxes=<mode>",
         "Delete all wallet transactions and only recover those parts of the "
         "blockchain through -rescan on startup (1 = keep tx meta data e.g. "
         "payment request information, 2 = drop tx meta data)",
         ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
 
     gArgs.AddArg("-dblogsize=<n>",
                  strprintf("Flush wallet database activity from memory to disk "
                            "log every <n> megabytes (default: %u)",
                            DEFAULT_WALLET_DBLOGSIZE),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::WALLET_DEBUG_TEST);
     gArgs.AddArg(
         "-flushwallet",
         strprintf("Run a thread to flush wallet periodically (default: %d)",
                   DEFAULT_FLUSHWALLET),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::WALLET_DEBUG_TEST);
     gArgs.AddArg("-privdb",
                  strprintf("Sets the DB_PRIVATE flag in the wallet db "
                            "environment (default: %d)",
                            DEFAULT_WALLET_PRIVDB),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::WALLET_DEBUG_TEST);
     gArgs.AddArg("-walletrejectlongchains",
                  strprintf("Wallet will not create transactions that violate "
                            "mempool chain limits (default: %d)",
                            DEFAULT_WALLET_REJECT_LONG_CHAINS),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::WALLET_DEBUG_TEST);
 }
 
 bool WalletInit::ParameterInteraction() const {
     const bool is_multiwallet = gArgs.GetArgs("-wallet").size() > 1;
 
     if (gArgs.GetBoolArg("-disablewallet", DEFAULT_DISABLE_WALLET)) {
         return true;
     }
 
     if (gArgs.GetBoolArg("-blocksonly", DEFAULT_BLOCKSONLY) &&
         gArgs.SoftSetBoolArg("-walletbroadcast", false)) {
         LogPrintf("%s: parameter interaction: -blocksonly=1 -> setting "
                   "-walletbroadcast=0\n",
                   __func__);
     }
 
     if (gArgs.GetBoolArg("-salvagewallet", false)) {
         if (is_multiwallet) {
             return InitError(
                 strprintf("%s is only allowed with a single wallet file",
                           "-salvagewallet"));
         }
         // Rewrite just private keys: rescan to find transactions
         if (gArgs.SoftSetBoolArg("-rescan", true)) {
             LogPrintf("%s: parameter interaction: -salvagewallet=1 -> setting "
                       "-rescan=1\n",
                       __func__);
         }
     }
 
     bool zapwallettxes = gArgs.GetBoolArg("-zapwallettxes", false);
     // -zapwallettxes implies dropping the mempool on startup
     if (zapwallettxes && gArgs.SoftSetBoolArg("-persistmempool", false)) {
         LogPrintf("%s: parameter interaction: -zapwallettxes enabled -> "
                   "setting -persistmempool=0\n",
                   __func__);
     }
 
     // -zapwallettxes implies a rescan
     if (zapwallettxes) {
         if (is_multiwallet) {
             return InitError(
                 strprintf("%s is only allowed with a single wallet file",
                           "-zapwallettxes"));
         }
         if (gArgs.SoftSetBoolArg("-rescan", true)) {
             LogPrintf("%s: parameter interaction: -zapwallettxes enabled -> "
                       "setting -rescan=1\n",
                       __func__);
         }
     }
 
     if (is_multiwallet) {
         if (gArgs.GetBoolArg("-upgradewallet", false)) {
             return InitError(
                 strprintf("%s is only allowed with a single wallet file",
                           "-upgradewallet"));
         }
     }
 
     if (gArgs.GetBoolArg("-sysperms", false)) {
         return InitError("-sysperms is not allowed in combination with enabled "
                          "wallet functionality");
     }
 
     if (gArgs.GetArg("-prune", 0) && gArgs.GetBoolArg("-rescan", false)) {
         return InitError(
             _("Rescans are not possible in pruned mode. You will need to use "
               "-reindex which will download the whole blockchain again.")
                 .translated);
     }
 
-    if (minRelayTxFee.GetFeePerK() > HIGH_TX_FEE_PER_KB) {
-        InitWarning(
-            AmountHighWarn("-minrelaytxfee") + " " +
-            _("The wallet will avoid paying less than the minimum relay fee.")
-                .translated);
-    }
-
-    if (gArgs.IsArgSet("-maxtxfee")) {
-        Amount nMaxFee = Amount::zero();
-        if (!ParseMoney(gArgs.GetArg("-maxtxfee", ""), nMaxFee)) {
-            return InitError(
-                AmountErrMsg("maxtxfee", gArgs.GetArg("-maxtxfee", "")));
-        }
-
-        if (nMaxFee > HIGH_MAX_TX_FEE) {
-            InitWarning(_("-maxtxfee is set very high! Fees this large could "
-                          "be paid on a single transaction.")
-                            .translated);
-        }
-
-        maxTxFee = nMaxFee;
-        if (CFeeRate(maxTxFee, 1000) < minRelayTxFee) {
-            return InitError(strprintf(
-                _("Invalid amount for -maxtxfee=<amount>: '%s' (must "
-                  "be at least the minrelay fee of %s to prevent "
-                  "stuck transactions)")
-                    .translated,
-                gArgs.GetArg("-maxtxfee", ""), minRelayTxFee.ToString()));
-        }
-    }
-
     return true;
 }
 
 void WalletInit::Construct(NodeContext &node) const {
     if (gArgs.GetBoolArg("-disablewallet", DEFAULT_DISABLE_WALLET)) {
         LogPrintf("Wallet disabled!\n");
         return;
     }
     gArgs.SoftSetArg("-wallet", "");
     node.chain_clients.emplace_back(
         interfaces::MakeWalletClient(*node.chain, gArgs.GetArgs("-wallet")));
 }
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 950766846..503b786aa 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -1,4986 +1,5017 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <wallet/wallet.h>
 
 #include <chain.h>
 #include <checkpoints.h>
 #include <config.h>
 #include <consensus/consensus.h>
 #include <consensus/validation.h>
 #include <fs.h>
 #include <interfaces/chain.h>
 #include <interfaces/wallet.h>
 #include <key.h>
 #include <key_io.h>
 #include <keystore.h>
 #include <net.h>
 #include <policy/mempool.h>
 #include <policy/policy.h>
 #include <policy/settings.h>
 #include <primitives/block.h>
 #include <primitives/transaction.h>
 #include <random.h>
 #include <script/script.h>
 #include <script/sighashtype.h>
 #include <script/sign.h>
 #include <shutdown.h>
 #include <timedata.h>
 #include <txmempool.h>
 #include <ui_interface.h>
 #include <util/bip32.h>
 #include <util/error.h>
 #include <util/moneystr.h>
 #include <util/system.h>
 #include <util/translation.h>
 #include <util/validation.h>
 #include <validation.h>
 #include <wallet/coincontrol.h>
 #include <wallet/coinselection.h>
 #include <wallet/fees.h>
 
 #include <boost/algorithm/string/replace.hpp>
 
 #include <algorithm>
 #include <cassert>
 #include <future>
 
 static RecursiveMutex cs_wallets;
 static std::vector<std::shared_ptr<CWallet>> vpwallets GUARDED_BY(cs_wallets);
 
 bool AddWallet(const std::shared_ptr<CWallet> &wallet) {
     LOCK(cs_wallets);
     assert(wallet);
     std::vector<std::shared_ptr<CWallet>>::const_iterator i =
         std::find(vpwallets.begin(), vpwallets.end(), wallet);
     if (i != vpwallets.end()) {
         return false;
     }
     vpwallets.push_back(wallet);
     return true;
 }
 
 bool RemoveWallet(const std::shared_ptr<CWallet> &wallet) {
     LOCK(cs_wallets);
     assert(wallet);
     std::vector<std::shared_ptr<CWallet>>::iterator i =
         std::find(vpwallets.begin(), vpwallets.end(), wallet);
     if (i == vpwallets.end()) {
         return false;
     }
     vpwallets.erase(i);
     return true;
 }
 
 bool HasWallets() {
     LOCK(cs_wallets);
     return !vpwallets.empty();
 }
 
 std::vector<std::shared_ptr<CWallet>> GetWallets() {
     LOCK(cs_wallets);
     return vpwallets;
 }
 
 std::shared_ptr<CWallet> GetWallet(const std::string &name) {
     LOCK(cs_wallets);
     for (const std::shared_ptr<CWallet> &wallet : vpwallets) {
         if (wallet->GetName() == name) {
             return wallet;
         }
     }
     return nullptr;
 }
 
 static Mutex g_wallet_release_mutex;
 static std::condition_variable g_wallet_release_cv;
 static std::set<std::string> g_unloading_wallet_set;
 
 // Custom deleter for shared_ptr<CWallet>.
 static void ReleaseWallet(CWallet *wallet) {
     // Unregister and delete the wallet right after
     // BlockUntilSyncedToCurrentChain so that it's in sync with the current
     // chainstate.
     const std::string name = wallet->GetName();
     wallet->WalletLogPrintf("Releasing wallet\n");
     wallet->BlockUntilSyncedToCurrentChain();
     wallet->Flush();
     wallet->m_chain_notifications_handler.reset();
     delete wallet;
     // Wallet is now released, notify UnloadWallet, if any.
     {
         LOCK(g_wallet_release_mutex);
         if (g_unloading_wallet_set.erase(name) == 0) {
             // UnloadWallet was not called for this wallet, all done.
             return;
         }
     }
     g_wallet_release_cv.notify_all();
 }
 
 void UnloadWallet(std::shared_ptr<CWallet> &&wallet) {
     // Mark wallet for unloading.
     const std::string name = wallet->GetName();
     {
         LOCK(g_wallet_release_mutex);
         auto it = g_unloading_wallet_set.insert(name);
         assert(it.second);
     }
     // The wallet can be in use so it's not possible to explicitly unload here.
     // Notify the unload intent so that all remaining shared pointers are
     // released.
     wallet->NotifyUnload();
     // Time to ditch our shared_ptr and wait for ReleaseWallet call.
     wallet.reset();
     {
         WAIT_LOCK(g_wallet_release_mutex, lock);
         while (g_unloading_wallet_set.count(name) == 1) {
             g_wallet_release_cv.wait(lock);
         }
     }
 }
 
 static const size_t OUTPUT_GROUP_MAX_ENTRIES = 10;
 
 std::shared_ptr<CWallet> LoadWallet(const CChainParams &chainParams,
                                     interfaces::Chain &chain,
                                     const WalletLocation &location,
                                     std::string &error, std::string &warning) {
     if (!CWallet::Verify(chainParams, chain, location, false, error, warning)) {
         error = "Wallet file verification failed: " + error;
         return nullptr;
     }
 
     std::shared_ptr<CWallet> wallet =
         CWallet::CreateWalletFromFile(chainParams, chain, location);
     if (!wallet) {
         error = "Wallet loading failed.";
         return nullptr;
     }
     AddWallet(wallet);
     wallet->postInitProcess();
     return wallet;
 }
 
 std::shared_ptr<CWallet> LoadWallet(const CChainParams &chainParams,
                                     interfaces::Chain &chain,
                                     const std::string &name, std::string &error,
                                     std::string &warning) {
     return LoadWallet(chainParams, chain, WalletLocation(name), error, warning);
 }
 
 const uint32_t BIP32_HARDENED_KEY_LIMIT = 0x80000000;
 
 const BlockHash CMerkleTx::ABANDON_HASH(uint256S(
     "0000000000000000000000000000000000000000000000000000000000000001"));
 
 /** @defgroup mapWallet
  *
  * @{
  */
 
 std::string COutput::ToString() const {
     return strprintf("COutput(%s, %d, %d) [%s]", tx->GetId().ToString(), i,
                      nDepth, FormatMoney(tx->tx->vout[i].nValue));
 }
 
 class CAffectedKeysVisitor : public boost::static_visitor<void> {
 private:
     const CKeyStore &keystore;
     std::vector<CKeyID> &vKeys;
 
 public:
     CAffectedKeysVisitor(const CKeyStore &keystoreIn,
                          std::vector<CKeyID> &vKeysIn)
         : keystore(keystoreIn), vKeys(vKeysIn) {}
 
     void Process(const CScript &script) {
         txnouttype type;
         std::vector<CTxDestination> vDest;
         int nRequired;
         if (ExtractDestinations(script, type, vDest, nRequired)) {
             for (const CTxDestination &dest : vDest) {
                 boost::apply_visitor(*this, dest);
             }
         }
     }
 
     void operator()(const CKeyID &keyId) {
         if (keystore.HaveKey(keyId)) {
             vKeys.push_back(keyId);
         }
     }
 
     void operator()(const CScriptID &scriptId) {
         CScript script;
         if (keystore.GetCScript(scriptId, script)) {
             Process(script);
         }
     }
 
     void operator()(const CNoDestination &none) {}
 };
 
 const CWalletTx *CWallet::GetWalletTx(const TxId &txid) const {
     LOCK(cs_wallet);
     std::map<TxId, CWalletTx>::const_iterator it = mapWallet.find(txid);
     if (it == mapWallet.end()) {
         return nullptr;
     }
 
     return &(it->second);
 }
 
 CPubKey CWallet::GenerateNewKey(WalletBatch &batch, bool internal) {
     assert(!IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS));
     assert(!IsWalletFlagSet(WALLET_FLAG_BLANK_WALLET));
     // mapKeyMetadata
     AssertLockHeld(cs_wallet);
     // default to compressed public keys if we want 0.6.0 wallets
     bool fCompressed = CanSupportFeature(FEATURE_COMPRPUBKEY);
 
     CKey secret;
 
     // Create new metadata
     int64_t nCreationTime = GetTime();
     CKeyMetadata metadata(nCreationTime);
 
     // use HD key derivation if HD was enabled during wallet creation and a seed
     // is present
     if (IsHDEnabled()) {
         DeriveNewChildKey(
             batch, metadata, secret,
             (CanSupportFeature(FEATURE_HD_SPLIT) ? internal : false));
     } else {
         secret.MakeNewKey(fCompressed);
     }
 
     // Compressed public keys were introduced in version 0.6.0
     if (fCompressed) {
         SetMinVersion(FEATURE_COMPRPUBKEY);
     }
 
     CPubKey pubkey = secret.GetPubKey();
     assert(secret.VerifyPubKey(pubkey));
 
     mapKeyMetadata[pubkey.GetID()] = metadata;
     UpdateTimeFirstKey(nCreationTime);
 
     if (!AddKeyPubKeyWithDB(batch, secret, pubkey)) {
         throw std::runtime_error(std::string(__func__) + ": AddKey failed");
     }
 
     return pubkey;
 }
 
 void CWallet::DeriveNewChildKey(WalletBatch &batch, CKeyMetadata &metadata,
                                 CKey &secret, bool internal) {
     // for now we use a fixed keypath scheme of m/0'/0'/k
     // seed (256bit)
     CKey seed;
     // hd master key
     CExtKey masterKey;
     // key at m/0'
     CExtKey accountKey;
     // key at m/0'/0' (external) or m/0'/1' (internal)
     CExtKey chainChildKey;
     // key at m/0'/0'/<n>'
     CExtKey childKey;
 
     // try to get the seed
     if (!GetKey(hdChain.seed_id, seed)) {
         throw std::runtime_error(std::string(__func__) + ": seed not found");
     }
 
     masterKey.SetSeed(seed.begin(), seed.size());
 
     // derive m/0'
     // use hardened derivation (child keys >= 0x80000000 are hardened after
     // bip32)
     masterKey.Derive(accountKey, BIP32_HARDENED_KEY_LIMIT);
 
     // derive m/0'/0' (external chain) OR m/0'/1' (internal chain)
     assert(internal ? CanSupportFeature(FEATURE_HD_SPLIT) : true);
     accountKey.Derive(chainChildKey,
                       BIP32_HARDENED_KEY_LIMIT + (internal ? 1 : 0));
 
     // derive child key at next index, skip keys already known to the wallet
     do {
         // always derive hardened keys
         // childIndex | BIP32_HARDENED_KEY_LIMIT = derive childIndex in hardened
         // child-index-range
         // example: 1 | BIP32_HARDENED_KEY_LIMIT == 0x80000001 == 2147483649
         if (internal) {
             chainChildKey.Derive(childKey, hdChain.nInternalChainCounter |
                                                BIP32_HARDENED_KEY_LIMIT);
             metadata.hdKeypath = "m/0'/1'/" +
                                  std::to_string(hdChain.nInternalChainCounter) +
                                  "'";
             metadata.key_origin.path.push_back(0 | BIP32_HARDENED_KEY_LIMIT);
             metadata.key_origin.path.push_back(1 | BIP32_HARDENED_KEY_LIMIT);
             metadata.key_origin.path.push_back(hdChain.nInternalChainCounter |
                                                BIP32_HARDENED_KEY_LIMIT);
             hdChain.nInternalChainCounter++;
         } else {
             chainChildKey.Derive(childKey, hdChain.nExternalChainCounter |
                                                BIP32_HARDENED_KEY_LIMIT);
             metadata.hdKeypath = "m/0'/0'/" +
                                  std::to_string(hdChain.nExternalChainCounter) +
                                  "'";
             metadata.key_origin.path.push_back(0 | BIP32_HARDENED_KEY_LIMIT);
             metadata.key_origin.path.push_back(0 | BIP32_HARDENED_KEY_LIMIT);
             metadata.key_origin.path.push_back(hdChain.nExternalChainCounter |
                                                BIP32_HARDENED_KEY_LIMIT);
             hdChain.nExternalChainCounter++;
         }
     } while (HaveKey(childKey.key.GetPubKey().GetID()));
     secret = childKey.key;
     metadata.hd_seed_id = hdChain.seed_id;
     CKeyID master_id = masterKey.key.GetPubKey().GetID();
     std::copy(master_id.begin(), master_id.begin() + 4,
               metadata.key_origin.fingerprint);
     metadata.has_key_origin = true;
     // update the chain model in the database
     if (!batch.WriteHDChain(hdChain)) {
         throw std::runtime_error(std::string(__func__) +
                                  ": Writing HD chain model failed");
     }
 }
 
 bool CWallet::AddKeyPubKeyWithDB(WalletBatch &batch, const CKey &secret,
                                  const CPubKey &pubkey) {
     // mapKeyMetadata
     AssertLockHeld(cs_wallet);
 
     // Make sure we aren't adding private keys to private key disabled wallets
     assert(!IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS));
 
     // CCryptoKeyStore has no concept of wallet databases, but calls
     // AddCryptedKey which is overridden below. To avoid flushes, the database
     // handle is tunneled through to it.
     bool needsDB = !encrypted_batch;
     if (needsDB) {
         encrypted_batch = &batch;
     }
     if (!CCryptoKeyStore::AddKeyPubKey(secret, pubkey)) {
         if (needsDB) {
             encrypted_batch = nullptr;
         }
         return false;
     }
 
     if (needsDB) {
         encrypted_batch = nullptr;
     }
 
     // Check if we need to remove from watch-only.
     CScript script;
     script = GetScriptForDestination(pubkey.GetID());
     if (HaveWatchOnly(script)) {
         RemoveWatchOnly(script);
     }
 
     script = GetScriptForRawPubKey(pubkey);
     if (HaveWatchOnly(script)) {
         RemoveWatchOnly(script);
     }
 
     if (!IsCrypted()) {
         return batch.WriteKey(pubkey, secret.GetPrivKey(),
                               mapKeyMetadata[pubkey.GetID()]);
     }
 
     UnsetWalletFlag(WALLET_FLAG_BLANK_WALLET);
     return true;
 }
 
 bool CWallet::AddKeyPubKey(const CKey &secret, const CPubKey &pubkey) {
     WalletBatch batch(*database);
     return CWallet::AddKeyPubKeyWithDB(batch, secret, pubkey);
 }
 
 bool CWallet::AddCryptedKey(const CPubKey &vchPubKey,
                             const std::vector<uint8_t> &vchCryptedSecret) {
     if (!CCryptoKeyStore::AddCryptedKey(vchPubKey, vchCryptedSecret)) {
         return false;
     }
 
     LOCK(cs_wallet);
     if (encrypted_batch) {
         return encrypted_batch->WriteCryptedKey(
             vchPubKey, vchCryptedSecret, mapKeyMetadata[vchPubKey.GetID()]);
     }
 
     return WalletBatch(*database).WriteCryptedKey(
         vchPubKey, vchCryptedSecret, mapKeyMetadata[vchPubKey.GetID()]);
 }
 
 void CWallet::LoadKeyMetadata(const CKeyID &keyID, const CKeyMetadata &meta) {
     // mapKeyMetadata
     AssertLockHeld(cs_wallet);
     UpdateTimeFirstKey(meta.nCreateTime);
     mapKeyMetadata[keyID] = meta;
 }
 
 void CWallet::LoadScriptMetadata(const CScriptID &script_id,
                                  const CKeyMetadata &meta) {
     // m_script_metadata
     AssertLockHeld(cs_wallet);
     UpdateTimeFirstKey(meta.nCreateTime);
     m_script_metadata[script_id] = meta;
 }
 
 // Writes a keymetadata for a public key. overwrite specifies whether to
 // overwrite an existing metadata for that key if there exists one.
 bool CWallet::WriteKeyMetadata(const CKeyMetadata &meta, const CPubKey &pubkey,
                                const bool overwrite) {
     return WalletBatch(*database).WriteKeyMetadata(meta, pubkey, overwrite);
 }
 
 void CWallet::UpgradeKeyMetadata() {
     // mapKeyMetadata
     AssertLockHeld(cs_wallet);
     if (IsLocked() || IsWalletFlagSet(WALLET_FLAG_KEY_ORIGIN_METADATA)) {
         return;
     }
 
     for (auto &meta_pair : mapKeyMetadata) {
         CKeyMetadata &meta = meta_pair.second;
         // If the hdKeypath is "s", that's the seed and it doesn't have a key
         // origin
         if (!meta.hd_seed_id.IsNull() && !meta.has_key_origin &&
             meta.hdKeypath != "s") {
             CKey key;
             GetKey(meta.hd_seed_id, key);
             CExtKey masterKey;
             masterKey.SetSeed(key.begin(), key.size());
             // Add to map
             CKeyID master_id = masterKey.key.GetPubKey().GetID();
             std::copy(master_id.begin(), master_id.begin() + 4,
                       meta.key_origin.fingerprint);
             if (!ParseHDKeypath(meta.hdKeypath, meta.key_origin.path)) {
                 throw std::runtime_error("Invalid stored hdKeypath");
             }
             meta.has_key_origin = true;
             if (meta.nVersion < CKeyMetadata::VERSION_WITH_KEY_ORIGIN) {
                 meta.nVersion = CKeyMetadata::VERSION_WITH_KEY_ORIGIN;
             }
 
             // Write meta to wallet
             CPubKey pubkey;
             if (GetPubKey(meta_pair.first, pubkey)) {
                 WriteKeyMetadata(meta, pubkey, true);
             }
         }
     }
     SetWalletFlag(WALLET_FLAG_KEY_ORIGIN_METADATA);
 }
 
 bool CWallet::LoadCryptedKey(const CPubKey &vchPubKey,
                              const std::vector<uint8_t> &vchCryptedSecret) {
     return CCryptoKeyStore::AddCryptedKey(vchPubKey, vchCryptedSecret);
 }
 
 /**
  * Update wallet first key creation time. This should be called whenever keys
  * are added to the wallet, with the oldest key creation time.
  */
 void CWallet::UpdateTimeFirstKey(int64_t nCreateTime) {
     AssertLockHeld(cs_wallet);
     if (nCreateTime <= 1) {
         // Cannot determine birthday information, so set the wallet birthday to
         // the beginning of time.
         nTimeFirstKey = 1;
     } else if (!nTimeFirstKey || nCreateTime < nTimeFirstKey) {
         nTimeFirstKey = nCreateTime;
     }
 }
 
 bool CWallet::AddCScript(const CScript &redeemScript) {
     if (!CCryptoKeyStore::AddCScript(redeemScript)) {
         return false;
     }
     if (WalletBatch(*database).WriteCScript(Hash160(redeemScript),
                                             redeemScript)) {
         UnsetWalletFlag(WALLET_FLAG_BLANK_WALLET);
         return true;
     }
     return false;
 }
 
 bool CWallet::LoadCScript(const CScript &redeemScript) {
     /**
      * A sanity check was added in pull #3843 to avoid adding redeemScripts that
      * never can be redeemed. However, old wallets may still contain these. Do
      * not add them to the wallet and warn.
      */
     if (redeemScript.size() > MAX_SCRIPT_ELEMENT_SIZE) {
         std::string strAddr =
             EncodeDestination(CScriptID(redeemScript), GetConfig());
         WalletLogPrintf("%s: Warning: This wallet contains a redeemScript "
                         "of size %i which exceeds maximum size %i thus can "
                         "never be redeemed. Do not use address %s.\n",
                         __func__, redeemScript.size(), MAX_SCRIPT_ELEMENT_SIZE,
                         strAddr);
         return true;
     }
 
     return CCryptoKeyStore::AddCScript(redeemScript);
 }
 
 bool CWallet::AddWatchOnly(const CScript &dest) {
     if (!CCryptoKeyStore::AddWatchOnly(dest)) {
         return false;
     }
 
     const CKeyMetadata &meta = m_script_metadata[CScriptID(dest)];
     UpdateTimeFirstKey(meta.nCreateTime);
     NotifyWatchonlyChanged(true);
     if (WalletBatch(*database).WriteWatchOnly(dest, meta)) {
         UnsetWalletFlag(WALLET_FLAG_BLANK_WALLET);
         return true;
     }
     return false;
 }
 
 bool CWallet::AddWatchOnly(const CScript &dest, int64_t nCreateTime) {
     m_script_metadata[CScriptID(dest)].nCreateTime = nCreateTime;
     return AddWatchOnly(dest);
 }
 
 bool CWallet::RemoveWatchOnly(const CScript &dest) {
     AssertLockHeld(cs_wallet);
     if (!CCryptoKeyStore::RemoveWatchOnly(dest)) {
         return false;
     }
 
     if (!HaveWatchOnly()) {
         NotifyWatchonlyChanged(false);
     }
 
     return WalletBatch(*database).EraseWatchOnly(dest);
 }
 
 bool CWallet::LoadWatchOnly(const CScript &dest) {
     return CCryptoKeyStore::AddWatchOnly(dest);
 }
 
 bool CWallet::Unlock(const SecureString &strWalletPassphrase,
                      bool accept_no_keys) {
     CCrypter crypter;
     CKeyingMaterial _vMasterKey;
 
     {
         LOCK(cs_wallet);
         for (const MasterKeyMap::value_type &pMasterKey : mapMasterKeys) {
             if (!crypter.SetKeyFromPassphrase(
                     strWalletPassphrase, pMasterKey.second.vchSalt,
                     pMasterKey.second.nDeriveIterations,
                     pMasterKey.second.nDerivationMethod)) {
                 return false;
             }
             if (!crypter.Decrypt(pMasterKey.second.vchCryptedKey,
                                  _vMasterKey)) {
                 // try another master key
                 continue;
             }
             if (CCryptoKeyStore::Unlock(_vMasterKey, accept_no_keys)) {
                 // Now that we've unlocked, upgrade the key metadata
                 UpgradeKeyMetadata();
                 return true;
             }
         }
     }
 
     return false;
 }
 
 bool CWallet::ChangeWalletPassphrase(
     const SecureString &strOldWalletPassphrase,
     const SecureString &strNewWalletPassphrase) {
     bool fWasLocked = IsLocked();
 
     LOCK(cs_wallet);
     Lock();
 
     CCrypter crypter;
     CKeyingMaterial _vMasterKey;
     for (MasterKeyMap::value_type &pMasterKey : mapMasterKeys) {
         if (!crypter.SetKeyFromPassphrase(
                 strOldWalletPassphrase, pMasterKey.second.vchSalt,
                 pMasterKey.second.nDeriveIterations,
                 pMasterKey.second.nDerivationMethod)) {
             return false;
         }
 
         if (!crypter.Decrypt(pMasterKey.second.vchCryptedKey, _vMasterKey)) {
             return false;
         }
 
         if (CCryptoKeyStore::Unlock(_vMasterKey)) {
             int64_t nStartTime = GetTimeMillis();
             crypter.SetKeyFromPassphrase(strNewWalletPassphrase,
                                          pMasterKey.second.vchSalt,
                                          pMasterKey.second.nDeriveIterations,
                                          pMasterKey.second.nDerivationMethod);
             pMasterKey.second.nDeriveIterations = static_cast<unsigned int>(
                 pMasterKey.second.nDeriveIterations *
                 (100 / ((double)(GetTimeMillis() - nStartTime))));
 
             nStartTime = GetTimeMillis();
             crypter.SetKeyFromPassphrase(strNewWalletPassphrase,
                                          pMasterKey.second.vchSalt,
                                          pMasterKey.second.nDeriveIterations,
                                          pMasterKey.second.nDerivationMethod);
             pMasterKey.second.nDeriveIterations =
                 (pMasterKey.second.nDeriveIterations +
                  static_cast<unsigned int>(
                      pMasterKey.second.nDeriveIterations * 100 /
                      double(GetTimeMillis() - nStartTime))) /
                 2;
 
             if (pMasterKey.second.nDeriveIterations < 25000) {
                 pMasterKey.second.nDeriveIterations = 25000;
             }
 
             WalletLogPrintf(
                 "Wallet passphrase changed to an nDeriveIterations of %i\n",
                 pMasterKey.second.nDeriveIterations);
 
             if (!crypter.SetKeyFromPassphrase(
                     strNewWalletPassphrase, pMasterKey.second.vchSalt,
                     pMasterKey.second.nDeriveIterations,
                     pMasterKey.second.nDerivationMethod)) {
                 return false;
             }
 
             if (!crypter.Encrypt(_vMasterKey,
                                  pMasterKey.second.vchCryptedKey)) {
                 return false;
             }
 
