diff --git a/src/blockindex.cpp b/src/blockindex.cpp
index d5ce79382..0f99e75d6 100644
--- a/src/blockindex.cpp
+++ b/src/blockindex.cpp
@@ -1,77 +1,80 @@
 // Copyright (c) 2009-2020 The Bitcoin developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <blockindex.h>
 
 /**
  * Turn the lowest '1' bit in the binary representation of a number into a '0'.
  */
 static inline int InvertLowestOne(int n) {
     return n & (n - 1);
 }
 
 /** Compute what height to jump back to with the CBlockIndex::pskip pointer. */
 static inline int GetSkipHeight(int height) {
     if (height < 2) {
         return 0;
     }
 
     // Determine which height to jump back to. Any number strictly lower than
     // height is acceptable, but the following expression seems to perform well
     // in simulations (max 110 steps to go back up to 2**18 blocks).
     return (height & 1) ? InvertLowestOne(InvertLowestOne(height - 1)) + 1
                         : InvertLowestOne(height);
 }
 
 bool CBlockIndex::UpdateChainStats() {
     if (pprev == nullptr) {
         nChainTx = nTx;
+        nChainSize = nSize;
         return true;
     }
 
     if (pprev->HaveTxsDownloaded()) {
         nChainTx = pprev->nChainTx + nTx;
+        nChainSize = pprev->nChainSize + nSize;
         return true;
     }
 
     nChainTx = 0;
+    nChainSize = 0;
     return false;
 }
 
 const CBlockIndex *CBlockIndex::GetAncestor(int height) const {
     if (height > nHeight || height < 0) {
         return nullptr;
     }
 
     const CBlockIndex *pindexWalk = this;
     int heightWalk = nHeight;
     while (heightWalk > height) {
         int heightSkip = GetSkipHeight(heightWalk);
         int heightSkipPrev = GetSkipHeight(heightWalk - 1);
         if (pindexWalk->pskip != nullptr &&
             (heightSkip == height ||
              (heightSkip > height && !(heightSkipPrev < heightSkip - 2 &&
                                        heightSkipPrev >= height)))) {
             // Only follow pskip if pprev->pskip isn't better than pskip->pprev.
             pindexWalk = pindexWalk->pskip;
             heightWalk = heightSkip;
         } else {
             assert(pindexWalk->pprev);
             pindexWalk = pindexWalk->pprev;
             heightWalk--;
         }
     }
     return pindexWalk;
 }
 
 CBlockIndex *CBlockIndex::GetAncestor(int height) {
     return const_cast<CBlockIndex *>(
         const_cast<const CBlockIndex *>(this)->GetAncestor(height));
 }
 
 void CBlockIndex::BuildSkip() {
     if (pprev) {
         pskip = pprev->GetAncestor(GetSkipHeight(nHeight));
     }
 }
diff --git a/src/blockindex.h b/src/blockindex.h
index 23f1be59b..3f6a7a88d 100644
--- a/src/blockindex.h
+++ b/src/blockindex.h
@@ -1,212 +1,227 @@
 // Copyright (c) 2009-2020 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_BLOCKINDEX_H
 #define BITCOIN_BLOCKINDEX_H
 
 #include <arith_uint256.h>
 #include <blockstatus.h>
 #include <flatfile.h>
 #include <primitives/block.h>
 #include <tinyformat.h>
 #include <uint256.h>
 
 struct BlockHash;
 
 /**
  * The block chain is a tree shaped structure starting with the genesis block at
  * the root, with each block potentially having multiple candidates to be the
  * next block. A blockindex may have multiple pprev pointing to it, but at most
  * one of them can be part of the currently active branch.
  */
 class CBlockIndex {
 public:
     //! pointer to the hash of the block, if any. Memory is owned by this
     //! CBlockIndex
     const BlockHash *phashBlock = nullptr;
 
     //! pointer to the index of the predecessor of this block
     CBlockIndex *pprev = nullptr;
 
     //! pointer to the index of some further predecessor of this block
     CBlockIndex *pskip = nullptr;
 
     //! height of the entry in the chain. The genesis block has height 0
     int nHeight = 0;
 
     //! Which # file this block is stored in (blk?????.dat)
     int nFile = 0;
 
     //! Byte offset within blk?????.dat where this block's data is stored
     unsigned int nDataPos = 0;
 
     //! Byte offset within rev?????.dat where this block's undo data is stored
     unsigned int nUndoPos = 0;
 
     //! (memory only) Total amount of work (expected number of hashes) in the
     //! chain up to and including this block
     arith_uint256 nChainWork = arith_uint256();
 
     //! Number of transactions in this block.
     //! Note: in a potential headers-first mode, this number cannot be relied
     //! upon
     unsigned int nTx = 0;
 
+    //! Size of this block.
+    //! Note: in a potential headers-first mode, this number cannot be relied
+    //! upon
+    unsigned int nSize = 0;
+
 private:
     //! (memory only) Number of transactions in the chain up to and including
     //! this block.
     //! This value will be non-zero only if and only if transactions for this
     //! block and all its parents are available. Change to 64-bit type when
     //! necessary; won't happen before 2030
     unsigned int nChainTx = 0;
 
+    //! (memory only) Size of all blocks in the chain up to and including this
+    //! block. This value will be non-zero only if and only if transactions for
+    //! this block and all its parents are available.
+    uint64_t nChainSize = 0;
+
 public:
     //! Verification status of this block. See enum BlockStatus
     BlockStatus nStatus = BlockStatus();
 
     //! block header
     int32_t nVersion = 0;
     uint256 hashMerkleRoot = uint256();
     uint32_t nTime = 0;
     uint32_t nBits = 0;
     uint32_t nNonce = 0;
 
     //! (memory only) Sequential id assigned to distinguish order in which
     //! blocks are received.
     int32_t nSequenceId = 0;
 
     //! (memory only) block header metadata
     uint64_t nTimeReceived = 0;
 
     //! (memory only) Maximum nTime in the chain up to and including this block.
     unsigned int nTimeMax = 0;
 
     explicit CBlockIndex() = default;
 
     explicit CBlockIndex(const CBlockHeader &block) : CBlockIndex() {
         nVersion = block.nVersion;
         hashMerkleRoot = block.hashMerkleRoot;
         nTime = block.nTime;
         nTimeReceived = 0;
         nBits = block.nBits;
         nNonce = block.nNonce;
     }
 
     FlatFilePos GetBlockPos() const {
         FlatFilePos ret;
         if (nStatus.hasData()) {
             ret.nFile = nFile;
             ret.nPos = nDataPos;
         }
         return ret;
     }
 
     FlatFilePos GetUndoPos() const {
         FlatFilePos ret;
         if (nStatus.hasUndo()) {
             ret.nFile = nFile;
             ret.nPos = nUndoPos;
         }
         return ret;
     }
 
     CBlockHeader GetBlockHeader() const {
         CBlockHeader block;
         block.nVersion = nVersion;
         if (pprev) {
             block.hashPrevBlock = pprev->GetBlockHash();
         }
         block.hashMerkleRoot = hashMerkleRoot;
         block.nTime = nTime;
         block.nBits = nBits;
         block.nNonce = nNonce;
         return block;
     }
 
     BlockHash GetBlockHash() const { return *phashBlock; }
 
     /**
      * Get the number of transaction in the chain so far.
      */
     int64_t GetChainTxCount() const { return nChainTx; }
 
+    /**
+     * Get the size of all the blocks in the chain so far.
+     */
+    uint64_t GetChainSize() const { return nChainSize; }
+
     /**
      * Update chain tx stats.
      */
     bool UpdateChainStats();
 
     /**
      * Check whether this block's and all previous blocks' transactions have
      * been downloaded (and stored to disk) at some point.
      *
      * Does not imply the transactions are consensus-valid (ConnectTip might
      * fail) Does not imply the transactions are still stored on disk.
      * (IsBlockPruned might return true)
      */
     bool HaveTxsDownloaded() const { return GetChainTxCount() != 0; }
 
     int64_t GetBlockTime() const { return int64_t(nTime); }
 
     int64_t GetBlockTimeMax() const { return int64_t(nTimeMax); }
 
     int64_t GetHeaderReceivedTime() const { return nTimeReceived; }
 
     int64_t GetReceivedTimeDiff() const {
         return GetHeaderReceivedTime() - GetBlockTime();
     }
 
     static constexpr int nMedianTimeSpan = 11;
 
     int64_t GetMedianTimePast() const {
         int64_t pmedian[nMedianTimeSpan];
         int64_t *pbegin = &pmedian[nMedianTimeSpan];
         int64_t *pend = &pmedian[nMedianTimeSpan];
 
         const CBlockIndex *pindex = this;
         for (int i = 0; i < nMedianTimeSpan && pindex;
              i++, pindex = pindex->pprev) {
             *(--pbegin) = pindex->GetBlockTime();
         }
 
         std::sort(pbegin, pend);
         return pbegin[(pend - pbegin) / 2];
     }
 
     std::string ToString() const {
         return strprintf(
             "CBlockIndex(pprev=%p, nHeight=%d, merkle=%s, hashBlock=%s)", pprev,
             nHeight, hashMerkleRoot.ToString(), GetBlockHash().ToString());
     }
 
     //! Check whether this block index entry is valid up to the passed validity
     //! level.
     bool IsValid(enum BlockValidity nUpTo = BlockValidity::TRANSACTIONS) const {
         return nStatus.isValid(nUpTo);
     }
 
     //! Raise the validity level of this block index entry.
     //! Returns true if the validity was changed.
     bool RaiseValidity(enum BlockValidity nUpTo) {
         // Only validity flags allowed.
         if (nStatus.isInvalid()) {
             return false;
         }
 
         if (nStatus.getValidity() >= nUpTo) {
             return false;
         }
 
         nStatus = nStatus.withValidity(nUpTo);
         return true;
     }
 
     //! Build the skiplist pointer for this entry.
     void BuildSkip();
 
     //! Efficiently find an ancestor of this block.
     CBlockIndex *GetAncestor(int height);
     const CBlockIndex *GetAncestor(int height) const;
 };
 
 #endif // BITCOIN_BLOCKINDEX_H
diff --git a/src/blockvalidity.h b/src/blockvalidity.h
index cbb80e680..82e178e33 100644
--- a/src/blockvalidity.h
+++ b/src/blockvalidity.h
@@ -1,49 +1,49 @@
 // Copyright (c) 2018 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_BLOCKVALIDITY_H
 #define BITCOIN_BLOCKVALIDITY_H
 
 #include <cstdint>
 
 enum class BlockValidity : uint32_t {
     /**
      * Unused.
      */
     UNKNOWN = 0,
 
     /**
      * Reserved (was HEADER).
      */
     RESERVED = 1,
 
     /**
      * All parent headers found, difficulty matches, timestamp >= median
      * previous, checkpoint. Implies all parents are also at least TREE.
      */
     TREE = 2,
 
     /**
      * Only first tx is coinbase, 2 <= coinbase input script length <= 100,
      * transactions valid, no duplicate txids, sigops, size, merkle root.
      * Implies all parents are at least TREE but not necessarily TRANSACTIONS.
-     * When all parent blocks also have TRANSACTIONS, CBlockIndex::nChainTx will
-     * be set.
+     * When all parent blocks also have TRANSACTIONS, CBlockIndex::nChainTx and
+     * CBlockIndex::nChainSize will be set.
      */
     TRANSACTIONS = 3,
 
     /**
      * Outputs do not overspend inputs, no double spends, coinbase output ok, no
      * immature coinbase spends, BIP30.
      * Implies all parents are also at least CHAIN.
      */
     CHAIN = 4,
 
     /**
      * Scripts & signatures ok. Implies all parents are also at least SCRIPTS.
      */
     SCRIPTS = 5,
 };
 
 #endif // BITCOIN_BLOCKVALIDITY_H
diff --git a/src/chain.h b/src/chain.h
index cbe4199c8..a317ca0d6 100644
--- a/src/chain.h
+++ b/src/chain.h
@@ -1,228 +1,236 @@
 // 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.
 
 #ifndef BITCOIN_CHAIN_H
 #define BITCOIN_CHAIN_H
 
 #include <arith_uint256.h>
 #include <blockindex.h>
 #include <blockstatus.h>
 #include <blockvalidity.h>
 #include <consensus/params.h>
 #include <crypto/common.h> // for ReadLE64
 #include <flatfile.h>
 #include <primitives/block.h>
 #include <sync.h>
 #include <tinyformat.h>
 #include <uint256.h>
 
 #include <unordered_map>
 #include <vector>
 
 /**
  * Maximum amount of time that a block timestamp is allowed to exceed the
  * current network-adjusted time before the block will be accepted.
  */
 static constexpr int64_t MAX_FUTURE_BLOCK_TIME = 2 * 60 * 60;
 
 /**
  * Timestamp window used as a grace period by code that compares external
  * timestamps (such as timestamps passed to RPCs, or wallet key creation times)
  * to block timestamps. This should be set at least as high as
  * MAX_FUTURE_BLOCK_TIME.
  */
 static constexpr int64_t TIMESTAMP_WINDOW = MAX_FUTURE_BLOCK_TIME;
 
 /**
  * Maximum gap between node time and block time used
  * for the "Catching up..." mode in GUI.
  *
  * Ref: https://github.com/bitcoin/bitcoin/pull/1026
  */
 static constexpr int64_t MAX_BLOCK_TIME_GAP = 90 * 60;
 
 /**
  * Maintain a map of CBlockIndex for all known headers.
  */
 struct BlockHasher {
     // this used to call `GetCheapHash()` in uint256, which was later moved; the
     // cheap hash function simply calls ReadLE64() however, so the end result is
     // identical
     size_t operator()(const BlockHash &hash) const {
         return ReadLE64(hash.begin());
     }
 };
 
 extern RecursiveMutex cs_main;
 
 arith_uint256 GetBlockProof(const CBlockIndex &block);
 
 /**
  * Return the time it would take to redo the work difference between from and
  * to, assuming the current hashrate corresponds to the difficulty at tip, in
  * seconds.
  */
 int64_t GetBlockProofEquivalentTime(const CBlockIndex &to,
                                     const CBlockIndex &from,
                                     const CBlockIndex &tip,
                                     const Consensus::Params &);
 /**
  * Find the forking point between two chain tips.
  */
 const CBlockIndex *LastCommonAncestor(const CBlockIndex *pa,
                                       const CBlockIndex *pb);
 
 /**
  * Check if two block index are on the same fork.
  */
 bool AreOnTheSameFork(const CBlockIndex *pa, const CBlockIndex *pb);
 
 /** Used to marshal pointers into hashes for db storage. */
 class CDiskBlockIndex : public CBlockIndex {
 public:
+    static constexpr int TRACK_SIZE_VERSION = 220800;
+
     BlockHash hashPrev;
 
-    CDiskBlockIndex() { hashPrev = BlockHash(); }
+    CDiskBlockIndex() : hashPrev() {}
 
     explicit CDiskBlockIndex(const CBlockIndex *pindex) : CBlockIndex(*pindex) {
         hashPrev = (pprev ? pprev->GetBlockHash() : BlockHash());
     }
 
     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(VARINT(_nVersion, VarIntMode::NONNEGATIVE_SIGNED));
         }
 
         READWRITE(VARINT(nHeight, VarIntMode::NONNEGATIVE_SIGNED));
         READWRITE(nStatus);
         READWRITE(VARINT(nTx));
+
+        // The size of the blocks are tracked starting at version 0.22.8
+        if (nStatus.hasData() && _nVersion >= TRACK_SIZE_VERSION) {
+            READWRITE(VARINT(nSize));
+        }
+
         if (nStatus.hasData() || nStatus.hasUndo()) {
             READWRITE(VARINT(nFile, VarIntMode::NONNEGATIVE_SIGNED));
         }
         if (nStatus.hasData()) {
             READWRITE(VARINT(nDataPos));
         }
         if (nStatus.hasUndo()) {
             READWRITE(VARINT(nUndoPos));
         }
 
         // block header
         READWRITE(this->nVersion);
         READWRITE(hashPrev);
         READWRITE(hashMerkleRoot);
         READWRITE(nTime);
         READWRITE(nBits);
         READWRITE(nNonce);
     }
 
     BlockHash GetBlockHash() const {
         CBlockHeader block;
         block.nVersion = nVersion;
         block.hashPrevBlock = hashPrev;
         block.hashMerkleRoot = hashMerkleRoot;
         block.nTime = nTime;
         block.nBits = nBits;
         block.nNonce = nNonce;
         return block.GetHash();
     }
 
     std::string ToString() const {
         std::string str = "CDiskBlockIndex(";
         str += CBlockIndex::ToString();
         str += strprintf("\n                hashBlock=%s, hashPrev=%s)",
                          GetBlockHash().ToString(), hashPrev.ToString());
         return str;
     }
 };
 
 /**
  * An in-memory indexed chain of blocks.
  */
 class CChain {
 private:
     std::vector<CBlockIndex *> vChain;
 
 public:
     /**
      * Returns the index entry for the genesis block of this chain, or nullptr
      * if none.
      */
     CBlockIndex *Genesis() const {
         return vChain.size() > 0 ? vChain[0] : nullptr;
     }
 
     /**
      * Returns the index entry for the tip of this chain, or nullptr if none.
      */
     CBlockIndex *Tip() const {
         return vChain.size() > 0 ? vChain[vChain.size() - 1] : nullptr;
     }
 
     /**
      * Returns the index entry at a particular height in this chain, or nullptr
      * if no such height exists.
      */
     CBlockIndex *operator[](int nHeight) const {
         if (nHeight < 0 || nHeight >= (int)vChain.size()) {
             return nullptr;
         }
         return vChain[nHeight];
     }
 
     /** Compare two chains efficiently. */
     friend bool operator==(const CChain &a, const CChain &b) {
         return a.vChain.size() == b.vChain.size() &&
                a.vChain[a.vChain.size() - 1] == b.vChain[b.vChain.size() - 1];
     }
 
     /** Efficiently check whether a block is present in this chain. */
     bool Contains(const CBlockIndex *pindex) const {
         return (*this)[pindex->nHeight] == pindex;
     }
 
     /**
      * Find the successor of a block in this chain, or nullptr if the given
      * index is not found or is the tip.
      */
     CBlockIndex *Next(const CBlockIndex *pindex) const {
         if (!Contains(pindex)) {
             return nullptr;
         }
 
         return (*this)[pindex->nHeight + 1];
     }
 
     /**
      * Return the maximal height in the chain. Is equal to chain.Tip() ?
      * chain.Tip()->nHeight : -1.
      */
     int Height() const { return vChain.size() - 1; }
 
     /** Set/initialize a chain with a given tip. */
     void SetTip(CBlockIndex *pindex);
 
     /**
      * Return a CBlockLocator that refers to a block in this chain (by default
      * the tip).
      */
     CBlockLocator GetLocator(const CBlockIndex *pindex = nullptr) const;
 
     /**
      * Find the last common block between this chain and a block index entry.
      */
     const CBlockIndex *FindFork(const CBlockIndex *pindex) const;
 
     /**
      * Find the earliest block with timestamp equal or greater than the given
      * time and height equal or greater than the given height.
      */
     CBlockIndex *FindEarliestAtLeast(int64_t nTime, int height) const;
 };
 
 #endif // BITCOIN_CHAIN_H
diff --git a/src/init.cpp b/src/init.cpp
index fa194b52a..ae642650b 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -1,2812 +1,2820 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2018 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #if defined(HAVE_CONFIG_H)
 #include <config/bitcoin-config.h>
 #endif
 