             WalletBatch(*database).WriteMasterKey(pMasterKey.first,
                                                   pMasterKey.second);
             if (fWasLocked) {
                 Lock();
             }
 
             return true;
         }
     }
 
     return false;
 }
 
 void CWallet::ChainStateFlushed(const CBlockLocator &loc) {
     WalletBatch batch(*database);
     batch.WriteBestBlock(loc);
 }
 
 void CWallet::SetMinVersion(enum WalletFeature nVersion, WalletBatch *batch_in,
                             bool fExplicit) {
     // nWalletVersion
     LOCK(cs_wallet);
     if (nWalletVersion >= nVersion) {
         return;
     }
 
     // When doing an explicit upgrade, if we pass the max version permitted,
     // upgrade all the way.
     if (fExplicit && nVersion > nWalletMaxVersion) {
         nVersion = FEATURE_LATEST;
     }
 
     nWalletVersion = nVersion;
 
     if (nVersion > nWalletMaxVersion) {
         nWalletMaxVersion = nVersion;
     }
 
     WalletBatch *batch = batch_in ? batch_in : new WalletBatch(*database);
     if (nWalletVersion > 40000) {
         batch->WriteMinVersion(nWalletVersion);
     }
     if (!batch_in) {
         delete batch;
     }
 }
 
 bool CWallet::SetMaxVersion(int nVersion) {
     // nWalletVersion, nWalletMaxVersion
     LOCK(cs_wallet);
 
     // Cannot downgrade below current version
     if (nWalletVersion > nVersion) {
         return false;
     }
 
     nWalletMaxVersion = nVersion;
 
     return true;
 }
 
 std::set<TxId> CWallet::GetConflicts(const TxId &txid) const {
     std::set<TxId> result;
     AssertLockHeld(cs_wallet);
 
     std::map<TxId, CWalletTx>::const_iterator it = mapWallet.find(txid);
     if (it == mapWallet.end()) {
         return result;
     }
 
     const CWalletTx &wtx = it->second;
 
     std::pair<TxSpends::const_iterator, TxSpends::const_iterator> range;
 
     for (const CTxIn &txin : wtx.tx->vin) {
         if (mapTxSpends.count(txin.prevout) <= 1) {
             // No conflict if zero or one spends.
             continue;
         }
 
         range = mapTxSpends.equal_range(txin.prevout);
         for (TxSpends::const_iterator _it = range.first; _it != range.second;
              ++_it) {
             result.insert(_it->second);
         }
     }
 
     return result;
 }
 
 bool CWallet::HasWalletSpend(const TxId &txid) const {
     AssertLockHeld(cs_wallet);
     auto iter = mapTxSpends.lower_bound(COutPoint(txid, 0));
     return (iter != mapTxSpends.end() && iter->first.GetTxId() == txid);
 }
 
 void CWallet::Flush(bool shutdown) {
     database->Flush(shutdown);
 }
 
 void CWallet::SyncMetaData(
     std::pair<TxSpends::iterator, TxSpends::iterator> range) {
     // We want all the wallet transactions in range to have the same metadata as
     // the oldest (smallest nOrderPos).
     // So: find smallest nOrderPos:
 
     int nMinOrderPos = std::numeric_limits<int>::max();
     const CWalletTx *copyFrom = nullptr;
     for (TxSpends::iterator it = range.first; it != range.second; ++it) {
         const CWalletTx *wtx = &mapWallet.at(it->second);
         if (wtx->nOrderPos < nMinOrderPos) {
             nMinOrderPos = wtx->nOrderPos;
             copyFrom = wtx;
         }
     }
 
     if (!copyFrom) {
         return;
     }
 
     // Now copy data from copyFrom to rest:
     for (TxSpends::iterator it = range.first; it != range.second; ++it) {
         const TxId &txid = it->second;
         CWalletTx *copyTo = &mapWallet.at(txid);
         if (copyFrom == copyTo) {
             continue;
         }
 
         assert(
             copyFrom &&
             "Oldest wallet transaction in range assumed to have been found.");
 
         if (!copyFrom->IsEquivalentTo(*copyTo)) {
             continue;
         }
 
         copyTo->mapValue = copyFrom->mapValue;
         copyTo->vOrderForm = copyFrom->vOrderForm;
         // fTimeReceivedIsTxTime not copied on purpose nTimeReceived not copied
         // on purpose.
         copyTo->nTimeSmart = copyFrom->nTimeSmart;
         copyTo->fFromMe = copyFrom->fFromMe;
         // nOrderPos not copied on purpose cached members not copied on purpose.
     }
 }
 
 /**
  * Outpoint is spent if any non-conflicted transaction, spends it:
  */
 bool CWallet::IsSpent(interfaces::Chain::Lock &locked_chain,
                       const COutPoint &outpoint) const {
     std::pair<TxSpends::const_iterator, TxSpends::const_iterator> range =
         mapTxSpends.equal_range(outpoint);
 
     for (TxSpends::const_iterator it = range.first; it != range.second; ++it) {
         const TxId &wtxid = it->second;
         std::map<TxId, CWalletTx>::const_iterator mit = mapWallet.find(wtxid);
         if (mit != mapWallet.end()) {
             int depth = mit->second.GetDepthInMainChain(locked_chain);
             if (depth > 0 || (depth == 0 && !mit->second.isAbandoned())) {
                 // Spent
                 return true;
             }
         }
     }
 
     return false;
 }
 
 void CWallet::AddToSpends(const COutPoint &outpoint, const TxId &wtxid) {
     mapTxSpends.insert(std::make_pair(outpoint, wtxid));
 
     std::pair<TxSpends::iterator, TxSpends::iterator> range;
     range = mapTxSpends.equal_range(outpoint);
     SyncMetaData(range);
 }
 
 void CWallet::AddToSpends(const TxId &wtxid) {
     auto it = mapWallet.find(wtxid);
     assert(it != mapWallet.end());
     CWalletTx &thisTx = it->second;
     // Coinbases don't spend anything!
     if (thisTx.IsCoinBase()) {
         return;
     }
 
     for (const CTxIn &txin : thisTx.tx->vin) {
         AddToSpends(txin.prevout, wtxid);
     }
 }
 
 bool CWallet::EncryptWallet(const SecureString &strWalletPassphrase) {
     if (IsCrypted()) {
         return false;
     }
 
     CKeyingMaterial _vMasterKey;
 
     _vMasterKey.resize(WALLET_CRYPTO_KEY_SIZE);
     GetStrongRandBytes(&_vMasterKey[0], WALLET_CRYPTO_KEY_SIZE);
 
     CMasterKey kMasterKey;
 
     kMasterKey.vchSalt.resize(WALLET_CRYPTO_SALT_SIZE);
     GetStrongRandBytes(&kMasterKey.vchSalt[0], WALLET_CRYPTO_SALT_SIZE);
 
     CCrypter crypter;
     int64_t nStartTime = GetTimeMillis();
     crypter.SetKeyFromPassphrase(strWalletPassphrase, kMasterKey.vchSalt, 25000,
                                  kMasterKey.nDerivationMethod);
     kMasterKey.nDeriveIterations = static_cast<unsigned int>(
         2500000 / double(GetTimeMillis() - nStartTime));
 
     nStartTime = GetTimeMillis();
     crypter.SetKeyFromPassphrase(strWalletPassphrase, kMasterKey.vchSalt,
                                  kMasterKey.nDeriveIterations,
                                  kMasterKey.nDerivationMethod);
     kMasterKey.nDeriveIterations =
         (kMasterKey.nDeriveIterations +
          static_cast<unsigned int>(kMasterKey.nDeriveIterations * 100 /
                                    double(GetTimeMillis() - nStartTime))) /
         2;
 
     if (kMasterKey.nDeriveIterations < 25000) {
         kMasterKey.nDeriveIterations = 25000;
     }
 
     WalletLogPrintf("Encrypting Wallet with an nDeriveIterations of %i\n",
                     kMasterKey.nDeriveIterations);
 
     if (!crypter.SetKeyFromPassphrase(strWalletPassphrase, kMasterKey.vchSalt,
                                       kMasterKey.nDeriveIterations,
                                       kMasterKey.nDerivationMethod)) {
         return false;
     }
 
     if (!crypter.Encrypt(_vMasterKey, kMasterKey.vchCryptedKey)) {
         return false;
     }
 
     {
         LOCK(cs_wallet);
         mapMasterKeys[++nMasterKeyMaxID] = kMasterKey;
         assert(!encrypted_batch);
         encrypted_batch = new WalletBatch(*database);
         if (!encrypted_batch->TxnBegin()) {
             delete encrypted_batch;
             encrypted_batch = nullptr;
             return false;
         }
         encrypted_batch->WriteMasterKey(nMasterKeyMaxID, kMasterKey);
 
         if (!EncryptKeys(_vMasterKey)) {
             encrypted_batch->TxnAbort();
             delete encrypted_batch;
             // We now probably have half of our keys encrypted in memory, and
             // half not... die and let the user reload the unencrypted wallet.
             assert(false);
         }
 
         // Encryption was introduced in version 0.4.0
         SetMinVersion(FEATURE_WALLETCRYPT, encrypted_batch, true);
 
         if (!encrypted_batch->TxnCommit()) {
             delete encrypted_batch;
             // We now have keys encrypted in memory, but not on disk...
             // die to avoid confusion and let the user reload the unencrypted
             // wallet.
             assert(false);
         }
 
         delete encrypted_batch;
         encrypted_batch = nullptr;
 
         Lock();
         Unlock(strWalletPassphrase);
 
         // If we are using HD, replace the HD seed with a new one
         if (IsHDEnabled()) {
             SetHDSeed(GenerateNewSeed());
         }
 
         NewKeyPool();
         Lock();
 
         // Need to completely rewrite the wallet file; if we don't, bdb might
         // keep bits of the unencrypted private key in slack space in the
         // database file.
         database->Rewrite();
 
         // BDB seems to have a bad habit of writing old data into
         // slack space in .dat files; that is bad if the old data is
         // unencrypted private keys. So:
         database->ReloadDbEnv();
     }
 
     NotifyStatusChanged(this);
     return true;
 }
 
 DBErrors CWallet::ReorderTransactions() {
     LOCK(cs_wallet);
     WalletBatch batch(*database);
 
     // Old wallets didn't have any defined order for transactions. Probably a
     // bad idea to change the output of this.
 
     // First: get all CWalletTx into a sorted-by-time
     // multimap.
     TxItems txByTime;
 
     for (auto &entry : mapWallet) {
         CWalletTx *wtx = &entry.second;
         txByTime.insert(std::make_pair(wtx->nTimeReceived, wtx));
     }
 
     nOrderPosNext = 0;
     std::vector<int64_t> nOrderPosOffsets;
     for (TxItems::iterator it = txByTime.begin(); it != txByTime.end(); ++it) {
         CWalletTx *const pwtx = (*it).second;
         int64_t &nOrderPos = pwtx->nOrderPos;
 
         if (nOrderPos == -1) {
             nOrderPos = nOrderPosNext++;
             nOrderPosOffsets.push_back(nOrderPos);
 
             if (!batch.WriteTx(*pwtx)) {
                 return DBErrors::LOAD_FAIL;
             }
         } else {
             int64_t nOrderPosOff = 0;
             for (const int64_t &nOffsetStart : nOrderPosOffsets) {
                 if (nOrderPos >= nOffsetStart) {
                     ++nOrderPosOff;
                 }
             }
 
             nOrderPos += nOrderPosOff;
             nOrderPosNext = std::max(nOrderPosNext, nOrderPos + 1);
 
             if (!nOrderPosOff) {
                 continue;
             }
 
             // Since we're changing the order, write it back.
             if (!batch.WriteTx(*pwtx)) {
                 return DBErrors::LOAD_FAIL;
             }
         }
     }
 
     batch.WriteOrderPosNext(nOrderPosNext);
 
     return DBErrors::LOAD_OK;
 }
 
 int64_t CWallet::IncOrderPosNext(WalletBatch *batch) {
     // nOrderPosNext
     AssertLockHeld(cs_wallet);
     int64_t nRet = nOrderPosNext++;
     if (batch) {
         batch->WriteOrderPosNext(nOrderPosNext);
     } else {
         WalletBatch(*database).WriteOrderPosNext(nOrderPosNext);
     }
 
     return nRet;
 }
 
 void CWallet::MarkDirty() {
     LOCK(cs_wallet);
     for (std::pair<const TxId, CWalletTx> &item : mapWallet) {
         item.second.MarkDirty();
     }
 }
 
 bool CWallet::AddToWallet(const CWalletTx &wtxIn, bool fFlushOnClose) {
     LOCK(cs_wallet);
 
     WalletBatch batch(*database, "r+", fFlushOnClose);
 
     const TxId &txid = wtxIn.GetId();
 
     // Inserts only if not already there, returns tx inserted or tx found.
     std::pair<std::map<TxId, CWalletTx>::iterator, bool> ret =
         mapWallet.insert(std::make_pair(txid, wtxIn));
     CWalletTx &wtx = (*ret.first).second;
     wtx.BindWallet(this);
     bool fInsertedNew = ret.second;
     if (fInsertedNew) {
         wtx.nTimeReceived = chain().getAdjustedTime();
         wtx.nOrderPos = IncOrderPosNext(&batch);
         wtx.m_it_wtxOrdered =
             wtxOrdered.insert(std::make_pair(wtx.nOrderPos, &wtx));
         wtx.nTimeSmart = ComputeTimeSmart(wtx);
         AddToSpends(txid);
     }
 
     bool fUpdated = false;
     if (!fInsertedNew) {
         // Merge
         if (!wtxIn.hashUnset() && wtxIn.hashBlock != wtx.hashBlock) {
             wtx.hashBlock = wtxIn.hashBlock;
             fUpdated = true;
         }
 
         // If no longer abandoned, update
         if (wtxIn.hashBlock.IsNull() && wtx.isAbandoned()) {
             wtx.hashBlock = wtxIn.hashBlock;
             fUpdated = true;
         }
 
         if (wtxIn.nIndex != -1 && (wtxIn.nIndex != wtx.nIndex)) {
             wtx.nIndex = wtxIn.nIndex;
             fUpdated = true;
         }
 
         if (wtxIn.fFromMe && wtxIn.fFromMe != wtx.fFromMe) {
             wtx.fFromMe = wtxIn.fFromMe;
             fUpdated = true;
         }
     }
 
     //// debug print
     WalletLogPrintf("AddToWallet %s  %s%s\n", wtxIn.GetId().ToString(),
                     (fInsertedNew ? "new" : ""), (fUpdated ? "update" : ""));
 
     // Write to disk
     if ((fInsertedNew || fUpdated) && !batch.WriteTx(wtx)) {
         return false;
     }
 
     // Break debit/credit balance caches:
     wtx.MarkDirty();
 
     // Notify UI of new or updated transaction.
     NotifyTransactionChanged(this, txid, fInsertedNew ? CT_NEW : CT_UPDATED);
 
     // Notify an external script when a wallet transaction comes in or is
     // updated.
     std::string strCmd = gArgs.GetArg("-walletnotify", "");
 
     if (!strCmd.empty()) {
         boost::replace_all(strCmd, "%s", wtxIn.GetId().GetHex());
         std::thread t(runCommand, strCmd);
         // Thread runs free.
         t.detach();
     }
 
     return true;
 }
 
 void CWallet::LoadToWallet(const CWalletTx &wtxIn) {
     const TxId &txid = wtxIn.GetId();
     const auto &ins = mapWallet.emplace(txid, wtxIn);
     CWalletTx &wtx = ins.first->second;
     wtx.BindWallet(this);
     if (/* insertion took place */ ins.second) {
         wtx.m_it_wtxOrdered =
             wtxOrdered.insert(std::make_pair(wtx.nOrderPos, &wtx));
     }
     AddToSpends(txid);
     for (const CTxIn &txin : wtx.tx->vin) {
         auto it = mapWallet.find(txin.prevout.GetTxId());
         if (it != mapWallet.end()) {
             CWalletTx &prevtx = it->second;
             if (prevtx.nIndex == -1 && !prevtx.hashUnset()) {
                 MarkConflicted(prevtx.hashBlock, wtx.GetId());
             }
         }
     }
 }
 
 bool CWallet::AddToWalletIfInvolvingMe(const CTransactionRef &ptx,
                                        const BlockHash &block_hash,
                                        int posInBlock, bool fUpdate) {
     const CTransaction &tx = *ptx;
     AssertLockHeld(cs_wallet);
 
     if (!block_hash.IsNull()) {
         for (const CTxIn &txin : tx.vin) {
             std::pair<TxSpends::const_iterator, TxSpends::const_iterator>
                 range = mapTxSpends.equal_range(txin.prevout);
             while (range.first != range.second) {
                 if (range.first->second != tx.GetId()) {
                     WalletLogPrintf(
                         "Transaction %s (in block %s) conflicts with wallet "
                         "transaction %s (both spend %s:%i)\n",
                         tx.GetId().ToString(), block_hash.ToString(),
                         range.first->second.ToString(),
                         range.first->first.GetTxId().ToString(),
                         range.first->first.GetN());
                     MarkConflicted(block_hash, range.first->second);
                 }
                 range.first++;
             }
         }
     }
 
     bool fExisted = mapWallet.count(tx.GetId()) != 0;
     if (fExisted && !fUpdate) {
         return false;
     }
     if (fExisted || IsMine(tx) || IsFromMe(tx)) {
         /**
          * Check if any keys in the wallet keypool that were supposed to be
          * unused have appeared in a new transaction. If so, remove those keys
          * from the keypool. This can happen when restoring an old wallet backup
          * that does not contain the mostly recently created transactions from
          * newer versions of the wallet.
          */
 
         // loop though all outputs
         for (const CTxOut &txout : tx.vout) {
             // extract addresses and check if they match with an unused keypool
             // key
             std::vector<CKeyID> vAffected;
             CAffectedKeysVisitor(*this, vAffected).Process(txout.scriptPubKey);
             for (const CKeyID &keyid : vAffected) {
                 std::map<CKeyID, int64_t>::const_iterator mi =
                     m_pool_key_to_index.find(keyid);
                 if (mi != m_pool_key_to_index.end()) {
                     WalletLogPrintf("%s: Detected a used keypool key, mark all "
                                     "keypool key up to this key as used\n",
                                     __func__);
                     MarkReserveKeysAsUsed(mi->second);
 
                     if (!TopUpKeyPool()) {
                         WalletLogPrintf(
                             "%s: Topping up keypool failed (locked wallet)\n",
                             __func__);
                     }
                 }
             }
         }
 
         CWalletTx wtx(this, ptx);
 
         // Get merkle branch if transaction was found in a block
         if (!block_hash.IsNull()) {
             wtx.SetMerkleBranch(block_hash, posInBlock);
         }
 
         return AddToWallet(wtx, false);
     }
 
     return false;
 }
 
 bool CWallet::TransactionCanBeAbandoned(const TxId &txid) const {
     auto locked_chain = chain().lock();
     LOCK(cs_wallet);
     const CWalletTx *wtx = GetWalletTx(txid);
     return wtx && !wtx->isAbandoned() &&
            wtx->GetDepthInMainChain(*locked_chain) == 0 && !wtx->InMempool();
 }
 
 void CWallet::MarkInputsDirty(const CTransactionRef &tx) {
     for (const CTxIn &txin : tx->vin) {
         auto it = mapWallet.find(txin.prevout.GetTxId());
         if (it != mapWallet.end()) {
             it->second.MarkDirty();
         }
     }
 }
 
 bool CWallet::AbandonTransaction(interfaces::Chain::Lock &locked_chain,
                                  const TxId &txid) {
     // Temporary. Removed in upcoming lock cleanup
     auto locked_chain_recursive = chain().lock();
     LOCK(cs_wallet);
 
     WalletBatch batch(*database, "r+");
 
     std::set<TxId> todo;
     std::set<TxId> done;
 
     // Can't mark abandoned if confirmed or in mempool
     auto it = mapWallet.find(txid);
     assert(it != mapWallet.end());
     CWalletTx &origtx = it->second;
     if (origtx.GetDepthInMainChain(locked_chain) != 0 || origtx.InMempool()) {
         return false;
     }
 
     todo.insert(txid);
 
     while (!todo.empty()) {
         const TxId now = *todo.begin();
         todo.erase(now);
         done.insert(now);
         it = mapWallet.find(now);
         assert(it != mapWallet.end());
         CWalletTx &wtx = it->second;
         int currentconfirm = wtx.GetDepthInMainChain(locked_chain);
         // If the orig tx was not in block, none of its spends can be.
         assert(currentconfirm <= 0);
         // If (currentconfirm < 0) {Tx and spends are already conflicted, no
         // need to abandon}
         if (currentconfirm == 0 && !wtx.isAbandoned()) {
             // If the orig tx was not in block/mempool, none of its spends can
             // be in mempool.
             assert(!wtx.InMempool());
             wtx.nIndex = -1;
             wtx.setAbandoned();
             wtx.MarkDirty();
             batch.WriteTx(wtx);
             NotifyTransactionChanged(this, wtx.GetId(), CT_UPDATED);
             // Iterate over all its outputs, and mark transactions in the wallet
             // that spend them abandoned too.
             TxSpends::const_iterator iter =
                 mapTxSpends.lower_bound(COutPoint(now, 0));
             while (iter != mapTxSpends.end() && iter->first.GetTxId() == now) {
                 if (!done.count(iter->second)) {
                     todo.insert(iter->second);
                 }
                 iter++;
             }
 
             // If a transaction changes 'conflicted' state, that changes the
             // balance available of the outputs it spends. So force those to be
             // recomputed.
             MarkInputsDirty(wtx.tx);
         }
     }
 
     return true;
 }
 
 void CWallet::MarkConflicted(const BlockHash &hashBlock, const TxId &txid) {
     auto locked_chain = chain().lock();
     LOCK(cs_wallet);
 
     int conflictconfirms = -locked_chain->getBlockDepth(hashBlock);
 
     // If number of conflict confirms cannot be determined, this means that the
     // block is still unknown or not yet part of the main chain, for example
     // when loading the wallet during a reindex. Do nothing in that case.
     if (conflictconfirms >= 0) {
         return;
     }
 
     // Do not flush the wallet here for performance reasons.
     WalletBatch batch(*database, "r+", false);
 
     std::set<TxId> todo;
     std::set<TxId> done;
 
     todo.insert(txid);
 
     while (!todo.empty()) {
         const TxId now = *todo.begin();
         todo.erase(now);
         done.insert(now);
         auto it = mapWallet.find(now);
         assert(it != mapWallet.end());
         CWalletTx &wtx = it->second;
         int currentconfirm = wtx.GetDepthInMainChain(*locked_chain);
         if (conflictconfirms < currentconfirm) {
             // Block is 'more conflicted' than current confirm; update.
             // Mark transaction as conflicted with this block.
             wtx.nIndex = -1;
             wtx.hashBlock = hashBlock;
             wtx.MarkDirty();
             batch.WriteTx(wtx);
             // Iterate over all its outputs, and mark transactions in the wallet
             // that spend them conflicted too.
             TxSpends::const_iterator iter =
                 mapTxSpends.lower_bound(COutPoint(now, 0));
             while (iter != mapTxSpends.end() && iter->first.GetTxId() == now) {
                 if (!done.count(iter->second)) {
                     todo.insert(iter->second);
                 }
                 iter++;
             }
             // If a transaction changes 'conflicted' state, that changes the
             // balance available of the outputs it spends. So force those to be
             // recomputed.
             MarkInputsDirty(wtx.tx);
         }
     }
 }
 
 void CWallet::SyncTransaction(const CTransactionRef &ptx,
                               const BlockHash &block_hash, int posInBlock,
                               bool update_tx) {
     if (!AddToWalletIfInvolvingMe(ptx, block_hash, posInBlock, update_tx)) {
         // Not one of ours
         return;
     }
 
     // If a transaction changes 'conflicted' state, that changes the balance
     // available of the outputs it spends. So force those to be
     // recomputed, also:
     MarkInputsDirty(ptx);
 }
 
 void CWallet::TransactionAddedToMempool(const CTransactionRef &ptx) {
     auto locked_chain = chain().lock();
     LOCK(cs_wallet);
     SyncTransaction(ptx, BlockHash(), 0 /* position in block */);
 
     auto it = mapWallet.find(ptx->GetId());
     if (it != mapWallet.end()) {
         it->second.fInMempool = true;
     }
 }
 
 void CWallet::TransactionRemovedFromMempool(const CTransactionRef &ptx) {
     LOCK(cs_wallet);
     auto it = mapWallet.find(ptx->GetId());
     if (it != mapWallet.end()) {
         it->second.fInMempool = false;
     }
 }
 
 void CWallet::BlockConnected(
     const CBlock &block, const std::vector<CTransactionRef> &vtxConflicted) {
     const BlockHash &block_hash = block.GetHash();
     auto locked_chain = chain().lock();
     LOCK(cs_wallet);
 
     // TODO: Temporarily ensure that mempool removals are notified before
     // connected transactions. This shouldn't matter, but the abandoned state of
     // transactions in our wallet is currently cleared when we receive another
     // notification and there is a race condition where notification of a
     // connected conflict might cause an outside process to abandon a
     // transaction and then have it inadvertently cleared by the notification
     // that the conflicted transaction was evicted.
     for (const CTransactionRef &ptx : vtxConflicted) {
         SyncTransaction(ptx, BlockHash(), 0 /* position in block */);
         TransactionRemovedFromMempool(ptx);
     }
 
     for (size_t i = 0; i < block.vtx.size(); i++) {
         SyncTransaction(block.vtx[i], block_hash, i);
         TransactionRemovedFromMempool(block.vtx[i]);
     }
 
     m_last_block_processed = block_hash;
 }
 
 void CWallet::BlockDisconnected(const CBlock &block) {
     auto locked_chain = chain().lock();
     LOCK(cs_wallet);
 
     for (const CTransactionRef &ptx : block.vtx) {
         SyncTransaction(ptx, BlockHash(), 0 /* position in block */);
     }
 }
 
 void CWallet::UpdatedBlockTip() {
     m_best_block_time = GetTime();
 }
 
 void CWallet::BlockUntilSyncedToCurrentChain() {
     AssertLockNotHeld(cs_wallet);
     // Skip the queue-draining stuff if we know we're caught up with
     // chainActive.Tip(), otherwise put a callback in the validation interface
     // queue and wait for the queue to drain enough to execute it (indicating we
     // are caught up at least with the time we entered this function).
     const BlockHash last_block_hash =
         WITH_LOCK(cs_wallet, return m_last_block_processed);
     chain().waitForNotificationsIfNewBlocksConnected(last_block_hash);
 }
 
 isminetype CWallet::IsMine(const CTxIn &txin) const {
     LOCK(cs_wallet);
     std::map<TxId, CWalletTx>::const_iterator mi =
         mapWallet.find(txin.prevout.GetTxId());
     if (mi != mapWallet.end()) {
         const CWalletTx &prev = (*mi).second;
         if (txin.prevout.GetN() < prev.tx->vout.size()) {
             return IsMine(prev.tx->vout[txin.prevout.GetN()]);
         }
     }
 
     return ISMINE_NO;
 }
 
 // Note that this function doesn't distinguish between a 0-valued input, and a
 // not-"is mine" (according to the filter) input.
 Amount CWallet::GetDebit(const CTxIn &txin, const isminefilter &filter) const {
     LOCK(cs_wallet);
     std::map<TxId, CWalletTx>::const_iterator mi =
         mapWallet.find(txin.prevout.GetTxId());
     if (mi != mapWallet.end()) {
         const CWalletTx &prev = (*mi).second;
         if (txin.prevout.GetN() < prev.tx->vout.size()) {
             if (IsMine(prev.tx->vout[txin.prevout.GetN()]) & filter) {
                 return prev.tx->vout[txin.prevout.GetN()].nValue;
             }
         }
     }
 
     return Amount::zero();
 }
 
 isminetype CWallet::IsMine(const CTxOut &txout) const {
     return ::IsMine(*this, txout.scriptPubKey);
 }
 
 Amount CWallet::GetCredit(const CTxOut &txout,
                           const isminefilter &filter) const {
     if (!MoneyRange(txout.nValue)) {
         throw std::runtime_error(std::string(__func__) +
                                  ": value out of range");
     }
 
     return (IsMine(txout) & filter) ? txout.nValue : Amount::zero();
 }
 
 bool CWallet::IsChange(const CTxOut &txout) const {
     return IsChange(txout.scriptPubKey);
 }
 
 bool CWallet::IsChange(const CScript &script) const {
     // TODO: fix handling of 'change' outputs. The assumption is that any
     // payment to a script that is ours, but is not in the address book is
     // change. That assumption is likely to break when we implement
     // multisignature wallets that return change back into a
     // multi-signature-protected address; a better way of identifying which
     // outputs are 'the send' and which are 'the change' will need to be
     // implemented (maybe extend CWalletTx to remember which output, if any, was
     // change).
     if (::IsMine(*this, script)) {
         CTxDestination address;
         if (!ExtractDestination(script, address)) {
             return true;
         }
 
         LOCK(cs_wallet);
         if (!mapAddressBook.count(address)) {
             return true;
         }
     }
 
     return false;
 }
 
 Amount CWallet::GetChange(const CTxOut &txout) const {
     if (!MoneyRange(txout.nValue)) {
         throw std::runtime_error(std::string(__func__) +
                                  ": value out of range");
     }
 
     return (IsChange(txout) ? txout.nValue : Amount::zero());
 }
 
 bool CWallet::IsMine(const CTransaction &tx) const {
     for (const CTxOut &txout : tx.vout) {
         if (IsMine(txout)) {
             return true;
         }
     }
 
     return false;
 }
 
 bool CWallet::IsFromMe(const CTransaction &tx) const {
     return GetDebit(tx, ISMINE_ALL) > Amount::zero();
 }
 
 Amount CWallet::GetDebit(const CTransaction &tx,
                          const isminefilter &filter) const {
     Amount nDebit = Amount::zero();
     for (const CTxIn &txin : tx.vin) {
         nDebit += GetDebit(txin, filter);
         if (!MoneyRange(nDebit)) {
             throw std::runtime_error(std::string(__func__) +
                                      ": value out of range");
         }
     }
 
     return nDebit;
 }
 
 bool CWallet::IsAllFromMe(const CTransaction &tx,
                           const isminefilter &filter) const {
     LOCK(cs_wallet);
 
     for (const CTxIn &txin : tx.vin) {
         auto mi = mapWallet.find(txin.prevout.GetTxId());
         if (mi == mapWallet.end()) {
             // Any unknown inputs can't be from us.
             return false;
         }
 
         const CWalletTx &prev = (*mi).second;
 
         if (txin.prevout.GetN() >= prev.tx->vout.size()) {
             // Invalid input!
             return false;
         }
 
         if (!(IsMine(prev.tx->vout[txin.prevout.GetN()]) & filter)) {
             return false;
         }
     }
 
     return true;
 }
 
 Amount CWallet::GetCredit(const CTransaction &tx,
                           const isminefilter &filter) const {
     Amount nCredit = Amount::zero();
     for (const CTxOut &txout : tx.vout) {
         nCredit += GetCredit(txout, filter);
         if (!MoneyRange(nCredit)) {
             throw std::runtime_error(std::string(__func__) +
                                      ": value out of range");
         }
     }
 
     return nCredit;
 }
 
 Amount CWallet::GetChange(const CTransaction &tx) const {
     Amount nChange = Amount::zero();
     for (const CTxOut &txout : tx.vout) {
         nChange += GetChange(txout);
         if (!MoneyRange(nChange)) {
             throw std::runtime_error(std::string(__func__) +
                                      ": value out of range");
         }
     }
 
     return nChange;
 }
 
 CPubKey CWallet::GenerateNewSeed() {
     assert(!IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS));
     CKey key;
     key.MakeNewKey(true);
     return DeriveNewSeed(key);
 }
 
 CPubKey CWallet::DeriveNewSeed(const CKey &key) {
     int64_t nCreationTime = GetTime();
     CKeyMetadata metadata(nCreationTime);
 
     // Calculate the seed
     CPubKey seed = key.GetPubKey();
     assert(key.VerifyPubKey(seed));
 
     // Set the hd keypath to "s" -> Seed, refers the seed to itself
     metadata.hdKeypath = "s";
     metadata.has_key_origin = false;
     metadata.hd_seed_id = seed.GetID();
 
     LOCK(cs_wallet);
 
     // mem store the metadata
     mapKeyMetadata[seed.GetID()] = metadata;
 
     // Write the key&metadata to the database
     if (!AddKeyPubKey(key, seed)) {
         throw std::runtime_error(std::string(__func__) +
                                  ": AddKeyPubKey failed");
     }
 
     return seed;
 }
 
 void CWallet::SetHDSeed(const CPubKey &seed) {
     LOCK(cs_wallet);
 
     // Store the keyid (hash160) together with the child index counter in the
     // database as a hdchain object.
     CHDChain newHdChain;
     newHdChain.nVersion = CanSupportFeature(FEATURE_HD_SPLIT)
                               ? CHDChain::VERSION_HD_CHAIN_SPLIT
                               : CHDChain::VERSION_HD_BASE;
     newHdChain.seed_id = seed.GetID();
     SetHDChain(newHdChain, false);
     NotifyCanGetAddressesChanged();
     UnsetWalletFlag(WALLET_FLAG_BLANK_WALLET);
 }
 
 void CWallet::SetHDChain(const CHDChain &chain, bool memonly) {
     LOCK(cs_wallet);
     if (!memonly && !WalletBatch(*database).WriteHDChain(chain)) {
         throw std::runtime_error(std::string(__func__) +
                                  ": writing chain failed");
     }
 
     hdChain = chain;
 }
 
 bool CWallet::IsHDEnabled() const {
     return !hdChain.seed_id.IsNull();
 }
 
 bool CWallet::CanGenerateKeys() {
     // A wallet can generate keys if it has an HD seed (IsHDEnabled) or it is a
     // non-HD wallet (pre FEATURE_HD)
     LOCK(cs_wallet);
     return IsHDEnabled() || !CanSupportFeature(FEATURE_HD);
 }
 
 bool CWallet::CanGetAddresses(bool internal) {
     LOCK(cs_wallet);
     // Check if the keypool has keys
     bool keypool_has_keys;
     if (internal && CanSupportFeature(FEATURE_HD_SPLIT)) {
         keypool_has_keys = setInternalKeyPool.size() > 0;
     } else {
         keypool_has_keys = KeypoolCountExternalKeys() > 0;
     }
     // If the keypool doesn't have keys, check if we can generate them
     if (!keypool_has_keys) {
         return CanGenerateKeys();
     }
     return keypool_has_keys;
 }
 
 void CWallet::SetWalletFlag(uint64_t flags) {
     LOCK(cs_wallet);
     m_wallet_flags |= flags;
     if (!WalletBatch(*database).WriteWalletFlags(m_wallet_flags)) {
         throw std::runtime_error(std::string(__func__) +
                                  ": writing wallet flags failed");
     }
 }
 
 void CWallet::UnsetWalletFlag(uint64_t flag) {
     LOCK(cs_wallet);
     m_wallet_flags &= ~flag;
     if (!WalletBatch(*database).WriteWalletFlags(m_wallet_flags)) {
         throw std::runtime_error(std::string(__func__) +
                                  ": writing wallet flags failed");
     }
 }
 
 bool CWallet::IsWalletFlagSet(uint64_t flag) {
     return (m_wallet_flags & flag);
 }
 
 bool CWallet::SetWalletFlags(uint64_t overwriteFlags, bool memonly) {
     LOCK(cs_wallet);
     m_wallet_flags = overwriteFlags;
     if (((overwriteFlags & g_known_wallet_flags) >> 32) ^
         (overwriteFlags >> 32)) {
         // contains unknown non-tolerable wallet flags
         return false;
     }
     if (!memonly && !WalletBatch(*database).WriteWalletFlags(m_wallet_flags)) {
         throw std::runtime_error(std::string(__func__) +
                                  ": writing wallet flags failed");
     }
 
     return true;
 }
 
 int64_t CWalletTx::GetTxTime() const {
     int64_t n = nTimeSmart;
     return n ? n : nTimeReceived;
 }
 
 // Helper for producing a max-sized low-S low-R signature (eg 71 bytes)
 // or a max-sized low-S signature (e.g. 72 bytes) if use_max_sig is true
 bool CWallet::DummySignInput(CTxIn &tx_in, const CTxOut &txout,
                              bool use_max_sig) const {
     // Fill in dummy signatures for fee calculation.
     const CScript &scriptPubKey = txout.scriptPubKey;
     SignatureData sigdata;
 
     if (!ProduceSignature(*this,
                           use_max_sig ? DUMMY_MAXIMUM_SIGNATURE_CREATOR
                                       : DUMMY_SIGNATURE_CREATOR,
                           scriptPubKey, sigdata)) {
         return false;
     }
 
     UpdateInput(tx_in, sigdata);
     return true;
 }
 
 // Helper for producing a bunch of max-sized low-S low-R signatures (eg 71
 // bytes)
 bool CWallet::DummySignTx(CMutableTransaction &txNew,
                           const std::vector<CTxOut> &txouts,
                           bool use_max_sig) const {
     // Fill in dummy signatures for fee calculation.
     int nIn = 0;
     for (const auto &txout : txouts) {
         if (!DummySignInput(txNew.vin[nIn], txout, use_max_sig)) {
             return false;
         }
 
         nIn++;
     }
     return true;
 }
 
 int64_t CalculateMaximumSignedTxSize(const CTransaction &tx,
                                      const CWallet *wallet, bool use_max_sig) {
     std::vector<CTxOut> txouts;
     // Look up the inputs.  We should have already checked that this transaction
     // IsAllFromMe(ISMINE_SPENDABLE), so every input should already be in our
     // wallet, with a valid index into the vout array, and the ability to sign.
     for (auto &input : tx.vin) {
         const auto mi = wallet->mapWallet.find(input.prevout.GetTxId());
         if (mi == wallet->mapWallet.end()) {
             return -1;
         }
         assert(input.prevout.GetN() < mi->second.tx->vout.size());
         txouts.emplace_back(mi->second.tx->vout[input.prevout.GetN()]);
     }
     return CalculateMaximumSignedTxSize(tx, wallet, txouts, use_max_sig);
 }
 
 // txouts needs to be in the order of tx.vin
 int64_t CalculateMaximumSignedTxSize(const CTransaction &tx,
                                      const CWallet *wallet,
                                      const std::vector<CTxOut> &txouts,
                                      bool use_max_sig) {
     CMutableTransaction txNew(tx);
     if (!wallet->DummySignTx(txNew, txouts, use_max_sig)) {
         // This should never happen, because IsAllFromMe(ISMINE_SPENDABLE)
         // implies that we can sign for every input.
         return -1;
     }
     return GetSerializeSize(txNew, PROTOCOL_VERSION);
 }
 
 int CalculateMaximumSignedInputSize(const CTxOut &txout, const CWallet *wallet,
                                     bool use_max_sig) {
     CMutableTransaction txn;
     txn.vin.push_back(CTxIn(COutPoint()));
     if (!wallet->DummySignInput(txn.vin[0], txout, use_max_sig)) {
         // This should never happen, because IsAllFromMe(ISMINE_SPENDABLE)
         // implies that we can sign for every input.
         return -1;
     }
     return GetSerializeSize(txn.vin[0], PROTOCOL_VERSION);
 }
 
 void CWalletTx::GetAmounts(std::list<COutputEntry> &listReceived,
                            std::list<COutputEntry> &listSent, Amount &nFee,
                            const isminefilter &filter) const {
     nFee = Amount::zero();
     listReceived.clear();
     listSent.clear();
 
     // Compute fee:
     Amount nDebit = GetDebit(filter);
     // debit>0 means we signed/sent this transaction.
     if (nDebit > Amount::zero()) {
         Amount nValueOut = tx->GetValueOut();
         nFee = (nDebit - nValueOut);
     }
 
     // Sent/received.
     for (unsigned int i = 0; i < tx->vout.size(); ++i) {
         const CTxOut &txout = tx->vout[i];
         isminetype fIsMine = pwallet->IsMine(txout);
         // Only need to handle txouts if AT LEAST one of these is true:
         //   1) they debit from us (sent)
         //   2) the output is to us (received)
         if (nDebit > Amount::zero()) {
             // Don't report 'change' txouts
             if (pwallet->IsChange(txout)) {
                 continue;
             }
         } else if (!(fIsMine & filter)) {
             continue;
         }
 
         // In either case, we need to get the destination address.
         CTxDestination address;
 
         if (!ExtractDestination(txout.scriptPubKey, address) &&
             !txout.scriptPubKey.IsUnspendable()) {
             pwallet->WalletLogPrintf("CWalletTx::GetAmounts: Unknown "
                                      "transaction type found, txid %s\n",
                                      this->GetId().ToString());
             address = CNoDestination();
         }
 
         COutputEntry output = {address, txout.nValue, (int)i};
 
         // If we are debited by the transaction, add the output as a "sent"
         // entry.
         if (nDebit > Amount::zero()) {
             listSent.push_back(output);
         }
 
         // If we are receiving the output, add it as a "received" entry.
         if (fIsMine & filter) {
             listReceived.push_back(output);
         }
     }
 }
 
 /**
  * Scan active chain for relevant transactions after importing keys. This should
  * be called whenever new keys are added to the wallet, with the oldest key
  * creation time.
  *
  * @return Earliest timestamp that could be successfully scanned from. Timestamp
  * returned will be higher than startTime if relevant blocks could not be read.
  */
 int64_t CWallet::RescanFromTime(int64_t startTime,
                                 const WalletRescanReserver &reserver,
                                 bool update) {
     // Find starting block. May be null if nCreateTime is greater than the
     // highest blockchain timestamp, in which case there is nothing that needs
     // to be scanned.
     BlockHash start_block;
     {
         auto locked_chain = chain().lock();
         const Optional<int> start_height =
             locked_chain->findFirstBlockWithTimeAndHeight(
                 startTime - TIMESTAMP_WINDOW, 0, &start_block);
         const Optional<int> tip_height = locked_chain->getHeight();
         WalletLogPrintf(
             "%s: Rescanning last %i blocks\n", __func__,
             tip_height && start_height ? *tip_height - *start_height + 1 : 0);
     }
 
     if (!start_block.IsNull()) {
         // TODO: this should take into account failure by ScanResult::USER_ABORT
         ScanResult result = ScanForWalletTransactions(start_block, BlockHash(),
                                                       reserver, update);
         if (result.status == ScanResult::FAILURE) {
             int64_t time_max;
             if (!chain().findBlock(result.last_failed_block,
                                    nullptr /* block */, nullptr /* time */,
                                    &time_max)) {
                 throw std::logic_error(
                     "ScanForWalletTransactions returned invalid block hash");
             }
             return time_max + TIMESTAMP_WINDOW + 1;
         }
     }
     return startTime;
 }
 
 /**
  * Scan the block chain (starting in start_block) for transactions from or to
  * us. If fUpdate is true, found transactions that already exist in the wallet
  * will be updated.
  *
  * @param[in] start_block Scan starting block. If block is not on the active
  *                        chain, the scan will return SUCCESS immediately.
  * @param[in] stop_block  Scan ending block. If block is not on the active
  *                        chain, the scan will continue until it reaches the
  *                        chain tip.
  *
  * @return ScanResult returning scan information and indicating success or
  *         failure. Return status will be set to SUCCESS if scan was
  *         successful. FAILURE if a complete rescan was not possible (due to
  *         pruning or corruption). USER_ABORT if the rescan was aborted before
  *         it could complete.
  *
  * @pre Caller needs to make sure start_block (and the optional stop_block) are
  * on the main chain after to the addition of any new keys you want to detect
  * transactions for.
  */
 CWallet::ScanResult CWallet::ScanForWalletTransactions(
     const BlockHash &start_block, const BlockHash &stop_block,
     const WalletRescanReserver &reserver, bool fUpdate) {
     int64_t nNow = GetTime();
 
     assert(reserver.isReserved());
 
     BlockHash block_hash = start_block;
     ScanResult result;
 
     WalletLogPrintf("Rescan started from block %s...\n",
                     start_block.ToString());
 
     {
         fAbortRescan = false;
 
         // Show rescan progress in GUI as dialog or on splashscreen, if -rescan
         // on startup.
         ShowProgress(
             strprintf("%s " + _("Rescanning...").translated, GetDisplayName()),
             0);
         BlockHash tip_hash;
         // The way the 'block_height' is initialized is just a workaround for
         // the gcc bug #47679 since version 4.6.0.
         Optional<int> block_height = MakeOptional(false, int());
         double progress_begin;
         double progress_end;
         {
             auto locked_chain = chain().lock();
             if (Optional<int> tip_height = locked_chain->getHeight()) {
                 tip_hash = locked_chain->getBlockHash(*tip_height);
             }
             block_height = locked_chain->getBlockHeight(block_hash);
             progress_begin = chain().guessVerificationProgress(block_hash);
             progress_end = chain().guessVerificationProgress(
                 stop_block.IsNull() ? tip_hash : stop_block);
         }
         double progress_current = progress_begin;
         while (block_height && !fAbortRescan && !chain().shutdownRequested()) {
             if (*block_height % 100 == 0 &&
                 progress_end - progress_begin > 0.0) {
                 ShowProgress(
                     strprintf("%s " + _("Rescanning...").translated,
                               GetDisplayName()),
                     std::max(
                         1,
                         std::min(99, (int)((progress_current - progress_begin) /
                                            (progress_end - progress_begin) *
                                            100))));
             }
             if (GetTime() >= nNow + 60) {
                 nNow = GetTime();
                 WalletLogPrintf("Still rescanning. At block %d. Progress=%f\n",
                                 *block_height, progress_current);
             }
 
             CBlock block;
             if (chain().findBlock(block_hash, &block) && !block.IsNull()) {
                 auto locked_chain = chain().lock();
                 LOCK(cs_wallet);
                 if (!locked_chain->getBlockHeight(block_hash)) {
                     // Abort scan if current block is no longer active, to
                     // prevent marking transactions as coming from the wrong
                     // block.
                     // TODO: This should return success instead of failure, see
                     // https://github.com/bitcoin/bitcoin/pull/14711#issuecomment-458342518
                     result.last_failed_block = block_hash;
                     result.status = ScanResult::FAILURE;
                     break;
                 }
                 for (size_t posInBlock = 0; posInBlock < block.vtx.size();
                      ++posInBlock) {
                     SyncTransaction(block.vtx[posInBlock], block_hash,
                                     posInBlock, fUpdate);
                 }
                 // scan succeeded, record block as most recent successfully
                 // scanned
                 result.last_scanned_block = block_hash;
                 result.last_scanned_height = *block_height;
             } else {
                 // could not scan block, keep scanning but record this block as
                 // the most recent failure
                 result.last_failed_block = block_hash;
                 result.status = ScanResult::FAILURE;
             }
             if (block_hash == stop_block) {
                 break;
             }
             {
                 auto locked_chain = chain().lock();
                 Optional<int> tip_height = locked_chain->getHeight();
                 if (!tip_height || *tip_height <= block_height ||
                     !locked_chain->getBlockHeight(block_hash)) {
                     // break successfully when rescan has reached the tip, or
                     // previous block is no longer on the chain due to a reorg
                     break;
                 }
 
                 // increment block and verification progress
                 block_hash = locked_chain->getBlockHash(++*block_height);
                 progress_current =
                     chain().guessVerificationProgress(block_hash);
 
                 // handle updated tip hash
                 const BlockHash prev_tip_hash = tip_hash;
                 tip_hash = locked_chain->getBlockHash(*tip_height);
                 if (stop_block.IsNull() && prev_tip_hash != tip_hash) {
                     // in case the tip has changed, update progress max
                     progress_end = chain().guessVerificationProgress(tip_hash);
                 }
             }
         }
 
         // Hide progress dialog in GUI.
         ShowProgress(
             strprintf("%s " + _("Rescanning...").translated, GetDisplayName()),
             100);
         if (block_height && fAbortRescan) {
             WalletLogPrintf("Rescan aborted at block %d. Progress=%f\n",
                             *block_height, progress_current);
             result.status = ScanResult::USER_ABORT;
         } else if (block_height && chain().shutdownRequested()) {
             WalletLogPrintf("Rescan interrupted by shutdown request at block "
                             "%d. Progress=%f\n",
                             *block_height, progress_current);
             result.status = ScanResult::USER_ABORT;
         }
     }
 
     return result;
 }
 
 void CWallet::ReacceptWalletTransactions(
     interfaces::Chain::Lock &locked_chain) {
     // If transactions aren't being broadcasted, don't let them into local
     // mempool either.
     if (!fBroadcastTransactions) {
         return;
     }
 
     std::map<int64_t, CWalletTx *> mapSorted;
 
     // Sort pending wallet transactions based on their initial wallet insertion
     // order.
     for (std::pair<const TxId, CWalletTx> &item : mapWallet) {
         const TxId &wtxid = item.first;
         CWalletTx &wtx = item.second;
         assert(wtx.GetId() == wtxid);
 
         int nDepth = wtx.GetDepthInMainChain(locked_chain);
 
         if (!wtx.IsCoinBase() && (nDepth == 0 && !wtx.isAbandoned())) {
             mapSorted.insert(std::make_pair(wtx.nOrderPos, &wtx));
         }
     }
 
     // Try to add wallet transactions to memory pool.
     for (const std::pair<const int64_t, CWalletTx *> &item : mapSorted) {
         CWalletTx &wtx = *(item.second);
         CValidationState state;
         wtx.AcceptToMemoryPool(locked_chain, state);
     }
 }
 
 bool CWalletTx::RelayWalletTransaction(interfaces::Chain::Lock &locked_chain) {
     assert(pwallet->GetBroadcastTransactions());
     if (IsCoinBase() || isAbandoned() ||
         GetDepthInMainChain(locked_chain) != 0) {
         return false;
     }
 
     CValidationState state;
     // GetDepthInMainChain already catches known conflicts.
     if (InMempool() || AcceptToMemoryPool(locked_chain, state)) {
         pwallet->WalletLogPrintf("Relaying wtx %s\n", GetId().ToString());
         if (pwallet->chain().p2pEnabled()) {
             pwallet->chain().relayTransaction(GetId());
             return true;
         }
     }
 
     return false;
 }
 
 std::set<TxId> CWalletTx::GetConflicts() const {
     std::set<TxId> result;
     if (pwallet != nullptr) {
         const TxId &txid = GetId();
         result = pwallet->GetConflicts(txid);
         result.erase(txid);
     }
 
     return result;
 }
 
 Amount CWalletTx::GetDebit(const isminefilter &filter) const {
     if (tx->vin.empty()) {
         return Amount::zero();
     }
 
     Amount debit = Amount::zero();
     if (filter & ISMINE_SPENDABLE) {
         if (fDebitCached) {
             debit += nDebitCached;
         } else {
             nDebitCached = pwallet->GetDebit(*tx, ISMINE_SPENDABLE);
             fDebitCached = true;
             debit += nDebitCached;
         }
     }
 
     if (filter & ISMINE_WATCH_ONLY) {
         if (fWatchDebitCached) {
             debit += nWatchDebitCached;
         } else {
             nWatchDebitCached = pwallet->GetDebit(*tx, ISMINE_WATCH_ONLY);
             fWatchDebitCached = true;
             debit += Amount(nWatchDebitCached);
         }
     }
 
     return debit;
 }
 
 Amount CWalletTx::GetCredit(interfaces::Chain::Lock &locked_chain,
                             const isminefilter &filter) const {
     // Must wait until coinbase is safely deep enough in the chain before
     // valuing it.
     if (IsImmatureCoinBase(locked_chain)) {
         return Amount::zero();
     }
 
     Amount credit = Amount::zero();
     if (filter & ISMINE_SPENDABLE) {
         // GetBalance can assume transactions in mapWallet won't change.
         if (fCreditCached) {
             credit += nCreditCached;
         } else {
             nCreditCached = pwallet->GetCredit(*tx, ISMINE_SPENDABLE);
             fCreditCached = true;
             credit += nCreditCached;
         }
     }
 
     if (filter & ISMINE_WATCH_ONLY) {
         if (fWatchCreditCached) {
             credit += nWatchCreditCached;
         } else {
             nWatchCreditCached = pwallet->GetCredit(*tx, ISMINE_WATCH_ONLY);
             fWatchCreditCached = true;
             credit += nWatchCreditCached;
         }
     }
 
     return credit;
 }
 
 Amount CWalletTx::GetImmatureCredit(interfaces::Chain::Lock &locked_chain,
                                     bool fUseCache) const {
     if (IsImmatureCoinBase(locked_chain) && IsInMainChain(locked_chain)) {
         if (fUseCache && fImmatureCreditCached) {
             return nImmatureCreditCached;
         }
 
         nImmatureCreditCached = pwallet->GetCredit(*tx, ISMINE_SPENDABLE);
         fImmatureCreditCached = true;
         return nImmatureCreditCached;
     }
 
     return Amount::zero();
 }
 
 Amount CWalletTx::GetAvailableCredit(interfaces::Chain::Lock &locked_chain,
                                      bool fUseCache,
                                      const isminefilter &filter) const {
     if (pwallet == nullptr) {
         return Amount::zero();
     }
 
     // Must wait until coinbase is safely deep enough in the chain before
     // valuing it.
     if (IsImmatureCoinBase(locked_chain)) {
         return Amount::zero();
     }
 
     Amount *cache = nullptr;
     bool *cache_used = nullptr;
 
     if (filter == ISMINE_SPENDABLE) {
         cache = &nAvailableCreditCached;
         cache_used = &fAvailableCreditCached;
     } else if (filter == ISMINE_WATCH_ONLY) {
         cache = &nAvailableWatchCreditCached;
         cache_used = &fAvailableWatchCreditCached;
     }
 
     if (fUseCache && cache_used && *cache_used) {
         return *cache;
     }
 
     Amount nCredit = Amount::zero();
     const TxId &txid = GetId();
     for (uint32_t i = 0; i < tx->vout.size(); i++) {
         if (!pwallet->IsSpent(locked_chain, COutPoint(txid, i))) {
             const CTxOut &txout = tx->vout[i];
             nCredit += pwallet->GetCredit(txout, filter);
             if (!MoneyRange(nCredit)) {
                 throw std::runtime_error(std::string(__func__) +
                                          " : value out of range");
             }
         }
     }
 
     if (cache) {
         *cache = nCredit;
         *cache_used = true;
     }
     return nCredit;
 }
 
 Amount
 CWalletTx::GetImmatureWatchOnlyCredit(interfaces::Chain::Lock &locked_chain,
                                       const bool fUseCache) const {
     if (IsImmatureCoinBase(locked_chain) && IsInMainChain(locked_chain)) {
         if (fUseCache && fImmatureWatchCreditCached) {
             return nImmatureWatchCreditCached;
         }
 
         nImmatureWatchCreditCached = pwallet->GetCredit(*tx, ISMINE_WATCH_ONLY);
         fImmatureWatchCreditCached = true;
         return nImmatureWatchCreditCached;
     }
 
     return Amount::zero();
 }
 
 Amount CWalletTx::GetChange() const {
     if (fChangeCached) {
         return nChangeCached;
     }
 
     nChangeCached = pwallet->GetChange(*tx);
     fChangeCached = true;
     return nChangeCached;
 }
 
 bool CWalletTx::InMempool() const {
     return fInMempool;
 }
 
 bool CWalletTx::IsTrusted(interfaces::Chain::Lock &locked_chain) const {
     // Quick answer in most cases
     CValidationState state;
     if (!locked_chain.contextualCheckTransactionForCurrentBlock(
             Params().GetConsensus(), *tx, state)) {
         return false;
     }
 
     int nDepth = GetDepthInMainChain(locked_chain);
     if (nDepth >= 1) {
         return true;
     }
 
     if (nDepth < 0) {
         return false;
     }
 
     // using wtx's cached debit
     if (!pwallet->m_spend_zero_conf_change || !IsFromMe(ISMINE_ALL)) {
         return false;
     }
 
     // Don't trust unconfirmed transactions from us unless they are in the
     // mempool.
     if (!InMempool()) {
         return false;
     }
 
     // Trusted if all inputs are from us and are in the mempool:
     for (const CTxIn &txin : tx->vin) {
         // Transactions not sent by us: not trusted
         const CWalletTx *parent = pwallet->GetWalletTx(txin.prevout.GetTxId());
         if (parent == nullptr) {
             return false;
         }
 
         const CTxOut &parentOut = parent->tx->vout[txin.prevout.GetN()];
         if (pwallet->IsMine(parentOut) != ISMINE_SPENDABLE) {
             return false;
         }
     }
 
     return true;
 }
 
 bool CWalletTx::IsEquivalentTo(const CWalletTx &_tx) const {
     CMutableTransaction tx1{*this->tx};
     CMutableTransaction tx2{*_tx.tx};
     for (auto &txin : tx1.vin) {
         txin.scriptSig = CScript();
     }
 
     for (auto &txin : tx2.vin) {
         txin.scriptSig = CScript();
     }
 
     return CTransaction(tx1) == CTransaction(tx2);
 }
 
 // Rebroadcast transactions from the wallet. We do this on a random timer
 // to slightly obfuscate which transactions come from our wallet.
 //
 // Ideally, we'd only resend transactions that we think should have been
 // mined in the most recent block. Any transaction that wasn't in the top
 // blockweight of transactions in the mempool shouldn't have been mined,
 // and so is probably just sitting in the mempool waiting to be confirmed.
 // Rebroadcasting does nothing to speed up confirmation and only damages
 // privacy.
 void CWallet::ResendWalletTransactions() {
     // During reindex, importing and IBD, old wallet transactions become
     // unconfirmed. Don't resend them as that would spam other nodes.
     if (!chain().isReadyToBroadcast()) {
         return;
     }
 
     // Do this infrequently and randomly to avoid giving away that these are our
     // transactions.
     if (GetTime() < nNextResend || !fBroadcastTransactions) {
         return;
     }
 
     bool fFirst = (nNextResend == 0);
     nNextResend = GetTime() + GetRand(30 * 60);
     if (fFirst) {
         return;
     }
 
     // Only do it if there's been a new block since last time
     if (m_best_block_time < nLastResend) {
         return;
     }
 
     nLastResend = GetTime();
 
     int relayed_tx_count = 0;
 
     { // locked_chain and cs_wallet scope
         auto locked_chain = chain().lock();
         LOCK(cs_wallet);
 
         // Relay transactions
         for (std::pair<const TxId, CWalletTx> &item : mapWallet) {
             CWalletTx &wtx = item.second;
             // only rebroadcast unconfirmed txes older than 5 minutes before the
             // last block was found
             if (wtx.nTimeReceived > m_best_block_time - 5 * 60) {
                 continue;
             }
             if (wtx.RelayWalletTransaction(*locked_chain)) {
                 ++relayed_tx_count;
             }
         }
     } // locked_chain and cs_wallet
 
     if (relayed_tx_count > 0) {
         WalletLogPrintf("%s: rebroadcast %u unconfirmed transactions\n",
                         __func__, relayed_tx_count);
     }
 }
 
 /** @} */ // end of mapWallet
 
 void MaybeResendWalletTxs() {
     for (const std::shared_ptr<CWallet> &pwallet : GetWallets()) {
         pwallet->ResendWalletTransactions();
     }
 }
 
 /**
  * @defgroup Actions
  *
  * @{
  */
 CWallet::Balance CWallet::GetBalance(const int min_depth) const {
     Balance ret;
     auto locked_chain = chain().lock();
     LOCK(cs_wallet);
     for (const auto &entry : mapWallet) {
         const CWalletTx &wtx = entry.second;
         const bool is_trusted{wtx.IsTrusted(*locked_chain)};
         const int tx_depth{wtx.GetDepthInMainChain(*locked_chain)};
         const Amount tx_credit_mine{wtx.GetAvailableCredit(
             *locked_chain, /* fUseCache */ true, ISMINE_SPENDABLE)};
         const Amount tx_credit_watchonly{wtx.GetAvailableCredit(
             *locked_chain, /* fUseCache */ true, ISMINE_WATCH_ONLY)};
         if (is_trusted && tx_depth >= min_depth) {
             ret.m_mine_trusted += tx_credit_mine;
             ret.m_watchonly_trusted += tx_credit_watchonly;
         }
         if (!is_trusted && tx_depth == 0 && wtx.InMempool()) {
             ret.m_mine_untrusted_pending += tx_credit_mine;
             ret.m_watchonly_untrusted_pending += tx_credit_watchonly;
         }
         ret.m_mine_immature += wtx.GetImmatureCredit(*locked_chain);
         ret.m_watchonly_immature +=
             wtx.GetImmatureWatchOnlyCredit(*locked_chain);
     }
     return ret;
 }
 
 Amount CWallet::GetAvailableBalance(const CCoinControl *coinControl) const {
     auto locked_chain = chain().lock();
     LOCK(cs_wallet);
 
     Amount balance = Amount::zero();
     std::vector<COutput> vCoins;
     AvailableCoins(*locked_chain, vCoins, true, coinControl);
     for (const COutput &out : vCoins) {
         if (out.fSpendable) {
             balance += out.tx->tx->vout[out.i].nValue;
         }
     }
     return balance;
 }
 
 void CWallet::AvailableCoins(interfaces::Chain::Lock &locked_chain,
                              std::vector<COutput> &vCoins, bool fOnlySafe,
                              const CCoinControl *coinControl,
                              const Amount nMinimumAmount,
                              const Amount nMaximumAmount,
                              const Amount nMinimumSumAmount,
                              const uint64_t nMaximumCount, const int nMinDepth,
                              const int nMaxDepth) const {
     AssertLockHeld(cs_wallet);
 
     vCoins.clear();
     Amount nTotal = Amount::zero();
 
     const Consensus::Params params = Params().GetConsensus();
 
     for (const auto &entry : mapWallet) {
         const TxId &wtxid = entry.first;
         const CWalletTx &wtx = entry.second;
 
         CValidationState state;
         if (!locked_chain.contextualCheckTransactionForCurrentBlock(
                 params, *wtx.tx, state)) {
             continue;
         }
 
         if (wtx.IsImmatureCoinBase(locked_chain)) {
             continue;
         }
 
         int nDepth = wtx.GetDepthInMainChain(locked_chain);
         if (nDepth < 0) {
             continue;
         }
 
         // We should not consider coins which aren't at least in our mempool.
         // It's possible for these to be conflicted via ancestors which we may
         // never be able to detect.
         if (nDepth == 0 && !wtx.InMempool()) {
             continue;
         }
 
         bool safeTx = wtx.IsTrusted(locked_chain);
 
         // Bitcoin-ABC: Removed check that prevents consideration of coins from
         // transactions that are replacing other transactions. This check based
         // on wtx.mapValue.count("replaces_txid") which was not being set
         // anywhere.
 