 #include <init.h>
 
 #include <addrman.h>
 #include <amount.h>
 #include <avalanche/processor.h>
 #include <banman.h>
 #include <blockdb.h>
 #include <blockfilter.h>
 #include <chain.h>
 #include <chainparams.h>
 #include <checkpoints.h>
 #include <compat/sanity.h>
 #include <config.h>
 #include <consensus/validation.h>
 #include <flatfile.h>
 #include <fs.h>
 #include <hash.h>
 #include <httprpc.h>
 #include <httpserver.h>
 #include <index/blockfilterindex.h>
 #include <index/txindex.h>
 #include <interfaces/chain.h>
 #include <key.h>
 #include <miner.h>
 #include <net.h>
 #include <net_permissions.h>
 #include <net_processing.h>
 #include <netbase.h>
 #include <network.h>
 #include <node/context.h>
 #include <policy/mempool.h>
 #include <policy/policy.h>
 #include <policy/settings.h>
 #include <rpc/blockchain.h>
 #include <rpc/register.h>
 #include <rpc/server.h>
 #include <rpc/util.h>
 #include <scheduler.h>
 #include <script/scriptcache.h>
 #include <script/sigcache.h>
 #include <script/standard.h>
 #include <shutdown.h>
 #include <timedata.h>
 #include <torcontrol.h>
 #include <txdb.h>
 #include <txmempool.h>
 #include <ui_interface.h>
 #include <util/asmap.h>
 #include <util/moneystr.h>
 #include <util/threadnames.h>
 #include <util/translation.h>
 #include <validation.h>
 #include <validationinterface.h>
 #include <walletinitinterface.h>
 
 #include <boost/algorithm/string/classification.hpp>
 #include <boost/algorithm/string/replace.hpp>
 #include <boost/algorithm/string/split.hpp>
 #include <boost/thread.hpp>
 
 #if ENABLE_ZMQ
 #include <zmq/zmqabstractnotifier.h>
 #include <zmq/zmqnotificationinterface.h>
 #include <zmq/zmqrpc.h>
 #endif
 
 #ifndef WIN32
 #include <attributes.h>
 #include <cerrno>
 #include <csignal>
 #include <sys/stat.h>
 #endif
 #include <cstdint>
 #include <cstdio>
 #include <functional>
 #include <set>
 
 static const bool DEFAULT_PROXYRANDOMIZE = true;
 static const bool DEFAULT_REST_ENABLE = false;
 static const bool DEFAULT_STOPAFTERBLOCKIMPORT = false;
 
 #ifdef WIN32
 // Win32 LevelDB doesn't use filedescriptors, and the ones used for accessing
 // block files don't count towards the fd_set size limit anyway.
 #define MIN_CORE_FILEDESCRIPTORS 0
 #else
 #define MIN_CORE_FILEDESCRIPTORS 150
 #endif
 
 static const char *DEFAULT_ASMAP_FILENAME = "ip_asn.map";
 
 /**
  * The PID file facilities.
  */
 static const char *BITCOIN_PID_FILENAME = "bitcoind.pid";
 
 static fs::path GetPidFile() {
     return AbsPathForConfigVal(
         fs::path(gArgs.GetArg("-pid", BITCOIN_PID_FILENAME)));
 }
 
 NODISCARD static bool CreatePidFile() {
     fsbridge::ofstream file{GetPidFile()};
     if (file) {
 #ifdef WIN32
         tfm::format(file, "%d\n", GetCurrentProcessId());
 #else
         tfm::format(file, "%d\n", getpid());
 #endif
         return true;
     } else {
         return InitError(strprintf(_("Unable to create the PID file '%s': %s"),
                                    GetPidFile().string(),
                                    std::strerror(errno)));
     }
 }
 
 //////////////////////////////////////////////////////////////////////////////
 //
 // Shutdown
 //
 
 //
 // Thread management and startup/shutdown:
 //
 // The network-processing threads are all part of a thread group created by
 // AppInit() or the Qt main() function.
 //
 // A clean exit happens when StartShutdown() or the SIGTERM signal handler sets
 // fRequestShutdown, which makes main thread's WaitForShutdown() interrupts the
 // thread group.
 // And then, WaitForShutdown() makes all other on-going threads in the thread
 // group join the main thread.
 // Shutdown() is then called to clean up database connections, and stop other
 // threads that should only be stopped after the main network-processing threads
 // have exited.
 //
 // Shutdown for Qt is very similar, only it uses a QTimer to detect
 // ShutdownRequested() getting set, and then does the normal Qt shutdown thing.
 //
 
 static std::unique_ptr<ECCVerifyHandle> globalVerifyHandle;
 
 static boost::thread_group threadGroup;
 
 void Interrupt(NodeContext &node) {
     InterruptHTTPServer();
     InterruptHTTPRPC();
     InterruptRPC();
     InterruptREST();
     InterruptTorControl();
     InterruptMapPort();
     if (g_avalanche) {
         // Avalanche needs to be stopped before we interrupt the thread group as
         // the scheduler will stop working then.
         g_avalanche->stopEventLoop();
     }
     if (node.connman) {
         node.connman->Interrupt();
     }
     if (g_txindex) {
         g_txindex->Interrupt();
     }
     ForEachBlockFilterIndex([](BlockFilterIndex &index) { index.Interrupt(); });
 }
 
 void Shutdown(NodeContext &node) {
     LogPrintf("%s: In progress...\n", __func__);
     static RecursiveMutex cs_Shutdown;
     TRY_LOCK(cs_Shutdown, lockShutdown);
     if (!lockShutdown) {
         return;
     }
 
     /// Note: Shutdown() must be able to handle cases in which initialization
     /// failed part of the way, for example if the data directory was found to
     /// be locked. Be sure that anything that writes files or flushes caches
     /// only does this if the respective module was initialized.
     util::ThreadRename("shutoff");
     g_mempool.AddTransactionsUpdated(1);
 
     StopHTTPRPC();
     StopREST();
     StopRPC();
     StopHTTPServer();
     for (const auto &client : node.chain_clients) {
         client->flush();
     }
     StopMapPort();
 
     // Because avalanche and the network depend on each other, it is important
     // to shut them down in this order:
     // 1. Stop avalanche event loop.
     // 2. Shutdown network processing.
     // 3. Destroy avalanche::Processor.
     // 4. Destroy CConnman
     if (g_avalanche) {
         g_avalanche->stopEventLoop();
     }
 
     // Because these depend on each-other, we make sure that neither can be
     // using the other before destroying them.
     if (node.peer_logic) {
         UnregisterValidationInterface(node.peer_logic.get());
     }
     if (node.connman) {
         node.connman->Stop();
     }
     if (g_txindex) {
         g_txindex->Stop();
     }
     ForEachBlockFilterIndex([](BlockFilterIndex &index) { index.Stop(); });
 
     StopTorControl();
 
     // After everything has been shut down, but before things get flushed, stop
     // the CScheduler/checkqueue threadGroup
     if (node.scheduler) {
         node.scheduler->stop();
     }
     threadGroup.interrupt_all();
     threadGroup.join_all();
 
     // After the threads that potentially access these pointers have been
     // stopped, destruct and reset all to nullptr.
     node.peer_logic.reset();
 
     // Destroy various global instances
     g_avalanche.reset();
     node.connman.reset();
     node.banman.reset();
     g_txindex.reset();
     DestroyAllBlockFilterIndexes();
 
     if (::g_mempool.IsLoaded() &&
         gArgs.GetArg("-persistmempool", DEFAULT_PERSIST_MEMPOOL)) {
         DumpMempool(::g_mempool);
     }
 
     // FlushStateToDisk generates a ChainStateFlushed callback, which we should
     // avoid missing
     // g_chainstate is referenced here directly (instead of
     // ::ChainstateActive()) because it may not have been initialized yet.
     {
         LOCK(cs_main);
         if (g_chainstate && g_chainstate->CanFlushToDisk()) {
             g_chainstate->ForceFlushStateToDisk();
         }
     }
 
     // After there are no more peers/RPC left to give us new data which may
     // generate CValidationInterface callbacks, flush them...
     GetMainSignals().FlushBackgroundCallbacks();
 
     // Any future callbacks will be dropped. This should absolutely be safe - if
     // missing a callback results in an unrecoverable situation, unclean
     // shutdown would too. The only reason to do the above flushes is to let the
     // wallet catch up with our current chain to avoid any strange pruning edge
     // cases and make next startup faster by avoiding rescan.
 
     {
         LOCK(cs_main);
         if (g_chainstate && g_chainstate->CanFlushToDisk()) {
             g_chainstate->ForceFlushStateToDisk();
             g_chainstate->ResetCoinsViews();
         }
         pblocktree.reset();
     }
     for (const auto &client : node.chain_clients) {
         client->stop();
     }
 
 #if ENABLE_ZMQ
     if (g_zmq_notification_interface) {
         UnregisterValidationInterface(g_zmq_notification_interface);
         delete g_zmq_notification_interface;
         g_zmq_notification_interface = nullptr;
     }
 #endif
 
     try {
         if (!fs::remove(GetPidFile())) {
             LogPrintf("%s: Unable to remove PID file: File does not exist\n",
                       __func__);
         }
     } catch (const fs::filesystem_error &e) {
         LogPrintf("%s: Unable to remove PID file: %s\n", __func__,
                   fsbridge::get_filesystem_error_message(e));
     }
     node.chain_clients.clear();
     UnregisterAllValidationInterfaces();
     GetMainSignals().UnregisterBackgroundSignalScheduler();
     globalVerifyHandle.reset();
     ECC_Stop();
     if (node.mempool) {
         node.mempool = nullptr;
     }
     node.scheduler.reset();
     LogPrintf("%s: done\n", __func__);
 }
 
 /**
  * Signal handlers are very limited in what they are allowed to do.
  * The execution context the handler is invoked in is not guaranteed,
  * so we restrict handler operations to just touching variables:
  */
 #ifndef WIN32
 static void HandleSIGTERM(int) {
     StartShutdown();
 }
 
 static void HandleSIGHUP(int) {
     LogInstance().m_reopen_file = true;
 }
 #else
 static BOOL WINAPI consoleCtrlHandler(DWORD dwCtrlType) {
     StartShutdown();
     Sleep(INFINITE);
     return true;
 }
 #endif
 
 #ifndef WIN32
 static void registerSignalHandler(int signal, void (*handler)(int)) {
     struct sigaction sa;
     sa.sa_handler = handler;
     sigemptyset(&sa.sa_mask);
     sa.sa_flags = 0;
     sigaction(signal, &sa, NULL);
 }
 #endif
 
 static boost::signals2::connection rpc_notify_block_change_connection;
 static void OnRPCStarted() {
     rpc_notify_block_change_connection = uiInterface.NotifyBlockTip_connect(
         std::bind(RPCNotifyBlockChange, std::placeholders::_2));
 }
 
 static void OnRPCStopped() {
     rpc_notify_block_change_connection.disconnect();
     RPCNotifyBlockChange(nullptr);
     g_best_block_cv.notify_all();
     LogPrint(BCLog::RPC, "RPC stopped.\n");
 }
 
 void SetupServerArgs() {
     SetupHelpOptions(gArgs);
     // server-only for now
     gArgs.AddArg("-help-debug",
                  "Print help message with debugging options and exit", false,
                  OptionsCategory::DEBUG_TEST);
 
     const auto defaultBaseParams =
         CreateBaseChainParams(CBaseChainParams::MAIN);
     const auto testnetBaseParams =
         CreateBaseChainParams(CBaseChainParams::TESTNET);
     const auto regtestBaseParams =
         CreateBaseChainParams(CBaseChainParams::REGTEST);
     const auto defaultChainParams = CreateChainParams(CBaseChainParams::MAIN);
     const auto testnetChainParams =
         CreateChainParams(CBaseChainParams::TESTNET);
     const auto regtestChainParams =
         CreateChainParams(CBaseChainParams::REGTEST);
 
     // Hidden Options
     std::vector<std::string> hidden_args = {
         "-dbcrashratio", "-forcecompactdb", "-parkdeepreorg",
         "-automaticunparking", "-replayprotectionactivationtime",
         "-enableminerfund",
         // GUI args. These will be overwritten by SetupUIArgs for the GUI
         "-allowselfsignedrootcertificates", "-choosedatadir", "-lang=<lang>",
         "-min", "-resetguisettings", "-rootcertificates=<file>", "-splash",
         "-uiplatform",
         // TODO remove after the November 2020 upgrade
         "-axionactivationtime"};
 
     // Set all of the args and their help
     // When adding new options to the categories, please keep and ensure
     // alphabetical ordering. Do not translate _(...) -help-debug options, Many
     // technical terms, and only a very small audience, so is unnecessary stress
     // to translators.
     gArgs.AddArg("-version", "Print version and exit", ArgsManager::ALLOW_ANY,
                  OptionsCategory::OPTIONS);
 #if defined(HAVE_SYSTEM)
     gArgs.AddArg("-alertnotify=<cmd>",
                  "Execute command when a relevant alert is received or we see "
                  "a really long fork (%s in cmd is replaced by message)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
 #endif
     gArgs.AddArg(
         "-assumevalid=<hex>",
         strprintf(
             "If this block is in the chain assume that it and its ancestors "
             "are valid and potentially skip their script verification (0 to "
             "verify all, default: %s, testnet: %s)",
             defaultChainParams->GetConsensus().defaultAssumeValid.GetHex(),
             testnetChainParams->GetConsensus().defaultAssumeValid.GetHex()),
         ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-blocksdir=<dir>",
                  "Specify directory to hold blocks subdirectory for *.dat "
                  "files (default: <datadir>)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
 #if defined(HAVE_SYSTEM)
     gArgs.AddArg("-blocknotify=<cmd>",
                  "Execute command when the best block changes (%s in cmd is "
                  "replaced by block hash)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
 #endif
     gArgs.AddArg("-blockreconstructionextratxn=<n>",
                  strprintf("Extra transactions to keep in memory for compact "
                            "block reconstructions (default: %u)",
                            DEFAULT_BLOCK_RECONSTRUCTION_EXTRA_TXN),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-blocksonly",
         strprintf(
             "Whether to reject transactions from network peers. Transactions "
             "from the wallet, RPC and relay whitelisted inbound peers RPC are"
             " not affected. (default: %u)",
             DEFAULT_BLOCKSONLY),
         ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-conf=<file>",
         strprintf("Specify path to read-only configuration file. Relative "
                   "paths will be prefixed by datadir location. (default: %s)",
                   BITCOIN_CONF_FILENAME),
         ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-datadir=<dir>", "Specify data directory",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-dbbatchsize",
         strprintf("Maximum database write batch size in bytes (default: %u)",
                   DEFAULT_DB_BATCH_SIZE),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-dbcache=<n>",
         strprintf("Set database cache size in MiB (%d to %d, default: %d)",
                   MIN_DB_CACHE_MB, MAX_DB_CACHE_MB, DEFAULT_DB_CACHE_MB),
         ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-debuglogfile=<file>",
                  strprintf("Specify location of debug log file. Relative paths "
                            "will be prefixed by a net-specific datadir "
                            "location. (0 to disable; default: %s)",
                            DEFAULT_DEBUGLOGFILE),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-feefilter",
                  strprintf("Tell other nodes to filter invs to us by our "
                            "mempool min fee (default: %d)",
                            DEFAULT_FEEFILTER),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::OPTIONS);
     gArgs.AddArg("-finalizationdelay=<n>",
                  strprintf("Set the minimum amount of time to wait between a "
                            "block header reception and the block finalization. "
                            "Unit is seconds (default: %d)",
                            DEFAULT_MIN_FINALIZATION_DELAY),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-includeconf=<file>",
         "Specify additional configuration file, relative to the -datadir path "
         "(only useable from configuration file, not command line)",
         ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-maxreorgdepth=<n>",
                  strprintf("Configure at what depth blocks are considered "
                            "final (default: %d). Use -1 to disable.",
                            DEFAULT_MAX_REORG_DEPTH),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-loadblock=<file>",
                  "Imports blocks from external file on startup",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-maxmempool=<n>",
                  strprintf("Keep the transaction memory pool below <n> "
                            "megabytes (default: %u)",
                            DEFAULT_MAX_MEMPOOL_SIZE),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-maxorphantx=<n>",
                  strprintf("Keep at most <n> unconnectable transactions in "
                            "memory (default: %u)",
                            DEFAULT_MAX_ORPHAN_TRANSACTIONS),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-mempoolexpiry=<n>",
                  strprintf("Do not keep transactions in the mempool longer "
                            "than <n> hours (default: %u)",
                            DEFAULT_MEMPOOL_EXPIRY),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-minimumchainwork=<hex>",
         strprintf(
             "Minimum work assumed to exist on a valid chain in hex "
             "(default: %s, testnet: %s)",
             defaultChainParams->GetConsensus().nMinimumChainWork.GetHex(),
             testnetChainParams->GetConsensus().nMinimumChainWork.GetHex()),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-par=<n>",
         strprintf("Set the number of script verification threads (%u to %d, 0 "
                   "= auto, <0 = leave that many cores free, default: %d)",
                   -GetNumCores(), MAX_SCRIPTCHECK_THREADS,
                   DEFAULT_SCRIPTCHECK_THREADS),
         ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-persistmempool",
                  strprintf("Whether to save the mempool on shutdown and load "
                            "on restart (default: %u)",
                            DEFAULT_PERSIST_MEMPOOL),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-pid=<file>",
                  strprintf("Specify pid file. Relative paths will be prefixed "
                            "by a net-specific datadir location. (default: %s)",
                            BITCOIN_PID_FILENAME),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-prune=<n>",
         strprintf("Reduce storage requirements by enabling pruning (deleting) "
                   "of old blocks. This allows the pruneblockchain RPC to be "
                   "called to delete specific blocks, and enables automatic "
                   "pruning of old blocks if a target size in MiB is provided. "
                   "This mode is incompatible with -txindex and -rescan. "
                   "Warning: Reverting this setting requires re-downloading the "
                   "entire blockchain. (default: 0 = disable pruning blocks, 1 "
                   "= allow manual pruning via RPC, >=%u = automatically prune "
                   "block files to stay under the specified target size in MiB)",
                   MIN_DISK_SPACE_FOR_BLOCK_FILES / 1024 / 1024),
         ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-reindex-chainstate",
                  "Rebuild chain state from the currently indexed blocks. When "
                  "in pruning mode or if blocks on disk might be corrupted, use "
                  "full -reindex instead.",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-reindex",
         "Rebuild chain state and block index from the blk*.dat files on disk",
         ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-settings=<file>",
         strprintf(
             "Specify path to dynamic settings data file. Can be disabled with "
             "-nosettings. File is written at runtime and not meant to be "
             "edited by users (use %s instead for custom settings). Relative "
             "paths will be prefixed by datadir location. (default: %s)",
             BITCOIN_CONF_FILENAME, BITCOIN_SETTINGS_FILENAME),
         ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
 #ifndef WIN32
     gArgs.AddArg(
         "-sysperms",
         "Create new files with system default permissions, instead of umask "
         "077 (only effective with disabled wallet functionality)",
         ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
 #else
     hidden_args.emplace_back("-sysperms");
 #endif
     gArgs.AddArg("-txindex",
                  strprintf("Maintain a full transaction index, used by the "
                            "getrawtransaction rpc call (default: %d)",
                            DEFAULT_TXINDEX),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-blockfilterindex=<type>",
                  strprintf("Maintain an index of compact filters by block "
                            "(default: %s, values: %s).",
                            DEFAULT_BLOCKFILTERINDEX, ListBlockFilterTypes()) +
                      " If <type> is not supplied or if <type> = 1, indexes for "
                      "all known types are enabled.",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-usecashaddr",
                  "Use Cash Address for destination encoding instead of base58 "
                  "(activate by default on Jan, 14)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
 