         // Similarly, we should not consider coins from transactions that have
         // been replaced. In the example above, we would want to prevent
         // creation of a transaction A' spending an output of A, because if
         // transaction B were initially confirmed, conflicting with A and A', we
         // wouldn't want to the user to create a transaction D intending to
         // replace A', but potentially resulting in a scenario where A, A', and
         // D could all be accepted (instead of just B and D, or just A and A'
         // like the user would want).
 
         // Bitcoin-ABC: retained this check as 'replaced_by_txid' is still set
         // in the wallet code.
         if (nDepth == 0 && wtx.mapValue.count("replaced_by_txid")) {
             safeTx = false;
         }
 
         if (fOnlySafe && !safeTx) {
             continue;
         }
 
         if (nDepth < nMinDepth || nDepth > nMaxDepth) {
             continue;
         }
 
         for (uint32_t i = 0; i < wtx.tx->vout.size(); i++) {
             if (wtx.tx->vout[i].nValue < nMinimumAmount ||
                 wtx.tx->vout[i].nValue > nMaximumAmount) {
                 continue;
             }
 
             const COutPoint outpoint(wtxid, i);
 
             if (coinControl && coinControl->HasSelected() &&
                 !coinControl->fAllowOtherInputs &&
                 !coinControl->IsSelected(outpoint)) {
                 continue;
             }
 
             if (IsLockedCoin(outpoint)) {
                 continue;
             }
 
             if (IsSpent(locked_chain, outpoint)) {
                 continue;
             }
 
             isminetype mine = IsMine(wtx.tx->vout[i]);
 
             if (mine == ISMINE_NO) {
                 continue;
             }
 
             bool solvable = IsSolvable(*this, wtx.tx->vout[i].scriptPubKey);
             bool spendable =
                 ((mine & ISMINE_SPENDABLE) != ISMINE_NO) ||
                 (((mine & ISMINE_WATCH_ONLY) != ISMINE_NO) &&
                  (coinControl && coinControl->fAllowWatchOnly && solvable));
 
             vCoins.push_back(
                 COutput(&wtx, i, nDepth, spendable, solvable, safeTx,
                         (coinControl && coinControl->fAllowWatchOnly)));
 
             // Checks the sum amount of all UTXO's.
             if (nMinimumSumAmount != MAX_MONEY) {
                 nTotal += wtx.tx->vout[i].nValue;
 
                 if (nTotal >= nMinimumSumAmount) {
                     return;
                 }
             }
 
             // Checks the maximum number of UTXO's.
             if (nMaximumCount > 0 && vCoins.size() >= nMaximumCount) {
                 return;
             }
         }
     }
 }
 
 std::map<CTxDestination, std::vector<COutput>>
 CWallet::ListCoins(interfaces::Chain::Lock &locked_chain) const {
     AssertLockHeld(cs_wallet);
 
     std::map<CTxDestination, std::vector<COutput>> result;
     std::vector<COutput> availableCoins;
 
     AvailableCoins(locked_chain, availableCoins);
 
     for (const auto &coin : availableCoins) {
         CTxDestination address;
         if (coin.fSpendable &&
             ExtractDestination(
                 FindNonChangeParentOutput(*coin.tx->tx, coin.i).scriptPubKey,
                 address)) {
             result[address].emplace_back(std::move(coin));
         }
     }
 
     std::vector<COutPoint> lockedCoins;
     ListLockedCoins(lockedCoins);
     for (const auto &output : lockedCoins) {
         auto it = mapWallet.find(output.GetTxId());
         if (it != mapWallet.end()) {
             int depth = it->second.GetDepthInMainChain(locked_chain);
             if (depth >= 0 && output.GetN() < it->second.tx->vout.size() &&
                 IsMine(it->second.tx->vout[output.GetN()]) ==
                     ISMINE_SPENDABLE) {
                 CTxDestination address;
                 if (ExtractDestination(
                         FindNonChangeParentOutput(*it->second.tx, output.GetN())
                             .scriptPubKey,
                         address)) {
                     result[address].emplace_back(
                         &it->second, output.GetN(), depth, true /* spendable */,
                         true /* solvable */, false /* safe */);
                 }
             }
         }
     }
 
     return result;
 }
 
 const CTxOut &CWallet::FindNonChangeParentOutput(const CTransaction &tx,
                                                  int output) const {
     const CTransaction *ptx = &tx;
     int n = output;
     while (IsChange(ptx->vout[n]) && ptx->vin.size() > 0) {
         const COutPoint &prevout = ptx->vin[0].prevout;
         auto it = mapWallet.find(prevout.GetTxId());
         if (it == mapWallet.end() ||
             it->second.tx->vout.size() <= prevout.GetN() ||
             !IsMine(it->second.tx->vout[prevout.GetN()])) {
             break;
         }
         ptx = it->second.tx.get();
         n = prevout.GetN();
     }
     return ptx->vout[n];
 }
 
 bool CWallet::SelectCoinsMinConf(
     const Amount nTargetValue, const CoinEligibilityFilter &eligibility_filter,
     std::vector<OutputGroup> groups, std::set<CInputCoin> &setCoinsRet,
     Amount &nValueRet, const CoinSelectionParams &coin_selection_params,
     bool &bnb_used) const {
     setCoinsRet.clear();
     nValueRet = Amount::zero();
 
     std::vector<OutputGroup> utxo_pool;
     if (coin_selection_params.use_bnb) {
         // Get long term estimate
         CCoinControl temp;
         temp.m_confirm_target = 1008;
         CFeeRate long_term_feerate = GetMinimumFeeRate(*this, temp);
 
         // Calculate cost of change
         Amount cost_of_change =
             dustRelayFee.GetFee(coin_selection_params.change_spend_size) +
             coin_selection_params.effective_fee.GetFee(
                 coin_selection_params.change_output_size);
 
         // Filter by the min conf specs and add to utxo_pool and calculate
         // effective value
         for (OutputGroup &group : groups) {
             if (!group.EligibleForSpending(eligibility_filter)) {
                 continue;
             }
 
             group.fee = Amount::zero();
             group.long_term_fee = Amount::zero();
             group.effective_value = Amount::zero();
             for (auto it = group.m_outputs.begin();
                  it != group.m_outputs.end();) {
                 const CInputCoin &coin = *it;
                 Amount effective_value =
                     coin.txout.nValue -
                     (coin.m_input_bytes < 0
                          ? Amount::zero()
                          : coin_selection_params.effective_fee.GetFee(
                                coin.m_input_bytes));
                 // Only include outputs that are positive effective value (i.e.
                 // not dust)
                 if (effective_value > Amount::zero()) {
                     group.fee +=
                         coin.m_input_bytes < 0
                             ? Amount::zero()
                             : coin_selection_params.effective_fee.GetFee(
                                   coin.m_input_bytes);
                     group.long_term_fee +=
                         coin.m_input_bytes < 0
                             ? Amount::zero()
                             : long_term_feerate.GetFee(coin.m_input_bytes);
                     group.effective_value += effective_value;
                     ++it;
                 } else {
                     it = group.Discard(coin);
                 }
             }
             if (group.effective_value > Amount::zero()) {
                 utxo_pool.push_back(group);
             }
         }
         // Calculate the fees for things that aren't inputs
         Amount not_input_fees = coin_selection_params.effective_fee.GetFee(
             coin_selection_params.tx_noinputs_size);
         bnb_used = true;
         return SelectCoinsBnB(utxo_pool, nTargetValue, cost_of_change,
                               setCoinsRet, nValueRet, not_input_fees);
     } else {
         // Filter by the min conf specs and add to utxo_pool
         for (const OutputGroup &group : groups) {
             if (!group.EligibleForSpending(eligibility_filter)) {
                 continue;
             }
             utxo_pool.push_back(group);
         }
         bnb_used = false;
         return KnapsackSolver(nTargetValue, utxo_pool, setCoinsRet, nValueRet);
     }
 }
 
 bool CWallet::SelectCoins(const std::vector<COutput> &vAvailableCoins,
                           const Amount nTargetValue,
                           std::set<CInputCoin> &setCoinsRet, Amount &nValueRet,
                           const CCoinControl &coin_control,
                           CoinSelectionParams &coin_selection_params,
                           bool &bnb_used) const {
     std::vector<COutput> vCoins(vAvailableCoins);
 
     // coin control -> return all selected outputs (we want all selected to go
     // into the transaction for sure)
     if (coin_control.HasSelected() && !coin_control.fAllowOtherInputs) {
         // We didn't use BnB here, so set it to false.
         bnb_used = false;
 
         for (const COutput &out : vCoins) {
             if (!out.fSpendable) {
                 continue;
             }
 
             nValueRet += out.tx->tx->vout[out.i].nValue;
             setCoinsRet.insert(out.GetInputCoin());
         }
 
         return (nValueRet >= nTargetValue);
     }
 
     // Calculate value from preset inputs and store them.
     std::set<CInputCoin> setPresetCoins;
     Amount nValueFromPresetInputs = Amount::zero();
 
     std::vector<COutPoint> vPresetInputs;
     coin_control.ListSelected(vPresetInputs);
 
     for (const COutPoint &outpoint : vPresetInputs) {
         // For now, don't use BnB if preset inputs are selected. TODO: Enable
         // this later
         bnb_used = false;
         coin_selection_params.use_bnb = false;
 
         std::map<TxId, CWalletTx>::const_iterator it =
             mapWallet.find(outpoint.GetTxId());
         if (it == mapWallet.end()) {
             // TODO: Allow non-wallet inputs
             return false;
         }
 
         const CWalletTx &wtx = it->second;
         // Clearly invalid input, fail.
         if (wtx.tx->vout.size() <= outpoint.GetN()) {
             return false;
         }
 
         // Just to calculate the marginal byte size
         nValueFromPresetInputs += wtx.tx->vout[outpoint.GetN()].nValue;
         setPresetCoins.insert(CInputCoin(wtx.tx, outpoint.GetN()));
     }
 
     // Remove preset inputs from vCoins
     for (std::vector<COutput>::iterator it = vCoins.begin();
          it != vCoins.end() && coin_control.HasSelected();) {
         if (setPresetCoins.count(it->GetInputCoin())) {
             it = vCoins.erase(it);
         } else {
             ++it;
         }
     }
 
     // form groups from remaining coins; note that preset coins will not
     // automatically have their associated (same address) coins included
     if (coin_control.m_avoid_partial_spends &&
         vCoins.size() > OUTPUT_GROUP_MAX_ENTRIES) {
         // Cases where we have 11+ outputs all pointing to the same destination
         // may result in privacy leaks as they will potentially be
         // deterministically sorted. We solve that by explicitly shuffling the
         // outputs before processing
         Shuffle(vCoins.begin(), vCoins.end(), FastRandomContext());
     }
     std::vector<OutputGroup> groups =
         GroupOutputs(vCoins, !coin_control.m_avoid_partial_spends);
 
     size_t max_ancestors = std::max<size_t>(
         1, gArgs.GetArg("-limitancestorcount", DEFAULT_ANCESTOR_LIMIT));
     size_t max_descendants = std::max<size_t>(
         1, gArgs.GetArg("-limitdescendantcount", DEFAULT_DESCENDANT_LIMIT));
     bool fRejectLongChains = gArgs.GetBoolArg(
         "-walletrejectlongchains", DEFAULT_WALLET_REJECT_LONG_CHAINS);
 
     bool res =
         nTargetValue <= nValueFromPresetInputs ||
         SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs,
                            CoinEligibilityFilter(1, 6, 0), groups, setCoinsRet,
                            nValueRet, coin_selection_params, bnb_used) ||
         SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs,
                            CoinEligibilityFilter(1, 1, 0), groups, setCoinsRet,
                            nValueRet, coin_selection_params, bnb_used) ||
         (m_spend_zero_conf_change &&
          SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs,
                             CoinEligibilityFilter(0, 1, 2), groups, setCoinsRet,
                             nValueRet, coin_selection_params, bnb_used)) ||
         (m_spend_zero_conf_change &&
          SelectCoinsMinConf(
              nTargetValue - nValueFromPresetInputs,
              CoinEligibilityFilter(0, 1, std::min<size_t>(4, max_ancestors / 3),
                                    std::min<size_t>(4, max_descendants / 3)),
              groups, setCoinsRet, nValueRet, coin_selection_params,
              bnb_used)) ||
         (m_spend_zero_conf_change &&
          SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs,
                             CoinEligibilityFilter(0, 1, max_ancestors / 2,
                                                   max_descendants / 2),
                             groups, setCoinsRet, nValueRet,
                             coin_selection_params, bnb_used)) ||
         (m_spend_zero_conf_change &&
          SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs,
                             CoinEligibilityFilter(0, 1, max_ancestors - 1,
                                                   max_descendants - 1),
                             groups, setCoinsRet, nValueRet,
                             coin_selection_params, bnb_used)) ||
         (m_spend_zero_conf_change && !fRejectLongChains &&
          SelectCoinsMinConf(
              nTargetValue - nValueFromPresetInputs,
              CoinEligibilityFilter(0, 1, std::numeric_limits<uint64_t>::max()),
              groups, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
 
     // Because SelectCoinsMinConf clears the setCoinsRet, we now add the
     // possible inputs to the coinset.
     util::insert(setCoinsRet, setPresetCoins);
 
     // Add preset inputs to the total value selected.
     nValueRet += nValueFromPresetInputs;
 
     return res;
 }
 
 bool CWallet::SignTransaction(CMutableTransaction &tx) {
     // sign the new tx
     int nIn = 0;
     for (CTxIn &input : tx.vin) {
         auto mi = mapWallet.find(input.prevout.GetTxId());
         if (mi == mapWallet.end() ||
             input.prevout.GetN() >= mi->second.tx->vout.size()) {
             return false;
         }
         const CScript &scriptPubKey =
             mi->second.tx->vout[input.prevout.GetN()].scriptPubKey;
         const Amount amount = mi->second.tx->vout[input.prevout.GetN()].nValue;
         SignatureData sigdata;
         SigHashType sigHashType = SigHashType().withForkId();
         if (!ProduceSignature(*this,
                               MutableTransactionSignatureCreator(
                                   &tx, nIn, amount, sigHashType),
                               scriptPubKey, sigdata)) {
             return false;
         }
         UpdateInput(input, sigdata);
         nIn++;
     }
     return true;
 }
 
 bool CWallet::FundTransaction(CMutableTransaction &tx, Amount &nFeeRet,
                               int &nChangePosInOut, std::string &strFailReason,
                               bool lockUnspents,
                               const std::set<int> &setSubtractFeeFromOutputs,
                               CCoinControl coinControl) {
     std::vector<CRecipient> vecSend;
 
     // Turn the txout set into a CRecipient vector.
     for (size_t idx = 0; idx < tx.vout.size(); idx++) {
         const CTxOut &txOut = tx.vout[idx];
         CRecipient recipient = {txOut.scriptPubKey, txOut.nValue,
                                 setSubtractFeeFromOutputs.count(idx) == 1};
         vecSend.push_back(recipient);
     }
 
     coinControl.fAllowOtherInputs = true;
 
     for (const CTxIn &txin : tx.vin) {
         coinControl.Select(txin.prevout);
     }
 
     // Acquire the locks to prevent races to the new locked unspents between the
     // CreateTransaction call and LockCoin calls (when lockUnspents is true).
     auto locked_chain = chain().lock();
     LOCK(cs_wallet);
 
     CReserveKey reservekey(this);
     CTransactionRef tx_new;
     if (!CreateTransaction(*locked_chain, vecSend, tx_new, reservekey, nFeeRet,
                            nChangePosInOut, strFailReason, coinControl,
                            false)) {
         return false;
     }
 
     if (nChangePosInOut != -1) {
         tx.vout.insert(tx.vout.begin() + nChangePosInOut,
                        tx_new->vout[nChangePosInOut]);
         // We don't have the normal Create/Commit cycle, and don't want to
         // risk reusing change, so just remove the key from the keypool
         // here.
         reservekey.KeepKey();
     }
 
     // Copy output sizes from new transaction; they may have had the fee
     // subtracted from them.
     for (size_t idx = 0; idx < tx.vout.size(); idx++) {
         tx.vout[idx].nValue = tx_new->vout[idx].nValue;
     }
 
     // Add new txins (keeping original txin scriptSig/order)
     for (const CTxIn &txin : tx_new->vin) {
         if (!coinControl.IsSelected(txin.prevout)) {
             tx.vin.push_back(txin);
 
             if (lockUnspents) {
                 LockCoin(txin.prevout);
             }
         }
     }
 
     return true;
 }
 
 static bool IsCurrentForAntiFeeSniping(interfaces::Chain &chain,
                                        interfaces::Chain::Lock &locked_chain) {
     if (chain.isInitialBlockDownload()) {
         return false;
     }
 
     // in seconds
     constexpr int64_t MAX_ANTI_FEE_SNIPING_TIP_AGE = 8 * 60 * 60;
     if (locked_chain.getBlockTime(*locked_chain.getHeight()) <
         (GetTime() - MAX_ANTI_FEE_SNIPING_TIP_AGE)) {
         return false;
     }
     return true;
 }
 
 /**
  * Return a height-based locktime for new transactions (uses the height of the
  * current chain tip unless we are not synced with the current chain
  */
 static uint32_t
 GetLocktimeForNewTransaction(interfaces::Chain &chain,
                              interfaces::Chain::Lock &locked_chain) {
     uint32_t const height = locked_chain.getHeight().value_or(-1);
     uint32_t locktime;
     // Discourage fee sniping.
     //
     // For a large miner the value of the transactions in the best block and
     // the mempool can exceed the cost of deliberately attempting to mine two
     // blocks to orphan the current best block. By setting nLockTime such that
     // only the next block can include the transaction, we discourage this
     // practice as the height restricted and limited blocksize gives miners
     // considering fee sniping fewer options for pulling off this attack.
     //
     // A simple way to think about this is from the wallet's point of view we
     // always want the blockchain to move forward. By setting nLockTime this
     // way we're basically making the statement that we only want this
     // transaction to appear in the next block; we don't want to potentially
     // encourage reorgs by allowing transactions to appear at lower heights
     // than the next block in forks of the best chain.
     //
     // Of course, the subsidy is high enough, and transaction volume low
     // enough, that fee sniping isn't a problem yet, but by implementing a fix
     // now we ensure code won't be written that makes assumptions about
     // nLockTime that preclude a fix later.
     if (IsCurrentForAntiFeeSniping(chain, locked_chain)) {
         locktime = height;
 
         // Secondly occasionally randomly pick a nLockTime even further back, so
         // that transactions that are delayed after signing for whatever reason,
         // e.g. high-latency mix networks and some CoinJoin implementations,
         // have better privacy.
         if (GetRandInt(10) == 0) {
             locktime = std::max(0, int(locktime) - GetRandInt(100));
         }
     } else {
         // If our chain is lagging behind, we can't discourage fee sniping nor
         // help the privacy of high-latency transactions. To avoid leaking a
         // potentially unique "nLockTime fingerprint", set nLockTime to a
         // constant.
         locktime = 0;
     }
     assert(locktime <= height);
     assert(locktime < LOCKTIME_THRESHOLD);
     return locktime;
 }
 
 OutputType
 CWallet::TransactionChangeType(OutputType change_type,
                                const std::vector<CRecipient> &vecSend) {
     // If -changetype is specified, always use that change type.
     if (change_type != OutputType::CHANGE_AUTO) {
         return change_type;
     }
 
     // if m_default_address_type is legacy, use legacy address as change.
     if (m_default_address_type == OutputType::LEGACY) {
         return OutputType::LEGACY;
     }
 
     // else use m_default_address_type for change
     return m_default_address_type;
 }
 
 bool CWallet::CreateTransaction(interfaces::Chain::Lock &locked_chainIn,
                                 const std::vector<CRecipient> &vecSend,
                                 CTransactionRef &tx, CReserveKey &reservekey,
                                 Amount &nFeeRet, int &nChangePosInOut,
                                 std::string &strFailReason,
                                 const CCoinControl &coinControl, bool sign) {
     Amount nValue = Amount::zero();
     int nChangePosRequest = nChangePosInOut;
     unsigned int nSubtractFeeFromAmount = 0;
     for (const auto &recipient : vecSend) {
         if (nValue < Amount::zero() || recipient.nAmount < Amount::zero()) {
             strFailReason =
                 _("Transaction amounts must not be negative").translated;
             return false;
         }
 
         nValue += recipient.nAmount;
 
         if (recipient.fSubtractFeeFromAmount) {
             nSubtractFeeFromAmount++;
         }
     }
 
     if (vecSend.empty()) {
         strFailReason =
             _("Transaction must have at least one recipient").translated;
         return false;
     }
 
     CMutableTransaction txNew;
 
     txNew.nLockTime = GetLocktimeForNewTransaction(chain(), locked_chainIn);
 
     {
         std::set<CInputCoin> setCoins;
         auto locked_chain = chain().lock();
         LOCK(cs_wallet);
 
         std::vector<COutput> vAvailableCoins;
         AvailableCoins(*locked_chain, vAvailableCoins, true, &coinControl);
         // Parameters for coin selection, init with dummy
         CoinSelectionParams coin_selection_params;
 
         // Create change script that will be used if we need change
         // TODO: pass in scriptChange instead of reservekey so
         // change transaction isn't always pay-to-bitcoin-address
         CScript scriptChange;
 
         // coin control: send change to custom address
         if (!boost::get<CNoDestination>(&coinControl.destChange)) {
             scriptChange = GetScriptForDestination(coinControl.destChange);
 
             // no coin control: send change to newly generated address
         } else {
             // Note: We use a new key here to keep it from being obvious
             // which side is the change.
             //  The drawback is that by not reusing a previous key, the
             //  change may be lost if a backup is restored, if the backup
             //  doesn't have the new private key for the change. If we
             //  reused the old key, it would be possible to add code to look
             //  for and rediscover unknown transactions that were written
             //  with keys of ours to recover post-backup change.
 
             // Reserve a new key pair from key pool
             if (IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS)) {
                 strFailReason =
                     _("Can't generate a change-address key. Private keys "
                       "are disabled for this wallet.")
                         .translated;
                 return false;
             }
             CPubKey vchPubKey;
             bool ret;
             ret = reservekey.GetReservedKey(vchPubKey, true);
             if (!ret) {
                 strFailReason =
                     _("Keypool ran out, please call keypoolrefill first")
                         .translated;
                 return false;
             }
 
             const OutputType change_type = TransactionChangeType(
                 coinControl.m_change_type ? *coinControl.m_change_type
                                           : m_default_change_type,
                 vecSend);
 
             LearnRelatedScripts(vchPubKey, change_type);
             scriptChange = GetScriptForDestination(
                 GetDestinationForKey(vchPubKey, change_type));
         }
         CTxOut change_prototype_txout(Amount::zero(), scriptChange);
         coin_selection_params.change_output_size =
             GetSerializeSize(change_prototype_txout);
 
         // Get the fee rate to use effective values in coin selection
         CFeeRate nFeeRateNeeded = GetMinimumFeeRate(*this, coinControl);
 
         nFeeRet = Amount::zero();
         bool pick_new_inputs = true;
         Amount nValueIn = Amount::zero();
 
         // BnB selector is the only selector used when this is true.
         // That should only happen on the first pass through the loop.
         // If we are doing subtract fee from recipient, then don't use BnB
         coin_selection_params.use_bnb = nSubtractFeeFromAmount == 0;
         // Start with no fee and loop until there is enough fee
         while (true) {
             nChangePosInOut = nChangePosRequest;
             txNew.vin.clear();
             txNew.vout.clear();
             bool fFirst = true;
 
             Amount nValueToSelect = nValue;
             if (nSubtractFeeFromAmount == 0) {
                 nValueToSelect += nFeeRet;
             }
 
             // Static size overhead + outputs vsize. 4 nVersion, 4 nLocktime, 1
             // input count, 1 output count
             coin_selection_params.tx_noinputs_size = 10;
             // vouts to the payees
             for (const auto &recipient : vecSend) {
                 CTxOut txout(recipient.nAmount, recipient.scriptPubKey);
 
                 if (recipient.fSubtractFeeFromAmount) {
                     assert(nSubtractFeeFromAmount != 0);
                     // Subtract fee equally from each selected recipient.
                     txout.nValue -= nFeeRet / int(nSubtractFeeFromAmount);
 
                     // First receiver pays the remainder not divisible by output
                     // count.
                     if (fFirst) {
                         fFirst = false;
                         txout.nValue -= nFeeRet % int(nSubtractFeeFromAmount);
                     }
                 }
 
                 // Include the fee cost for outputs. Note this is only used for
                 // BnB right now
                 coin_selection_params.tx_noinputs_size +=
                     ::GetSerializeSize(txout, PROTOCOL_VERSION);
 
                 if (IsDust(txout, chain().relayDustFee())) {
                     if (recipient.fSubtractFeeFromAmount &&
                         nFeeRet > Amount::zero()) {
                         if (txout.nValue < Amount::zero()) {
                             strFailReason = _("The transaction amount is too "
                                               "small to pay the fee")
                                                 .translated;
                         } else {
                             strFailReason =
                                 _("The transaction amount is too small to "
                                   "send after the fee has been deducted")
                                     .translated;
                         }
                     } else {
                         strFailReason =
                             _("Transaction amount too small").translated;
                     }
 
                     return false;
                 }
 
                 txNew.vout.push_back(txout);
             }
 
             // Choose coins to use
             bool bnb_used;
             if (pick_new_inputs) {
                 nValueIn = Amount::zero();
                 setCoins.clear();
                 coin_selection_params.change_spend_size =
                     CalculateMaximumSignedInputSize(change_prototype_txout,
                                                     this);
                 coin_selection_params.effective_fee = nFeeRateNeeded;
                 if (!SelectCoins(vAvailableCoins, nValueToSelect, setCoins,
                                  nValueIn, coinControl, coin_selection_params,
                                  bnb_used)) {
                     // If BnB was used, it was the first pass. No longer the
                     // first pass and continue loop with knapsack.
                     if (bnb_used) {
                         coin_selection_params.use_bnb = false;
                         continue;
                     } else {
                         strFailReason = _("Insufficient funds").translated;
                         return false;
                     }
                 }
             }
 
             const Amount nChange = nValueIn - nValueToSelect;
             if (nChange > Amount::zero()) {
                 // Fill a vout to ourself.
                 CTxOut newTxOut(nChange, scriptChange);
 
                 // Never create dust outputs; if we would, just add the dust to
                 // the fee.
                 // The nChange when BnB is used is always going to go to fees.
                 if (IsDust(newTxOut, dustRelayFee) || bnb_used) {
                     nChangePosInOut = -1;
                     nFeeRet += nChange;
                 } else {
                     if (nChangePosInOut == -1) {
                         // Insert change txn at random position:
                         nChangePosInOut = GetRandInt(txNew.vout.size() + 1);
                     } else if ((unsigned int)nChangePosInOut >
                                txNew.vout.size()) {
                         strFailReason =
                             _("Change index out of range").translated;
                         return false;
                     }
 
                     std::vector<CTxOut>::iterator position =
                         txNew.vout.begin() + nChangePosInOut;
                     txNew.vout.insert(position, newTxOut);
                 }
             } else {
                 nChangePosInOut = -1;
             }
 
             // Dummy fill vin for maximum size estimation
             //
             for (const auto &coin : setCoins) {
                 txNew.vin.push_back(CTxIn(coin.outpoint, CScript()));
             }
 
             CTransaction txNewConst(txNew);
             int nBytes = CalculateMaximumSignedTxSize(
                 txNewConst, this, coinControl.fAllowWatchOnly);
             if (nBytes < 0) {
                 strFailReason = _("Signing transaction failed").translated;
                 return false;
             }
 
             Amount nFeeNeeded = GetMinimumFee(*this, nBytes, coinControl);
 
             // If we made it here and we aren't even able to meet the relay fee
             // on the next pass, give up because we must be at the maximum
             // allowed fee.
             if (nFeeNeeded < chain().relayMinFee().GetFee(nBytes)) {
                 strFailReason =
                     _("Transaction too large for fee policy").translated;
                 return false;
             }
 
             if (nFeeRet >= nFeeNeeded) {
                 // Reduce fee to only the needed amount if possible. This
                 // prevents potential overpayment in fees if the coins selected
                 // to meet nFeeNeeded result in a transaction that requires less
                 // fee than the prior iteration.
 