     gArgs.AddArg("-addnode=<ip>",
                  "Add a node to connect to and attempt to keep the connection "
                  "open (see the `addnode` RPC command help for more info)",
                  ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY,
                  OptionsCategory::CONNECTION);
     gArgs.AddArg("-asmap=<file>",
                  strprintf("Specify asn mapping used for bucketing of the "
                            "peers (default: %s). Relative paths will be "
                            "prefixed by the net-specific datadir location.",
                            DEFAULT_ASMAP_FILENAME),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-banscore=<n>",
                  strprintf("Threshold for disconnecting and discouraging "
                            "misbehaving peers (default: %u)",
                            DEFAULT_BANSCORE_THRESHOLD),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-bantime=<n>",
                  strprintf("Default duration (in seconds) of manually "
                            "configured bans (default: %u)",
                            DEFAULT_MISBEHAVING_BANTIME),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-bind=<addr>",
                  "Bind to given address and always listen on it. Use "
                  "[host]:port notation for IPv6",
                  ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY,
                  OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-connect=<ip>",
         "Connect only to the specified node(s); -connect=0 disables automatic "
         "connections (the rules for this peer are the same as for -addnode)",
         ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY,
         OptionsCategory::CONNECTION);
     gArgs.AddArg("-discover",
                  "Discover own IP addresses (default: 1 when listening and no "
                  "-externalip or -proxy)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-dns",
                  strprintf("Allow DNS lookups for -addnode, -seednode and "
                            "-connect (default: %d)",
                            DEFAULT_NAME_LOOKUP),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-dnsseed",
                  "Query for peer addresses via DNS lookup, if low on addresses "
                  "(default: 1 unless -connect used)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
 
     gArgs.AddArg("-externalip=<ip>", "Specify your own public address",
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-forcednsseed",
         strprintf(
             "Always query for peer addresses via DNS lookup (default: %d)",
             DEFAULT_FORCEDNSSEED),
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-listen",
         "Accept connections from outside (default: 1 if no -proxy or -connect)",
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-listenonion",
         strprintf("Automatically create Tor hidden service (default: %d)",
                   DEFAULT_LISTEN_ONION),
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-maxconnections=<n>",
         strprintf("Maintain at most <n> connections to peers (default: %u)",
                   DEFAULT_MAX_PEER_CONNECTIONS),
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-maxreceivebuffer=<n>",
                  strprintf("Maximum per-connection receive buffer, <n>*1000 "
                            "bytes (default: %u)",
                            DEFAULT_MAXRECEIVEBUFFER),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-maxsendbuffer=<n>",
         strprintf(
             "Maximum per-connection send buffer, <n>*1000 bytes (default: %u)",
             DEFAULT_MAXSENDBUFFER),
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-maxtimeadjustment",
         strprintf("Maximum allowed median peer time offset adjustment. Local "
                   "perspective of time may be influenced by peers forward or "
                   "backward by this amount. (default: %u seconds)",
                   DEFAULT_MAX_TIME_ADJUSTMENT),
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-onion=<ip:port>",
                  strprintf("Use separate SOCKS5 proxy to reach peers via Tor "
                            "hidden services (default: %s)",
                            "-proxy"),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-onlynet=<net>",
         "Make outgoing connections only through network <net> (ipv4, ipv6 or "
         "onion). Incoming connections are not affected by this option. This "
         "option can be specified multiple times to allow multiple networks.",
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-peerbloomfilters",
                  strprintf("Support filtering of blocks and transaction with "
                            "bloom filters (default: %d)",
                            DEFAULT_PEERBLOOMFILTERS),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-permitbaremultisig",
                  strprintf("Relay non-P2SH multisig (default: %d)",
                            DEFAULT_PERMIT_BAREMULTISIG),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-port=<port>",
                  strprintf("Listen for connections on <port> (default: %u, "
                            "testnet: %u, regtest: %u)",
                            defaultChainParams->GetDefaultPort(),
                            testnetChainParams->GetDefaultPort(),
                            regtestChainParams->GetDefaultPort()),
                  ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY,
                  OptionsCategory::CONNECTION);
     gArgs.AddArg("-proxy=<ip:port>", "Connect through SOCKS5 proxy",
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-proxyrandomize",
                  strprintf("Randomize credentials for every proxy connection. "
                            "This enables Tor stream isolation (default: %d)",
                            DEFAULT_PROXYRANDOMIZE),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-seednode=<ip>",
                  "Connect to a node to retrieve peer addresses, and disconnect",
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-timeout=<n>",
                  strprintf("Specify connection timeout in milliseconds "
                            "(minimum: 1, default: %d)",
                            DEFAULT_CONNECT_TIMEOUT),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-peertimeout=<n>",
         strprintf("Specify p2p connection timeout in seconds. This option "
                   "determines the amount of time a peer may be inactive before "
                   "the connection to it is dropped. (minimum: 1, default: %d)",
                   DEFAULT_PEER_CONNECT_TIMEOUT),
         true, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-torcontrol=<ip>:<port>",
         strprintf(
             "Tor control port to use if onion listening enabled (default: %s)",
             DEFAULT_TOR_CONTROL),
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-torpassword=<pass>",
                  "Tor control port password (default: empty)",
                  ArgsManager::ALLOW_ANY | ArgsManager::SENSITIVE,
                  OptionsCategory::CONNECTION);
 #ifdef USE_UPNP
 #if USE_UPNP
     gArgs.AddArg("-upnp",
                  "Use UPnP to map the listening port (default: 1 when "
                  "listening and no -proxy)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
 #else
     gArgs.AddArg(
         "-upnp",
         strprintf("Use UPnP to map the listening port (default: %u)", 0),
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
 #endif
 #else
     hidden_args.emplace_back("-upnp");
 #endif
     gArgs.AddArg("-whitebind=<[permissions@]addr>",
                  "Bind to given address and whitelist peers connecting to it."
                  " Use [host]:port notation for IPv6. Allowed permissions are "
                  "bloomfilter (allow requesting BIP37 filtered blocks and "
                  "transactions), noban (do not ban for misbehavior), "
                  "forcerelay (relay even non-standard transactions), "
                  "relay (relay even in -blocksonly mode), "
                  "and mempool (allow requesting BIP35 mempool contents). "
                  "Specify multiple permissions separated by commas (default: "
                  "noban,mempool,relay). Can be specified multiple times.",
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
 
     gArgs.AddArg("-whitelist=<[permissions@]IP address or network>",
                  "Whitelist peers connecting from the given IP address "
                  "(e.g. 1.2.3.4) or CIDR notated network(e.g. 1.2.3.0/24). "
                  "Uses same permissions as -whitebind. Can be specified "
                  "multiple times.",
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-maxuploadtarget=<n>",
         strprintf("Tries to keep outbound traffic under the given target (in "
                   "MiB per 24h), 0 = no limit (default: %d)",
                   DEFAULT_MAX_UPLOAD_TARGET),
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
 
     g_wallet_init_interface.AddWalletOptions();
 
 #if ENABLE_ZMQ
     gArgs.AddArg("-zmqpubhashblock=<address>",
                  "Enable publish hash block in <address>",
                  ArgsManager::ALLOW_ANY, OptionsCategory::ZMQ);
     gArgs.AddArg("-zmqpubhashtx=<address>",
                  "Enable publish hash transaction in <address>",
                  ArgsManager::ALLOW_ANY, OptionsCategory::ZMQ);
     gArgs.AddArg("-zmqpubrawblock=<address>",
                  "Enable publish raw block in <address>",
                  ArgsManager::ALLOW_ANY, OptionsCategory::ZMQ);
     gArgs.AddArg("-zmqpubrawtx=<address>",
                  "Enable publish raw transaction in <address>",
                  ArgsManager::ALLOW_ANY, OptionsCategory::ZMQ);
     gArgs.AddArg("-zmqpubhashblockhwm=<n>",
                  strprintf("Set publish hash block outbound message high water "
                            "mark (default: %d)",
                            CZMQAbstractNotifier::DEFAULT_ZMQ_SNDHWM),
                  false, OptionsCategory::ZMQ);
     gArgs.AddArg("-zmqpubhashtxhwm=<n>",
                  strprintf("Set publish hash transaction outbound message high "
                            "water mark (default: %d)",
                            CZMQAbstractNotifier::DEFAULT_ZMQ_SNDHWM),
                  false, OptionsCategory::ZMQ);
     gArgs.AddArg("-zmqpubrawblockhwm=<n>",
                  strprintf("Set publish raw block outbound message high water "
                            "mark (default: %d)",
                            CZMQAbstractNotifier::DEFAULT_ZMQ_SNDHWM),
                  false, OptionsCategory::ZMQ);
     gArgs.AddArg("-zmqpubrawtxhwm=<n>",
                  strprintf("Set publish raw transaction outbound message high "
                            "water mark (default: %d)",
                            CZMQAbstractNotifier::DEFAULT_ZMQ_SNDHWM),
                  false, OptionsCategory::ZMQ);
 #else
     hidden_args.emplace_back("-zmqpubhashblock=<address>");
     hidden_args.emplace_back("-zmqpubhashtx=<address>");
     hidden_args.emplace_back("-zmqpubrawblock=<address>");
     hidden_args.emplace_back("-zmqpubrawtx=<address>");
     hidden_args.emplace_back("-zmqpubhashblockhwm=<n>");
     hidden_args.emplace_back("-zmqpubhashtxhwm=<n>");
     hidden_args.emplace_back("-zmqpubrawblockhwm=<n>");
     hidden_args.emplace_back("-zmqpubrawtxhwm=<n>");
 #endif
 
     gArgs.AddArg(
         "-checkblocks=<n>",
         strprintf("How many blocks to check at startup (default: %u, 0 = all)",
                   DEFAULT_CHECKBLOCKS),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-checklevel=<n>",
         strprintf("How thorough the block verification of "
                   "-checkblocks is: "
                   "level 0 reads the blocks from disk, "
                   "level 1 verifies block validity, "
                   "level 2 verifies undo data, "
                   "level 3 checks disconnection of tip blocks, "
                   "and level 4 tries to reconnect the blocks. "
                   "Each level includes the checks of the previous levels "
                   "(0-4, default: %u)",
                   DEFAULT_CHECKLEVEL),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-checkblockindex",
                  strprintf("Do a consistency check for the block tree, "
                            "chainstate, and other validation data structures "
                            "occasionally. (default: %u, regtest: %u)",
                            defaultChainParams->DefaultConsistencyChecks(),
                            regtestChainParams->DefaultConsistencyChecks()),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-checkmempool=<n>",
         strprintf(
             "Run checks every <n> transactions (default: %u, regtest: %u)",
             defaultChainParams->DefaultConsistencyChecks(),
             regtestChainParams->DefaultConsistencyChecks()),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-checkpoints",
                  strprintf("Only accept block chain matching built-in "
                            "checkpoints (default: %d)",
                            DEFAULT_CHECKPOINTS_ENABLED),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-deprecatedrpc=<method>",
                  "Allows deprecated RPC method(s) to be used",
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-dropmessagestest=<n>",
                  "Randomly drop 1 of every <n> network messages",
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-stopafterblockimport",
         strprintf("Stop running after importing blocks from disk (default: %d)",
                   DEFAULT_STOPAFTERBLOCKIMPORT),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-stopatheight",
                  strprintf("Stop running after reaching the given height in "
                            "the main chain (default: %u)",
                            DEFAULT_STOPATHEIGHT),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-limitancestorcount=<n>",
                  strprintf("Do not accept transactions if number of in-mempool "
                            "ancestors is <n> or more (default: %u)",
                            DEFAULT_ANCESTOR_LIMIT),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-limitancestorsize=<n>",
         strprintf("Do not accept transactions whose size with all in-mempool "
                   "ancestors exceeds <n> kilobytes (default: %u)",
                   DEFAULT_ANCESTOR_SIZE_LIMIT),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-limitdescendantcount=<n>",
         strprintf("Do not accept transactions if any ancestor would have <n> "
                   "or more in-mempool descendants (default: %u)",
                   DEFAULT_DESCENDANT_LIMIT),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-limitdescendantsize=<n>",
         strprintf("Do not accept transactions if any ancestor would have more "
                   "than <n> kilobytes of in-mempool descendants (default: %u).",
                   DEFAULT_DESCENDANT_SIZE_LIMIT),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-addrmantest", "Allows to test address relay on localhost",
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::DEBUG_TEST);
 
     gArgs.AddArg("-debug=<category>",
                  strprintf("Output debugging information (default: %u, "
                            "supplying <category> is optional)",
                            0) +
                      ". " +
                      "If <category> is not supplied or if <category> = 1, "
                      "output all debugging information."
                      "<category> can be: " +
                      ListLogCategories() + ".",
                  ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-debugexclude=<category>",
         strprintf("Exclude debugging information for a category. Can be used "
                   "in conjunction with -debug=1 to output debug logs for all "
                   "categories except one or more specified categories."),
         ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-logips",
                  strprintf("Include IP addresses in debug output (default: %d)",
                            DEFAULT_LOGIPS),
                  ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-logtimestamps",
                  strprintf("Prepend debug output with timestamp (default: %d)",
                            DEFAULT_LOGTIMESTAMPS),
                  ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-logthreadnames",
         strprintf(
             "Prepend debug output with name of the originating thread (only "
             "available on platforms supporting thread_local) (default: %u)",
             DEFAULT_LOGTHREADNAMES),
         ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-logtimemicros",
         strprintf("Add microsecond precision to debug timestamps (default: %d)",
                   DEFAULT_LOGTIMEMICROS),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-mocktime=<n>",
                  "Replace actual time with " + UNIX_EPOCH_TIME +
                      " (default: 0)",
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-maxsigcachesize=<n>",
         strprintf("Limit size of signature cache to <n> MiB (default: %u)",
                   DEFAULT_MAX_SIG_CACHE_SIZE),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-maxscriptcachesize=<n>",
         strprintf("Limit size of script cache to <n> MiB (default: %u)",
                   DEFAULT_MAX_SCRIPT_CACHE_SIZE),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-maxtipage=<n>",
                  strprintf("Maximum tip age in seconds to consider node in "
                            "initial block download (default: %u)",
                            DEFAULT_MAX_TIP_AGE),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::DEBUG_TEST);
 
     gArgs.AddArg(
         "-printtoconsole",
         "Send trace/debug info to console instead of debug.log file (default: "
         "1 when no -daemon. To disable logging to file, set debuglogfile=0)",
         ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-printpriority",
                  strprintf("Log transaction priority and fee per kB when "
                            "mining blocks (default: %d)",
                            DEFAULT_PRINTPRIORITY),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-shrinkdebugfile",
         "Shrink debug.log file on client startup (default: 1 when no -debug)",
         ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
 
     gArgs.AddArg("-uacomment=<cmt>", "Append comment to the user agent string",
                  ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
 
     SetupChainParamsBaseOptions();
 
     gArgs.AddArg(
         "-acceptnonstdtxn",
         strprintf(
             "Relay and mine \"non-standard\" transactions (%sdefault: %u)",
             "testnet/regtest only; ", defaultChainParams->RequireStandard()),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::NODE_RELAY);
     gArgs.AddArg("-excessiveblocksize=<n>",
                  strprintf("Do not accept blocks larger than this limit, in "
                            "bytes (default: %d)",
                            DEFAULT_MAX_BLOCK_SIZE),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::NODE_RELAY);
     gArgs.AddArg(
         "-dustrelayfee=<amt>",
         strprintf("Fee rate (in %s/kB) used to define dust, the value of an "
                   "output such that it will cost about 1/3 of its value in "
                   "fees at this fee rate to spend it. (default: %s)",
                   CURRENCY_UNIT, FormatMoney(DUST_RELAY_TX_FEE)),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::NODE_RELAY);
 
     gArgs.AddArg("-bytespersigop",
                  strprintf("Equivalent bytes per sigop in transactions for "
                            "relay and mining (default: %u)",
                            DEFAULT_BYTES_PER_SIGOP),
                  ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     gArgs.AddArg(
         "-datacarrier",
         strprintf("Relay and mine data carrier transactions (default: %d)",
                   DEFAULT_ACCEPT_DATACARRIER),
         ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     gArgs.AddArg("-datacarriersize",
                  strprintf("Maximum size of data in data carrier transactions "
                            "we relay and mine (default: %u)",
                            MAX_OP_RETURN_RELAY),
                  ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     gArgs.AddArg(
         "-minrelaytxfee=<amt>",
         strprintf("Fees (in %s/kB) smaller than this are rejected for "
                   "relaying, mining and transaction creation (default: %s)",
                   CURRENCY_UNIT, FormatMoney(DEFAULT_MIN_RELAY_TX_FEE_PER_KB)),
         ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     gArgs.AddArg(
         "-whitelistrelay",
         strprintf("Add 'relay' permission to whitelisted inbound peers "
                   "with default permissions. This will accept relayed "
                   "transactions even when not relaying transactions "
                   "(default: %d)",
                   DEFAULT_WHITELISTRELAY),
         ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     gArgs.AddArg(
         "-whitelistforcerelay",
         strprintf("Add 'forcerelay' permission to whitelisted inbound peers"
                   " with default permissions. This will relay transactions "
                   "even if the transactions were already in the mempool or "
                   "violate local relay policy (default: %d)",
                   DEFAULT_WHITELISTFORCERELAY),
         ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
 