                 // If we have no change and a big enough excess fee, then try to
                 // construct transaction again only without picking new inputs.
                 // We now know we only need the smaller fee (because of reduced
                 // tx size) and so we should add a change output. Only try this
                 // once.
                 if (nChangePosInOut == -1 && nSubtractFeeFromAmount == 0 &&
                     pick_new_inputs) {
                     // Add 2 as a buffer in case increasing # of outputs changes
                     // compact size
                     unsigned int tx_size_with_change =
                         nBytes + coin_selection_params.change_output_size + 2;
                     Amount fee_needed_with_change =
                         GetMinimumFee(*this, tx_size_with_change, coinControl);
                     Amount minimum_value_for_change =
                         GetDustThreshold(change_prototype_txout, dustRelayFee);
                     if (nFeeRet >=
                         fee_needed_with_change + minimum_value_for_change) {
                         pick_new_inputs = false;
                         nFeeRet = fee_needed_with_change;
                         continue;
                     }
                 }
 
                 // If we have change output already, just increase it
                 if (nFeeRet > nFeeNeeded && nChangePosInOut != -1 &&
                     nSubtractFeeFromAmount == 0) {
                     Amount extraFeePaid = nFeeRet - nFeeNeeded;
                     std::vector<CTxOut>::iterator change_position =
                         txNew.vout.begin() + nChangePosInOut;
                     change_position->nValue += extraFeePaid;
                     nFeeRet -= extraFeePaid;
                 }
 
                 // Done, enough fee included.
                 break;
             } else if (!pick_new_inputs) {
                 // This shouldn't happen, we should have had enough excess fee
                 // to pay for the new output and still meet nFeeNeeded.
                 // Or we should have just subtracted fee from recipients and
                 // nFeeNeeded should not have changed.
                 strFailReason =
                     _("Transaction fee and change calculation failed")
                         .translated;
                 return false;
             }
 
             // Try to reduce change to include necessary fee.
             if (nChangePosInOut != -1 && nSubtractFeeFromAmount == 0) {
                 Amount additionalFeeNeeded = nFeeNeeded - nFeeRet;
                 std::vector<CTxOut>::iterator change_position =
                     txNew.vout.begin() + nChangePosInOut;
                 // Only reduce change if remaining amount is still a large
                 // enough output.
                 if (change_position->nValue >=
                     MIN_FINAL_CHANGE + additionalFeeNeeded) {
                     change_position->nValue -= additionalFeeNeeded;
                     nFeeRet += additionalFeeNeeded;
                     // Done, able to increase fee from change.
                     break;
                 }
             }
 
             // If subtracting fee from recipients, we now know what fee we
             // need to subtract, we have no reason to reselect inputs.
             if (nSubtractFeeFromAmount > 0) {
                 pick_new_inputs = false;
             }
 
             // Include more fee and try again.
             nFeeRet = nFeeNeeded;
             coin_selection_params.use_bnb = false;
             continue;
         }
 
         if (nChangePosInOut == -1) {
             // Return any reserved key if we don't have change
             reservekey.ReturnKey();
         }
 
         // Shuffle selected coins and fill in final vin
         txNew.vin.clear();
         std::vector<CInputCoin> selected_coins(setCoins.begin(),
                                                setCoins.end());
         Shuffle(selected_coins.begin(), selected_coins.end(),
                 FastRandomContext());
 
         // Note how the sequence number is set to non-maxint so that
         // the nLockTime set above actually works.
         for (const auto &coin : selected_coins) {
             txNew.vin.push_back(
                 CTxIn(coin.outpoint, CScript(),
                       std::numeric_limits<uint32_t>::max() - 1));
         }
 
         if (sign) {
             SigHashType sigHashType = SigHashType().withForkId();
 
             int nIn = 0;
             for (const auto &coin : selected_coins) {
                 const CScript &scriptPubKey = coin.txout.scriptPubKey;
                 SignatureData sigdata;
 
                 if (!ProduceSignature(
                         *this,
                         MutableTransactionSignatureCreator(
                             &txNew, nIn, coin.txout.nValue, sigHashType),
                         scriptPubKey, sigdata)) {
                     strFailReason = _("Signing transaction failed").translated;
                     return false;
                 }
 
                 UpdateInput(txNew.vin.at(nIn), sigdata);
                 nIn++;
             }
         }
 
         // Return the constructed transaction data.
         tx = MakeTransactionRef(std::move(txNew));
 
         // Limit size.
         if (tx->GetTotalSize() >= MAX_STANDARD_TX_SIZE) {
             strFailReason = _("Transaction too large").translated;
             return false;
         }
     }
 
     if (gArgs.GetBoolArg("-walletrejectlongchains",
                          DEFAULT_WALLET_REJECT_LONG_CHAINS)) {
         // Lastly, ensure this tx will pass the mempool's chain limits
         if (!chain().checkChainLimits(tx)) {
             strFailReason =
                 _("Transaction has too long of a mempool chain").translated;
             return false;
         }
     }
 
     return true;
 }
 
 /**
  * Call after CreateTransaction unless you want to abort
  */
 bool CWallet::CommitTransaction(
     CTransactionRef tx, mapValue_t mapValue,
     std::vector<std::pair<std::string, std::string>> orderForm,
     CReserveKey &reservekey, CValidationState &state) {
     auto locked_chain = chain().lock();
     LOCK(cs_wallet);
 
     CWalletTx wtxNew(this, std::move(tx));
     wtxNew.mapValue = std::move(mapValue);
     wtxNew.vOrderForm = std::move(orderForm);
     wtxNew.fTimeReceivedIsTxTime = true;
     wtxNew.fFromMe = true;
 
     WalletLogPrintfToBeContinued("CommitTransaction:\n%s",
                                  wtxNew.tx->ToString());
 
     // Take key pair from key pool so it won't be used again.
     reservekey.KeepKey();
 
     // Add tx to wallet, because if it has change it's also ours, otherwise just
     // for transaction history.
     AddToWallet(wtxNew);
 
     // Notify that old coins are spent.
     for (const CTxIn &txin : wtxNew.tx->vin) {
         CWalletTx &coin = mapWallet.at(txin.prevout.GetTxId());
         coin.BindWallet(this);
         NotifyTransactionChanged(this, coin.GetId(), CT_UPDATED);
     }
 
     // Get the inserted-CWalletTx from mapWallet so that the
     // fInMempool flag is cached properly
     CWalletTx &wtx = mapWallet.at(wtxNew.GetId());
 
     if (fBroadcastTransactions) {
         // Broadcast
         if (!wtx.AcceptToMemoryPool(*locked_chain, state)) {
             WalletLogPrintf("CommitTransaction(): Transaction cannot be "
                             "broadcast immediately, %s\n",
                             FormatStateMessage(state));
             // TODO: if we expect the failure to be long term or permanent,
             // instead delete wtx from the wallet and return failure.
         } else {
             wtx.RelayWalletTransaction(*locked_chain);
         }
     }
 
     return true;
 }
 
 DBErrors CWallet::LoadWallet(bool &fFirstRunRet) {
     LOCK(cs_wallet);
 
     fFirstRunRet = false;
     DBErrors nLoadWalletRet = WalletBatch(*database, "cr+").LoadWallet(this);
     if (nLoadWalletRet == DBErrors::NEED_REWRITE) {
         if (database->Rewrite("\x04pool")) {
             setInternalKeyPool.clear();
             setExternalKeyPool.clear();
             m_pool_key_to_index.clear();
             // Note: can't top-up keypool here, because wallet is locked.
             // User will be prompted to unlock wallet the next operation
             // that requires a new key.
         }
     }
 
     {
         LOCK(cs_KeyStore);
         // This wallet is in its first run if all of these are empty
         fFirstRunRet = mapKeys.empty() && mapCryptedKeys.empty() &&
                        mapWatchKeys.empty() && setWatchOnly.empty() &&
                        mapScripts.empty() &&
                        !IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) &&
                        !IsWalletFlagSet(WALLET_FLAG_BLANK_WALLET);
     }
 
     if (nLoadWalletRet != DBErrors::LOAD_OK) {
         return nLoadWalletRet;
     }
 
     return DBErrors::LOAD_OK;
 }
 
 DBErrors CWallet::ZapSelectTx(std::vector<TxId> &txIdsIn,
                               std::vector<TxId> &txIdsOut) {
     // mapWallet
     AssertLockHeld(cs_wallet);
     DBErrors nZapSelectTxRet =
         WalletBatch(*database, "cr+").ZapSelectTx(txIdsIn, txIdsOut);
     for (const TxId &txid : txIdsOut) {
         const auto &it = mapWallet.find(txid);
         wtxOrdered.erase(it->second.m_it_wtxOrdered);
         mapWallet.erase(it);
     }
 
     if (nZapSelectTxRet == DBErrors::NEED_REWRITE) {
         if (database->Rewrite("\x04pool")) {
             setInternalKeyPool.clear();
             setExternalKeyPool.clear();
             m_pool_key_to_index.clear();
             // Note: can't top-up keypool here, because wallet is locked.
             // User will be prompted to unlock wallet the next operation
             // that requires a new key.
         }
     }
 
     if (nZapSelectTxRet != DBErrors::LOAD_OK) {
         return nZapSelectTxRet;
     }
 
     MarkDirty();
 
     return DBErrors::LOAD_OK;
 }
 
 DBErrors CWallet::ZapWalletTx(std::vector<CWalletTx> &vWtx) {
     DBErrors nZapWalletTxRet = WalletBatch(*database, "cr+").ZapWalletTx(vWtx);
     if (nZapWalletTxRet == DBErrors::NEED_REWRITE) {
         if (database->Rewrite("\x04pool")) {
             LOCK(cs_wallet);
             setInternalKeyPool.clear();
             setExternalKeyPool.clear();
             m_pool_key_to_index.clear();
             // Note: can't top-up keypool here, because wallet is locked.
             // User will be prompted to unlock wallet the next operation
             // that requires a new key.
         }
     }
 
     if (nZapWalletTxRet != DBErrors::LOAD_OK) {
         return nZapWalletTxRet;
     }
 
     return DBErrors::LOAD_OK;
 }
 
 bool CWallet::SetAddressBook(const CTxDestination &address,
                              const std::string &strName,
                              const std::string &strPurpose) {
     bool fUpdated = false;
     {
         // mapAddressBook
         LOCK(cs_wallet);
         std::map<CTxDestination, CAddressBookData>::iterator mi =
             mapAddressBook.find(address);
         fUpdated = mi != mapAddressBook.end();
         mapAddressBook[address].name = strName;
         // Update purpose only if requested.
         if (!strPurpose.empty()) {
             mapAddressBook[address].purpose = strPurpose;
         }
     }
 
     NotifyAddressBookChanged(this, address, strName,
                              ::IsMine(*this, address) != ISMINE_NO, strPurpose,
                              (fUpdated ? CT_UPDATED : CT_NEW));
     if (!strPurpose.empty() &&
         !WalletBatch(*database).WritePurpose(address, strPurpose)) {
         return false;
     }
     return WalletBatch(*database).WriteName(address, strName);
 }
 
 bool CWallet::DelAddressBook(const CTxDestination &address) {
     {
         // mapAddressBook
         LOCK(cs_wallet);
 
         // Delete destdata tuples associated with address.
         for (const std::pair<const std::string, std::string> &item :
              mapAddressBook[address].destdata) {
             WalletBatch(*database).EraseDestData(address, item.first);
         }
 
         mapAddressBook.erase(address);
     }
 
     NotifyAddressBookChanged(this, address, "",
                              ::IsMine(*this, address) != ISMINE_NO, "",
                              CT_DELETED);
 
     WalletBatch(*database).ErasePurpose(address);
     return WalletBatch(*database).EraseName(address);
 }
 
 const std::string &CWallet::GetLabelName(const CScript &scriptPubKey) const {
     CTxDestination address;
     if (ExtractDestination(scriptPubKey, address) &&
         !scriptPubKey.IsUnspendable()) {
         auto mi = mapAddressBook.find(address);
         if (mi != mapAddressBook.end()) {
             return mi->second.name;
         }
     }
     // A scriptPubKey that doesn't have an entry in the address book is
     // associated with the default label ("").
     const static std::string DEFAULT_LABEL_NAME;
     return DEFAULT_LABEL_NAME;
 }
 
 /**
  * Mark old keypool keys as used, and generate all new keys.
  */
 bool CWallet::NewKeyPool() {
     if (IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS)) {
         return false;
     }
     LOCK(cs_wallet);
     WalletBatch batch(*database);
 
     for (const int64_t nIndex : setInternalKeyPool) {
         batch.ErasePool(nIndex);
     }
     setInternalKeyPool.clear();
 
     for (const int64_t nIndex : setExternalKeyPool) {
         batch.ErasePool(nIndex);
     }
     setExternalKeyPool.clear();
 
     for (int64_t nIndex : set_pre_split_keypool) {
         batch.ErasePool(nIndex);
     }
     set_pre_split_keypool.clear();
 
     m_pool_key_to_index.clear();
 
     if (!TopUpKeyPool()) {
         return false;
     }
 
     WalletLogPrintf("CWallet::NewKeyPool rewrote keypool\n");
     return true;
 }
 
 size_t CWallet::KeypoolCountExternalKeys() {
     // setExternalKeyPool
     AssertLockHeld(cs_wallet);
     return setExternalKeyPool.size() + set_pre_split_keypool.size();
 }
 
 void CWallet::LoadKeyPool(int64_t nIndex, const CKeyPool &keypool) {
     AssertLockHeld(cs_wallet);
     if (keypool.m_pre_split) {
         set_pre_split_keypool.insert(nIndex);
     } else if (keypool.fInternal) {
         setInternalKeyPool.insert(nIndex);
     } else {
         setExternalKeyPool.insert(nIndex);
     }
     m_max_keypool_index = std::max(m_max_keypool_index, nIndex);
     m_pool_key_to_index[keypool.vchPubKey.GetID()] = nIndex;
 
     // If no metadata exists yet, create a default with the pool key's
     // creation time. Note that this may be overwritten by actually
     // stored metadata for that key later, which is fine.
     CKeyID keyid = keypool.vchPubKey.GetID();
     if (mapKeyMetadata.count(keyid) == 0) {
         mapKeyMetadata[keyid] = CKeyMetadata(keypool.nTime);
     }
 }
 
 bool CWallet::TopUpKeyPool(unsigned int kpSize) {
     if (!CanGenerateKeys()) {
         return false;
     }
     {
         LOCK(cs_wallet);
 
         if (IsLocked()) {
             return false;
         }
 
         // Top up key pool
         unsigned int nTargetSize;
         if (kpSize > 0) {
             nTargetSize = kpSize;
         } else {
             nTargetSize = std::max<int64_t>(
                 gArgs.GetArg("-keypool", DEFAULT_KEYPOOL_SIZE), 0);
         }
 
         // count amount of available keys (internal, external)
         // make sure the keypool of external and internal keys fits the user
         // selected target (-keypool)
         int64_t missingExternal = std::max<int64_t>(
             std::max<int64_t>(nTargetSize, 1) - setExternalKeyPool.size(), 0);
         int64_t missingInternal = std::max<int64_t>(
             std::max<int64_t>(nTargetSize, 1) - setInternalKeyPool.size(), 0);
 
         if (!IsHDEnabled() || !CanSupportFeature(FEATURE_HD_SPLIT)) {
             // don't create extra internal keys
             missingInternal = 0;
         }
         bool internal = false;
         WalletBatch batch(*database);
         for (int64_t i = missingInternal + missingExternal; i--;) {
             if (i < missingInternal) {
                 internal = true;
             }
 
             // How in the hell did you use so many keys?
             assert(m_max_keypool_index < std::numeric_limits<int64_t>::max());
             int64_t index = ++m_max_keypool_index;
 
             CPubKey pubkey(GenerateNewKey(batch, internal));
             if (!batch.WritePool(index, CKeyPool(pubkey, internal))) {
                 throw std::runtime_error(std::string(__func__) +
                                          ": writing generated key failed");
             }
 
             if (internal) {
                 setInternalKeyPool.insert(index);
             } else {
                 setExternalKeyPool.insert(index);
             }
             m_pool_key_to_index[pubkey.GetID()] = index;
         }
         if (missingInternal + missingExternal > 0) {
             WalletLogPrintf(
                 "keypool added %d keys (%d internal), size=%u (%u internal)\n",
                 missingInternal + missingExternal, missingInternal,
                 setInternalKeyPool.size() + setExternalKeyPool.size() +
                     set_pre_split_keypool.size(),
                 setInternalKeyPool.size());
         }
     }
     NotifyCanGetAddressesChanged();
     return true;
 }
 
 bool CWallet::ReserveKeyFromKeyPool(int64_t &nIndex, CKeyPool &keypool,
                                     bool fRequestedInternal) {
     nIndex = -1;
     keypool.vchPubKey = CPubKey();
     {
         LOCK(cs_wallet);
 
         if (!IsLocked()) {
             TopUpKeyPool();
         }
 
         bool fReturningInternal = IsHDEnabled() &&
                                   CanSupportFeature(FEATURE_HD_SPLIT) &&
                                   fRequestedInternal;
         bool use_split_keypool = set_pre_split_keypool.empty();
         std::set<int64_t> &setKeyPool =
             use_split_keypool
                 ? (fReturningInternal ? setInternalKeyPool : setExternalKeyPool)
                 : set_pre_split_keypool;
 
         // Get the oldest key
         if (setKeyPool.empty()) {
             return false;
         }
 
         WalletBatch batch(*database);
 
         auto it = setKeyPool.begin();
         nIndex = *it;
         setKeyPool.erase(it);
         if (!batch.ReadPool(nIndex, keypool)) {
             throw std::runtime_error(std::string(__func__) + ": read failed");
         }
         if (!HaveKey(keypool.vchPubKey.GetID())) {
             throw std::runtime_error(std::string(__func__) +
                                      ": unknown key in key pool");
         }
         // If the key was pre-split keypool, we don't care about what type it is
         if (use_split_keypool && keypool.fInternal != fReturningInternal) {
             throw std::runtime_error(std::string(__func__) +
                                      ": keypool entry misclassified");
         }
         if (!keypool.vchPubKey.IsValid()) {
             throw std::runtime_error(std::string(__func__) +
                                      ": keypool entry invalid");
         }
 
         m_pool_key_to_index.erase(keypool.vchPubKey.GetID());
         WalletLogPrintf("keypool reserve %d\n", nIndex);
     }
     NotifyCanGetAddressesChanged();
     return true;
 }
 
 void CWallet::KeepKey(int64_t nIndex) {
     // Remove from key pool.
     WalletBatch batch(*database);
     batch.ErasePool(nIndex);
     WalletLogPrintf("keypool keep %d\n", nIndex);
 }
 
 void CWallet::ReturnKey(int64_t nIndex, bool fInternal, const CPubKey &pubkey) {
     // Return to key pool
     {
         LOCK(cs_wallet);
         if (fInternal) {
             setInternalKeyPool.insert(nIndex);
         } else if (!set_pre_split_keypool.empty()) {
             set_pre_split_keypool.insert(nIndex);
         } else {
             setExternalKeyPool.insert(nIndex);
         }
         m_pool_key_to_index[pubkey.GetID()] = nIndex;
         NotifyCanGetAddressesChanged();
     }
 
     WalletLogPrintf("keypool return %d\n", nIndex);
 }
 
 bool CWallet::GetKeyFromPool(CPubKey &result, bool internal) {
     if (!CanGetAddresses(internal)) {
         return false;
     }
 
     CKeyPool keypool;
     LOCK(cs_wallet);
     int64_t nIndex;
     if (!ReserveKeyFromKeyPool(nIndex, keypool, internal)) {
         if (IsLocked()) {
             return false;
         }
         WalletBatch batch(*database);
         result = GenerateNewKey(batch, internal);
         return true;
     }
 
     KeepKey(nIndex);
     result = keypool.vchPubKey;
 
     return true;
 }
 
 static int64_t GetOldestKeyTimeInPool(const std::set<int64_t> &setKeyPool,
                                       WalletBatch &batch) {
     if (setKeyPool.empty()) {
         return GetTime();
     }
 
     CKeyPool keypool;
     int64_t nIndex = *(setKeyPool.begin());
     if (!batch.ReadPool(nIndex, keypool)) {
         throw std::runtime_error(std::string(__func__) +
                                  ": read oldest key in keypool failed");
     }
 
     assert(keypool.vchPubKey.IsValid());
     return keypool.nTime;
 }
 
 int64_t CWallet::GetOldestKeyPoolTime() {
     LOCK(cs_wallet);
 
     WalletBatch batch(*database);
 
     // load oldest key from keypool, get time and return
     int64_t oldestKey = GetOldestKeyTimeInPool(setExternalKeyPool, batch);
     if (IsHDEnabled() && CanSupportFeature(FEATURE_HD_SPLIT)) {
         oldestKey = std::max(GetOldestKeyTimeInPool(setInternalKeyPool, batch),
                              oldestKey);
         if (!set_pre_split_keypool.empty()) {
             oldestKey =
                 std::max(GetOldestKeyTimeInPool(set_pre_split_keypool, batch),
                          oldestKey);
         }
     }
 
     return oldestKey;
 }
 
 std::map<CTxDestination, Amount>
 CWallet::GetAddressBalances(interfaces::Chain::Lock &locked_chain) {
     std::map<CTxDestination, Amount> balances;
 
     LOCK(cs_wallet);
     for (const auto &walletEntry : mapWallet) {
         const CWalletTx &wtx = walletEntry.second;
 
         if (!wtx.IsTrusted(locked_chain)) {
             continue;
         }
 
         if (wtx.IsImmatureCoinBase(locked_chain)) {
             continue;
         }
 
         int nDepth = wtx.GetDepthInMainChain(locked_chain);
         if (nDepth < (wtx.IsFromMe(ISMINE_ALL) ? 0 : 1)) {
             continue;
         }
 
         for (uint32_t i = 0; i < wtx.tx->vout.size(); i++) {
             CTxDestination addr;
             if (!IsMine(wtx.tx->vout[i])) {
                 continue;
             }
 
             if (!ExtractDestination(wtx.tx->vout[i].scriptPubKey, addr)) {
                 continue;
             }
 
             Amount n = IsSpent(locked_chain, COutPoint(walletEntry.first, i))
                            ? Amount::zero()
                            : wtx.tx->vout[i].nValue;
 
             if (!balances.count(addr)) {
                 balances[addr] = Amount::zero();
             }
             balances[addr] += n;
         }
     }
 
     return balances;
 }
 
 std::set<std::set<CTxDestination>> CWallet::GetAddressGroupings() {
     // mapWallet
     AssertLockHeld(cs_wallet);
     std::set<std::set<CTxDestination>> groupings;
     std::set<CTxDestination> grouping;
 
     for (const auto &walletEntry : mapWallet) {
         const CWalletTx &wtx = walletEntry.second;
 
         if (wtx.tx->vin.size() > 0) {
             bool any_mine = false;
             // Group all input addresses with each other.
             for (const auto &txin : wtx.tx->vin) {
                 CTxDestination address;
                 // If this input isn't mine, ignore it.
                 if (!IsMine(txin)) {
                     continue;
                 }
 
                 if (!ExtractDestination(mapWallet.at(txin.prevout.GetTxId())
                                             .tx->vout[txin.prevout.GetN()]
                                             .scriptPubKey,
                                         address)) {
                     continue;
                 }
 
                 grouping.insert(address);
                 any_mine = true;
             }
 
             // Group change with input addresses.
             if (any_mine) {
                 for (const auto &txout : wtx.tx->vout) {
                     if (IsChange(txout)) {
                         CTxDestination txoutAddr;
                         if (!ExtractDestination(txout.scriptPubKey,
                                                 txoutAddr)) {
                             continue;
                         }
 
                         grouping.insert(txoutAddr);
                     }
                 }
             }
 
             if (grouping.size() > 0) {
                 groupings.insert(grouping);
                 grouping.clear();
             }
         }
 
         // Group lone addrs by themselves.
         for (const auto &txout : wtx.tx->vout) {
             if (IsMine(txout)) {
                 CTxDestination address;
                 if (!ExtractDestination(txout.scriptPubKey, address)) {
                     continue;
                 }
 
                 grouping.insert(address);
                 groupings.insert(grouping);
                 grouping.clear();
             }
         }
     }
 
     // A set of pointers to groups of addresses.
     std::set<std::set<CTxDestination> *> uniqueGroupings;
     // Map addresses to the unique group containing it.
     std::map<CTxDestination, std::set<CTxDestination> *> setmap;
     for (std::set<CTxDestination> _grouping : groupings) {
         // Make a set of all the groups hit by this new group.
         std::set<std::set<CTxDestination> *> hits;
         std::map<CTxDestination, std::set<CTxDestination> *>::iterator it;
         for (const CTxDestination &address : _grouping) {
             if ((it = setmap.find(address)) != setmap.end()) {
                 hits.insert((*it).second);
             }
         }
 
         // Merge all hit groups into a new single group and delete old groups.
         std::set<CTxDestination> *merged =
             new std::set<CTxDestination>(_grouping);
         for (std::set<CTxDestination> *hit : hits) {
             merged->insert(hit->begin(), hit->end());
             uniqueGroupings.erase(hit);
             delete hit;
         }
         uniqueGroupings.insert(merged);
 
         // Update setmap.
         for (const CTxDestination &element : *merged) {
             setmap[element] = merged;
         }
     }
 
     std::set<std::set<CTxDestination>> ret;
     for (const std::set<CTxDestination> *uniqueGrouping : uniqueGroupings) {
         ret.insert(*uniqueGrouping);
         delete uniqueGrouping;
     }
 
     return ret;
 }
 
 std::set<CTxDestination>
 CWallet::GetLabelAddresses(const std::string &label) const {
     LOCK(cs_wallet);
     std::set<CTxDestination> result;
     for (const std::pair<const CTxDestination, CAddressBookData> &item :
          mapAddressBook) {
         const CTxDestination &address = item.first;
         const std::string &strName = item.second.name;
         if (strName == label) {
             result.insert(address);
         }
     }
 
     return result;
 }
 
 bool CReserveKey::GetReservedKey(CPubKey &pubkey, bool internal) {
     if (!pwallet->CanGetAddresses(internal)) {
         return false;
     }
 
     if (nIndex == -1) {
         CKeyPool keypool;
         if (!pwallet->ReserveKeyFromKeyPool(nIndex, keypool, internal)) {
             return false;
         }
 
         vchPubKey = keypool.vchPubKey;
         fInternal = keypool.fInternal;
     }
 
     assert(vchPubKey.IsValid());
     pubkey = vchPubKey;
     return true;
 }
 
 void CReserveKey::KeepKey() {
     if (nIndex != -1) {
         pwallet->KeepKey(nIndex);
     }
 
     nIndex = -1;
     vchPubKey = CPubKey();
 }
 
 void CReserveKey::ReturnKey() {
     if (nIndex != -1) {
         pwallet->ReturnKey(nIndex, fInternal, vchPubKey);
     }
     nIndex = -1;
     vchPubKey = CPubKey();
 }
 
 void CWallet::MarkReserveKeysAsUsed(int64_t keypool_id) {
     AssertLockHeld(cs_wallet);
     bool internal = setInternalKeyPool.count(keypool_id);
     if (!internal) {
         assert(setExternalKeyPool.count(keypool_id) ||
                set_pre_split_keypool.count(keypool_id));
     }
 
     std::set<int64_t> *setKeyPool =
         internal ? &setInternalKeyPool
                  : (set_pre_split_keypool.empty() ? &setExternalKeyPool
                                                   : &set_pre_split_keypool);
     auto it = setKeyPool->begin();
 
     WalletBatch batch(*database);
     while (it != std::end(*setKeyPool)) {
         const int64_t &index = *(it);
         if (index > keypool_id) {
             // set*KeyPool is ordered
             break;
         }
 
         CKeyPool keypool;
         if (batch.ReadPool(index, keypool)) {
             // TODO: This should be unnecessary
             m_pool_key_to_index.erase(keypool.vchPubKey.GetID());
         }
         LearnAllRelatedScripts(keypool.vchPubKey);
         batch.ErasePool(index);
         WalletLogPrintf("keypool index %d removed\n", index);
         it = setKeyPool->erase(it);
     }
 }
 
 void CWallet::GetScriptForMining(std::shared_ptr<CReserveScript> &script) {
     std::shared_ptr<CReserveKey> rKey = std::make_shared<CReserveKey>(this);
     CPubKey pubkey;
     if (!rKey->GetReservedKey(pubkey)) {
         return;
     }
 
     script = rKey;
     script->reserveScript = CScript() << ToByteVector(pubkey) << OP_CHECKSIG;
 }
 
 void CWallet::LockCoin(const COutPoint &output) {
     // setLockedCoins
     AssertLockHeld(cs_wallet);
     setLockedCoins.insert(output);
 }
 
 void CWallet::UnlockCoin(const COutPoint &output) {
     // setLockedCoins
     AssertLockHeld(cs_wallet);
     setLockedCoins.erase(output);
 }
 
 void CWallet::UnlockAllCoins() {
     // setLockedCoins
     AssertLockHeld(cs_wallet);
     setLockedCoins.clear();
 }
 
 bool CWallet::IsLockedCoin(const COutPoint &outpoint) const {
     // setLockedCoins
     AssertLockHeld(cs_wallet);
 
     return setLockedCoins.count(outpoint) > 0;
 }
 
 void CWallet::ListLockedCoins(std::vector<COutPoint> &vOutpts) const {
     // setLockedCoins
     AssertLockHeld(cs_wallet);
     for (COutPoint outpoint : setLockedCoins) {
         vOutpts.push_back(outpoint);
     }
 }
 
 /** @} */ // end of Actions
 
 void CWallet::GetKeyBirthTimes(
     interfaces::Chain::Lock &locked_chain,
     std::map<CTxDestination, int64_t> &mapKeyBirth) const {
     // mapKeyMetadata
     AssertLockHeld(cs_wallet);
     mapKeyBirth.clear();
 
     // Get birth times for keys with metadata.
     for (const auto &entry : mapKeyMetadata) {
         if (entry.second.nCreateTime) {
             mapKeyBirth[entry.first] = entry.second.nCreateTime;
         }
     }
 
     // Map in which we'll infer heights of other keys
     const Optional<int> tip_height = locked_chain.getHeight();
     // the tip can be reorganized; use a 144-block safety margin
     const int max_height =
         tip_height && *tip_height > 144 ? *tip_height - 144 : 0;
     std::map<CKeyID, int> mapKeyFirstBlock;
     for (const CKeyID &keyid : GetKeys()) {
         if (mapKeyBirth.count(keyid) == 0) {
             mapKeyFirstBlock[keyid] = max_height;
         }
     }
 
     // If there are no such keys, we're done.
     if (mapKeyFirstBlock.empty()) {
         return;
     }
 
     // Find first block that affects those keys, if there are any left.
     std::vector<CKeyID> vAffected;
     for (const auto &entry : mapWallet) {
         // iterate over all wallet transactions...
         const CWalletTx &wtx = entry.second;
         if (Optional<int> height = locked_chain.getBlockHeight(wtx.hashBlock)) {
             // ... which are already in a block
             for (const CTxOut &txout : wtx.tx->vout) {
                 // Iterate over all their outputs...
                 CAffectedKeysVisitor(*this, vAffected)
                     .Process(txout.scriptPubKey);
                 for (const CKeyID &keyid : vAffected) {
                     // ... and all their affected keys.
                     std::map<CKeyID, int>::iterator rit =
                         mapKeyFirstBlock.find(keyid);
                     if (rit != mapKeyFirstBlock.end() &&
                         *height < rit->second) {
                         rit->second = *height;
                     }
                 }
                 vAffected.clear();
             }
         }
     }
 
     // Extract block timestamps for those keys.
     for (const auto &entry : mapKeyFirstBlock) {
         // block times can be 2h off
         mapKeyBirth[entry.first] =
             locked_chain.getBlockTime(entry.second) - TIMESTAMP_WINDOW;
     }
 }
 
 /**
  * Compute smart timestamp for a transaction being added to the wallet.
  *
  * Logic:
  * - If sending a transaction, assign its timestamp to the current time.
  * - If receiving a transaction outside a block, assign its timestamp to the
  *   current time.
  * - If receiving a block with a future timestamp, assign all its (not already
  *   known) transactions' timestamps to the current time.
  * - If receiving a block with a past timestamp, before the most recent known
  *   transaction (that we care about), assign all its (not already known)
  *   transactions' timestamps to the same timestamp as that most-recent-known
  *   transaction.
  * - If receiving a block with a past timestamp, but after the most recent known
  *   transaction, assign all its (not already known) transactions' timestamps to
  *   the block time.
  *
  * For more information see CWalletTx::nTimeSmart,
  * https://bitcointalk.org/?topic=54527, or
  * https://github.com/bitcoin/bitcoin/pull/1393.
  */
 unsigned int CWallet::ComputeTimeSmart(const CWalletTx &wtx) const {
     unsigned int nTimeSmart = wtx.nTimeReceived;
     if (!wtx.hashUnset()) {
         int64_t blocktime;
         if (chain().findBlock(wtx.hashBlock, nullptr /* block */, &blocktime)) {
             int64_t latestNow = wtx.nTimeReceived;
             int64_t latestEntry = 0;
 
             // Tolerate times up to the last timestamp in the wallet not more
             // than 5 minutes into the future
             int64_t latestTolerated = latestNow + 300;
             const TxItems &txOrdered = wtxOrdered;
             for (auto it = txOrdered.rbegin(); it != txOrdered.rend(); ++it) {
                 CWalletTx *const pwtx = it->second;
                 if (pwtx == &wtx) {
                     continue;
                 }
                 int64_t nSmartTime;
                 nSmartTime = pwtx->nTimeSmart;
                 if (!nSmartTime) {
                     nSmartTime = pwtx->nTimeReceived;
                 }
                 if (nSmartTime <= latestTolerated) {
                     latestEntry = nSmartTime;
                     if (nSmartTime > latestNow) {
                         latestNow = nSmartTime;
                     }
                     break;
                 }
             }
 
             nTimeSmart = std::max(latestEntry, std::min(blocktime, latestNow));
         } else {
             WalletLogPrintf("%s: found %s in block %s not in index\n", __func__,
                             wtx.GetId().ToString(), wtx.hashBlock.ToString());
         }
     }
     return nTimeSmart;
 }
 
 bool CWallet::AddDestData(const CTxDestination &dest, const std::string &key,
                           const std::string &value) {
     if (boost::get<CNoDestination>(&dest)) {
         return false;
     }
 
     mapAddressBook[dest].destdata.insert(std::make_pair(key, value));
     return WalletBatch(*database).WriteDestData(dest, key, value);
 }
 
 bool CWallet::EraseDestData(const CTxDestination &dest,
                             const std::string &key) {
     if (!mapAddressBook[dest].destdata.erase(key)) {
         return false;
     }
 
     return WalletBatch(*database).EraseDestData(dest, key);
 }
 
 void CWallet::LoadDestData(const CTxDestination &dest, const std::string &key,
                            const std::string &value) {
     mapAddressBook[dest].destdata.insert(std::make_pair(key, value));
 }
 
 bool CWallet::GetDestData(const CTxDestination &dest, const std::string &key,
                           std::string *value) const {
     std::map<CTxDestination, CAddressBookData>::const_iterator i =
         mapAddressBook.find(dest);
     if (i != mapAddressBook.end()) {
         CAddressBookData::StringMap::const_iterator j =
             i->second.destdata.find(key);
         if (j != i->second.destdata.end()) {
             if (value) {
                 *value = j->second;
             }
 
             return true;
         }
     }
     return false;
 }
 
 std::vector<std::string>
 CWallet::GetDestValues(const std::string &prefix) const {
     LOCK(cs_wallet);
     std::vector<std::string> values;
     for (const auto &address : mapAddressBook) {
         for (const auto &data : address.second.destdata) {
             if (!data.first.compare(0, prefix.size(), prefix)) {
                 values.emplace_back(data.second);
             }
         }
     }
     return values;
 }
 
 bool CWallet::Verify(const CChainParams &chainParams, interfaces::Chain &chain,
                      const WalletLocation &location, bool salvage_wallet,
                      std::string &error_string, std::string &warning_string) {
     // Do some checking on wallet path. It should be either a:
     //
     // 1. Path where a directory can be created.
     // 2. Path to an existing directory.
     // 3. Path to a symlink to a directory.
     // 4. For backwards compatibility, the name of a data file in -walletdir.
     LOCK(cs_wallets);
     const fs::path &wallet_path = location.GetPath();
     fs::file_type path_type = fs::symlink_status(wallet_path).type();
     if (!(path_type == fs::file_not_found || path_type == fs::directory_file ||
           (path_type == fs::symlink_file && fs::is_directory(wallet_path)) ||
           (path_type == fs::regular_file &&
            fs::path(location.GetName()).filename() == location.GetName()))) {
         error_string =
             strprintf("Invalid -wallet path '%s'. -wallet path should point to "
                       "a directory where wallet.dat and "
                       "database/log.?????????? files can be stored, a location "
                       "where such a directory could be created, "
                       "or (for backwards compatibility) the name of an "
                       "existing data file in -walletdir (%s)",
                       location.GetName(), GetWalletDir());
         return false;
     }
 
     // Make sure that the wallet path doesn't clash with an existing wallet path
     if (IsWalletLoaded(wallet_path)) {
         error_string = strprintf(
             "Error loading wallet %s. Duplicate -wallet filename specified.",
             location.GetName());
         return false;
     }
 
     // Keep same database environment instance across Verify/Recover calls
     // below.
     std::unique_ptr<WalletDatabase> database =
         WalletDatabase::Create(wallet_path);
 
     try {
         if (!WalletBatch::VerifyEnvironment(wallet_path, error_string)) {
             return false;
         }
     } catch (const fs::filesystem_error &e) {
         error_string =
             strprintf("Error loading wallet %s. %s", location.GetName(),
                       fsbridge::get_filesystem_error_message(e));
         return false;
     }
 
     if (salvage_wallet) {
         // Recover readable keypairs:
         CWallet dummyWallet(chainParams, &chain, WalletLocation(),
                             WalletDatabase::CreateDummy());
         std::string backup_filename;
         if (!WalletBatch::Recover(
                 wallet_path, static_cast<void *>(&dummyWallet),
                 WalletBatch::RecoverKeysOnlyFilter, backup_filename)) {
             return false;
         }
     }
 
     return WalletBatch::VerifyDatabaseFile(wallet_path, warning_string,
                                            error_string);
 }
 
 void CWallet::MarkPreSplitKeys() {
     WalletBatch batch(*database);
     for (auto it = setExternalKeyPool.begin();
          it != setExternalKeyPool.end();) {
         int64_t index = *it;
         CKeyPool keypool;
         if (!batch.ReadPool(index, keypool)) {
             throw std::runtime_error(std::string(__func__) +
                                      ": read keypool entry failed");
         }
         keypool.m_pre_split = true;
         if (!batch.WritePool(index, keypool)) {
             throw std::runtime_error(std::string(__func__) +
                                      ": writing modified keypool entry failed");
         }
         set_pre_split_keypool.insert(index);
         it = setExternalKeyPool.erase(it);
     }
 }
 
 std::shared_ptr<CWallet> CWallet::CreateWalletFromFile(
     const CChainParams &chainParams, interfaces::Chain &chain,
     const WalletLocation &location, uint64_t wallet_creation_flags) {
     const std::string &walletFile = location.GetName();
 
     // Needed to restore wallet transaction meta data after -zapwallettxes
     std::vector<CWalletTx> vWtx;
 
     if (gArgs.GetBoolArg("-zapwallettxes", false)) {
         chain.initMessage(
             _("Zapping all transactions from wallet...").translated);
 
         std::unique_ptr<CWallet> tempWallet = std::make_unique<CWallet>(
             chainParams, &chain, location,
             WalletDatabase::Create(location.GetPath()));
         DBErrors nZapWalletRet = tempWallet->ZapWalletTx(vWtx);
         if (nZapWalletRet != DBErrors::LOAD_OK) {
             chain.initError(
                 strprintf(_("Error loading %s: Wallet corrupted").translated,
                           walletFile));
             return nullptr;
         }
     }
 
     chain.initMessage(_("Loading wallet...").translated);
 
     int64_t nStart = GetTimeMillis();
     bool fFirstRun = true;
     // TODO: Can't use std::make_shared because we need a custom deleter but
     // should be possible to use std::allocate_shared.
     std::shared_ptr<CWallet> walletInstance(
         new CWallet(chainParams, &chain, location,
                     WalletDatabase::Create(location.GetPath())),
         ReleaseWallet);
     DBErrors nLoadWalletRet = walletInstance->LoadWallet(fFirstRun);
     if (nLoadWalletRet != DBErrors::LOAD_OK) {
         if (nLoadWalletRet == DBErrors::CORRUPT) {
             chain.initError(
                 strprintf(_("Error loading %s: Wallet corrupted").translated,
                           walletFile));
             return nullptr;
         }
 
         if (nLoadWalletRet == DBErrors::NONCRITICAL_ERROR) {
             chain.initError(strprintf(
                 _("Error reading %s! All keys read correctly, but transaction "
                   "data or address book entries might be missing or incorrect.")
                     .translated,
                 walletFile));
         } else if (nLoadWalletRet == DBErrors::TOO_NEW) {
             chain.initError(strprintf(
                 _("Error loading %s: Wallet requires newer version of %s")
                     .translated,
                 walletFile, PACKAGE_NAME));
             return nullptr;
         } else if (nLoadWalletRet == DBErrors::NEED_REWRITE) {
             chain.initError(strprintf(
                 _("Wallet needed to be rewritten: restart %s to complete")
                     .translated,
                 PACKAGE_NAME));
             return nullptr;
         } else {
             chain.initError(
                 strprintf(_("Error loading %s").translated, walletFile));
             return nullptr;
         }
     }
 
     int prev_version = walletInstance->nWalletVersion;
     if (gArgs.GetBoolArg("-upgradewallet", fFirstRun)) {
         int nMaxVersion = gArgs.GetArg("-upgradewallet", 0);
         // The -upgradewallet without argument case
         if (nMaxVersion == 0) {
             walletInstance->WalletLogPrintf("Performing wallet upgrade to %i\n",
                                             FEATURE_LATEST);
             nMaxVersion = FEATURE_LATEST;
             // permanently upgrade the wallet immediately
             walletInstance->SetMinVersion(FEATURE_LATEST);
         } else {
             walletInstance->WalletLogPrintf(
                 "Allowing wallet upgrade up to %i\n", nMaxVersion);
         }
 
         if (nMaxVersion < walletInstance->GetVersion()) {
             chain.initError(_("Cannot downgrade wallet").translated);
             return nullptr;
         }
 
         walletInstance->SetMaxVersion(nMaxVersion);
     }
 
     // Upgrade to HD if explicit upgrade
     if (gArgs.GetBoolArg("-upgradewallet", false)) {
         LOCK(walletInstance->cs_wallet);
 
         // Do not upgrade versions to any version between HD_SPLIT and
         // FEATURE_PRE_SPLIT_KEYPOOL unless already supporting HD_SPLIT
         int max_version = walletInstance->nWalletVersion;
         if (!walletInstance->CanSupportFeature(FEATURE_HD_SPLIT) &&
             max_version >= FEATURE_HD_SPLIT &&
             max_version < FEATURE_PRE_SPLIT_KEYPOOL) {
             chain.initError(
                 _("Cannot upgrade a non HD split wallet without upgrading to "
                   "support pre split keypool. Please use -upgradewallet=200300 "
                   "or -upgradewallet with no version specified.")
                     .translated);
             return nullptr;
         }
 
         bool hd_upgrade = false;
         bool split_upgrade = false;
         if (walletInstance->CanSupportFeature(FEATURE_HD) &&
             !walletInstance->IsHDEnabled()) {
             walletInstance->WalletLogPrintf("Upgrading wallet to HD\n");
             walletInstance->SetMinVersion(FEATURE_HD);
 
             // generate a new master key
             CPubKey masterPubKey = walletInstance->GenerateNewSeed();
             walletInstance->SetHDSeed(masterPubKey);
             hd_upgrade = true;
         }
         // Upgrade to HD chain split if necessary
         if (walletInstance->CanSupportFeature(FEATURE_HD_SPLIT)) {
             walletInstance->WalletLogPrintf(
                 "Upgrading wallet to use HD chain split\n");
             walletInstance->SetMinVersion(FEATURE_PRE_SPLIT_KEYPOOL);
             split_upgrade = FEATURE_HD_SPLIT > prev_version;
         }
         // Mark all keys currently in the keypool as pre-split
         if (split_upgrade) {
             walletInstance->MarkPreSplitKeys();
         }
         // Regenerate the keypool if upgraded to HD
         if (hd_upgrade) {
             if (!walletInstance->TopUpKeyPool()) {
                 chain.initError(_("Unable to generate keys").translated);
                 return nullptr;
             }
         }
     }
 
     if (fFirstRun) {
         // Ensure this wallet.dat can only be opened by clients supporting
         // HD with chain split and expects no default key.
         walletInstance->SetMinVersion(FEATURE_LATEST);
 
         if ((wallet_creation_flags & WALLET_FLAG_DISABLE_PRIVATE_KEYS)) {
             // selective allow to set flags
             walletInstance->SetWalletFlag(WALLET_FLAG_DISABLE_PRIVATE_KEYS);
         } else if (wallet_creation_flags & WALLET_FLAG_BLANK_WALLET) {
             walletInstance->SetWalletFlag(WALLET_FLAG_BLANK_WALLET);
         } else {
             // generate a new seed
             CPubKey seed = walletInstance->GenerateNewSeed();
             walletInstance->SetHDSeed(seed);
         } // Otherwise, do not generate a new seed
 
         // Top up the keypool
         if (walletInstance->CanGenerateKeys() &&
             !walletInstance->TopUpKeyPool()) {
             chain.initError(_("Unable to generate initial keys").translated);
             return nullptr;
         }
 
         auto locked_chain = chain.lock();
         walletInstance->ChainStateFlushed(locked_chain->getTipLocator());
     } else if (wallet_creation_flags & WALLET_FLAG_DISABLE_PRIVATE_KEYS) {
         // Make it impossible to disable private keys after creation
         chain.initError(
             strprintf(_("Error loading %s: Private keys can only be "
                         "disabled during creation")
                           .translated,
                       walletFile));
         return nullptr;
     } else if (walletInstance->IsWalletFlagSet(
                    WALLET_FLAG_DISABLE_PRIVATE_KEYS)) {
         LOCK(walletInstance->cs_KeyStore);
         if (!walletInstance->mapKeys.empty() ||
             !walletInstance->mapCryptedKeys.empty()) {
             chain.initWarning(
                 strprintf(_("Warning: Private keys detected in wallet "
                             "{%s} with disabled private keys")
                               .translated,
                           walletFile));
         }
     }
 
     if (gArgs.IsArgSet("-mintxfee")) {
         Amount n = Amount::zero();
         if (!ParseMoney(gArgs.GetArg("-mintxfee", ""), n) ||
             n == Amount::zero()) {
             chain.initError(
                 AmountErrMsg("mintxfee", gArgs.GetArg("-mintxfee", "")));
             return nullptr;
         }
         if (n > HIGH_TX_FEE_PER_KB) {
             chain.initWarning(
                 AmountHighWarn("-mintxfee") + " " +
                 _("This is the minimum transaction fee you pay on "
                   "every transaction.")
                     .translated);
         }
         walletInstance->m_min_fee = CFeeRate(n);
     }
 
     if (gArgs.IsArgSet("-fallbackfee")) {
         Amount nFeePerK = Amount::zero();
         if (!ParseMoney(gArgs.GetArg("-fallbackfee", ""), nFeePerK)) {
             chain.initError(strprintf(
                 _("Invalid amount for -fallbackfee=<amount>: '%s'").translated,
                 gArgs.GetArg("-fallbackfee", "")));
             return nullptr;
         }
         if (nFeePerK > HIGH_TX_FEE_PER_KB) {
             chain.initWarning(
                 AmountHighWarn("-fallbackfee") + " " +
                 _("This is the transaction fee you may pay when fee "
                   "estimates are not available.")
                     .translated);
         }
         walletInstance->m_fallback_fee = CFeeRate(nFeePerK);
         // disable fallback fee in case value was set to 0, enable if non-null
         // value
         walletInstance->m_allow_fallback_fee = (nFeePerK != Amount::zero());
     }
     if (gArgs.IsArgSet("-paytxfee")) {
         Amount nFeePerK = Amount::zero();
         if (!ParseMoney(gArgs.GetArg("-paytxfee", ""), nFeePerK)) {
             chain.initError(
                 AmountErrMsg("paytxfee", gArgs.GetArg("-paytxfee", "")));
             return nullptr;
         }
         if (nFeePerK > HIGH_TX_FEE_PER_KB) {
             chain.initWarning(
                 AmountHighWarn("-paytxfee") + " " +
                 _("This is the transaction fee you will pay if you "
                   "send a transaction.")
                     .translated);
         }
         walletInstance->m_pay_tx_fee = CFeeRate(nFeePerK, 1000);
         if (walletInstance->m_pay_tx_fee < chain.relayMinFee()) {
             chain.initError(strprintf(
                 _("Invalid amount for -paytxfee=<amount>: '%s' "
                   "(must be at least %s)")
                     .translated,
                 gArgs.GetArg("-paytxfee", ""), chain.relayMinFee().ToString()));
             return nullptr;
         }
     }
+
+    if (gArgs.IsArgSet("-maxtxfee")) {
+        Amount nMaxFee = Amount::zero();
+        if (!ParseMoney(gArgs.GetArg("-maxtxfee", ""), nMaxFee)) {
+            chain.initError(
+                AmountErrMsg("maxtxfee", gArgs.GetArg("-maxtxfee", "")));
+            return nullptr;
+        }
+        if (nMaxFee > HIGH_MAX_TX_FEE) {
+            chain.initWarning(_("-maxtxfee is set very high! Fees this large "
+                                "could be paid on a single transaction.")
+                                  .translated);
+        }
+        if (CFeeRate(nMaxFee, 1000) < chain.relayMinFee()) {
+            chain.initError(strprintf(
+                _("Invalid amount for -maxtxfee=<amount>: '%s' (must be at "
+                  "least the minrelay fee of %s to prevent stuck transactions)")
+                    .translated,
+                gArgs.GetArg("-maxtxfee", ""), chain.relayMinFee().ToString()));
+            return nullptr;
+        }
+        walletInstance->m_default_max_tx_fee = nMaxFee;
+    }
+
+    if (chain.relayMinFee().GetFeePerK() > HIGH_TX_FEE_PER_KB) {
+        chain.initWarning(
+            AmountHighWarn("-minrelaytxfee") + " " +
+            _("The wallet will avoid paying less than the minimum relay fee.")
+                .translated);
+    }
+
     walletInstance->m_spend_zero_conf_change =
         gArgs.GetBoolArg("-spendzeroconfchange", DEFAULT_SPEND_ZEROCONF_CHANGE);
 
     walletInstance->m_default_address_type = DEFAULT_ADDRESS_TYPE;
     walletInstance->m_default_change_type = DEFAULT_CHANGE_TYPE;
 
     walletInstance->WalletLogPrintf("Wallet completed loading in %15dms\n",
                                     GetTimeMillis() - nStart);
 
     // Try to top up keypool. No-op if the wallet is locked.
     walletInstance->TopUpKeyPool();
 
     auto locked_chain = chain.lock();
     LOCK(walletInstance->cs_wallet);
 
     int rescan_height = 0;
     if (!gArgs.GetBoolArg("-rescan", false)) {
         WalletBatch batch(*walletInstance->database);
         CBlockLocator locator;
         if (batch.ReadBestBlock(locator)) {
             if (const Optional<int> fork_height =
                     locked_chain->findLocatorFork(locator)) {
                 rescan_height = *fork_height;
             }
         }
     }
 
     const Optional<int> tip_height = locked_chain->getHeight();
     if (tip_height) {
         walletInstance->m_last_block_processed =
             locked_chain->getBlockHash(*tip_height);
     } else {
         walletInstance->m_last_block_processed.SetNull();
     }
 
     if (tip_height && *tip_height != rescan_height) {
         // We can't rescan beyond non-pruned blocks, stop and throw an error.
         // This might happen if a user uses an old wallet within a pruned node
         // or if he ran -disablewallet for a longer time, then decided to
         // re-enable.
         if (chain.getPruneMode()) {
             int block_height = *tip_height;
             while (block_height > 0 &&
                    locked_chain->haveBlockOnDisk(block_height - 1) &&
                    rescan_height != block_height) {
                 --block_height;
             }
 
             if (rescan_height != block_height) {
                 chain.initError(
                     _("Prune: last wallet synchronisation goes beyond "
                       "pruned data. You need to -reindex (download the "
                       "whole blockchain again in case of pruned node)")
                         .translated);
                 return nullptr;
             }
         }
 
         chain.initMessage(_("Rescanning...").translated);
         walletInstance->WalletLogPrintf(
             "Rescanning last %i blocks (from block %i)...\n",
             *tip_height - rescan_height, rescan_height);
 
         // No need to read and scan block if block was created before our wallet
         // birthday (as adjusted for block time variability)
         if (walletInstance->nTimeFirstKey) {
             if (Optional<int> first_block =
                     locked_chain->findFirstBlockWithTimeAndHeight(
                         walletInstance->nTimeFirstKey - TIMESTAMP_WINDOW,
                         rescan_height, nullptr)) {
                 rescan_height = *first_block;
             }
         }
 
         nStart = GetTimeMillis();
         {
             WalletRescanReserver reserver(walletInstance.get());
             if (!reserver.reserve() ||
                 (ScanResult::SUCCESS !=
                  walletInstance
                      ->ScanForWalletTransactions(
                          locked_chain->getBlockHash(rescan_height), BlockHash(),
                          reserver, true /* update */)
                      .status)) {
                 chain.initError(
                     _("Failed to rescan the wallet during initialization")
                         .translated);
                 return nullptr;
             }
         }
         walletInstance->WalletLogPrintf("Rescan completed in %15dms\n",
                                         GetTimeMillis() - nStart);
         walletInstance->ChainStateFlushed(locked_chain->getTipLocator());
         walletInstance->database->IncrementUpdateCounter();
 
         // Restore wallet transaction metadata after -zapwallettxes=1
         if (gArgs.GetBoolArg("-zapwallettxes", false) &&
             gArgs.GetArg("-zapwallettxes", "1") != "2") {
             WalletBatch batch(*walletInstance->database);
 
             for (const CWalletTx &wtxOld : vWtx) {
                 const TxId txid = wtxOld.GetId();
                 std::map<TxId, CWalletTx>::iterator mi =
                     walletInstance->mapWallet.find(txid);
                 if (mi != walletInstance->mapWallet.end()) {
                     const CWalletTx *copyFrom = &wtxOld;
                     CWalletTx *copyTo = &mi->second;
                     copyTo->mapValue = copyFrom->mapValue;
                     copyTo->vOrderForm = copyFrom->vOrderForm;
                     copyTo->nTimeReceived = copyFrom->nTimeReceived;
                     copyTo->nTimeSmart = copyFrom->nTimeSmart;
                     copyTo->fFromMe = copyFrom->fFromMe;
                     copyTo->nOrderPos = copyFrom->nOrderPos;
                     batch.WriteTx(*copyTo);
                 }
             }
         }
     }
 
     chain.loadWallet(interfaces::MakeWallet(walletInstance));
 
     // Register with the validation interface. It's ok to do this after rescan
     // since we're still holding locked_chain.
     walletInstance->handleNotifications();
 
     walletInstance->SetBroadcastTransactions(
         gArgs.GetBoolArg("-walletbroadcast", DEFAULT_WALLETBROADCAST));
 
     walletInstance->WalletLogPrintf("setKeyPool.size() = %u\n",
                                     walletInstance->GetKeyPoolSize());
     walletInstance->WalletLogPrintf("mapWallet.size() = %u\n",
                                     walletInstance->mapWallet.size());
     walletInstance->WalletLogPrintf("mapAddressBook.size() = %u\n",
                                     walletInstance->mapAddressBook.size());
 
     return walletInstance;
 }
 
 void CWallet::handleNotifications() {
     m_chain_notifications_handler = m_chain->handleNotifications(*this);
 }
 
 void CWallet::postInitProcess() {
     auto locked_chain = chain().lock();
     LOCK(cs_wallet);
 
     // Add wallet transactions that aren't already in a block to mempool.
     // Do this here as mempool requires genesis block to be loaded.
     ReacceptWalletTransactions(*locked_chain);
 
     // Update wallet transactions with current mempool transactions.
     chain().requestMempoolTransactions(*this);
 }
 
 bool CWallet::BackupWallet(const std::string &strDest) {
     return database->Backup(strDest);
 }
 
 CKeyPool::CKeyPool() {
     nTime = GetTime();
     fInternal = false;
     m_pre_split = false;
 }
 
 CKeyPool::CKeyPool(const CPubKey &vchPubKeyIn, bool internalIn) {
     nTime = GetTime();
     vchPubKey = vchPubKeyIn;
     fInternal = internalIn;
     m_pre_split = false;
 }
 
 CWalletKey::CWalletKey(int64_t nExpires) {
     nTimeCreated = (nExpires ? GetTime() : 0);
     nTimeExpires = nExpires;
 }
 
 void CMerkleTx::SetMerkleBranch(const BlockHash &block_hash, int posInBlock) {
     // Update the tx's hashBlock
     hashBlock = block_hash;
 