     // Not sure this really belongs here, but it will do for now.
     // FIXME: This doesn't work anyways.
     gArgs.AddArg("-excessutxocharge=<amt>",
                  strprintf("Fees (in %s/kB) to charge per utxo created for "
                            "relaying, and mining (default: %s)",
                            CURRENCY_UNIT, FormatMoney(DEFAULT_UTXO_FEE)),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::NODE_RELAY);
 
     gArgs.AddArg("-blockmaxsize=<n>",
                  strprintf("Set maximum block size in bytes (default: %d)",
                            DEFAULT_MAX_GENERATED_BLOCK_SIZE),
                  ArgsManager::ALLOW_ANY, OptionsCategory::BLOCK_CREATION);
     gArgs.AddArg("-blockmintxfee=<amt>",
                  strprintf("Set lowest fee rate (in %s/kB) for transactions to "
                            "be included in block creation. (default: %s)",
                            CURRENCY_UNIT,
                            FormatMoney(DEFAULT_BLOCK_MIN_TX_FEE_PER_KB)),
                  ArgsManager::ALLOW_ANY, OptionsCategory::BLOCK_CREATION);
 
     gArgs.AddArg("-blockversion=<n>",
                  "Override block version to test forking scenarios",
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::BLOCK_CREATION);
 
     gArgs.AddArg("-server", "Accept command line and JSON-RPC commands",
                  ArgsManager::ALLOW_ANY, OptionsCategory::RPC);
     gArgs.AddArg("-rest",
                  strprintf("Accept public REST requests (default: %d)",
                            DEFAULT_REST_ENABLE),
                  ArgsManager::ALLOW_ANY, OptionsCategory::RPC);
     gArgs.AddArg(
         "-rpcbind=<addr>[:port]",
         "Bind to given address to listen for JSON-RPC connections. Do not "
         "expose the RPC server to untrusted networks such as the public "
         "internet! This option is ignored unless -rpcallowip is also passed. "
         "Port is optional and overrides -rpcport.  Use [host]:port notation "
         "for IPv6. This option can be specified multiple times (default: "
         "127.0.0.1 and ::1 i.e., localhost)",
         ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY |
             ArgsManager::SENSITIVE,
         OptionsCategory::RPC);
     gArgs.AddArg("-rpccookiefile=<loc>",
                  "Location of the auth cookie. Relative paths will be prefixed "
                  "by a net-specific datadir location. (default: data dir)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::RPC);
     gArgs.AddArg("-rpcuser=<user>", "Username for JSON-RPC connections",
                  ArgsManager::ALLOW_ANY | ArgsManager::SENSITIVE,
                  OptionsCategory::RPC);
     gArgs.AddArg("-rpcpassword=<pw>", "Password for JSON-RPC connections",
                  ArgsManager::ALLOW_ANY | ArgsManager::SENSITIVE,
                  OptionsCategory::RPC);
     gArgs.AddArg(
         "-rpcwhitelist=<whitelist>",
         "Set a whitelist to filter incoming RPC calls for a specific user. The "
         "field <whitelist> comes in the format: <USERNAME>:<rpc 1>,<rpc "
         "2>,...,<rpc n>. If multiple whitelists are set for a given user, they "
         "are set-intersected. See -rpcwhitelistdefault documentation for "
         "information on default whitelist behavior.",
         ArgsManager::ALLOW_ANY, OptionsCategory::RPC);
     gArgs.AddArg(
         "-rpcwhitelistdefault",
         "Sets default behavior for rpc whitelisting. Unless "
         "rpcwhitelistdefault is set to 0, if any -rpcwhitelist is set, the rpc "
         "server acts as if all rpc users are subject to "
         "empty-unless-otherwise-specified whitelists. If rpcwhitelistdefault "
         "is set to 1 and no -rpcwhitelist is set, rpc server acts as if all "
         "rpc users are subject to empty whitelists.",
         ArgsManager::ALLOW_BOOL, OptionsCategory::RPC);
     gArgs.AddArg(
         "-rpcauth=<userpw>",
         "Username and HMAC-SHA-256 hashed password for JSON-RPC connections. "
         "The field <userpw> comes in the format: <USERNAME>:<SALT>$<HASH>. A "
         "canonical python script is included in share/rpcauth. The client then "
         "connects normally using the rpcuser=<USERNAME>/rpcpassword=<PASSWORD> "
         "pair of arguments. This option can be specified multiple times",
         ArgsManager::ALLOW_ANY | ArgsManager::SENSITIVE, OptionsCategory::RPC);
     gArgs.AddArg("-rpcport=<port>",
                  strprintf("Listen for JSON-RPC connections on <port> "
                            "(default: %u, testnet: %u, regtest: %u)",
                            defaultBaseParams->RPCPort(),
                            testnetBaseParams->RPCPort(),
                            regtestBaseParams->RPCPort()),
                  ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY,
                  OptionsCategory::RPC);
     gArgs.AddArg("-rpcallowip=<ip>",
                  "Allow JSON-RPC connections from specified source. Valid for "
                  "<ip> are a single IP (e.g. 1.2.3.4), a network/netmask (e.g. "
                  "1.2.3.4/255.255.255.0) or a network/CIDR (e.g. 1.2.3.4/24). "
                  "This option can be specified multiple times",
                  ArgsManager::ALLOW_ANY, OptionsCategory::RPC);
     gArgs.AddArg(
         "-rpcthreads=<n>",
         strprintf(
             "Set the number of threads to service RPC calls (default: %d)",
             DEFAULT_HTTP_THREADS),
         ArgsManager::ALLOW_ANY, OptionsCategory::RPC);
     gArgs.AddArg(
         "-rpccorsdomain=value",
         "Domain from which to accept cross origin requests (browser enforced)",
         ArgsManager::ALLOW_ANY, OptionsCategory::RPC);
 
     gArgs.AddArg("-rpcworkqueue=<n>",
                  strprintf("Set the depth of the work queue to service RPC "
                            "calls (default: %d)",
                            DEFAULT_HTTP_WORKQUEUE),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::RPC);
     gArgs.AddArg("-rpcservertimeout=<n>",
                  strprintf("Timeout during HTTP requests (default: %d)",
                            DEFAULT_HTTP_SERVER_TIMEOUT),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::RPC);
 
 #if HAVE_DECL_DAEMON
     gArgs.AddArg("-daemon",
                  "Run in the background as a daemon and accept commands",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
 #else
     hidden_args.emplace_back("-daemon");
 #endif
 
     // Avalanche options.
     gArgs.AddArg(
         "-enableavalanche",
         strprintf("Enable avalanche (default: %u)", AVALANCHE_DEFAULT_ENABLED),
         ArgsManager::ALLOW_ANY, OptionsCategory::AVALANCHE);
     gArgs.AddArg(
         "-avacooldown",
         strprintf("Mandatory cooldown between two avapoll (default: %u)",
                   AVALANCHE_DEFAULT_COOLDOWN),
         ArgsManager::ALLOW_ANY, OptionsCategory::AVALANCHE);
 
     // Add the hidden options
     gArgs.AddHiddenArgs(hidden_args);
 }
 
 std::string LicenseInfo() {
     const std::string URL_SOURCE_CODE =
         "<https://github.com/Bitcoin-ABC/bitcoin-abc>";
     const std::string URL_WEBSITE = "<https://www.bitcoinabc.org>";
 
     return CopyrightHolders(strprintf(_("Copyright (C) %i-%i").translated, 2009,
                                       COPYRIGHT_YEAR) +
                             " ") +
            "\n" + "\n" +
            strprintf(_("Please contribute if you find %s useful. "
                        "Visit %s for further information about the software.")
                          .translated,
                      PACKAGE_NAME, URL_WEBSITE) +
            "\n" +
            strprintf(_("The source code is available from %s.").translated,
                      URL_SOURCE_CODE) +
            "\n" + "\n" + _("This is experimental software.").translated + "\n" +
            strprintf(_("Distributed under the MIT software license, see the "
                        "accompanying file %s or %s")
                          .translated,
                      "COPYING", "<https://opensource.org/licenses/MIT>") +
            "\n" + "\n" +
            strprintf(_("This product includes software developed by the "
                        "OpenSSL Project for use in the OpenSSL Toolkit %s and "
                        "cryptographic software written by Eric Young and UPnP "
                        "software written by Thomas Bernard.")
                          .translated,
                      "<https://www.openssl.org>") +
            "\n";
 }
 
 #if defined(HAVE_SYSTEM)
 static void BlockNotifyCallback(SynchronizationState sync_state,
                                 const CBlockIndex *pBlockIndex) {
     if (sync_state != SynchronizationState::POST_INIT || !pBlockIndex) {
         return;
     }
 
     std::string strCmd = gArgs.GetArg("-blocknotify", "");
     if (!strCmd.empty()) {
         boost::replace_all(strCmd, "%s", pBlockIndex->GetBlockHash().GetHex());
         std::thread t(runCommand, strCmd);
         // thread runs free
         t.detach();
     }
 }
 #endif
 
 static bool fHaveGenesis = false;
 static Mutex g_genesis_wait_mutex;
 static std::condition_variable g_genesis_wait_cv;
 
 static void BlockNotifyGenesisWait(const CBlockIndex *pBlockIndex) {
     if (pBlockIndex != nullptr) {
         {
             LOCK(g_genesis_wait_mutex);
             fHaveGenesis = true;
         }
         g_genesis_wait_cv.notify_all();
     }
 }
 
 struct CImportingNow {
     CImportingNow() {
         assert(fImporting == false);
         fImporting = true;
     }
 
     ~CImportingNow() {
         assert(fImporting == true);
         fImporting = false;
     }
 };
 
 // If we're using -prune with -reindex, then delete block files that will be
 // ignored by the reindex.  Since reindexing works by starting at block file 0
 // and looping until a blockfile is missing, do the same here to delete any
 // later block files after a gap. Also delete all rev files since they'll be
 // rewritten by the reindex anyway. This ensures that vinfoBlockFile is in sync
 // with what's actually on disk by the time we start downloading, so that
 // pruning works correctly.
 static void CleanupBlockRevFiles() {
     std::map<std::string, fs::path> mapBlockFiles;
 
     // Glob all blk?????.dat and rev?????.dat files from the blocks directory.
     // Remove the rev files immediately and insert the blk file paths into an
     // ordered map keyed by block file index.
     LogPrintf("Removing unusable blk?????.dat and rev?????.dat files for "
               "-reindex with -prune\n");
     const auto directoryIterator = fs::directory_iterator{GetBlocksDir()};
     for (const auto &file : directoryIterator) {
         const auto fileName = file.path().filename().string();
         if (fs::is_regular_file(file) && fileName.length() == 12 &&
             fileName.substr(8, 4) == ".dat") {
             if (fileName.substr(0, 3) == "blk") {
                 mapBlockFiles[fileName.substr(3, 5)] = file.path();
             } else if (fileName.substr(0, 3) == "rev") {
                 remove(file.path());
             }
         }
     }
 
     // Remove all block files that aren't part of a contiguous set starting at
     // zero by walking the ordered map (keys are block file indices) by keeping
     // a separate counter. Once we hit a gap (or if 0 doesn't exist) start
     // removing block files.
     int contiguousCounter = 0;
     for (const auto &item : mapBlockFiles) {
         if (atoi(item.first) == contiguousCounter) {
             contiguousCounter++;
             continue;
         }
         remove(item.second);
     }
 }
 
 static void ThreadImport(const Config &config,
                          std::vector<fs::path> vImportFiles) {
     util::ThreadRename("loadblk");
     ScheduleBatchPriority();
 
     {
         const CChainParams &chainParams = config.GetChainParams();
 
         CImportingNow imp;
 
         // -reindex
         if (fReindex) {
             int nFile = 0;
             while (true) {
                 FlatFilePos pos(nFile, 0);
                 if (!fs::exists(GetBlockPosFilename(pos))) {
                     // No block files left to reindex
                     break;
                 }
                 FILE *file = OpenBlockFile(pos, true);
                 if (!file) {
                     // This error is logged in OpenBlockFile
                     break;
                 }
                 LogPrintf("Reindexing block file blk%05u.dat...\n",
                           (unsigned int)nFile);
                 LoadExternalBlockFile(config, file, &pos);
                 nFile++;
             }
             pblocktree->WriteReindexing(false);
             fReindex = false;
             LogPrintf("Reindexing finished\n");
             // To avoid ending up in a situation without genesis block, re-try
             // initializing (no-op if reindexing worked):
             LoadGenesisBlock(chainParams);
         }
 
         // -loadblock=
         for (const fs::path &path : vImportFiles) {
             FILE *file = fsbridge::fopen(path, "rb");
             if (file) {
                 LogPrintf("Importing blocks file %s...\n", path.string());
                 LoadExternalBlockFile(config, file);
             } else {
                 LogPrintf("Warning: Could not open blocks file %s\n",
                           path.string());
             }
         }
 
         // Reconsider blocks we know are valid. They may have been marked
         // invalid by, for instance, running an outdated version of the node
         // software.
         const MapCheckpoints &checkpoints =
             chainParams.Checkpoints().mapCheckpoints;
         for (const MapCheckpoints::value_type &i : checkpoints) {
             const BlockHash &hash = i.second;
 
             LOCK(cs_main);
             CBlockIndex *pblockindex = LookupBlockIndex(hash);
             if (pblockindex && !pblockindex->nStatus.isValid()) {
                 LogPrintf("Reconsidering checkpointed block %s ...\n",
                           hash.GetHex());
                 ResetBlockFailureFlags(pblockindex);
             }
         }
 
         // scan for better chains in the block chain database, that are not yet
         // connected in the active best chain
         BlockValidationState state;
         if (!ActivateBestChain(config, state)) {
             LogPrintf("Failed to connect best block (%s)\n", state.ToString());
             StartShutdown();
             return;
         }
 
         if (gArgs.GetBoolArg("-stopafterblockimport",
                              DEFAULT_STOPAFTERBLOCKIMPORT)) {
             LogPrintf("Stopping after block import\n");
             StartShutdown();
             return;
         }
     } // End scope of CImportingNow
     if (gArgs.GetArg("-persistmempool", DEFAULT_PERSIST_MEMPOOL)) {
         LoadMempool(config, ::g_mempool);
     }
     ::g_mempool.SetIsLoaded(!ShutdownRequested());
 }
 
 /** Sanity checks
  *  Ensure that Bitcoin is running in a usable environment with all
  *  necessary library support.
  */
 static bool InitSanityCheck() {
     if (!ECC_InitSanityCheck()) {
         return InitError(Untranslated(
             "Elliptic curve cryptography sanity check failure. Aborting."));
     }
 
     if (!glibcxx_sanity_test()) {
         return false;
     }
 
     if (!Random_SanityCheck()) {
         return InitError(Untranslated(
             "OS cryptographic RNG sanity check failure. Aborting."));
     }
 
     return true;
 }
 
 static bool AppInitServers(Config &config,
                            HTTPRPCRequestProcessor &httpRPCRequestProcessor) {
     RPCServerSignals::OnStarted(&OnRPCStarted);
     RPCServerSignals::OnStopped(&OnRPCStopped);
     if (!InitHTTPServer(config)) {
         return false;
     }
 
     StartRPC();
 
     if (!StartHTTPRPC(httpRPCRequestProcessor)) {
         return false;
     }
     if (gArgs.GetBoolArg("-rest", DEFAULT_REST_ENABLE)) {
         StartREST(httpRPCRequestProcessor.context);
     }
 
     StartHTTPServer();
     return true;
 }
 
 // Parameter interaction based on rules
 void InitParameterInteraction() {
     // when specifying an explicit binding address, you want to listen on it
     // even when -connect or -proxy is specified.
     if (gArgs.IsArgSet("-bind")) {
         if (gArgs.SoftSetBoolArg("-listen", true)) {
             LogPrintf(
                 "%s: parameter interaction: -bind set -> setting -listen=1\n",
                 __func__);
         }
     }
     if (gArgs.IsArgSet("-whitebind")) {
         if (gArgs.SoftSetBoolArg("-listen", true)) {
             LogPrintf("%s: parameter interaction: -whitebind set -> setting "
                       "-listen=1\n",
                       __func__);
         }
     }
 
     if (gArgs.IsArgSet("-connect")) {
         // when only connecting to trusted nodes, do not seed via DNS, or listen
         // by default.
         if (gArgs.SoftSetBoolArg("-dnsseed", false)) {
             LogPrintf("%s: parameter interaction: -connect set -> setting "
                       "-dnsseed=0\n",
                       __func__);
         }
         if (gArgs.SoftSetBoolArg("-listen", false)) {
             LogPrintf("%s: parameter interaction: -connect set -> setting "
                       "-listen=0\n",
                       __func__);
         }
     }
 
     if (gArgs.IsArgSet("-proxy")) {
         // to protect privacy, do not listen by default if a default proxy
         // server is specified.
         if (gArgs.SoftSetBoolArg("-listen", false)) {
             LogPrintf(
                 "%s: parameter interaction: -proxy set -> setting -listen=0\n",
                 __func__);
         }
         // to protect privacy, do not use UPNP when a proxy is set. The user may
         // still specify -listen=1 to listen locally, so don't rely on this
         // happening through -listen below.
         if (gArgs.SoftSetBoolArg("-upnp", false)) {
             LogPrintf(
                 "%s: parameter interaction: -proxy set -> setting -upnp=0\n",
                 __func__);
         }
         // to protect privacy, do not discover addresses by default
         if (gArgs.SoftSetBoolArg("-discover", false)) {
             LogPrintf("%s: parameter interaction: -proxy set -> setting "
                       "-discover=0\n",
                       __func__);
         }
     }
 
     if (!gArgs.GetBoolArg("-listen", DEFAULT_LISTEN)) {
         // do not map ports or try to retrieve public IP when not listening
         // (pointless)
         if (gArgs.SoftSetBoolArg("-upnp", false)) {
             LogPrintf(
                 "%s: parameter interaction: -listen=0 -> setting -upnp=0\n",
                 __func__);
         }
         if (gArgs.SoftSetBoolArg("-discover", false)) {
             LogPrintf(
                 "%s: parameter interaction: -listen=0 -> setting -discover=0\n",
                 __func__);
         }
         if (gArgs.SoftSetBoolArg("-listenonion", false)) {
             LogPrintf("%s: parameter interaction: -listen=0 -> setting "
                       "-listenonion=0\n",
                       __func__);
         }
     }
 
     if (gArgs.IsArgSet("-externalip")) {
         // if an explicit public IP is specified, do not try to find others
         if (gArgs.SoftSetBoolArg("-discover", false)) {
             LogPrintf("%s: parameter interaction: -externalip set -> setting "
                       "-discover=0\n",
                       __func__);
         }
     }
 
     // disable whitelistrelay in blocksonly mode
     if (gArgs.GetBoolArg("-blocksonly", DEFAULT_BLOCKSONLY)) {
         if (gArgs.SoftSetBoolArg("-whitelistrelay", false)) {
             LogPrintf("%s: parameter interaction: -blocksonly=1 -> setting "
                       "-whitelistrelay=0\n",
                       __func__);
         }
     }
 
     // Forcing relay from whitelisted hosts implies we will accept relays from
     // them in the first place.
     if (gArgs.GetBoolArg("-whitelistforcerelay", DEFAULT_WHITELISTFORCERELAY)) {
         if (gArgs.SoftSetBoolArg("-whitelistrelay", true)) {
             LogPrintf("%s: parameter interaction: -whitelistforcerelay=1 -> "
                       "setting -whitelistrelay=1\n",
                       __func__);
         }
     }
 }
 
 /**
  * Initialize global loggers.
  *
  * Note that this is called very early in the process lifetime, so you should be
  * careful about what global state you rely on here.
  */
 void InitLogging() {
     LogInstance().m_print_to_file = !gArgs.IsArgNegated("-debuglogfile");
     LogInstance().m_file_path = AbsPathForConfigVal(
         gArgs.GetArg("-debuglogfile", DEFAULT_DEBUGLOGFILE));
 
     LogInstance().m_print_to_console = gArgs.GetBoolArg(
         "-printtoconsole", !gArgs.GetBoolArg("-daemon", false));
     LogInstance().m_log_timestamps =
         gArgs.GetBoolArg("-logtimestamps", DEFAULT_LOGTIMESTAMPS);
     LogInstance().m_log_time_micros =
         gArgs.GetBoolArg("-logtimemicros", DEFAULT_LOGTIMEMICROS);
     LogInstance().m_log_threadnames =
         gArgs.GetBoolArg("-logthreadnames", DEFAULT_LOGTHREADNAMES);
 
     fLogIPs = gArgs.GetBoolArg("-logips", DEFAULT_LOGIPS);
 
     std::string version_string = FormatFullVersion();
 #ifdef DEBUG
     version_string += " (debug build)";
 #else
     version_string += " (release build)";
 #endif
     LogPrintf("%s version %s\n", CLIENT_NAME, version_string);
 }
 
 namespace { // Variables internal to initialization process only
 
 int nMaxConnections;
 int nUserMaxConnections;
 int nFD;
 ServiceFlags nLocalServices = ServiceFlags(NODE_NETWORK | NODE_NETWORK_LIMITED);
 int64_t peer_connect_timeout;
 std::set<BlockFilterType> g_enabled_filter_types;
 
 } // namespace
 
 [[noreturn]] static void new_handler_terminate() {
     // Rather than throwing std::bad-alloc if allocation fails, terminate
     // immediately to (try to) avoid chain corruption. Since LogPrintf may
     // itself allocate memory, set the handler directly to terminate first.
     std::set_new_handler(std::terminate);
     LogPrintf("Error: Out of memory. Terminating.\n");
 
     // The log was successful, terminate now.
     std::terminate();
 };
 
 bool AppInitBasicSetup() {
 // Step 1: setup
 #ifdef _MSC_VER
     // Turn off Microsoft heap dump noise
     _CrtSetReportMode(_CRT_WARN, _CRTDBG_MODE_FILE);
     _CrtSetReportFile(_CRT_WARN, CreateFileA("NUL", GENERIC_WRITE, 0, nullptr,
                                              OPEN_EXISTING, 0, 0));
     // Disable confusing "helpful" text message on abort, Ctrl-C
     _set_abort_behavior(0, _WRITE_ABORT_MSG | _CALL_REPORTFAULT);
 #endif
 #ifdef WIN32
     // Enable Data Execution Prevention (DEP)
     SetProcessDEPPolicy(PROCESS_DEP_ENABLE);
 #endif
 
     if (!SetupNetworking()) {
         return InitError(Untranslated("Initializing networking failed"));
     }
 