     // Set the position of the transaction in the block.
     nIndex = posInBlock;
 }
 
 int CMerkleTx::GetDepthInMainChain(
     interfaces::Chain::Lock &locked_chain) const {
     if (hashUnset()) {
         return 0;
     }
 
     return locked_chain.getBlockDepth(hashBlock) * (nIndex == -1 ? -1 : 1);
 }
 
 int CMerkleTx::GetBlocksToMaturity(
     interfaces::Chain::Lock &locked_chain) const {
     if (!IsCoinBase()) {
         return 0;
     }
 
     return std::max(0, (COINBASE_MATURITY + 1) -
                            GetDepthInMainChain(locked_chain));
 }
 
 bool CMerkleTx::IsImmatureCoinBase(
     interfaces::Chain::Lock &locked_chain) const {
     // note GetBlocksToMaturity is 0 for non-coinbase tx
     return GetBlocksToMaturity(locked_chain) > 0;
 }
 
 bool CWalletTx::AcceptToMemoryPool(interfaces::Chain::Lock &locked_chain,
                                    CValidationState &state) {
     // We must set fInMempool here - while it will be re-set to true by the
     // entered-mempool callback, if we did not there would be a race where a
     // user could call sendmoney in a loop and hit spurious out of funds errors
     // because we think that this newly generated transaction's change is
     // unavailable as we're not yet aware that it is in the mempool.
     bool ret = locked_chain.submitToMemoryPool(
-        ::GetConfig(), tx, pwallet->chain().maxTxFee(), state);
+        ::GetConfig(), tx, pwallet->m_default_max_tx_fee, state);
     fInMempool |= ret;
     return ret;
 }
 
 void CWallet::LearnRelatedScripts(const CPubKey &key, OutputType type) {
     // Nothing to do...
 }
 
 void CWallet::LearnAllRelatedScripts(const CPubKey &key) {
     // Nothing to do...
 }
 
 std::vector<OutputGroup>
 CWallet::GroupOutputs(const std::vector<COutput> &outputs,
                       bool single_coin) const {
     std::vector<OutputGroup> groups;
     std::map<CTxDestination, OutputGroup> gmap;
     CTxDestination dst;
     for (const auto &output : outputs) {
         if (output.fSpendable) {
             CInputCoin input_coin = output.GetInputCoin();
 
             size_t ancestors, descendants;
             chain().getTransactionAncestry(output.tx->GetId(), ancestors,
                                            descendants);
             if (!single_coin &&
                 ExtractDestination(output.tx->tx->vout[output.i].scriptPubKey,
                                    dst)) {
                 // Limit output groups to no more than 10 entries, to protect
                 // against inadvertently creating a too-large transaction
                 // when using -avoidpartialspends
                 if (gmap[dst].m_outputs.size() >= OUTPUT_GROUP_MAX_ENTRIES) {
                     groups.push_back(gmap[dst]);
                     gmap.erase(dst);
                 }
                 gmap[dst].Insert(input_coin, output.nDepth,
                                  output.tx->IsFromMe(ISMINE_ALL), ancestors,
                                  descendants);
             } else {
                 groups.emplace_back(input_coin, output.nDepth,
                                     output.tx->IsFromMe(ISMINE_ALL), ancestors,
                                     descendants);
             }
         }
     }
     if (!single_coin) {
         for (const auto &it : gmap) {
             groups.push_back(it.second);
         }
     }
     return groups;
 }
 
 bool CWallet::GetKeyOrigin(const CKeyID &keyID, KeyOriginInfo &info) const {
     CKeyMetadata meta;
     {
         LOCK(cs_wallet);
         auto it = mapKeyMetadata.find(keyID);
         if (it != mapKeyMetadata.end()) {
             meta = it->second;
         }
     }
     if (meta.has_key_origin) {
         std::copy(meta.key_origin.fingerprint, meta.key_origin.fingerprint + 4,
                   info.fingerprint);
         info.path = meta.key_origin.path;
     } else {
         // Single pubkeys get the master fingerprint of themselves
         std::copy(keyID.begin(), keyID.begin() + 4, info.fingerprint);
     }
     return true;
 }
 
 bool CWallet::AddKeyOrigin(const CPubKey &pubkey, const KeyOriginInfo &info) {
     LOCK(cs_wallet);
     std::copy(info.fingerprint, info.fingerprint + 4,
               mapKeyMetadata[pubkey.GetID()].key_origin.fingerprint);
     mapKeyMetadata[pubkey.GetID()].key_origin.path = info.path;
     mapKeyMetadata[pubkey.GetID()].has_key_origin = true;
     mapKeyMetadata[pubkey.GetID()].hdKeypath = WriteHDKeypath(info.path);
     return WriteKeyMetadata(mapKeyMetadata[pubkey.GetID()], pubkey, true);
 }
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index f606888a3..9cf5652c3 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -1,1530 +1,1542 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Copyright (c) 2018-2020 The Bitcoin developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_WALLET_WALLET_H
 #define BITCOIN_WALLET_WALLET_H
 
 #include <amount.h>
 #include <interfaces/chain.h>
 #include <interfaces/handler.h>
 #include <outputtype.h>
 #include <primitives/blockhash.h>
 #include <script/ismine.h>
 #include <script/sign.h>
 #include <streams.h>
 #include <tinyformat.h>
 #include <ui_interface.h>
 #include <util/strencodings.h>
 #include <util/system.h>
 #include <validationinterface.h>
 #include <wallet/coinselection.h>
 #include <wallet/crypter.h>
 #include <wallet/rpcwallet.h>
 #include <wallet/walletdb.h>
 #include <wallet/walletutil.h>
 
 #include <algorithm>
 #include <atomic>
 #include <cstdint>
 #include <map>
 #include <memory>
 #include <set>
 #include <stdexcept>
 #include <string>
 #include <utility>
 #include <vector>
 
 //! Explicitly unload and delete the wallet.
 //  Blocks the current thread after signaling the unload intent so that all
 //  wallet clients release the wallet.
 //  Note that, when blocking is not required, the wallet is implicitly unloaded
 //  by the shared pointer deleter.
 void UnloadWallet(std::shared_ptr<CWallet> &&wallet);
 
 bool AddWallet(const std::shared_ptr<CWallet> &wallet);
 bool RemoveWallet(const std::shared_ptr<CWallet> &wallet);
 bool HasWallets();
 std::vector<std::shared_ptr<CWallet>> GetWallets();
 std::shared_ptr<CWallet> GetWallet(const std::string &name);
 std::shared_ptr<CWallet> LoadWallet(const CChainParams &chainParams,
                                     interfaces::Chain &chain,
                                     const WalletLocation &location,
                                     std::string &error, std::string &warning);
 
 //! Default for -keypool
 static const unsigned int DEFAULT_KEYPOOL_SIZE = 1000;
 //! -paytxfee default
 constexpr Amount DEFAULT_PAY_TX_FEE = Amount::zero();
 //! -fallbackfee default
 static const Amount DEFAULT_FALLBACK_FEE(20000 * SATOSHI);
 //! -mintxfee default
 static const Amount DEFAULT_TRANSACTION_MINFEE_PER_KB = 1000 * SATOSHI;
 //! minimum recommended increment for BIP 125 replacement txs
 static const Amount WALLET_INCREMENTAL_RELAY_FEE(5000 * SATOSHI);
 //! Default for -spendzeroconfchange
 static const bool DEFAULT_SPEND_ZEROCONF_CHANGE = true;
 //! Default for -walletrejectlongchains
 static const bool DEFAULT_WALLET_REJECT_LONG_CHAINS = false;
 //! Default for -avoidpartialspends
 static const bool DEFAULT_AVOIDPARTIALSPENDS = false;
 static const bool DEFAULT_WALLETBROADCAST = true;
 static const bool DEFAULT_DISABLE_WALLET = false;
+//! -maxtxfee default
+constexpr Amount DEFAULT_TRANSACTION_MAXFEE{COIN / 10};
+//! Discourage users to set fees higher than this amount (in satoshis) per kB
+constexpr Amount HIGH_TX_FEE_PER_KB{COIN / 100};
+//! -maxtxfee will warn if called with a higher fee than this amount (in
+//! satoshis)
+constexpr Amount HIGH_MAX_TX_FEE{100 * HIGH_TX_FEE_PER_KB};
 
 class CChainParams;
 class CCoinControl;
 class COutput;
 class CReserveKey;
 class CScript;
 class CTxMemPool;
 class CWalletTx;
 
 /** (client) version numbers for particular wallet features */
 enum WalletFeature {
     // the earliest version new wallets supports (only useful for
     // getwalletinfo's clientversion output)
     FEATURE_BASE = 10500,
 
     // wallet encryption
     FEATURE_WALLETCRYPT = 40000,
     // compressed public keys
     FEATURE_COMPRPUBKEY = 60000,
 
     // Hierarchical key derivation after BIP32 (HD Wallet)
     FEATURE_HD = 130000,
 
     // Wallet with HD chain split (change outputs will use m/0'/1'/k)
     FEATURE_HD_SPLIT = 160300,
 
     // Wallet without a default key written
     FEATURE_NO_DEFAULT_KEY = 190700,
 
     // Upgraded to HD SPLIT and can have a pre-split keypool
     FEATURE_PRE_SPLIT_KEYPOOL = 200300,
 
     FEATURE_LATEST = FEATURE_PRE_SPLIT_KEYPOOL,
 };
 
 //! Default for -addresstype
 constexpr OutputType DEFAULT_ADDRESS_TYPE{OutputType::LEGACY};
 
 //! Default for -changetype
 constexpr OutputType DEFAULT_CHANGE_TYPE{OutputType::CHANGE_AUTO};
 
 enum WalletFlags : uint64_t {
     // Wallet flags in the upper section (> 1 << 31) will lead to not opening
     // the wallet if flag is unknown.
     // Unknown wallet flags in the lower section <= (1 << 31) will be tolerated.
 
     // Indicates that the metadata has already been upgraded to contain key
     // origins
     WALLET_FLAG_KEY_ORIGIN_METADATA = (1ULL << 1),
 
     // Will enforce the rule that the wallet can't contain any private keys
     // (only watch-only/pubkeys).
     WALLET_FLAG_DISABLE_PRIVATE_KEYS = (1ULL << 32),
 
     //! Flag set when a wallet contains no HD seed and no private keys, scripts,
     //! addresses, and other watch only things, and is therefore "blank."
     //!
     //! The only function this flag serves is to distinguish a blank wallet from
     //! a newly created wallet when the wallet database is loaded, to avoid
     //! initialization that should only happen on first run.
     //!
     //! This flag is also a mandatory flag to prevent previous versions of
     //! bitcoin from opening the wallet, thinking it was newly created, and
     //! then improperly reinitializing it.
     WALLET_FLAG_BLANK_WALLET = (1ULL << 33),
 };
 
 static constexpr uint64_t g_known_wallet_flags =
     WALLET_FLAG_DISABLE_PRIVATE_KEYS | WALLET_FLAG_BLANK_WALLET |
     WALLET_FLAG_KEY_ORIGIN_METADATA;
 
 /** A key pool entry */
 class CKeyPool {
 public:
     int64_t nTime;
     CPubKey vchPubKey;
     // for change outputs
     bool fInternal;
     // For keys generated before keypool split upgrade
     bool m_pre_split;
 
     CKeyPool();
     CKeyPool(const CPubKey &vchPubKeyIn, bool internalIn);
 
     ADD_SERIALIZE_METHODS;
 
     template <typename Stream, typename Operation>
     inline void SerializationOp(Stream &s, Operation ser_action) {
         int nVersion = s.GetVersion();
         if (!(s.GetType() & SER_GETHASH)) {
             READWRITE(nVersion);
         }
 
         READWRITE(nTime);
         READWRITE(vchPubKey);
         if (ser_action.ForRead()) {
             try {
                 READWRITE(fInternal);
             } catch (std::ios_base::failure &) {
                 /**
                  * flag as external address if we can't read the internal
                  * boolean (this will be the case for any wallet before the HD
                  * chain split version)
                  */
                 fInternal = false;
             }
             try {
                 READWRITE(m_pre_split);
             } catch (std::ios_base::failure &) {
                 /**
                  * flag as postsplit address if we can't read the m_pre_split
                  * boolean (this will be the case for any wallet that upgrades
                  * to HD chain split)
                  */
                 m_pre_split = false;
             }
         } else {
             READWRITE(fInternal);
             READWRITE(m_pre_split);
         }
     }
 };
 
 /** Address book data */
 class CAddressBookData {
 public:
     std::string name;
     std::string purpose;
 
     CAddressBookData() : purpose("unknown") {}
 
     typedef std::map<std::string, std::string> StringMap;
     StringMap destdata;
 };
 
 struct CRecipient {
     CScript scriptPubKey;
     Amount nAmount;
     bool fSubtractFeeFromAmount;
 };
 
 typedef std::map<std::string, std::string> mapValue_t;
 
 static inline void ReadOrderPos(int64_t &nOrderPos, mapValue_t &mapValue) {
     if (!mapValue.count("n")) {
         // TODO: calculate elsewhere
         nOrderPos = -1;
         return;
     }
 
     nOrderPos = atoi64(mapValue["n"].c_str());
 }
 
 static inline void WriteOrderPos(const int64_t &nOrderPos,
                                  mapValue_t &mapValue) {
     if (nOrderPos == -1) {
         return;
     }
     mapValue["n"] = i64tostr(nOrderPos);
 }
 
 struct COutputEntry {
     CTxDestination destination;
     Amount amount;
     int vout;
 };
 
 /** A transaction with a merkle branch linking it to the block chain. */
 class CMerkleTx {
 private:
     /** Constant used in hashBlock to indicate tx has been abandoned */
     static const BlockHash ABANDON_HASH;
 
 public:
     CTransactionRef tx;
     BlockHash hashBlock;
 
     /**
      * An nIndex == -1 means that hashBlock (in nonzero) refers to the earliest
      * block in the chain we know this or any in-wallet dependency conflicts
      * with. Older clients interpret nIndex == -1 as unconfirmed for backward
      * compatibility.
      */
     int nIndex;
 
     CMerkleTx() {
         SetTx(MakeTransactionRef());
         Init();
     }
 
     explicit CMerkleTx(CTransactionRef arg) {
         SetTx(std::move(arg));
         Init();
     }
 
     void Init() {
         hashBlock = BlockHash();
         nIndex = -1;
     }
 
     void SetTx(CTransactionRef arg) { tx = std::move(arg); }
 
     ADD_SERIALIZE_METHODS;
 
     template <typename Stream, typename Operation>
     inline void SerializationOp(Stream &s, Operation ser_action) {
         // For compatibility with older versions.
         std::vector<uint256> vMerkleBranch;
         READWRITE(tx);
         READWRITE(hashBlock);
         READWRITE(vMerkleBranch);
         READWRITE(nIndex);
     }
 
     void SetMerkleBranch(const BlockHash &block_hash, int posInBlock);
 
     /**
      * Return depth of transaction in blockchain:
      * <0  : conflicts with a transaction this deep in the blockchain
      *  0  : in memory pool, waiting to be included in a block
      * >=1 : this many blocks deep in the main chain
      */
     int GetDepthInMainChain(interfaces::Chain::Lock &locked_chain) const;
     bool IsInMainChain(interfaces::Chain::Lock &locked_chain) const {
         return GetDepthInMainChain(locked_chain) > 0;
     }
 
     /**
      * @return number of blocks to maturity for this transaction:
      *  0 : is not a coinbase transaction, or is a mature coinbase transaction
      * >0 : is a coinbase transaction which matures in this many blocks
      */
     int GetBlocksToMaturity(interfaces::Chain::Lock &locked_chain) const;
     bool hashUnset() const {
         return (hashBlock.IsNull() || hashBlock == ABANDON_HASH);
     }
     bool isAbandoned() const { return (hashBlock == ABANDON_HASH); }
     void setAbandoned() { hashBlock = ABANDON_HASH; }
 
     TxId GetId() const { return tx->GetId(); }
     bool IsCoinBase() const { return tx->IsCoinBase(); }
     bool IsImmatureCoinBase(interfaces::Chain::Lock &locked_chain) const;
 };
 
 // Get the marginal bytes of spending the specified output
 int CalculateMaximumSignedInputSize(const CTxOut &txout, const CWallet *pwallet,
                                     bool use_max_sig = false);
 
 /**
  * A transaction with a bunch of additional info that only the owner cares
  * about. It includes any unrecorded transactions needed to link it back to the
  * block chain.
  */
 class CWalletTx : public CMerkleTx {
 private:
     const CWallet *pwallet;
 
 public:
     /**
      * Key/value map with information about the transaction.
      *
      * The following keys can be read and written through the map and are
      * serialized in the wallet database:
      *
      *     "comment", "to"   - comment strings provided to sendtoaddress,
      *                         and sendmany wallet RPCs
      *     "replaces_txid"   - txid (as HexStr) of transaction replaced by
      *                         bumpfee on transaction created by bumpfee
      *     "replaced_by_txid" - txid (as HexStr) of transaction created by
      *                         bumpfee on transaction replaced by bumpfee
      *     "from", "message" - obsolete fields that could be set in UI prior to
      *                         2011 (removed in commit 4d9b223)
      *
      * The following keys are serialized in the wallet database, but shouldn't
      * be read or written through the map (they will be temporarily added and
      * removed from the map during serialization):
      *
      *     "fromaccount"     - serialized strFromAccount value
      *     "n"               - serialized nOrderPos value
      *     "timesmart"       - serialized nTimeSmart value
      *     "spent"           - serialized vfSpent value that existed prior to
      *                         2014 (removed in commit 93a18a3)
      */
     mapValue_t mapValue;
     std::vector<std::pair<std::string, std::string>> vOrderForm;
     unsigned int fTimeReceivedIsTxTime;
     //! time received by this node
     unsigned int nTimeReceived;
     /**
      * Stable timestamp that never changes, and reflects the order a transaction
      * was added to the wallet. Timestamp is based on the block time for a
      * transaction added as part of a block, or else the time when the
      * transaction was received if it wasn't part of a block, with the timestamp
      * adjusted in both cases so timestamp order matches the order transactions
      * were added to the wallet. More details can be found in
      * CWallet::ComputeTimeSmart().
      */
     unsigned int nTimeSmart;
     /**
      * From me flag is set to 1 for transactions that were created by the wallet
      * on this bitcoin node, and set to 0 for transactions that were created
      * externally and came in through the network or sendrawtransaction RPC.
      */
     char fFromMe;
     //! position in ordered transaction list
     int64_t nOrderPos;
     std::multimap<int64_t, CWalletTx *>::const_iterator m_it_wtxOrdered;
 
     // memory only
     mutable bool fDebitCached;
     mutable bool fCreditCached;
     mutable bool fImmatureCreditCached;
     mutable bool fAvailableCreditCached;
     mutable bool fWatchDebitCached;
     mutable bool fWatchCreditCached;
     mutable bool fImmatureWatchCreditCached;
     mutable bool fAvailableWatchCreditCached;
     mutable bool fChangeCached;
     mutable bool fInMempool;
     mutable Amount nDebitCached;
     mutable Amount nCreditCached;
     mutable Amount nImmatureCreditCached;
     mutable Amount nAvailableCreditCached;
     mutable Amount nWatchDebitCached;
     mutable Amount nWatchCreditCached;
     mutable Amount nImmatureWatchCreditCached;
     mutable Amount nAvailableWatchCreditCached;
     mutable Amount nChangeCached;
 
     CWalletTx(const CWallet *pwalletIn, CTransactionRef arg)
         : CMerkleTx(std::move(arg)) {
         Init(pwalletIn);
     }
 
     void Init(const CWallet *pwalletIn) {
         pwallet = pwalletIn;
         mapValue.clear();
         vOrderForm.clear();
         fTimeReceivedIsTxTime = false;
         nTimeReceived = 0;
         nTimeSmart = 0;
         fFromMe = false;
         fDebitCached = false;
         fCreditCached = false;
         fImmatureCreditCached = false;
         fAvailableCreditCached = false;
         fWatchDebitCached = false;
         fWatchCreditCached = false;
         fImmatureWatchCreditCached = false;
         fAvailableWatchCreditCached = false;
         fChangeCached = false;
         fInMempool = false;
         nDebitCached = Amount::zero();
         nCreditCached = Amount::zero();
         nImmatureCreditCached = Amount::zero();
         nAvailableCreditCached = Amount::zero();
         nWatchDebitCached = Amount::zero();
         nWatchCreditCached = Amount::zero();
         nAvailableWatchCreditCached = Amount::zero();
         nImmatureWatchCreditCached = Amount::zero();
         nChangeCached = Amount::zero();
         nOrderPos = -1;
     }
 
     template <typename Stream> void Serialize(Stream &s) const {
         char fSpent = false;
         mapValue_t mapValueCopy = mapValue;
 
         mapValueCopy["fromaccount"] = "";
         WriteOrderPos(nOrderPos, mapValueCopy);
         if (nTimeSmart) {
             mapValueCopy["timesmart"] = strprintf("%u", nTimeSmart);
         }
 
         s << static_cast<const CMerkleTx &>(*this);
         //! Used to be vtxPrev
         std::vector<CMerkleTx> vUnused;
         s << vUnused << mapValueCopy << vOrderForm << fTimeReceivedIsTxTime
           << nTimeReceived << fFromMe << fSpent;
     }
 
     template <typename Stream> void Unserialize(Stream &s) {
         Init(nullptr);
         char fSpent;
 
         s >> static_cast<CMerkleTx &>(*this);
         //! Used to be vtxPrev
         std::vector<CMerkleTx> vUnused;
         s >> vUnused >> mapValue >> vOrderForm >> fTimeReceivedIsTxTime >>
             nTimeReceived >> fFromMe >> fSpent;
 
         ReadOrderPos(nOrderPos, mapValue);
         nTimeSmart = mapValue.count("timesmart")
                          ? (unsigned int)atoi64(mapValue["timesmart"])
                          : 0;
 
         mapValue.erase("fromaccount");
         mapValue.erase("spent");
         mapValue.erase("n");
         mapValue.erase("timesmart");
     }
 
     //! make sure balances are recalculated
     void MarkDirty() {
         fCreditCached = false;
         fAvailableCreditCached = false;
         fImmatureCreditCached = false;
         fWatchDebitCached = false;
         fWatchCreditCached = false;
         fAvailableWatchCreditCached = false;
         fImmatureWatchCreditCached = false;
         fDebitCached = false;
         fChangeCached = false;
     }
 
     void BindWallet(CWallet *pwalletIn) {
         pwallet = pwalletIn;
         MarkDirty();
     }
 
     //! filter decides which addresses will count towards the debit
     Amount GetDebit(const isminefilter &filter) const;
     Amount GetCredit(interfaces::Chain::Lock &locked_chain,
                      const isminefilter &filter) const;
     Amount GetImmatureCredit(interfaces::Chain::Lock &locked_chain,
                              bool fUseCache = true) const;
     // TODO: Remove "NO_THREAD_SAFETY_ANALYSIS" and replace it with the correct
     // annotation "EXCLUSIVE_LOCKS_REQUIRED(pwallet->cs_wallet)". The
     // annotation "NO_THREAD_SAFETY_ANALYSIS" was temporarily added to avoid
     // having to resolve the issue of member access into incomplete type
     // CWallet.
     Amount GetAvailableCredit(interfaces::Chain::Lock &locked_chain,
                               bool fUseCache = true,
                               const isminefilter &filter = ISMINE_SPENDABLE)
         const NO_THREAD_SAFETY_ANALYSIS;
     Amount GetImmatureWatchOnlyCredit(interfaces::Chain::Lock &locked_chain,
                                       const bool fUseCache = true) const;
     Amount GetChange() const;
 
     // Get the marginal bytes if spending the specified output from this
     // transaction
     int GetSpendSize(unsigned int out, bool use_max_sig = false) const {
         return CalculateMaximumSignedInputSize(tx->vout[out], pwallet,
                                                use_max_sig);
     }
 
     void GetAmounts(std::list<COutputEntry> &listReceived,
                     std::list<COutputEntry> &listSent, Amount &nFee,
                     const isminefilter &filter) const;
 
     bool IsFromMe(const isminefilter &filter) const {
         return GetDebit(filter) > Amount::zero();
     }
 
     // True if only scriptSigs are different
     bool IsEquivalentTo(const CWalletTx &tx) const;
 
     bool InMempool() const;
     bool IsTrusted(interfaces::Chain::Lock &locked_chain) const;
 
     int64_t GetTxTime() const;
 
     // RelayWalletTransaction may only be called if fBroadcastTransactions!
     bool RelayWalletTransaction(interfaces::Chain::Lock &locked_chain);
 
     /**
      * Pass this transaction to the mempool. Fails if absolute fee exceeds
      * absurd fee.
      */
     bool AcceptToMemoryPool(interfaces::Chain::Lock &locked_chain,
                             CValidationState &state);
 
     // TODO: Remove "NO_THREAD_SAFETY_ANALYSIS" and replace it with the correct
     // annotation "EXCLUSIVE_LOCKS_REQUIRED(pwallet->cs_wallet)". The annotation
     // "NO_THREAD_SAFETY_ANALYSIS" was temporarily added to avoid having to
     // resolve the issue of member access into incomplete type CWallet. Note
     // that we still have the runtime check "AssertLockHeld(pwallet->cs_wallet)"
     // in place.
     std::set<TxId> GetConflicts() const NO_THREAD_SAFETY_ANALYSIS;
 };
 
 class COutput {
 public:
     const CWalletTx *tx;
     int i;
     int nDepth;
 
     /**
      * Pre-computed estimated size of this output as a fully-signed input in a
      * transaction. Can be -1 if it could not be calculated.
      */
     int nInputBytes;
 
     /** Whether we have the private keys to spend this output */
     bool fSpendable;
 
     /** Whether we know how to spend this output, ignoring the lack of keys */
     bool fSolvable;
 
     /**
      * Whether to use the maximum sized, 72 byte signature when calculating the
      * size of the input spend. This should only be set when watch-only outputs
      * are allowed.
      */
     bool use_max_sig;
 
     /**
      * Whether this output is considered safe to spend. Unconfirmed transactions
      * from outside keys are considered unsafe and will not be used to fund new
      * spending transactions.
      */
     bool fSafe;
 
     COutput(const CWalletTx *txIn, int iIn, int nDepthIn, bool fSpendableIn,
             bool fSolvableIn, bool fSafeIn, bool use_max_sig_in = false) {
         tx = txIn;
         i = iIn;
         nDepth = nDepthIn;
         fSpendable = fSpendableIn;
         fSolvable = fSolvableIn;
         fSafe = fSafeIn;
         nInputBytes = -1;
         use_max_sig = use_max_sig_in;
         // If known and signable by the given wallet, compute nInputBytes
         // Failure will keep this value -1
         if (fSpendable && tx) {
             nInputBytes = tx->GetSpendSize(i, use_max_sig);
         }
     }
 
     std::string ToString() const;
 
     inline CInputCoin GetInputCoin() const {
         return CInputCoin(tx->tx, i, nInputBytes);
     }
 };
 
 /** Private key that includes an expiration date in case it never gets used. */
 class CWalletKey {
 public:
     CPrivKey vchPrivKey;
     int64_t nTimeCreated;
     int64_t nTimeExpires;
     std::string strComment;
     //! todo: add something to note what created it (user, getnewaddress,
     //! change) maybe should have a map<string, string> property map
 
     explicit CWalletKey(int64_t nExpires = 0);
 
     ADD_SERIALIZE_METHODS;
 
     template <typename Stream, typename Operation>
     inline void SerializationOp(Stream &s, Operation ser_action) {
         int nVersion = s.GetVersion();
         if (!(s.GetType() & SER_GETHASH)) {
             READWRITE(nVersion);
         }
         READWRITE(vchPrivKey);
         READWRITE(nTimeCreated);
         READWRITE(nTimeExpires);
         READWRITE(LIMITED_STRING(strComment, 65536));
     }
 };
 
 struct CoinSelectionParams {
     bool use_bnb = true;
     size_t change_output_size = 0;
     size_t change_spend_size = 0;
     CFeeRate effective_fee = CFeeRate(Amount::zero());
     size_t tx_noinputs_size = 0;
 
     CoinSelectionParams(bool use_bnb_, size_t change_output_size_,
                         size_t change_spend_size_, CFeeRate effective_fee_,
                         size_t tx_noinputs_size_)
         : use_bnb(use_bnb_), change_output_size(change_output_size_),
           change_spend_size(change_spend_size_), effective_fee(effective_fee_),
           tx_noinputs_size(tx_noinputs_size_) {}
     CoinSelectionParams() {}
 };
 
 // forward declarations for ScanForWalletTransactions/RescanFromTime
 class WalletRescanReserver;
 
 /**
  * A CWallet is an extension of a keystore, which also maintains a set of
  * transactions and balances, and provides the ability to create new
  * transactions.
  */
 class CWallet final : public CCryptoKeyStore,
                       private interfaces::Chain::Notifications {
 private:
     static std::atomic<bool> fFlushScheduled;
     std::atomic<bool> fAbortRescan{false};
     // controlled by WalletRescanReserver
     std::atomic<bool> fScanningWallet{false};
     std::mutex mutexScanning;
     friend class WalletRescanReserver;
 
     WalletBatch *encrypted_batch GUARDED_BY(cs_wallet) = nullptr;
 
     //! the current wallet version: clients below this version are not able to
     //! load the wallet
     int nWalletVersion = FEATURE_BASE;
 
     //! the maximum wallet format version: memory-only variable that specifies
     //! to what version this wallet may be upgraded
     int nWalletMaxVersion GUARDED_BY(cs_wallet) = FEATURE_BASE;
 
     int64_t nNextResend = 0;
     int64_t nLastResend = 0;
     bool fBroadcastTransactions = false;
     // Local time that the tip block was received. Used to schedule wallet
     // rebroadcasts.
     std::atomic<int64_t> m_best_block_time{0};
 
     /**
      * Used to keep track of spent outpoints, and detect and report conflicts
      * (double-spends or mutated transactions where the mutant gets mined).
      */
     typedef std::multimap<COutPoint, TxId> TxSpends;
     TxSpends mapTxSpends GUARDED_BY(cs_wallet);
     void AddToSpends(const COutPoint &outpoint, const TxId &wtxid)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     void AddToSpends(const TxId &wtxid) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     /**
      * Add a transaction to the wallet, or update it. pIndex and posInBlock
      * should be set when the transaction was known to be included in a
      * block. When *pIndex == nullptr, then wallet state is not updated in
      * AddToWallet, but notifications happen and cached balances are marked
      * dirty.
      *
      * If fUpdate is true, existing transactions will be updated.
      * TODO: One exception to this is that the abandoned state is cleared under
      * the assumption that any further notification of a transaction that was
      * considered abandoned is an indication that it is not safe to be
      * considered abandoned. Abandoned state should probably be more carefully
      * tracked via different posInBlock signals or by checking mempool presence
      * when necessary.
      */
     bool AddToWalletIfInvolvingMe(const CTransactionRef &tx,
                                   const BlockHash &block_hash, int posInBlock,
                                   bool fUpdate)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     /**
      * Mark a transaction (and its in-wallet descendants) as conflicting with a
      * particular block.
      */
     void MarkConflicted(const BlockHash &hashBlock, const TxId &txid);
 