 #ifndef WIN32
     if (!gArgs.GetBoolArg("-sysperms", false)) {
         umask(077);
     }
 
     // Clean shutdown on SIGTERM
     registerSignalHandler(SIGTERM, HandleSIGTERM);
     registerSignalHandler(SIGINT, HandleSIGTERM);
 
     // Reopen debug.log on SIGHUP
     registerSignalHandler(SIGHUP, HandleSIGHUP);
 
     // Ignore SIGPIPE, otherwise it will bring the daemon down if the client
     // closes unexpectedly
     signal(SIGPIPE, SIG_IGN);
 #else
     SetConsoleCtrlHandler(consoleCtrlHandler, true);
 #endif
 
     std::set_new_handler(new_handler_terminate);
 
     return true;
 }
 
 bool AppInitParameterInteraction(Config &config) {
     const CChainParams &chainparams = config.GetChainParams();
     // Step 2: parameter interactions
 
     // also see: InitParameterInteraction()
 
     // Warn if network-specific options (-addnode, -connect, etc) are
     // specified in default section of config file, but not overridden
     // on the command line or in this network's section of the config file.
     std::string network = gArgs.GetChainName();
     for (const auto &arg : gArgs.GetUnsuitableSectionOnlyArgs()) {
         return InitError(strprintf(_("Config setting for %s only applied on %s "
                                      "network when in [%s] section."),
                                    arg, network, network));
     }
 
     // Warn if unrecognized section name are present in the config file.
     for (const auto &section : gArgs.GetUnrecognizedSections()) {
         InitWarning(strprintf(
             "%s:%i " + _("Section [%s] is not recognized.").translated,
             section.m_file, section.m_line, section.m_name));
     }
 
     if (!fs::is_directory(GetBlocksDir())) {
         return InitError(
             strprintf(_("Specified blocks directory \"%s\" does not exist."),
                       gArgs.GetArg("-blocksdir", "")));
     }
 
     // parse and validate enabled filter types
     std::string blockfilterindex_value =
         gArgs.GetArg("-blockfilterindex", DEFAULT_BLOCKFILTERINDEX);
     if (blockfilterindex_value == "" || blockfilterindex_value == "1") {
         g_enabled_filter_types = AllBlockFilterTypes();
     } else if (blockfilterindex_value != "0") {
         const std::vector<std::string> names =
             gArgs.GetArgs("-blockfilterindex");
         for (const auto &name : names) {
             BlockFilterType filter_type;
             if (!BlockFilterTypeByName(name, filter_type)) {
                 return InitError(
                     strprintf(_("Unknown -blockfilterindex value %s."), name));
             }
             g_enabled_filter_types.insert(filter_type);
         }
     }
 
     // if using block pruning, then disallow txindex
     if (gArgs.GetArg("-prune", 0)) {
         if (gArgs.GetBoolArg("-txindex", DEFAULT_TXINDEX)) {
             return InitError(_("Prune mode is incompatible with -txindex."));
         }
         if (!g_enabled_filter_types.empty()) {
             return InitError(
                 _("Prune mode is incompatible with -blockfilterindex."));
         }
     }
 
     // -bind and -whitebind can't be set when not listening
     size_t nUserBind =
         gArgs.GetArgs("-bind").size() + gArgs.GetArgs("-whitebind").size();
     if (nUserBind != 0 && !gArgs.GetBoolArg("-listen", DEFAULT_LISTEN)) {
         return InitError(Untranslated(
             "Cannot set -bind or -whitebind together with -listen=0"));
     }
 
     // Make sure enough file descriptors are available
     int nBind = std::max(nUserBind, size_t(1));
     nUserMaxConnections =
         gArgs.GetArg("-maxconnections", DEFAULT_MAX_PEER_CONNECTIONS);
     nMaxConnections = std::max(nUserMaxConnections, 0);
 
     // Trim requested connection counts, to fit into system limitations
     // <int> in std::min<int>(...) to work around FreeBSD compilation issue
     // described in #2695
     nFD = RaiseFileDescriptorLimit(nMaxConnections + MIN_CORE_FILEDESCRIPTORS +
                                    MAX_ADDNODE_CONNECTIONS);
 #ifdef USE_POLL
     int fd_max = nFD;
 #else
     int fd_max = FD_SETSIZE;
 #endif
     nMaxConnections =
         std::max(std::min<int>(nMaxConnections, fd_max - nBind -
                                                     MIN_CORE_FILEDESCRIPTORS -
                                                     MAX_ADDNODE_CONNECTIONS),
                  0);
     if (nFD < MIN_CORE_FILEDESCRIPTORS) {
         return InitError(_("Not enough file descriptors available."));
     }
     nMaxConnections =
         std::min(nFD - MIN_CORE_FILEDESCRIPTORS - MAX_ADDNODE_CONNECTIONS,
                  nMaxConnections);
 
     if (nMaxConnections < nUserMaxConnections) {
         InitWarning(strprintf(_("Reducing -maxconnections from %d to %d, "
                                 "because of system limitations.")
                                   .translated,
                               nUserMaxConnections, nMaxConnections));
     }
 
     // Step 3: parameter-to-internal-flags
     if (gArgs.IsArgSet("-debug")) {
         // Special-case: if -debug=0/-nodebug is set, turn off debugging
         // messages
         const std::vector<std::string> &categories = gArgs.GetArgs("-debug");
         if (std::none_of(
                 categories.begin(), categories.end(),
                 [](std::string cat) { return cat == "0" || cat == "none"; })) {
             for (const auto &cat : categories) {
                 if (!LogInstance().EnableCategory(cat)) {
                     InitWarning(strprintf(
                         _("Unsupported logging category %s=%s.").translated,
                         "-debug", cat));
                 }
             }
         }
     }
 
     // Now remove the logging categories which were explicitly excluded
     for (const std::string &cat : gArgs.GetArgs("-debugexclude")) {
         if (!LogInstance().DisableCategory(cat)) {
             InitWarning(
                 strprintf(_("Unsupported logging category %s=%s.").translated,
                           "-debugexclude", cat));
         }
     }
 
     // Checkmempool and checkblockindex default to true in regtest mode
     int ratio = std::min<int>(
         std::max<int>(
             gArgs.GetArg("-checkmempool",
                          chainparams.DefaultConsistencyChecks() ? 1 : 0),
             0),
         1000000);
     if (ratio != 0) {
         g_mempool.setSanityCheck(1.0 / ratio);
     }
     fCheckBlockIndex = gArgs.GetBoolArg("-checkblockindex",
                                         chainparams.DefaultConsistencyChecks());
     fCheckpointsEnabled =
         gArgs.GetBoolArg("-checkpoints", DEFAULT_CHECKPOINTS_ENABLED);
     if (fCheckpointsEnabled) {
         LogPrintf("Checkpoints will be verified.\n");
     } else {
         LogPrintf("Skipping checkpoint verification.\n");
     }
 
     hashAssumeValid = BlockHash::fromHex(
         gArgs.GetArg("-assumevalid",
                      chainparams.GetConsensus().defaultAssumeValid.GetHex()));
     if (!hashAssumeValid.IsNull()) {
         LogPrintf("Assuming ancestors of block %s have valid signatures.\n",
                   hashAssumeValid.GetHex());
     } else {
         LogPrintf("Validating signatures for all blocks.\n");
     }
 
     if (gArgs.IsArgSet("-minimumchainwork")) {
         const std::string minChainWorkStr =
             gArgs.GetArg("-minimumchainwork", "");
         if (!IsHexNumber(minChainWorkStr)) {
             return InitError(strprintf(
                 Untranslated(
                     "Invalid non-hex (%s) minimum chain work value specified"),
                 minChainWorkStr));
         }
         nMinimumChainWork = UintToArith256(uint256S(minChainWorkStr));
     } else {
         nMinimumChainWork =
             UintToArith256(chainparams.GetConsensus().nMinimumChainWork);
     }
     LogPrintf("Setting nMinimumChainWork=%s\n", nMinimumChainWork.GetHex());
     if (nMinimumChainWork <
         UintToArith256(chainparams.GetConsensus().nMinimumChainWork)) {
         LogPrintf("Warning: nMinimumChainWork set below default value of %s\n",
                   chainparams.GetConsensus().nMinimumChainWork.GetHex());
     }
 
     // mempool limits
     int64_t nMempoolSizeMax =
         gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000;
     int64_t nMempoolSizeMin =
         gArgs.GetArg("-limitdescendantsize", DEFAULT_DESCENDANT_SIZE_LIMIT) *
         1000 * 40;
     if (nMempoolSizeMax < 0 || nMempoolSizeMax < nMempoolSizeMin) {
         return InitError(strprintf(_("-maxmempool must be at least %d MB"),
                                    std::ceil(nMempoolSizeMin / 1000000.0)));
     }
 
     // Configure excessive block size.
     const uint64_t nProposedExcessiveBlockSize =
         gArgs.GetArg("-excessiveblocksize", DEFAULT_MAX_BLOCK_SIZE);
     if (!config.SetMaxBlockSize(nProposedExcessiveBlockSize)) {
         return InitError(
             _("Excessive block size must be > 1,000,000 bytes (1MB)"));
     }
 
     // Check blockmaxsize does not exceed maximum accepted block size.
     const uint64_t nProposedMaxGeneratedBlockSize =
         gArgs.GetArg("-blockmaxsize", DEFAULT_MAX_GENERATED_BLOCK_SIZE);
     if (nProposedMaxGeneratedBlockSize > config.GetMaxBlockSize()) {
         auto msg = _("Max generated block size (blockmaxsize) cannot exceed "
                      "the excessive block size (excessiveblocksize)");
         return InitError(msg);
     }
 
     // block pruning; get the amount of disk space (in MiB) to allot for block &
     // undo files
     int64_t nPruneArg = gArgs.GetArg("-prune", 0);
     if (nPruneArg < 0) {
         return InitError(
             _("Prune cannot be configured with a negative value."));
     }
     nPruneTarget = (uint64_t)nPruneArg * 1024 * 1024;
     if (nPruneArg == 1) {
         // manual pruning: -prune=1
         LogPrintf("Block pruning enabled.  Use RPC call "
                   "pruneblockchain(height) to manually prune block and undo "
                   "files.\n");
         nPruneTarget = std::numeric_limits<uint64_t>::max();
         fPruneMode = true;
     } else if (nPruneTarget) {
         if (nPruneTarget < MIN_DISK_SPACE_FOR_BLOCK_FILES) {
             return InitError(
                 strprintf(_("Prune configured below the minimum of %d MiB. "
                             "Please use a higher number."),
                           MIN_DISK_SPACE_FOR_BLOCK_FILES / 1024 / 1024));
         }
         LogPrintf("Prune configured to target %u MiB on disk for block and "
                   "undo files.\n",
                   nPruneTarget / 1024 / 1024);
         fPruneMode = true;
     }
 
     nConnectTimeout = gArgs.GetArg("-timeout", DEFAULT_CONNECT_TIMEOUT);
     if (nConnectTimeout <= 0) {
         nConnectTimeout = DEFAULT_CONNECT_TIMEOUT;
     }
 
     peer_connect_timeout =
         gArgs.GetArg("-peertimeout", DEFAULT_PEER_CONNECT_TIMEOUT);
     if (peer_connect_timeout <= 0) {
         return InitError(Untranslated(
             "peertimeout cannot be configured with a negative value."));
     }
 
     // Obtain the amount to charge excess UTXO
     if (gArgs.IsArgSet("-excessutxocharge")) {
         Amount n = Amount::zero();
         auto parsed = ParseMoney(gArgs.GetArg("-excessutxocharge", ""), n);
         if (!parsed || Amount::zero() > n) {
             return InitError(AmountErrMsg(
                 "excessutxocharge", gArgs.GetArg("-excessutxocharge", "")));
         }
         config.SetExcessUTXOCharge(n);
     } else {
         config.SetExcessUTXOCharge(DEFAULT_UTXO_FEE);
     }
 
     if (gArgs.IsArgSet("-minrelaytxfee")) {
         Amount n = Amount::zero();
         auto parsed = ParseMoney(gArgs.GetArg("-minrelaytxfee", ""), n);
         if (!parsed || n == Amount::zero()) {
             return InitError(AmountErrMsg("minrelaytxfee",
                                           gArgs.GetArg("-minrelaytxfee", "")));
         }
         // High fee check is done afterward in CWallet::CreateWalletFromFile()
         ::minRelayTxFee = CFeeRate(n);
     }
 
     // Sanity check argument for min fee for including tx in block
     // TODO: Harmonize which arguments need sanity checking and where that
     // happens.
     if (gArgs.IsArgSet("-blockmintxfee")) {
         Amount n = Amount::zero();
         if (!ParseMoney(gArgs.GetArg("-blockmintxfee", ""), n)) {
             return InitError(AmountErrMsg("blockmintxfee",
                                           gArgs.GetArg("-blockmintxfee", "")));
         }
     }
 
     // Feerate used to define dust.  Shouldn't be changed lightly as old
     // implementations may inadvertently create non-standard transactions.
     if (gArgs.IsArgSet("-dustrelayfee")) {
         Amount n = Amount::zero();
         auto parsed = ParseMoney(gArgs.GetArg("-dustrelayfee", ""), n);
         if (!parsed || Amount::zero() == n) {
             return InitError(AmountErrMsg("dustrelayfee",
                                           gArgs.GetArg("-dustrelayfee", "")));
         }
         dustRelayFee = CFeeRate(n);
     }
 
     fRequireStandard =
         !gArgs.GetBoolArg("-acceptnonstdtxn", !chainparams.RequireStandard());
     if (!chainparams.IsTestChain() && !fRequireStandard) {
         return InitError(strprintf(
             Untranslated(
                 "acceptnonstdtxn is not currently supported for %s chain"),
             chainparams.NetworkIDString()));
     }
     nBytesPerSigOp = gArgs.GetArg("-bytespersigop", nBytesPerSigOp);
 
     if (!g_wallet_init_interface.ParameterInteraction()) {
         return false;
     }
 
     fIsBareMultisigStd =
         gArgs.GetBoolArg("-permitbaremultisig", DEFAULT_PERMIT_BAREMULTISIG);
     fAcceptDatacarrier =
         gArgs.GetBoolArg("-datacarrier", DEFAULT_ACCEPT_DATACARRIER);
 
     // Option to startup with mocktime set (used for regression testing):
     SetMockTime(gArgs.GetArg("-mocktime", 0)); // SetMockTime(0) is a no-op
 
     if (gArgs.GetBoolArg("-peerbloomfilters", DEFAULT_PEERBLOOMFILTERS)) {
         nLocalServices = ServiceFlags(nLocalServices | NODE_BLOOM);
     }
 
     // Signal Bitcoin Cash support.
     // TODO: remove some time after the hardfork when no longer needed
     // to differentiate the network nodes.
     nLocalServices = ServiceFlags(nLocalServices | NODE_BITCOIN_CASH);
 
     nMaxTipAge = gArgs.GetArg("-maxtipage", DEFAULT_MAX_TIP_AGE);
 
     return true;
 }
 
 static bool LockDataDirectory(bool probeOnly) {
     // Make sure only a single Bitcoin process is using the data directory.
     fs::path datadir = GetDataDir();
     if (!DirIsWritable(datadir)) {
         return InitError(strprintf(
             _("Cannot write to data directory '%s'; check permissions."),
             datadir.string()));
     }
     if (!LockDirectory(datadir, ".lock", probeOnly)) {
         return InitError(strprintf(_("Cannot obtain a lock on data directory "
                                      "%s. %s is probably already running."),
                                    datadir.string(), PACKAGE_NAME));
     }
     return true;
 }
 
 bool AppInitSanityChecks() {
     // Step 4: sanity checks
 
     // Initialize elliptic curve code
     std::string sha256_algo = SHA256AutoDetect();
     LogPrintf("Using the '%s' SHA256 implementation\n", sha256_algo);
     RandomInit();
     ECC_Start();
     globalVerifyHandle.reset(new ECCVerifyHandle());
 
     // Sanity check
     if (!InitSanityCheck()) {
         return InitError(strprintf(
             _("Initialization sanity check failed. %s is shutting down."),
             PACKAGE_NAME));
     }
 
     // Probe the data directory lock to give an early error message, if possible
     // We cannot hold the data directory lock here, as the forking for daemon()
     // hasn't yet happened, and a fork will cause weird behavior to it.
     return LockDataDirectory(true);
 }
 
 bool AppInitLockDataDirectory() {
     // After daemonization get the data directory lock again and hold on to it
     // until exit. This creates a slight window for a race condition to happen,
     // however this condition is harmless: it will at most make us exit without
     // printing a message to console.
     if (!LockDataDirectory(false)) {
         // Detailed error printed inside LockDataDirectory
         return false;
     }
     return true;
 }
 
 bool AppInitMain(Config &config, RPCServer &rpcServer,
                  HTTPRPCRequestProcessor &httpRPCRequestProcessor,
                  NodeContext &node) {
     // Step 4a: application initialization
     const CChainParams &chainparams = config.GetChainParams();
 
     if (!CreatePidFile()) {
         // Detailed error printed inside CreatePidFile().
         return false;
     }
 
     BCLog::Logger &logger = LogInstance();
     if (logger.m_print_to_file) {
         if (gArgs.GetBoolArg("-shrinkdebugfile",
                              logger.DefaultShrinkDebugFile())) {
             // Do this first since it both loads a bunch of debug.log into
             // memory, and because this needs to happen before any other
             // debug.log printing.
             logger.ShrinkDebugFile();
         }
     }
 
     if (!logger.StartLogging()) {
         return InitError(
             strprintf(Untranslated("Could not open debug log file %s"),
                       logger.m_file_path.string()));
     }
 
     if (!logger.m_log_timestamps) {
         LogPrintf("Startup time: %s\n", FormatISO8601DateTime(GetTime()));
     }
     LogPrintf("Default data directory %s\n", GetDefaultDataDir().string());
     LogPrintf("Using data directory %s\n", GetDataDir().string());
 
     // Only log conf file usage message if conf file actually exists.
     fs::path config_file_path =
         GetConfigFile(gArgs.GetArg("-conf", BITCOIN_CONF_FILENAME));
     if (fs::exists(config_file_path)) {
         LogPrintf("Config file: %s\n", config_file_path.string());
     } else if (gArgs.IsArgSet("-conf")) {
         // Warn if no conf file exists at path provided by user
         InitWarning(strprintf(
             _("The specified config file %s does not exist\n").translated,
             config_file_path.string()));
     } else {
         // Not categorizing as "Warning" because it's the default behavior
         LogPrintf("Config file: %s (not found, skipping)\n",
                   config_file_path.string());
     }
 
     // Log the config arguments to debug.log
     gArgs.LogArgs();
 
     LogPrintf("Using at most %i automatic connections (%i file descriptors "
               "available)\n",
               nMaxConnections, nFD);
 
     // Warn about relative -datadir path.
     if (gArgs.IsArgSet("-datadir") &&
         !fs::path(gArgs.GetArg("-datadir", "")).is_absolute()) {
         LogPrintf("Warning: relative datadir option '%s' specified, which will "
                   "be interpreted relative to the current working directory "
                   "'%s'. This is fragile, because if bitcoin is started in the "
                   "future from a different location, it will be unable to "
                   "locate the current data files. There could also be data "
                   "loss if bitcoin is started while in a temporary "
                   "directory.\n",
                   gArgs.GetArg("-datadir", ""), fs::current_path().string());
     }
 
     InitSignatureCache();
     InitScriptExecutionCache();
 
     int script_threads = gArgs.GetArg("-par", DEFAULT_SCRIPTCHECK_THREADS);
     if (script_threads <= 0) {
         // -par=0 means autodetect (number of cores - 1 script threads)
         // -par=-n means "leave n cores free" (number of cores - n - 1 script
         // threads)
         script_threads += GetNumCores();
     }
 
     // Subtract 1 because the main thread counts towards the par threads
     script_threads = std::max(script_threads - 1, 0);
 
     // Number of script-checking threads <= MAX_SCRIPTCHECK_THREADS
     script_threads = std::min(script_threads, MAX_SCRIPTCHECK_THREADS);
 
     LogPrintf("Script verification uses %d additional threads\n",
               script_threads);
     if (script_threads >= 1) {
         for (int i = 0; i < script_threads; ++i) {
             threadGroup.create_thread([i]() { return ThreadScriptCheck(i); });
         }
     }
 
     assert(!node.scheduler);
     node.scheduler = std::make_unique<CScheduler>();
 
     // Start the lightweight task scheduler thread
     CScheduler::Function serviceLoop = [&node] {
         node.scheduler->serviceQueue();
     };
     threadGroup.create_thread(std::bind(&TraceThread<CScheduler::Function>,
                                         "scheduler", serviceLoop));
 
     // Gather some entropy once per minute.
     node.scheduler->scheduleEvery(
         [] {
             RandAddPeriodic();
             return true;
         },
         std::chrono::minutes{1});
 
     GetMainSignals().RegisterBackgroundSignalScheduler(*node.scheduler);
 
     // Create client interfaces for wallets that are supposed to be loaded
     // according to -wallet and -disablewallet options. This only constructs
     // the interfaces, it doesn't load wallet data. Wallets actually get loaded
     // when load() and start() interface methods are called below.
     g_wallet_init_interface.Construct(node);
 
     /**
      * Register RPC commands regardless of -server setting so they will be
      * available in the GUI RPC console even if external calls are disabled.
      */
     RegisterAllRPCCommands(config, rpcServer, tableRPC);
     for (const auto &client : node.chain_clients) {
         client->registerRpcs();
     }
 #if ENABLE_ZMQ
     RegisterZMQRPCCommands(tableRPC);
 #endif
 
     /**
      * Start the RPC server.  It will be started in "warmup" mode and not
      * process calls yet (but it will verify that the server is there and will
      * be ready later).  Warmup mode will be completed when initialisation is
      * finished.
      */
     if (gArgs.GetBoolArg("-server", false)) {
         uiInterface.InitMessage_connect(SetRPCWarmupStatus);
         if (!AppInitServers(config, httpRPCRequestProcessor)) {
             return InitError(
                 _("Unable to start HTTP server. See debug log for details."));
         }
     }
 
     // Step 5: verify wallet database integrity
     for (const auto &client : node.chain_clients) {
         if (!client->verify(chainparams)) {
             return false;
         }
     }
 
     // Step 6: network initialization
 
     // Note that we absolutely cannot open any actual connections
     // until the very end ("start node") as the UTXO/block state
     // is not yet setup and may end up being set up twice if we
     // need to reindex later.
 
     assert(!node.banman);
     node.banman = std::make_unique<BanMan>(
         GetDataDir() / "banlist.dat", config.GetChainParams(), &uiInterface,
         gArgs.GetArg("-bantime", DEFAULT_MISBEHAVING_BANTIME));
     assert(!node.connman);
     node.connman = std::make_unique<CConnman>(
         config, GetRand(std::numeric_limits<uint64_t>::max()),
         GetRand(std::numeric_limits<uint64_t>::max()));
 
     node.peer_logic.reset(new PeerLogicValidation(
         node.connman.get(), node.banman.get(), *node.scheduler));
     RegisterValidationInterface(node.peer_logic.get());
 
     // sanitize comments per BIP-0014, format user agent and check total size
     std::vector<std::string> uacomments;
     for (const std::string &cmt : gArgs.GetArgs("-uacomment")) {
         if (cmt != SanitizeString(cmt, SAFE_CHARS_UA_COMMENT)) {
             return InitError(strprintf(
                 _("User Agent comment (%s) contains unsafe characters."), cmt));
         }
         uacomments.push_back(cmt);
     }
     const std::string strSubVersion =
         FormatSubVersion(CLIENT_NAME, CLIENT_VERSION, uacomments);
     if (strSubVersion.size() > MAX_SUBVERSION_LENGTH) {
         return InitError(strprintf(
             _("Total length of network version string (%i) exceeds maximum "
               "length (%i). Reduce the number or size of uacomments."),
             strSubVersion.size(), MAX_SUBVERSION_LENGTH));
     }
 
     if (gArgs.IsArgSet("-onlynet")) {
         std::set<enum Network> nets;
         for (const std::string &snet : gArgs.GetArgs("-onlynet")) {
             enum Network net = ParseNetwork(snet);
             if (net == NET_UNROUTABLE) {
                 return InitError(strprintf(
                     _("Unknown network specified in -onlynet: '%s'"), snet));
             }
             nets.insert(net);
         }
         for (int n = 0; n < NET_MAX; n++) {
             enum Network net = (enum Network)n;
             if (!nets.count(net)) {
                 SetReachable(net, false);
             }
         }
     }
 
     // Check for host lookup allowed before parsing any network related
     // parameters
     fNameLookup = gArgs.GetBoolArg("-dns", DEFAULT_NAME_LOOKUP);
 
     bool proxyRandomize =
         gArgs.GetBoolArg("-proxyrandomize", DEFAULT_PROXYRANDOMIZE);
     // -proxy sets a proxy for all outgoing network traffic
     // -noproxy (or -proxy=0) as well as the empty string can be used to not set
     // a proxy, this is the default
     std::string proxyArg = gArgs.GetArg("-proxy", "");
     SetReachable(NET_ONION, false);
     if (proxyArg != "" && proxyArg != "0") {
         CService proxyAddr;
         if (!Lookup(proxyArg.c_str(), proxyAddr, 9050, fNameLookup)) {
             return InitError(strprintf(
                 _("Invalid -proxy address or hostname: '%s'"), proxyArg));
         }
 
         proxyType addrProxy = proxyType(proxyAddr, proxyRandomize);
         if (!addrProxy.IsValid()) {
             return InitError(strprintf(
                 _("Invalid -proxy address or hostname: '%s'"), proxyArg));
         }
 
         SetProxy(NET_IPV4, addrProxy);
         SetProxy(NET_IPV6, addrProxy);
         SetProxy(NET_ONION, addrProxy);
         SetNameProxy(addrProxy);
         // by default, -proxy sets onion as reachable, unless -noonion later
         SetReachable(NET_ONION, true);
     }
 
     // -onion can be used to set only a proxy for .onion, or override normal
     // proxy for .onion addresses.
     // -noonion (or -onion=0) disables connecting to .onion entirely. An empty
     // string is used to not override the onion proxy (in which case it defaults
     // to -proxy set above, or none)
     std::string onionArg = gArgs.GetArg("-onion", "");
     if (onionArg != "") {
         if (onionArg == "0") {
             // Handle -noonion/-onion=0
             SetReachable(NET_ONION, false);
         } else {
             CService onionProxy;
             if (!Lookup(onionArg.c_str(), onionProxy, 9050, fNameLookup)) {
                 return InitError(strprintf(
                     _("Invalid -onion address or hostname: '%s'"), onionArg));
             }
             proxyType addrOnion = proxyType(onionProxy, proxyRandomize);
             if (!addrOnion.IsValid()) {
                 return InitError(strprintf(
                     _("Invalid -onion address or hostname: '%s'"), onionArg));
             }
             SetProxy(NET_ONION, addrOnion);
             SetReachable(NET_ONION, true);
         }
     }
 
     // see Step 2: parameter interactions for more information about these
     fListen = gArgs.GetBoolArg("-listen", DEFAULT_LISTEN);
     fDiscover = gArgs.GetBoolArg("-discover", true);
     g_relay_txes = !gArgs.GetBoolArg("-blocksonly", DEFAULT_BLOCKSONLY);
 
     for (const std::string &strAddr : gArgs.GetArgs("-externalip")) {
         CService addrLocal;
         if (Lookup(strAddr.c_str(), addrLocal, GetListenPort(), fNameLookup) &&
             addrLocal.IsValid()) {
             AddLocal(addrLocal, LOCAL_MANUAL);
         } else {
             return InitError(
                 Untranslated(ResolveErrMsg("externalip", strAddr)));
         }
     }
 
     // Read asmap file if configured
     if (gArgs.IsArgSet("-asmap")) {
         fs::path asmap_path = fs::path(gArgs.GetArg("-asmap", ""));
         if (asmap_path.empty()) {
             asmap_path = DEFAULT_ASMAP_FILENAME;
         }
         if (!asmap_path.is_absolute()) {
             asmap_path = GetDataDir() / asmap_path;
         }
         if (!fs::exists(asmap_path)) {
             InitError(strprintf(_("Could not find asmap file %s"), asmap_path));
             return false;
         }
         std::vector<bool> asmap = CAddrMan::DecodeAsmap(asmap_path);
         if (asmap.size() == 0) {
             InitError(
                 strprintf(_("Could not parse asmap file %s"), asmap_path));
             return false;
         }
         const uint256 asmap_version = SerializeHash(asmap);
         node.connman->SetAsmap(std::move(asmap));
         LogPrintf("Using asmap version %s for IP bucketing\n",
                   asmap_version.ToString());
     } else {
         LogPrintf("Using /16 prefix for IP bucketing\n");
     }
 
 #if ENABLE_ZMQ
     g_zmq_notification_interface = CZMQNotificationInterface::Create();
 
     if (g_zmq_notification_interface) {
         RegisterValidationInterface(g_zmq_notification_interface);
     }
 #endif
     // unlimited unless -maxuploadtarget is set
     uint64_t nMaxOutboundLimit = 0;
     uint64_t nMaxOutboundTimeframe = MAX_UPLOAD_TIMEFRAME;
 
     if (gArgs.IsArgSet("-maxuploadtarget")) {
         nMaxOutboundLimit =
             gArgs.GetArg("-maxuploadtarget", DEFAULT_MAX_UPLOAD_TARGET) * 1024 *
             1024;
     }
 
     // Step 6.5 (I guess ?): Initialize Avalanche.
     g_avalanche = std::make_unique<avalanche::Processor>(node.connman.get());
 
     // Step 7: load block chain
 
     fReindex = gArgs.GetBoolArg("-reindex", false);
     bool fReindexChainState = gArgs.GetBoolArg("-reindex-chainstate", false);
 
     // cache size calculations
     int64_t nTotalCache = (gArgs.GetArg("-dbcache", DEFAULT_DB_CACHE_MB) << 20);
     // total cache cannot be less than MIN_DB_CACHE_MB
     nTotalCache = std::max(nTotalCache, MIN_DB_CACHE_MB << 20);
     // total cache cannot be greater than MAX_DB_CACHE_MB
     nTotalCache = std::min(nTotalCache, MAX_DB_CACHE_MB << 20);
     int64_t nBlockTreeDBCache =
         std::min(nTotalCache / 8, MAX_BLOCK_DB_CACHE_MB << 20);
     nTotalCache -= nBlockTreeDBCache;
     int64_t nTxIndexCache =
         std::min(nTotalCache / 8, gArgs.GetBoolArg("-txindex", DEFAULT_TXINDEX)
                                       ? MAX_TX_INDEX_CACHE_MB << 20
                                       : 0);
     nTotalCache -= nTxIndexCache;
     int64_t filter_index_cache = 0;
     if (!g_enabled_filter_types.empty()) {
         size_t n_indexes = g_enabled_filter_types.size();
         int64_t max_cache =
             std::min(nTotalCache / 8, MAX_FILTER_INDEX_CACHE_MB << 20);
         filter_index_cache = max_cache / n_indexes;
         nTotalCache -= filter_index_cache * n_indexes;
     }
     // use 25%-50% of the remainder for disk cache
     int64_t nCoinDBCache =
         std::min(nTotalCache / 2, (nTotalCache / 4) + (1 << 23));
     // cap total coins db cache
     nCoinDBCache = std::min(nCoinDBCache, MAX_COINS_DB_CACHE_MB << 20);
     nTotalCache -= nCoinDBCache;
     // the rest goes to in-memory cache
     nCoinCacheUsage = nTotalCache;
     int64_t nMempoolSizeMax =
         gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000;
     LogPrintf("Cache configuration:\n");
     LogPrintf("* Using %.1f MiB for block index database\n",
               nBlockTreeDBCache * (1.0 / 1024 / 1024));
     if (gArgs.GetBoolArg("-txindex", DEFAULT_TXINDEX)) {
         LogPrintf("* Using %.1f MiB for transaction index database\n",
                   nTxIndexCache * (1.0 / 1024 / 1024));
     }
     for (BlockFilterType filter_type : g_enabled_filter_types) {
         LogPrintf("* Using %.1f MiB for %s block filter index database\n",
                   filter_index_cache * (1.0 / 1024 / 1024),
                   BlockFilterTypeName(filter_type));
     }
     LogPrintf("* Using %.1f MiB for chain state database\n",
               nCoinDBCache * (1.0 / 1024 / 1024));
     LogPrintf("* Using %.1f MiB for in-memory UTXO set (plus up to %.1f MiB of "
               "unused mempool space)\n",
               nCoinCacheUsage * (1.0 / 1024 / 1024),
               nMempoolSizeMax * (1.0 / 1024 / 1024));
 
     bool fLoaded = false;
     while (!fLoaded && !ShutdownRequested()) {
         const bool fReset = fReindex;
         bilingual_str strLoadError;
 
         uiInterface.InitMessage(_("Loading block index...").translated);
         do {
             const int64_t load_block_index_start_time = GetTimeMillis();
             try {
                 LOCK(cs_main);
                 // This statement makes ::ChainstateActive() usable.
                 g_chainstate = std::make_unique<CChainState>();
                 UnloadBlockIndex();
 
                 // new CBlockTreeDB tries to delete the existing file, which
                 // fails if it's still open from the previous loop. Close it
                 // first:
                 pblocktree.reset();
                 pblocktree.reset(
                     new CBlockTreeDB(nBlockTreeDBCache, false, fReset));
 
                 if (fReset) {
                     pblocktree->WriteReindexing(true);
                     // If we're reindexing in prune mode, wipe away unusable
                     // block files and all undo data files
                     if (fPruneMode) {
                         CleanupBlockRevFiles();
                     }
                 }
 
-                if (ShutdownRequested()) {
+                const Consensus::Params &params = chainparams.GetConsensus();
+
+                // If necessary, upgrade from older database format.
+                // This is a no-op if we cleared the block tree db with -reindex
+                // or -reindex-chainstate
+                if (!pblocktree->Upgrade(params)) {
+                    strLoadError = _("Error upgrading block index database");
                     break;
                 }
 
-                const Consensus::Params &params = chainparams.GetConsensus();
+                if (ShutdownRequested()) {
+                    break;
+                }
 
                 // LoadBlockIndex will load fHavePruned if we've ever removed a
                 // block file from disk.
                 // Note that it also sets fReindex based on the disk flag!
                 // From here on out fReindex and fReset mean something
                 // different!
                 if (!LoadBlockIndex(params)) {
                     if (ShutdownRequested()) {
                         break;
                     }
                     strLoadError = _("Error loading block database");
                     break;
                 }
 
                 // If the loaded chain has a wrong genesis, bail out immediately
                 // (we're likely using a testnet datadir, or the other way
                 // around).
                 if (!::BlockIndex().empty() &&
                     !LookupBlockIndex(params.hashGenesisBlock)) {
                     return InitError(_("Incorrect or no genesis block found. "
                                        "Wrong datadir for network?"));
                 }
 
                 // Check for changed -prune state.  What we are concerned about
                 // is a user who has pruned blocks in the past, but is now
                 // trying to run unpruned.
                 if (fHavePruned && !fPruneMode) {
                     strLoadError =
                         _("You need to rebuild the database using -reindex to "
                           "go back to unpruned mode.  This will redownload the "
                           "entire blockchain");
                     break;
                 }
 
                 // At this point blocktree args are consistent with what's on
                 // disk. If we're not mid-reindex (based on disk + args), add a
                 // genesis block on disk (otherwise we use the one already on
                 // disk).
                 // This is called again in ThreadImport after the reindex
                 // completes.
                 if (!fReindex && !LoadGenesisBlock(chainparams)) {
                     strLoadError = _("Error initializing block database");
                     break;
                 }
 
                 // At this point we're either in reindex or we've loaded a
                 // useful block tree into BlockIndex()!
 