     /**
      * Mark a transaction's inputs dirty, thus forcing the outputs to be
      * recomputed
      */
     void MarkInputsDirty(const CTransactionRef &tx)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     void SyncMetaData(std::pair<TxSpends::iterator, TxSpends::iterator>)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     /**
      * Used by
      * TransactionAddedToMemorypool/BlockConnected/Disconnected/ScanForWalletTransactions.
      * Should be called with non-zero block_hash and posInBlock if this is for a
      * transaction that is included in a block.
      */
     void SyncTransaction(const CTransactionRef &tx, const BlockHash &block_hash,
                          int posInBlock = 0, bool update_tx = true)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     /* the HD chain data model (external chain counters) */
     CHDChain hdChain;
 
     /* HD derive new child key (on internal or external chain) */
     void DeriveNewChildKey(WalletBatch &batch, CKeyMetadata &metadata,
                            CKey &secret, bool internal = false)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     std::set<int64_t> setInternalKeyPool;
     std::set<int64_t> setExternalKeyPool GUARDED_BY(cs_wallet);
     std::set<int64_t> set_pre_split_keypool;
     int64_t m_max_keypool_index GUARDED_BY(cs_wallet) = 0;
     std::map<CKeyID, int64_t> m_pool_key_to_index;
     std::atomic<uint64_t> m_wallet_flags{0};
 
     int64_t nTimeFirstKey GUARDED_BY(cs_wallet) = 0;
 
     /**
      * Private version of AddWatchOnly method which does not accept a timestamp,
      * and which will reset the wallet's nTimeFirstKey value to 1 if the watch
      * key did not previously have a timestamp associated with it. Because this
      * is an inherited virtual method, it is accessible despite being marked
      * private, but it is marked private anyway to encourage use of the other
      * AddWatchOnly which accepts a timestamp and sets nTimeFirstKey more
      * intelligently for more efficient rescans.
      */
     bool AddWatchOnly(const CScript &dest) override
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     /** Interface for accessing chain state. */
     interfaces::Chain *m_chain;
 
     /**
      * Wallet location which includes wallet name (see WalletLocation).
      */
     WalletLocation m_location;
 
     /** Internal database handle. */
     std::unique_ptr<WalletDatabase> database;
 
     /**
      * The following is used to keep track of how far behind the wallet is
      * from the chain sync, and to allow clients to block on us being caught up.
      *
      * Note that this is *not* how far we've processed, we may need some rescan
      * to have seen all transactions in the chain, but is only used to track
      * live BlockConnected callbacks.
      */
     BlockHash m_last_block_processed GUARDED_BY(cs_wallet);
 
 public:
     const CChainParams &chainParams;
     /*
      * Main wallet lock.
      * This lock protects all the fields added by CWallet.
      */
     mutable RecursiveMutex cs_wallet;
 
     /**
      * Get database handle used by this wallet. Ideally this function would not
      * be necessary.
      */
     WalletDatabase &GetDBHandle() { return *database; }
 
     /**
      * Select a set of coins such that nValueRet >= nTargetValue and at least
      * all coins from coinControl are selected; Never select unconfirmed coins
      * if they are not ours.
      */
     bool SelectCoins(const std::vector<COutput> &vAvailableCoins,
                      const Amount nTargetValue,
                      std::set<CInputCoin> &setCoinsRet, Amount &nValueRet,
                      const CCoinControl &coin_control,
                      CoinSelectionParams &coin_selection_params,
                      bool &bnb_used) const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     const WalletLocation &GetLocation() const { return m_location; }
 
     /**
      * Get a name for this wallet for logging/debugging purposes.
      */
     const std::string &GetName() const { return m_location.GetName(); }
 
     void LoadKeyPool(int64_t nIndex, const CKeyPool &keypool)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     void MarkPreSplitKeys() EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     // Map from Key ID to key metadata.
     std::map<CKeyID, CKeyMetadata> mapKeyMetadata GUARDED_BY(cs_wallet);
 
     // Map from Script ID to key metadata (for watch-only keys).
     std::map<CScriptID, CKeyMetadata> m_script_metadata GUARDED_BY(cs_wallet);
 
     bool WriteKeyMetadata(const CKeyMetadata &meta, const CPubKey &pubkey,
                           bool overwrite);
 
     typedef std::map<unsigned int, CMasterKey> MasterKeyMap;
     MasterKeyMap mapMasterKeys;
     unsigned int nMasterKeyMaxID = 0;
 
     /** Construct wallet with specified name and database implementation. */
     CWallet(const CChainParams &chainParamsIn, interfaces::Chain *chain,
             const WalletLocation &location,
             std::unique_ptr<WalletDatabase> databaseIn)
         : m_chain(chain), m_location(location), database(std::move(databaseIn)),
           chainParams(chainParamsIn) {}
 
     ~CWallet() {
         // Should not have slots connected at this point.
         assert(NotifyUnload.empty());
         delete encrypted_batch;
         encrypted_batch = nullptr;
     }
 
     std::map<TxId, CWalletTx> mapWallet GUARDED_BY(cs_wallet);
 
     typedef std::multimap<int64_t, CWalletTx *> TxItems;
     TxItems wtxOrdered;
 
     int64_t nOrderPosNext GUARDED_BY(cs_wallet) = 0;
     uint64_t nAccountingEntryNumber = 0;
 
     std::map<CTxDestination, CAddressBookData> mapAddressBook;
 
     std::set<COutPoint> setLockedCoins GUARDED_BY(cs_wallet);
 
     /** Registered interfaces::Chain::Notifications handler. */
     std::unique_ptr<interfaces::Handler> m_chain_notifications_handler;
 
     /** Register the wallet for chain notifications */
     void handleNotifications();
 
     /** Interface for accessing chain state. */
     interfaces::Chain &chain() const {
         assert(m_chain);
         return *m_chain;
     }
 
     const CWalletTx *GetWalletTx(const TxId &txid) const;
 
     //! check whether we are allowed to upgrade (or already support) to the
     //! named feature
     bool CanSupportFeature(enum WalletFeature wf) const
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet) {
         AssertLockHeld(cs_wallet);
         return nWalletMaxVersion >= wf;
     }
 
     /**
      * populate vCoins with vector of available COutputs.
      */
     void AvailableCoins(interfaces::Chain::Lock &locked_chain,
                         std::vector<COutput> &vCoins, bool fOnlySafe = true,
                         const CCoinControl *coinControl = nullptr,
                         const Amount nMinimumAmount = SATOSHI,
                         const Amount nMaximumAmount = MAX_MONEY,
                         const Amount nMinimumSumAmount = MAX_MONEY,
                         const uint64_t nMaximumCount = 0,
                         const int nMinDepth = 0,
                         const int nMaxDepth = 9999999) const
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     /**
      * Return list of available coins and locked coins grouped by non-change
      * output address.
      */
     std::map<CTxDestination, std::vector<COutput>>
     ListCoins(interfaces::Chain::Lock &locked_chain) const
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     /**
      * Find non-change parent output.
      */
     const CTxOut &FindNonChangeParentOutput(const CTransaction &tx,
                                             int output) const
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     /**
      * Shuffle and select coins until nTargetValue is reached while avoiding
      * small change; This method is stochastic for some inputs and upon
      * completion the coin set and corresponding actual target value is
      * assembled.
      */
     bool SelectCoinsMinConf(const Amount nTargetValue,
                             const CoinEligibilityFilter &eligibility_filter,
                             std::vector<OutputGroup> groups,
                             std::set<CInputCoin> &setCoinsRet,
                             Amount &nValueRet,
                             const CoinSelectionParams &coin_selection_params,
                             bool &bnb_used) const;
 
     bool IsSpent(interfaces::Chain::Lock &locked_chain,
                  const COutPoint &outpoint) const
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     std::vector<OutputGroup> GroupOutputs(const std::vector<COutput> &outputs,
                                           bool single_coin) const;
 
     bool IsLockedCoin(const COutPoint &outpoint) const
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     void LockCoin(const COutPoint &output) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     void UnlockCoin(const COutPoint &output)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     void UnlockAllCoins() EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     void ListLockedCoins(std::vector<COutPoint> &vOutpts) const
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     /*
      * Rescan abort properties
      */
     void AbortRescan() { fAbortRescan = true; }
     bool IsAbortingRescan() { return fAbortRescan; }
     bool IsScanning() { return fScanningWallet; }
 
     /**
      * keystore implementation
      * Generate a new key
      */
     CPubKey GenerateNewKey(WalletBatch &batch, bool internal = false)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     //! Adds a key to the store, and saves it to disk.
     bool AddKeyPubKey(const CKey &key, const CPubKey &pubkey) override
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     bool AddKeyPubKeyWithDB(WalletBatch &batch, const CKey &key,
                             const CPubKey &pubkey)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     //! Adds a key to the store, without saving it to disk (used by LoadWallet)
     bool LoadKey(const CKey &key, const CPubKey &pubkey) {
         return CCryptoKeyStore::AddKeyPubKey(key, pubkey);
     }
 
     //! Load metadata (used by LoadWallet)
     void LoadKeyMetadata(const CKeyID &keyID, const CKeyMetadata &metadata)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     void LoadScriptMetadata(const CScriptID &script_id,
                             const CKeyMetadata &metadata)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     //! Upgrade stored CKeyMetadata objects to store key origin info as
     //! KeyOriginInfo
     void UpgradeKeyMetadata() EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     bool LoadMinVersion(int nVersion) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet) {
         AssertLockHeld(cs_wallet);
         nWalletVersion = nVersion;
         nWalletMaxVersion = std::max(nWalletMaxVersion, nVersion);
         return true;
     }
     void UpdateTimeFirstKey(int64_t nCreateTime)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     //! Adds an encrypted key to the store, and saves it to disk.
     bool AddCryptedKey(const CPubKey &vchPubKey,
                        const std::vector<uint8_t> &vchCryptedSecret) override;
     //! Adds an encrypted key to the store, without saving it to disk (used by
     //! LoadWallet)
     bool LoadCryptedKey(const CPubKey &vchPubKey,
                         const std::vector<uint8_t> &vchCryptedSecret);
     bool AddCScript(const CScript &redeemScript) override;
     bool LoadCScript(const CScript &redeemScript);
 
     //! Adds a destination data tuple to the store, and saves it to disk
     bool AddDestData(const CTxDestination &dest, const std::string &key,
                      const std::string &value);
     //! Erases a destination data tuple in the store and on disk
     bool EraseDestData(const CTxDestination &dest, const std::string &key);
     //! Adds a destination data tuple to the store, without saving it to disk
     void LoadDestData(const CTxDestination &dest, const std::string &key,
                       const std::string &value);
     //! Look up a destination data tuple in the store, return true if found
     //! false otherwise
     bool GetDestData(const CTxDestination &dest, const std::string &key,
                      std::string *value) const;
     //! Get all destination values matching a prefix.
     std::vector<std::string> GetDestValues(const std::string &prefix) const;
 
     //! Adds a watch-only address to the store, and saves it to disk.
     bool AddWatchOnly(const CScript &dest, int64_t nCreateTime)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     bool RemoveWatchOnly(const CScript &dest) override
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     //! Adds a watch-only address to the store, without saving it to disk (used
     //! by LoadWallet)
     bool LoadWatchOnly(const CScript &dest);
 
     //! Holds a timestamp at which point the wallet is scheduled (externally) to
     //! be relocked. Caller must arrange for actual relocking to occur via
     //! Lock().
     int64_t nRelockTime = 0;
 
     bool Unlock(const SecureString &strWalletPassphrase,
                 bool accept_no_keys = false);
     bool ChangeWalletPassphrase(const SecureString &strOldWalletPassphrase,
                                 const SecureString &strNewWalletPassphrase);
     bool EncryptWallet(const SecureString &strWalletPassphrase);
 
     void GetKeyBirthTimes(interfaces::Chain::Lock &locked_chain,
                           std::map<CTxDestination, int64_t> &mapKeyBirth) const
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     unsigned int ComputeTimeSmart(const CWalletTx &wtx) const;
 
     /**
      * Increment the next transaction order id
      * @return next transaction order id
      */
     int64_t IncOrderPosNext(WalletBatch *batch = nullptr)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     DBErrors ReorderTransactions();
 
     void MarkDirty();
     bool AddToWallet(const CWalletTx &wtxIn, bool fFlushOnClose = true);
     void LoadToWallet(const CWalletTx &wtxIn)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     void TransactionAddedToMempool(const CTransactionRef &tx) override;
     void
     BlockConnected(const CBlock &block,
                    const std::vector<CTransactionRef> &vtxConflicted) override;
     void BlockDisconnected(const CBlock &block) override;
     void UpdatedBlockTip() override;
     int64_t RescanFromTime(int64_t startTime,
                            const WalletRescanReserver &reserver, bool update);
 
     struct ScanResult {
         enum { SUCCESS, FAILURE, USER_ABORT } status = SUCCESS;
 
         //! Hash and height of most recent block that was successfully scanned.
         //! Unset if no blocks were scanned due to read errors or the chain
         //! being empty.
         BlockHash last_scanned_block;
         Optional<int> last_scanned_height;
 
         //! Hash of the most recent block that could not be scanned due to
         //! read errors or pruning. Will be set if status is FAILURE, unset if
         //! status is SUCCESS, and may or may not be set if status is
         //! USER_ABORT.
         BlockHash last_failed_block;
     };
     ScanResult ScanForWalletTransactions(const BlockHash &first_block,
                                          const BlockHash &last_block,
                                          const WalletRescanReserver &reserver,
                                          bool fUpdate);
     void TransactionRemovedFromMempool(const CTransactionRef &ptx) override;
     void ReacceptWalletTransactions(interfaces::Chain::Lock &locked_chain)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     void ResendWalletTransactions();
     struct Balance {
         //! Trusted, at depth=GetBalance.min_depth or more
         Amount m_mine_trusted{Amount::zero()};
         //! Untrusted, but in mempool (pending)
         Amount m_mine_untrusted_pending{Amount::zero()};
         //! Immature coinbases in the main chain
         Amount m_mine_immature{Amount::zero()};
         Amount m_watchonly_trusted{Amount::zero()};
         Amount m_watchonly_untrusted_pending{Amount::zero()};
         Amount m_watchonly_immature{Amount::zero()};
     };
     Balance GetBalance(int min_depth = 0) const;
     Amount GetAvailableBalance(const CCoinControl *coinControl = nullptr) const;
 
     OutputType TransactionChangeType(OutputType change_type,
                                      const std::vector<CRecipient> &vecSend);
 
     /**
      * Insert additional inputs into the transaction by calling
      * CreateTransaction();
      */
     bool FundTransaction(CMutableTransaction &tx, Amount &nFeeRet,
                          int &nChangePosInOut, std::string &strFailReason,
                          bool lockUnspents,
                          const std::set<int> &setSubtractFeeFromOutputs,
                          CCoinControl coinControl);
     bool SignTransaction(CMutableTransaction &tx)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     /**
      * Create a new transaction paying the recipients with a set of coins
      * selected by SelectCoins(); Also create the change output, when needed
      * @note passing nChangePosInOut as -1 will result in setting a random
      * position
      */
     bool CreateTransaction(interfaces::Chain::Lock &locked_chain,
                            const std::vector<CRecipient> &vecSend,
                            CTransactionRef &tx, CReserveKey &reservekey,
                            Amount &nFeeRet, int &nChangePosInOut,
                            std::string &strFailReason,
                            const CCoinControl &coin_control, bool sign = true);
     bool CommitTransaction(
         CTransactionRef tx, mapValue_t mapValue,
         std::vector<std::pair<std::string, std::string>> orderForm,
         CReserveKey &reservekey, CValidationState &state);
 
     bool DummySignTx(CMutableTransaction &txNew, const std::set<CTxOut> &txouts,
                      bool use_max_sig = false) const {
         std::vector<CTxOut> v_txouts(txouts.size());
         std::copy(txouts.begin(), txouts.end(), v_txouts.begin());
         return DummySignTx(txNew, v_txouts, use_max_sig);
     }
     bool DummySignTx(CMutableTransaction &txNew,
                      const std::vector<CTxOut> &txouts,
                      bool use_max_sig = false) const;
     bool DummySignInput(CTxIn &tx_in, const CTxOut &txout,
                         bool use_max_sig = false) const;
 
     CFeeRate m_pay_tx_fee{DEFAULT_PAY_TX_FEE};
     bool m_spend_zero_conf_change{DEFAULT_SPEND_ZEROCONF_CHANGE};
     // will be defined via chainparams
     bool m_allow_fallback_fee{true};
     // Override with -mintxfee
     CFeeRate m_min_fee{DEFAULT_TRANSACTION_MINFEE_PER_KB};
     /**
      * If fee estimation does not have enough data to provide estimates, use
      * this fee instead. Has no effect if not using fee estimation Override with
      * -fallbackfee
      */
     CFeeRate m_fallback_fee{DEFAULT_FALLBACK_FEE};
     OutputType m_default_address_type{DEFAULT_ADDRESS_TYPE};
     OutputType m_default_change_type{DEFAULT_CHANGE_TYPE};
+    /**
+     * Absolute maximum transaction fee (in satoshis) used by default for the
+     * wallet.
+     */
+    Amount m_default_max_tx_fee{DEFAULT_TRANSACTION_MAXFEE};
 
     bool NewKeyPool();
     size_t KeypoolCountExternalKeys() EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     bool TopUpKeyPool(unsigned int kpSize = 0);
 
     /**
      * Reserves a key from the keypool and sets nIndex to its index
      *
      * @param[out] nIndex the index of the key in keypool
      * @param[out] keypool the keypool the key was drawn from, which could be
      * the the pre-split pool if present, or the internal or external pool
      * @param fRequestedInternal true if the caller would like the key drawn
      *     from the internal keypool, false if external is preferred
      *
      * @return true if succeeded, false if failed due to empty keypool
      * @throws std::runtime_error if keypool read failed, key was invalid,
      *     was not found in the wallet, or was misclassified in the internal
      *     or external keypool
      */
     bool ReserveKeyFromKeyPool(int64_t &nIndex, CKeyPool &keypool,
                                bool fRequestedInternal);
     void KeepKey(int64_t nIndex);
     void ReturnKey(int64_t nIndex, bool fInternal, const CPubKey &pubkey);
     bool GetKeyFromPool(CPubKey &key, bool internal = false);
     int64_t GetOldestKeyPoolTime();
     /**
      * Marks all keys in the keypool up to and including reserve_key as used.
      */
     void MarkReserveKeysAsUsed(int64_t keypool_id)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     const std::map<CKeyID, int64_t> &GetAllReserveKeys() const {
         return m_pool_key_to_index;
     }
 
     std::set<std::set<CTxDestination>> GetAddressGroupings()
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     std::map<CTxDestination, Amount>
     GetAddressBalances(interfaces::Chain::Lock &locked_chain);
 
     std::set<CTxDestination> GetLabelAddresses(const std::string &label) const;
 
     isminetype IsMine(const CTxIn &txin) const;
     /**
      * Returns amount of debit if the input matches the filter, otherwise
      * returns 0
      */
     Amount GetDebit(const CTxIn &txin, const isminefilter &filter) const;
     isminetype IsMine(const CTxOut &txout) const;
     Amount GetCredit(const CTxOut &txout, const isminefilter &filter) const;
     bool IsChange(const CTxOut &txout) const;
     bool IsChange(const CScript &script) const;
     Amount GetChange(const CTxOut &txout) const;
     bool IsMine(const CTransaction &tx) const;
     /** should probably be renamed to IsRelevantToMe */
     bool IsFromMe(const CTransaction &tx) const;
     Amount GetDebit(const CTransaction &tx, const isminefilter &filter) const;
     /** Returns whether all of the inputs match the filter */
     bool IsAllFromMe(const CTransaction &tx, const isminefilter &filter) const;
     Amount GetCredit(const CTransaction &tx, const isminefilter &filter) const;
     Amount GetChange(const CTransaction &tx) const;
     void ChainStateFlushed(const CBlockLocator &loc) override;
 
     DBErrors LoadWallet(bool &fFirstRunRet);
     DBErrors ZapWalletTx(std::vector<CWalletTx> &vWtx);
     DBErrors ZapSelectTx(std::vector<TxId> &txIdsIn,
                          std::vector<TxId> &txIdsOut)
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     bool SetAddressBook(const CTxDestination &address,
                         const std::string &strName, const std::string &purpose);
 
     bool DelAddressBook(const CTxDestination &address);
 
     const std::string &GetLabelName(const CScript &scriptPubKey) const;
 
     void GetScriptForMining(std::shared_ptr<CReserveScript> &script);
 
     unsigned int GetKeyPoolSize() EXCLUSIVE_LOCKS_REQUIRED(cs_wallet) {
         // set{Ex,In}ternalKeyPool
         AssertLockHeld(cs_wallet);
         return setInternalKeyPool.size() + setExternalKeyPool.size();
     }
 
     //! signify that a particular wallet feature is now used. this may change
     //! nWalletVersion and nWalletMaxVersion if those are lower
     void SetMinVersion(enum WalletFeature, WalletBatch *batch_in = nullptr,
                        bool fExplicit = false);
 
     //! change which version we're allowed to upgrade to (note that this does
     //! not immediately imply upgrading to that format)
     bool SetMaxVersion(int nVersion);
 
     //! get the current wallet format (the oldest client version guaranteed to
     //! understand this wallet)
     int GetVersion() {
         LOCK(cs_wallet);
         return nWalletVersion;
     }
 
     //! Get wallet transactions that conflict with given transaction (spend same
     //! outputs)
     std::set<TxId> GetConflicts(const TxId &txid) const
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     //! Check if a given transaction has any of its outputs spent by another
     //! transaction in the wallet
     bool HasWalletSpend(const TxId &txid) const
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     //! Flush wallet (bitdb flush)
     void Flush(bool shutdown = false);
 
     /** Wallet is about to be unloaded */
     boost::signals2::signal<void()> NotifyUnload;
 
     /**
      * Address book entry changed.
      * @note called with lock cs_wallet held.
      */
     boost::signals2::signal<void(CWallet *wallet, const CTxDestination &address,
                                  const std::string &label, bool isMine,
                                  const std::string &purpose, ChangeType status)>
         NotifyAddressBookChanged;
 
     /**
      * Wallet transaction added, removed or updated.
      * @note called with lock cs_wallet held.
      */
     boost::signals2::signal<void(CWallet *wallet, const TxId &txid,
                                  ChangeType status)>
         NotifyTransactionChanged;
 
     /** Show progress e.g. for rescan */
     boost::signals2::signal<void(const std::string &title, int nProgress)>
         ShowProgress;
 
     /** Watch-only address added */
     boost::signals2::signal<void(bool fHaveWatchOnly)> NotifyWatchonlyChanged;
 
     /** Keypool has new keys */
     boost::signals2::signal<void()> NotifyCanGetAddressesChanged;
 
     /** Inquire whether this wallet broadcasts transactions. */
     bool GetBroadcastTransactions() const { return fBroadcastTransactions; }
     /** Set whether this wallet broadcasts transactions. */
     void SetBroadcastTransactions(bool broadcast) {
         fBroadcastTransactions = broadcast;
     }
 
     /** Return whether transaction can be abandoned */
     bool TransactionCanBeAbandoned(const TxId &txid) const;
 
     /**
      * Mark a transaction (and it in-wallet descendants) as abandoned so its
      * inputs may be respent.
      */
     bool AbandonTransaction(interfaces::Chain::Lock &locked_chain,
                             const TxId &txid);
 
     //! Verify wallet naming and perform salvage on the wallet if required
     static bool Verify(const CChainParams &chainParams,
                        interfaces::Chain &chain, const WalletLocation &location,
                        bool salvage_wallet, std::string &error_string,
                        std::string &warning_string);
 
     /**
      * Initializes the wallet, returns a new CWallet instance or a null pointer
      * in case of an error.
      */
     static std::shared_ptr<CWallet> CreateWalletFromFile(
         const CChainParams &chainParams, interfaces::Chain &chain,
         const WalletLocation &location, uint64_t wallet_creation_flags = 0);
 
     /**
      * Wallet post-init setup
      * Gives the wallet a chance to register repetitive tasks and complete
      * post-init tasks
      */
     void postInitProcess();
 
     bool BackupWallet(const std::string &strDest);
 
     /* Set the HD chain model (chain child index counters) */
     void SetHDChain(const CHDChain &chain, bool memonly);
     const CHDChain &GetHDChain() const { return hdChain; }
 
     /* Returns true if HD is enabled */
     bool IsHDEnabled() const;
 
     /* Returns true if the wallet can generate new keys */
     bool CanGenerateKeys();
 
     /**
      * Returns true if the wallet can give out new addresses. This means it has
      * keys in the keypool or can generate new keys.
      */
     bool CanGetAddresses(bool internal = false);
 
     /* Generates a new HD seed (will not be activated) */
     CPubKey GenerateNewSeed();
 
     /**
      * Derives a new HD seed (will not be activated)
      */
     CPubKey DeriveNewSeed(const CKey &key);
 
     /**
      * Set the current HD seed (will reset the chain child index counters)
      * Sets the seed's version based on the current wallet version (so the
      * caller must ensure the current wallet version is correct before calling
      * this function).
      */
     void SetHDSeed(const CPubKey &key);
 
     /**
      * Blocks until the wallet state is up-to-date to /at least/ the current
      * chain at the time this function is entered.
      * Obviously holding cs_main/cs_wallet when going into this call may cause
      * deadlock
      */
     void BlockUntilSyncedToCurrentChain() LOCKS_EXCLUDED(cs_main, cs_wallet);
 
     /**
      * Explicitly make the wallet learn the related scripts for outputs to the
      * given key. This is purely to make the wallet file compatible with older
      * software, as CBasicKeyStore automatically does this implicitly for all
      * keys now.
      */
     void LearnRelatedScripts(const CPubKey &key, OutputType);
 
     /**
      * Same as LearnRelatedScripts, but when the OutputType is not known (and
      * could be anything).
      */
     void LearnAllRelatedScripts(const CPubKey &key);
 
     /**
      * Set a single wallet flag.
      */
     void SetWalletFlag(uint64_t flags);
 
     /**
      * Unsets a single wallet flag.
      */
     void UnsetWalletFlag(uint64_t flag);
 
     /**
      * Check if a certain wallet flag is set.
      */
     bool IsWalletFlagSet(uint64_t flag);
 
     /**
      * Overwrite all flags by the given uint64_t.
      * Returns false if unknown, non-tolerable flags are present.
      */
     bool SetWalletFlags(uint64_t overwriteFlags, bool memOnly);
 
     /**
      * Returns a bracketed wallet name for displaying in logs, will return
      * [default wallet] if the wallet has no name.
      */
     const std::string GetDisplayName() const {
         std::string wallet_name =
             GetName().length() == 0 ? "default wallet" : GetName();
         return strprintf("[%s]", wallet_name);
     };
 
     /**
      * Prepends the wallet name in logging output to ease debugging in
      * multi-wallet use cases.
      */
     template <typename... Params>
     void WalletLogPrintf(std::string fmt, Params... parameters) const {
         LogPrintf(("%s " + fmt).c_str(), GetDisplayName(), parameters...);
     };
 
     template <typename... Params>
     void WalletLogPrintfToBeContinued(std::string fmt,
                                       Params... parameters) const {
         LogPrintfToBeContinued(("%s " + fmt).c_str(), GetDisplayName(),
                                parameters...);
     };
 
     /**
      * Implement lookup of key origin information through wallet key metadata.
      */
     bool GetKeyOrigin(const CKeyID &keyid, KeyOriginInfo &info) const override;
 
     /**
      * Add a KeyOriginInfo to the wallet
      */
     bool AddKeyOrigin(const CPubKey &pubkey, const KeyOriginInfo &info);
 };
 
 /**
  * Called periodically by the schedule thread. Prompts individual wallets to
  * resend their transactions. Actual rebroadcast schedule is managed by the
  * wallets themselves.
  */
 void MaybeResendWalletTxs();
 
 /** A key allocated from the key pool. */
 class CReserveKey final : public CReserveScript {
 protected:
     CWallet *pwallet;
     int64_t nIndex{-1};
     CPubKey vchPubKey;
     bool fInternal{false};
 
 public:
     explicit CReserveKey(CWallet *pwalletIn) { pwallet = pwalletIn; }
 
     CReserveKey(const CReserveKey &) = delete;
     CReserveKey &operator=(const CReserveKey &) = delete;
 
     ~CReserveKey() { ReturnKey(); }
 
     void ReturnKey();
     bool GetReservedKey(CPubKey &pubkey, bool internal = false);
     void KeepKey();
     void KeepScript() override { KeepKey(); }
 };
 
 /** RAII object to check and reserve a wallet rescan */
 class WalletRescanReserver {
 private:
     CWallet *m_wallet;
     bool m_could_reserve;
 
 public:
     explicit WalletRescanReserver(CWallet *w)
         : m_wallet(w), m_could_reserve(false) {}
 
     bool reserve() {
         assert(!m_could_reserve);
         std::lock_guard<std::mutex> lock(m_wallet->mutexScanning);
         if (m_wallet->fScanningWallet) {
             return false;
         }
         m_wallet->fScanningWallet = true;
         m_could_reserve = true;
         return true;
     }
 
     bool isReserved() const {
         return (m_could_reserve && m_wallet->fScanningWallet);
     }
 
     ~WalletRescanReserver() {
         std::lock_guard<std::mutex> lock(m_wallet->mutexScanning);
         if (m_could_reserve) {
             m_wallet->fScanningWallet = false;
         }
     }
 };
 
 // Calculate the size of the transaction assuming all signatures are max size
 // Use DummySignatureCreator, which inserts 71 byte signatures everywhere.
 // NOTE: this requires that all inputs must be in mapWallet (eg the tx should
 // be IsAllFromMe).
 int64_t CalculateMaximumSignedTxSize(const CTransaction &tx,
                                      const CWallet *wallet,
                                      bool use_max_sig = false)
     EXCLUSIVE_LOCKS_REQUIRED(wallet->cs_wallet);
 int64_t CalculateMaximumSignedTxSize(const CTransaction &tx,
                                      const CWallet *wallet,
                                      const std::vector<CTxOut> &txouts,
                                      bool use_max_sig = false);
 
 #endif // BITCOIN_WALLET_WALLET_H