                 ::ChainstateActive().InitCoinsDB(
                     /* cache_size_bytes */ nCoinDBCache,
                     /* in_memory */ false,
                     /* should_wipe */ fReset || fReindexChainState);
 
                 ::ChainstateActive().CoinsErrorCatcher().AddReadErrCallback(
                     []() {
                         uiInterface.ThreadSafeMessageBox(
                             _("Error reading from database, shutting down."),
                             "", CClientUIInterface::MSG_ERROR);
                     });
 
                 // If necessary, upgrade from older database format.
                 // This is a no-op if we cleared the coinsviewdb with -reindex
                 // or -reindex-chainstate
                 if (!::ChainstateActive().CoinsDB().Upgrade()) {
                     strLoadError = _("Error upgrading chainstate database");
                     break;
                 }
 
                 // ReplayBlocks is a no-op if we cleared the coinsviewdb with
                 // -reindex or -reindex-chainstate
                 if (!::ChainstateActive().ReplayBlocks(params)) {
                     strLoadError =
                         _("Unable to replay blocks. You will need to rebuild "
                           "the database using -reindex-chainstate.");
                     break;
                 }
 
                 // The on-disk coinsdb is now in a good state, create the cache
                 ::ChainstateActive().InitCoinsCache();
                 assert(::ChainstateActive().CanFlushToDisk());
 
                 bool is_coinsview_empty =
                     fReset || fReindexChainState ||
                     ::ChainstateActive().CoinsTip().GetBestBlock().IsNull();
                 if (!is_coinsview_empty) {
                     // LoadChainTip initializes the chain based on CoinsTip()'s
                     // best block
                     if (!::ChainstateActive().LoadChainTip(chainparams)) {
                         strLoadError = _("Error initializing block database");
                         break;
                     }
                     assert(::ChainActive().Tip() != nullptr);
 
                     uiInterface.InitMessage(
                         _("Verifying blocks...").translated);
                     if (fHavePruned &&
                         gArgs.GetArg("-checkblocks", DEFAULT_CHECKBLOCKS) >
                             MIN_BLOCKS_TO_KEEP) {
                         LogPrintf(
                             "Prune: pruned datadir may not have more than %d "
                             "blocks; only checking available blocks\n",
                             MIN_BLOCKS_TO_KEEP);
                     }
 
                     CBlockIndex *tip = ::ChainActive().Tip();
                     RPCNotifyBlockChange(tip);
                     if (tip && tip->nTime >
                                    GetAdjustedTime() + MAX_FUTURE_BLOCK_TIME) {
                         strLoadError =
                             _("The block database contains a block which "
                               "appears to be from the future. This may be due "
                               "to your computer's date and time being set "
                               "incorrectly. Only rebuild the block database if "
                               "you are sure that your computer's date and time "
                               "are correct");
                         break;
                     }
 
                     if (!CVerifyDB().VerifyDB(
                             config, &::ChainstateActive().CoinsDB(),
                             gArgs.GetArg("-checklevel", DEFAULT_CHECKLEVEL),
                             gArgs.GetArg("-checkblocks",
                                          DEFAULT_CHECKBLOCKS))) {
                         strLoadError = _("Corrupted block database detected");
                         break;
                     }
                 }
             } catch (const std::exception &e) {
                 LogPrintf("%s\n", e.what());
                 strLoadError = _("Error opening block database");
                 break;
             }
 
             fLoaded = true;
             LogPrintf(" block index %15dms\n",
                       GetTimeMillis() - load_block_index_start_time);
         } while (false);
 
         if (!fLoaded && !ShutdownRequested()) {
             // first suggest a reindex
             if (!fReset) {
                 bool fRet = uiInterface.ThreadSafeQuestion(
                     strLoadError + Untranslated(".\n\n") +
                         _("Do you want to rebuild the block database now?"),
                     strLoadError.original +
                         ".\nPlease restart with -reindex or "
                         "-reindex-chainstate to recover.",
                     "",
                     CClientUIInterface::MSG_ERROR |
                         CClientUIInterface::BTN_ABORT);
                 if (fRet) {
                     fReindex = true;
                     AbortShutdown();
                 } else {
                     LogPrintf("Aborted block database rebuild. Exiting.\n");
                     return false;
                 }
             } else {
                 return InitError(strLoadError);
             }
         }
     }
 
     // As LoadBlockIndex can take several minutes, it's possible the user
     // requested to kill the GUI during the last operation. If so, exit.
     // As the program has not fully started yet, Shutdown() is possibly
     // overkill.
     if (ShutdownRequested()) {
         LogPrintf("Shutdown requested. Exiting.\n");
         return false;
     }
 
     // Encoded addresses using cashaddr instead of base58.
     // We do this by default to avoid confusion with BTC addresses.
     config.SetCashAddrEncoding(gArgs.GetBoolArg("-usecashaddr", true));
 
     // Now that the chain state is loaded, make mempool generally available in
     // the node context. For example the connection manager, wallet, or RPC
     // threads, which are all started after this, may use it from the node
     // context.
     assert(!node.mempool);
     node.mempool = &::g_mempool;
 
     // Step 8: load indexers
     if (gArgs.GetBoolArg("-txindex", DEFAULT_TXINDEX)) {
         g_txindex = std::make_unique<TxIndex>(nTxIndexCache, false, fReindex);
         g_txindex->Start();
     }
 
     for (const auto &filter_type : g_enabled_filter_types) {
         InitBlockFilterIndex(filter_type, filter_index_cache, false, fReindex);
         GetBlockFilterIndex(filter_type)->Start();
     }
 
     // Step 9: load wallet
     for (const auto &client : node.chain_clients) {
         if (!client->load(chainparams)) {
             return false;
         }
     }
 
     // Step 10: data directory maintenance
 
     // if pruning, unset the service bit and perform the initial blockstore
     // prune after any wallet rescanning has taken place.
     if (fPruneMode) {
         LogPrintf("Unsetting NODE_NETWORK on prune mode\n");
         nLocalServices = ServiceFlags(nLocalServices & ~NODE_NETWORK);
         if (!fReindex) {
             uiInterface.InitMessage(_("Pruning blockstore...").translated);
             ::ChainstateActive().PruneAndFlush();
         }
     }
 
     // Step 11: import blocks
     if (!CheckDiskSpace(GetDataDir())) {
         InitError(
             strprintf(_("Error: Disk space is low for %s"), GetDataDir()));
         return false;
     }
     if (!CheckDiskSpace(GetBlocksDir())) {
         InitError(
             strprintf(_("Error: Disk space is low for %s"), GetBlocksDir()));
         return false;
     }
 
     // Either install a handler to notify us when genesis activates, or set
     // fHaveGenesis directly.
     // No locking, as this happens before any background thread is started.
     boost::signals2::connection block_notify_genesis_wait_connection;
     if (::ChainActive().Tip() == nullptr) {
         block_notify_genesis_wait_connection =
             uiInterface.NotifyBlockTip_connect(
                 std::bind(BlockNotifyGenesisWait, std::placeholders::_2));
     } else {
         fHaveGenesis = true;
     }
 
 #if defined(HAVE_SYSTEM)
     if (gArgs.IsArgSet("-blocknotify")) {
         uiInterface.NotifyBlockTip_connect(BlockNotifyCallback);
     }
 #endif
 
     std::vector<fs::path> vImportFiles;
     for (const std::string &strFile : gArgs.GetArgs("-loadblock")) {
         vImportFiles.push_back(strFile);
     }
 
     threadGroup.create_thread(
         std::bind(&ThreadImport, std::ref(config), vImportFiles));
 
     // Wait for genesis block to be processed
     {
         WAIT_LOCK(g_genesis_wait_mutex, lock);
         // We previously could hang here if StartShutdown() is called prior to
         // ThreadImport getting started, so instead we just wait on a timer to
         // check ShutdownRequested() regularly.
         while (!fHaveGenesis && !ShutdownRequested()) {
             g_genesis_wait_cv.wait_for(lock, std::chrono::milliseconds(500));
         }
         block_notify_genesis_wait_connection.disconnect();
     }
 
     if (ShutdownRequested()) {
         return false;
     }
 
     // Step 12: start node
 
     int chain_active_height;
 
     //// debug print
     {
         LOCK(cs_main);
         LogPrintf("block tree size = %u\n", ::BlockIndex().size());
         chain_active_height = ::ChainActive().Height();
     }
     LogPrintf("nBestHeight = %d\n", chain_active_height);
 
     if (gArgs.GetBoolArg("-listenonion", DEFAULT_LISTEN_ONION)) {
         StartTorControl();
     }
 
     Discover();
 
     // Map ports with UPnP
     if (gArgs.GetBoolArg("-upnp", DEFAULT_UPNP)) {
         StartMapPort();
     }
 
     CConnman::Options connOptions;
     connOptions.nLocalServices = nLocalServices;
     connOptions.nMaxConnections = nMaxConnections;
     connOptions.m_max_outbound_full_relay = std::min(
         MAX_OUTBOUND_FULL_RELAY_CONNECTIONS, connOptions.nMaxConnections);
     connOptions.m_max_outbound_block_relay = std::min(
         MAX_BLOCKS_ONLY_CONNECTIONS,
         connOptions.nMaxConnections - connOptions.m_max_outbound_full_relay);
     connOptions.nMaxAddnode = MAX_ADDNODE_CONNECTIONS;
     connOptions.nMaxFeeler = 1;
     connOptions.nBestHeight = chain_active_height;
     connOptions.uiInterface = &uiInterface;
     connOptions.m_banman = node.banman.get();
     connOptions.m_msgproc = node.peer_logic.get();
     connOptions.nSendBufferMaxSize =
         1000 * gArgs.GetArg("-maxsendbuffer", DEFAULT_MAXSENDBUFFER);
     connOptions.nReceiveFloodSize =
         1000 * gArgs.GetArg("-maxreceivebuffer", DEFAULT_MAXRECEIVEBUFFER);
     connOptions.m_added_nodes = gArgs.GetArgs("-addnode");
 
     connOptions.nMaxOutboundTimeframe = nMaxOutboundTimeframe;
     connOptions.nMaxOutboundLimit = nMaxOutboundLimit;
     connOptions.m_peer_connect_timeout = peer_connect_timeout;
 
     for (const std::string &strBind : gArgs.GetArgs("-bind")) {
         CService addrBind;
         if (!Lookup(strBind.c_str(), addrBind, GetListenPort(), false)) {
             return InitError(Untranslated(ResolveErrMsg("bind", strBind)));
         }
         connOptions.vBinds.push_back(addrBind);
     }
 
     for (const std::string &strBind : gArgs.GetArgs("-whitebind")) {
         NetWhitebindPermissions whitebind;
         std::string error;
         if (!NetWhitebindPermissions::TryParse(strBind, whitebind, error)) {
             return InitError(Untranslated(error));
         }
         connOptions.vWhiteBinds.push_back(whitebind);
     }
 
     for (const auto &net : gArgs.GetArgs("-whitelist")) {
         NetWhitelistPermissions subnet;
         std::string error;
         if (!NetWhitelistPermissions::TryParse(net, subnet, error)) {
             return InitError(Untranslated(error));
         }
         connOptions.vWhitelistedRange.push_back(subnet);
     }
 
     connOptions.vSeedNodes = gArgs.GetArgs("-seednode");
 
     // Initiate outbound connections unless connect=0
     connOptions.m_use_addrman_outgoing = !gArgs.IsArgSet("-connect");
     if (!connOptions.m_use_addrman_outgoing) {
         const auto connect = gArgs.GetArgs("-connect");
         if (connect.size() != 1 || connect[0] != "0") {
             connOptions.m_specified_outgoing = connect;
         }
     }
     if (!node.connman->Start(*node.scheduler, connOptions)) {
         return false;
     }
 
     // Step 13: finished
 
     SetRPCWarmupFinished();
     uiInterface.InitMessage(_("Done loading").translated);
 
     for (const auto &client : node.chain_clients) {
         client->start(*node.scheduler);
     }
 
     BanMan *banman = node.banman.get();
     node.scheduler->scheduleEvery(
         [banman] {
             banman->DumpBanlist();
             return true;
         },
         DUMP_BANS_INTERVAL);
 
     // Start Avalanche's event loop.
     g_avalanche->startEventLoop(*node.scheduler);
 
     return true;
 }
diff --git a/src/txdb.cpp b/src/txdb.cpp
index 54d33c5d4..5d620e449 100644
--- a/src/txdb.cpp
+++ b/src/txdb.cpp
@@ -1,446 +1,564 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2018 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 <txdb.h>
 
+#include <blockdb.h>
 #include <chain.h>
 #include <pow/pow.h>
 #include <random.h>
 #include <shutdown.h>
 #include <ui_interface.h>
 #include <util/system.h>
 #include <util/translation.h>
 #include <util/vector.h>
+#include <version.h>
 
 #include <boost/thread.hpp> // boost::this_thread::interruption_point() (mingw)
 
 #include <cstdint>
 
 static const char DB_COIN = 'C';
 static const char DB_COINS = 'c';
 static const char DB_BLOCK_FILES = 'f';
 static const char DB_BLOCK_INDEX = 'b';
 
 static const char DB_BEST_BLOCK = 'B';
 static const char DB_HEAD_BLOCKS = 'H';
 static const char DB_FLAG = 'F';
 static const char DB_REINDEX_FLAG = 'R';
 static const char DB_LAST_BLOCK = 'l';
 
 namespace {
 
 struct CoinEntry {
     COutPoint *outpoint;
     char key;
     explicit CoinEntry(const COutPoint *ptr)
         : outpoint(const_cast<COutPoint *>(ptr)), key(DB_COIN) {}
 
     template <typename Stream> void Serialize(Stream &s) const {
         s << key;
         s << outpoint->GetTxId();
         s << VARINT(outpoint->GetN());
     }
 
     template <typename Stream> void Unserialize(Stream &s) {
         s >> key;
         TxId id;
         s >> id;
         uint32_t n = 0;
         s >> VARINT(n);
         *outpoint = COutPoint(id, n);
     }
 };
 } // namespace
 
 CCoinsViewDB::CCoinsViewDB(fs::path ldb_path, size_t nCacheSize, bool fMemory,
                            bool fWipe)
     : db(ldb_path, nCacheSize, fMemory, fWipe, true) {}
 
 bool CCoinsViewDB::GetCoin(const COutPoint &outpoint, Coin &coin) const {
     return db.Read(CoinEntry(&outpoint), coin);
 }
 
 bool CCoinsViewDB::HaveCoin(const COutPoint &outpoint) const {
     return db.Exists(CoinEntry(&outpoint));
 }
 
 BlockHash CCoinsViewDB::GetBestBlock() const {
     BlockHash hashBestChain;
     if (!db.Read(DB_BEST_BLOCK, hashBestChain)) {
         return BlockHash();
     }
     return hashBestChain;
 }
 
 std::vector<BlockHash> CCoinsViewDB::GetHeadBlocks() const {
     std::vector<BlockHash> vhashHeadBlocks;
     if (!db.Read(DB_HEAD_BLOCKS, vhashHeadBlocks)) {
         return std::vector<BlockHash>();
     }
     return vhashHeadBlocks;
 }
 
 bool CCoinsViewDB::BatchWrite(CCoinsMap &mapCoins, const BlockHash &hashBlock) {
     CDBBatch batch(db);
     size_t count = 0;
     size_t changed = 0;
     size_t batch_size =
         (size_t)gArgs.GetArg("-dbbatchsize", DEFAULT_DB_BATCH_SIZE);
     int crash_simulate = gArgs.GetArg("-dbcrashratio", 0);
     assert(!hashBlock.IsNull());
 
     BlockHash old_tip = GetBestBlock();
     if (old_tip.IsNull()) {
         // We may be in the middle of replaying.
         std::vector<BlockHash> old_heads = GetHeadBlocks();
         if (old_heads.size() == 2) {
             assert(old_heads[0] == hashBlock);
             old_tip = old_heads[1];
         }
     }
 
     // In the first batch, mark the database as being in the middle of a
     // transition from old_tip to hashBlock.
     // A vector is used for future extensibility, as we may want to support
     // interrupting after partial writes from multiple independent reorgs.
     batch.Erase(DB_BEST_BLOCK);
     batch.Write(DB_HEAD_BLOCKS, Vector(hashBlock, old_tip));
 
     for (CCoinsMap::iterator it = mapCoins.begin(); it != mapCoins.end();) {
         if (it->second.flags & CCoinsCacheEntry::DIRTY) {
             CoinEntry entry(&it->first);
             if (it->second.coin.IsSpent()) {
                 batch.Erase(entry);
             } else {
                 batch.Write(entry, it->second.coin);
             }
             changed++;
         }
         count++;
         CCoinsMap::iterator itOld = it++;
         mapCoins.erase(itOld);
         if (batch.SizeEstimate() > batch_size) {
             LogPrint(BCLog::COINDB, "Writing partial batch of %.2f MiB\n",
                      batch.SizeEstimate() * (1.0 / 1048576.0));
             db.WriteBatch(batch);
             batch.Clear();
             if (crash_simulate) {
                 static FastRandomContext rng;
                 if (rng.randrange(crash_simulate) == 0) {
                     LogPrintf("Simulating a crash. Goodbye.\n");
                     _Exit(0);
                 }
             }
         }
     }
 
     // In the last batch, mark the database as consistent with hashBlock again.
     batch.Erase(DB_HEAD_BLOCKS);
     batch.Write(DB_BEST_BLOCK, hashBlock);
 
     LogPrint(BCLog::COINDB, "Writing final batch of %.2f MiB\n",
              batch.SizeEstimate() * (1.0 / 1048576.0));
     bool ret = db.WriteBatch(batch);
     LogPrint(BCLog::COINDB,
              "Committed %u changed transaction outputs (out of "
              "%u) to coin database...\n",
              (unsigned int)changed, (unsigned int)count);
     return ret;
 }
 
 size_t CCoinsViewDB::EstimateSize() const {
     return db.EstimateSize(DB_COIN, char(DB_COIN + 1));
 }
 
 CBlockTreeDB::CBlockTreeDB(size_t nCacheSize, bool fMemory, bool fWipe)
     : CDBWrapper(GetDataDir() / "blocks" / "index", nCacheSize, fMemory,
                  fWipe) {}
 
 bool CBlockTreeDB::ReadBlockFileInfo(int nFile, CBlockFileInfo &info) {
     return Read(std::make_pair(DB_BLOCK_FILES, nFile), info);
 }
 
 bool CBlockTreeDB::WriteReindexing(bool fReindexing) {
     if (fReindexing) {
         return Write(DB_REINDEX_FLAG, '1');
     } else {
         return Erase(DB_REINDEX_FLAG);
     }
 }
 
 bool CBlockTreeDB::IsReindexing() const {
     return Exists(DB_REINDEX_FLAG);
 }
 
 bool CBlockTreeDB::ReadLastBlockFile(int &nFile) {
     return Read(DB_LAST_BLOCK, nFile);
 }
 
 CCoinsViewCursor *CCoinsViewDB::Cursor() const {
     CCoinsViewDBCursor *i = new CCoinsViewDBCursor(
         const_cast<CDBWrapper &>(db).NewIterator(), GetBestBlock());
     /**
      * It seems that there are no "const iterators" for LevelDB. Since we only
      * need read operations on it, use a const-cast to get around that
      * restriction.
      */
     i->pcursor->Seek(DB_COIN);
     // Cache key of first record
     if (i->pcursor->Valid()) {
         CoinEntry entry(&i->keyTmp.second);
         i->pcursor->GetKey(entry);
         i->keyTmp.first = entry.key;
     } else {
         // Make sure Valid() and GetKey() return false
         i->keyTmp.first = 0;
     }
     return i;
 }
 
 bool CCoinsViewDBCursor::GetKey(COutPoint &key) const {
     // Return cached key
     if (keyTmp.first == DB_COIN) {
         key = keyTmp.second;
         return true;
     }
     return false;
 }
 
 bool CCoinsViewDBCursor::GetValue(Coin &coin) const {
     return pcursor->GetValue(coin);
 }
 
 unsigned int CCoinsViewDBCursor::GetValueSize() const {
     return pcursor->GetValueSize();
 }
 
 bool CCoinsViewDBCursor::Valid() const {
     return keyTmp.first == DB_COIN;
 }
 
 void CCoinsViewDBCursor::Next() {
     pcursor->Next();
     CoinEntry entry(&keyTmp.second);
     if (!pcursor->Valid() || !pcursor->GetKey(entry)) {
         // Invalidate cached key after last record so that Valid() and GetKey()
         // return false
         keyTmp.first = 0;
     } else {
         keyTmp.first = entry.key;
     }
 }
 
 bool CBlockTreeDB::WriteBatchSync(
     const std::vector<std::pair<int, const CBlockFileInfo *>> &fileInfo,
     int nLastFile, const std::vector<const CBlockIndex *> &blockinfo) {
     CDBBatch batch(*this);
     for (std::vector<std::pair<int, const CBlockFileInfo *>>::const_iterator
              it = fileInfo.begin();
          it != fileInfo.end(); it++) {
         batch.Write(std::make_pair(DB_BLOCK_FILES, it->first), *it->second);
     }
     batch.Write(DB_LAST_BLOCK, nLastFile);
     for (std::vector<const CBlockIndex *>::const_iterator it =
              blockinfo.begin();
          it != blockinfo.end(); it++) {
         batch.Write(std::make_pair(DB_BLOCK_INDEX, (*it)->GetBlockHash()),
                     CDiskBlockIndex(*it));
     }
     return WriteBatch(batch, true);
 }
 
 bool CBlockTreeDB::WriteFlag(const std::string &name, bool fValue) {
     return Write(std::make_pair(DB_FLAG, name), fValue ? '1' : '0');
 }
 
 bool CBlockTreeDB::ReadFlag(const std::string &name, bool &fValue) {
     char ch;
     if (!Read(std::make_pair(DB_FLAG, name), ch)) {
         return false;
     }
     fValue = ch == '1';
     return true;
 }
 
 bool CBlockTreeDB::LoadBlockIndexGuts(
     const Consensus::Params &params,
     std::function<CBlockIndex *(const BlockHash &)> insertBlockIndex) {
     std::unique_ptr<CDBIterator> pcursor(NewIterator());
 
+    uint64_t version = 0;
+    pcursor->Seek("version");
+    if (pcursor->Valid()) {
+        pcursor->GetValue(version);
+    }
+
+    if (version != CLIENT_VERSION) {
+        return error("%s: Invalid block index database version: %s", __func__,
+                     version);
+    }
+
     pcursor->Seek(std::make_pair(DB_BLOCK_INDEX, uint256()));
 
     // Load m_block_index
     while (pcursor->Valid()) {
         boost::this_thread::interruption_point();
         if (ShutdownRequested()) {
             return false;
         }
         std::pair<char, uint256> key;
         if (!pcursor->GetKey(key) || key.first != DB_BLOCK_INDEX) {
             break;
         }
 
         CDiskBlockIndex diskindex;
         if (!pcursor->GetValue(diskindex)) {
             return error("%s : failed to read value", __func__);
         }
 
         // Construct block index object
         CBlockIndex *pindexNew = insertBlockIndex(diskindex.GetBlockHash());
         pindexNew->pprev = insertBlockIndex(diskindex.hashPrev);
         pindexNew->nHeight = diskindex.nHeight;
         pindexNew->nFile = diskindex.nFile;
         pindexNew->nDataPos = diskindex.nDataPos;
         pindexNew->nUndoPos = diskindex.nUndoPos;
         pindexNew->nVersion = diskindex.nVersion;
         pindexNew->hashMerkleRoot = diskindex.hashMerkleRoot;
         pindexNew->nTime = diskindex.nTime;
         pindexNew->nBits = diskindex.nBits;
         pindexNew->nNonce = diskindex.nNonce;
         pindexNew->nStatus = diskindex.nStatus;
         pindexNew->nTx = diskindex.nTx;
 
         if (!CheckProofOfWork(pindexNew->GetBlockHash(), pindexNew->nBits,
                               params)) {
             return error("%s: CheckProofOfWork failed: %s", __func__,
                          pindexNew->ToString());
         }
 
         pcursor->Next();
     }
 
     return true;
 }
 
 namespace {
 //! Legacy class to deserialize pre-pertxout database entries without reindex.
 class CCoins {
 public:
     //! whether transaction is a coinbase
     bool fCoinBase;
 
     //! unspent transaction outputs; spent outputs are .IsNull(); spent outputs
     //! at the end of the array are dropped
     std::vector<CTxOut> vout;
 
     //! at which height this transaction was included in the active block chain
     int nHeight;
 
     //! empty constructor
     CCoins() : fCoinBase(false), vout(0), nHeight(0) {}
 
     template <typename Stream> void Unserialize(Stream &s) {
         uint32_t nCode = 0;
         // version
         unsigned int nVersionDummy = 0;
         ::Unserialize(s, VARINT(nVersionDummy));
         // header code
         ::Unserialize(s, VARINT(nCode));
         fCoinBase = nCode & 1;
         std::vector<bool> vAvail(2, false);
         vAvail[0] = (nCode & 2) != 0;
         vAvail[1] = (nCode & 4) != 0;
         uint32_t nMaskCode = (nCode / 8) + ((nCode & 6) != 0 ? 0 : 1);
         // spentness bitmask
         while (nMaskCode > 0) {
             uint8_t chAvail = 0;
             ::Unserialize(s, chAvail);
             for (unsigned int p = 0; p < 8; p++) {
                 bool f = (chAvail & (1 << p)) != 0;
                 vAvail.push_back(f);
             }
             if (chAvail != 0) {
                 nMaskCode--;
             }
         }
         // txouts themself
         vout.assign(vAvail.size(), CTxOut());
         for (size_t i = 0; i < vAvail.size(); i++) {
             if (vAvail[i]) {
                 ::Unserialize(s, CTxOutCompressor(vout[i]));
             }
         }
         // coinbase height
         ::Unserialize(s, VARINT(nHeight, VarIntMode::NONNEGATIVE_SIGNED));
     }
 };
 } // namespace
 
 /**
  * Upgrade the database from older formats.
  *
  * Currently implemented: from the per-tx utxo model (0.8..0.14.x) to per-txout.
  */
 bool CCoinsViewDB::Upgrade() {
     std::unique_ptr<CDBIterator> pcursor(db.NewIterator());
     pcursor->Seek(std::make_pair(DB_COINS, uint256()));
     if (!pcursor->Valid()) {
         return true;
     }
 
     int64_t count = 0;
     LogPrintf("Upgrading utxo-set database...\n");
     size_t batch_size = 1 << 24;
     CDBBatch batch(db);
     int reportDone = -1;
     std::pair<uint8_t, uint256> key;
     std::pair<uint8_t, uint256> prev_key = {DB_COINS, uint256()};
     while (pcursor->Valid()) {
         boost::this_thread::interruption_point();
         if (ShutdownRequested()) {
             break;
         }
 
         if (!pcursor->GetKey(key) || key.first != DB_COINS) {
             break;
         }
 
         if (count++ % 256 == 0) {
             uint32_t high =
                 0x100 * *key.second.begin() + *(key.second.begin() + 1);
             int percentageDone = (int)(high * 100.0 / 65536.0 + 0.5);
             uiInterface.ShowProgress(_("Upgrading UTXO database").translated,
                                      percentageDone, true);
             if (reportDone < percentageDone / 10) {
                 // report max. every 10% step
                 LogPrintfToBeContinued("[%d%%]...", percentageDone);
                 reportDone = percentageDone / 10;
             }
         }
 
         CCoins old_coins;
         if (!pcursor->GetValue(old_coins)) {
             return error("%s: cannot parse CCoins record", __func__);
         }
 
         const TxId id(key.second);
         for (size_t i = 0; i < old_coins.vout.size(); ++i) {
             if (!old_coins.vout[i].IsNull() &&
                 !old_coins.vout[i].scriptPubKey.IsUnspendable()) {
                 Coin newcoin(std::move(old_coins.vout[i]), old_coins.nHeight,
                              old_coins.fCoinBase);
                 COutPoint outpoint(id, i);
                 CoinEntry entry(&outpoint);
                 batch.Write(entry, newcoin);
             }
         }
 
         batch.Erase(key);
         if (batch.SizeEstimate() > batch_size) {
             db.WriteBatch(batch);
             batch.Clear();
             db.CompactRange(prev_key, key);
             prev_key = key;
         }
 
         pcursor->Next();
     }
 
     db.WriteBatch(batch);
     db.CompactRange({DB_COINS, uint256()}, key);
     uiInterface.ShowProgress("", 100, false);
     LogPrintf("[%s].\n", ShutdownRequested() ? "CANCELLED" : "DONE");
     return !ShutdownRequested();
 }
+
+bool CBlockTreeDB::Upgrade(const Consensus::Params &params) {
+    std::unique_ptr<CDBIterator> pcursor(NewIterator());
+
+    uint64_t version = 0;
+    pcursor->Seek("version");
+    if (pcursor->Valid()) {
+        pcursor->GetValue(version);
+    }
+
+    if (version >= CLIENT_VERSION) {
+        // The DB is already up to date.
+        return true;
+    }
+
+    CDBBatch batch(*this);
+
+    pcursor->Seek(std::make_pair(DB_BLOCK_INDEX, uint256()));
+    if (!pcursor->Valid()) {
+        // The DB is empty, so just write the version number and consider the
+        // upgrade done.
+        batch.Write("version", uint64_t(CLIENT_VERSION));
+        WriteBatch(batch);
+        return true;
+    }
+
+    int64_t count = 0;
+    LogPrintf("Upgrading block index database...\n");
+    int reportDone = -1;
+    std::pair<uint8_t, uint256> key = {DB_BLOCK_INDEX, uint256()};
+    while (pcursor->Valid()) {
+        boost::this_thread::interruption_point();
+        if (ShutdownRequested()) {
+            break;
+        }
+
+        if (!pcursor->GetKey(key) || key.first != DB_BLOCK_INDEX) {
+            break;
+        }
+
+        if (count++ % 256 == 0) {
+            uint32_t high =
+                0x100 * *key.second.begin() + *(key.second.begin() + 1);
+            int percentageDone = (int)(high * 100.0 / 65536.0 + 0.5);
+            uiInterface.ShowProgress(
+                _("Upgrading block index database").translated, percentageDone,
+                true);
+            if (reportDone < percentageDone / 10) {
+                // report max. every 10% step
+                LogPrintfToBeContinued("[%d%%]...", percentageDone);
+                reportDone = percentageDone / 10;
+            }
+        }
+
+        // Read the block index entry and update it.
+        CDiskBlockIndex diskindex;
+        if (!pcursor->GetValue(diskindex)) {
+            return error("%s: cannot parse CDiskBlockIndex record", __func__);
+        }
+
+        // The block hash needs to be usable.
+        BlockHash blockhash = diskindex.GetBlockHash();
+        diskindex.phashBlock = &blockhash;
+
+        bool mustUpdate = false;
+
+        // We must update the block index to add the size.
+        if (CLIENT_VERSION >= CDiskBlockIndex::TRACK_SIZE_VERSION &&
+            version < CDiskBlockIndex::TRACK_SIZE_VERSION &&
+            diskindex.nTx > 0 && diskindex.nSize == 0) {
+            if (!diskindex.nStatus.hasData()) {
+                // The block was pruned, we need a full reindex.
+                LogPrintf("\nThe block %s is pruned. The block index cannot be "
+                          "upgraded and reindexing is required.\n",
+                          blockhash.GetHex());
+                return false;
+            }
+
+            CBlock block;
+            if (!ReadBlockFromDisk(block, &diskindex, params)) {
+                // Failed to read the block from disk, even though it is marked
+                // that we have data for this block.
+                return false;
+            }
+
+            mustUpdate = true;
+            diskindex.nSize = ::GetSerializeSize(block, PROTOCOL_VERSION);
+        }
+
+        if (mustUpdate) {
+            batch.Write(std::make_pair(DB_BLOCK_INDEX, blockhash), diskindex);
+        }
+
+        pcursor->Next();
+    }
+
+    // Upgrade is done, now let's update the version number.
+    batch.Write("version", uint64_t(CLIENT_VERSION));
+
+    WriteBatch(batch);
+    CompactRange({DB_BLOCK_INDEX, uint256()}, key);
+    uiInterface.ShowProgress("", 100, false);
+    LogPrintf("[%s].\n", ShutdownRequested() ? "CANCELLED" : "DONE");
+    return !ShutdownRequested();
+}
diff --git a/src/txdb.h b/src/txdb.h
index d11c0de19..f159bcc15 100644
--- a/src/txdb.h
+++ b/src/txdb.h
@@ -1,117 +1,121 @@
 // 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.
 
 #ifndef BITCOIN_TXDB_H
 #define BITCOIN_TXDB_H
 
 #include <blockfileinfo.h>
 #include <coins.h>
 #include <dbwrapper.h>
 #include <flatfile.h>
 #include <primitives/block.h>
 
 #include <memory>
 #include <string>
 #include <utility>
 #include <vector>
 
 struct BlockHash;
 class CBlockIndex;
 class CCoinsViewDBCursor;
 
 namespace Consensus {
 struct Params;
 }
 
 //! No need to periodic flush if at least this much space still available.
 static constexpr int MAX_BLOCK_COINSDB_USAGE = 10;
 //! min. -dbcache (MiB)
 static constexpr int64_t MIN_DB_CACHE_MB = 4;
 //! max. -dbcache (MiB)
 static constexpr int64_t MAX_DB_CACHE_MB = sizeof(void *) > 4 ? 16384 : 1024;
 //! -dbcache default (MiB)
 static constexpr int64_t DEFAULT_DB_CACHE_MB = 1024;
 //! -dbbatchsize default (bytes)
 static constexpr int64_t DEFAULT_DB_BATCH_SIZE = 16 << 20;
 //! Max memory allocated to block tree DB specific cache, if no -txindex (MiB)
 static constexpr int64_t MAX_BLOCK_DB_CACHE_MB = 2;
 //! Max memory allocated to block tree DB specific cache, if -txindex (MiB)
 // Unlike for the UTXO database, for the txindex scenario the leveldb cache make
 // a meaningful difference:
 // https://github.com/bitcoin/bitcoin/pull/8273#issuecomment-229601991
 static constexpr int64_t MAX_TX_INDEX_CACHE_MB = 1024;
 //! Max memory allocated to all block filter index caches combined in MiB.
 static constexpr int64_t MAX_FILTER_INDEX_CACHE_MB = 1024;
 //! Max memory allocated to coin DB specific cache (MiB)
 static constexpr int64_t MAX_COINS_DB_CACHE_MB = 8;
 
 /** CCoinsView backed by the coin database (chainstate/) */
 class CCoinsViewDB final : public CCoinsView {
 protected:
     CDBWrapper db;
 
 public:
     /**
      * @param[in] ldb_path    Location in the filesystem where leveldb data will
      * be stored.
      */
     explicit CCoinsViewDB(fs::path ldb_path, size_t nCacheSize, bool fMemory,
                           bool fWipe);
 
     bool GetCoin(const COutPoint &outpoint, Coin &coin) const override;
     bool HaveCoin(const COutPoint &outpoint) const override;
     BlockHash GetBestBlock() const override;
     std::vector<BlockHash> GetHeadBlocks() const override;
     bool BatchWrite(CCoinsMap &mapCoins, const BlockHash &hashBlock) override;
     CCoinsViewCursor *Cursor() const override;
 
     //! Attempt to update from an older database format.
     //! Returns whether an error occurred.
     bool Upgrade();
     size_t EstimateSize() const override;
 };
 
 /** Specialization of CCoinsViewCursor to iterate over a CCoinsViewDB */
 class CCoinsViewDBCursor : public CCoinsViewCursor {
 public:
     ~CCoinsViewDBCursor() {}
 
     bool GetKey(COutPoint &key) const override;
     bool GetValue(Coin &coin) const override;
     unsigned int GetValueSize() const override;
 
     bool Valid() const override;
     void Next() override;
 
 private:
     CCoinsViewDBCursor(CDBIterator *pcursorIn, const BlockHash &hashBlockIn)
         : CCoinsViewCursor(hashBlockIn), pcursor(pcursorIn) {}
     std::unique_ptr<CDBIterator> pcursor;
     std::pair<char, COutPoint> keyTmp;
 
     friend class CCoinsViewDB;
 };
 
 /** Access to the block database (blocks/index/) */
 class CBlockTreeDB : public CDBWrapper {
 public:
     explicit CBlockTreeDB(size_t nCacheSize, bool fMemory = false,
                           bool fWipe = false);
 
     bool WriteBatchSync(
         const std::vector<std::pair<int, const CBlockFileInfo *>> &fileInfo,
         int nLastFile, const std::vector<const CBlockIndex *> &blockinfo);
     bool ReadBlockFileInfo(int nFile, CBlockFileInfo &info);
     bool ReadLastBlockFile(int &nFile);
     bool WriteReindexing(bool fReindexing);
     bool IsReindexing() const;
     bool WriteFlag(const std::string &name, bool fValue);
     bool ReadFlag(const std::string &name, bool &fValue);
     bool LoadBlockIndexGuts(
         const Consensus::Params &params,
         std::function<CBlockIndex *(const BlockHash &)> insertBlockIndex);
+
+    //! Attempt to update from an older database format.
+    //! Returns whether an error occurred.
+    bool Upgrade(const Consensus::Params &params);
 };
 
 #endif // BITCOIN_TXDB_H
diff --git a/src/validation.cpp b/src/validation.cpp
index 1614f5567..8a19c3ebf 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -1,5797 +1,5798 @@
 // 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/processor.h>
 #include <blockdb.h>
 #include <blockvalidity.h>
 #include <chainparams.h>
 #include <checkpoints.h>
 #include <checkqueue.h>
 #include <config.h>
 #include <consensus/activation.h>
 #include <consensus/merkle.h>
 #include <consensus/tx_check.h>
 #include <consensus/tx_verify.h>
 #include <consensus/validation.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/aserti32d.h> // For ResetASERTAnchorBlockCache
 #include <pow/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 <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 <validationinterface.h>
 #include <warnings.h>
 
 #include <boost/algorithm/string/replace.hpp>
 #include <boost/thread.hpp> // boost::this_thread::interruption_point() (mingw)
 
 #include <string>
 #include <thread>
 
 #define MICRO 0.000001
 #define MILLI 0.001
 
 namespace {
 BlockManager g_blockman;
 } // namespace
 
 std::unique_ptr<CChainState> g_chainstate;
 
 CChainState &ChainstateActive() {
     assert(g_chainstate);
     return *g_chainstate;
 }
 
 CChain &ChainActive() {
     assert(g_chainstate);
     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;
 
 CBlockIndex *pindexBestHeader = nullptr;
 Mutex g_best_block_mutex;
 std::condition_variable g_best_block_cv;
 uint256 g_best_block;
 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);
 
 CTxMemPool g_mempool;
 
 // Internal stuff
 namespace {
 CBlockIndex *pindexBestInvalid = nullptr;
 CBlockIndex *pindexBestParked = nullptr;
 
 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 *LookupBlockIndex(const BlockHash &hash) {
     AssertLockHeld(cs_main);
     BlockMap::const_iterator it = g_blockman.m_block_index.find(hash);
     return it == g_blockman.m_block_index.end() ? nullptr : it->second;
 }
 
 CBlockIndex *FindForkInGlobalIndex(const CChain &chain,
                                    const CBlockLocator &locator) {
     AssertLockHeld(cs_main);
 
     // Find the latest block common to locator and chain - we expect that
     // locator.vHave is sorted descending by height.
     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<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 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 {
         // CoinsTip() contains the UTXO set for ::ChainActive().Tip()
         CCoinsViewMemPool viewMemPool(&::ChainstateActive().CoinsTip(), 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.tachyonActivationTime);
 }
 
 static bool IsReplayProtectionEnabled(const Consensus::Params &params,
                                       const CBlockIndex *pindexPrev) {
     if (pindexPrev == nullptr) {
         return false;
     }
 
     return IsReplayProtectionEnabled(params, pindexPrev->GetMedianTimePast());
 }
 
 // Used to avoid mempool polluting consensus critical paths if CCoinsViewMempool
 // were somehow broken and returning the wrong scriptPubKeys
 static bool CheckInputsFromMempoolAndCache(
     const CTransaction &tx, TxValidationState &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 =
                 ::ChainstateActive().CoinsTip().AccessCoin(txin.prevout);
             assert(!coinFromDisk.IsSpent());
             assert(coinFromDisk.GetTxOut() == coin.GetTxOut());
         }
     }
 
     return CheckInputs(tx, state, view, flags, cacheSigStore, true, txdata,
                        nSigChecksOut);
 }
 
 /**
  * @param[out] coins_to_uncache   Return any outpoints which were not previously
  * present in the coins cache, but were added as a result of validating the tx
  *                                for mempool acceptance. This allows the caller
  * to optionally remove the cache additions if the associated transaction ends
  *                                up being rejected by the mempool.
  */
 static bool AcceptToMemoryPoolWorker(
     const Config &config, CTxMemPool &pool, TxValidationState &state,
     const CTransactionRef &ptx, 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);
 
     // 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.Invalid(TxValidationResult::TX_NOT_STANDARD, 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.
     TxValidationState 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.Invalid(TxValidationResult::TX_PREMATURE_SPEND,
                              ctxState.GetRejectReason(),
                              ctxState.GetDebugMessage());
     }
 
     // Is it already in the memory pool?
     if (pool.exists(txid)) {
         return state.Invalid(TxValidationResult::TX_CONFLICT,
                              "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(TxValidationResult::TX_MEMPOOL_POLICY,
                                  "txn-mempool-conflict");
         }
     }
 
     {
         CCoinsView dummy;
         CCoinsViewCache view(&dummy);
 
         LockPoints lp;
         CCoinsViewCache &coins_cache = ::ChainstateActive().CoinsTip();
         CCoinsViewMemPool viewMemPool(&coins_cache, pool);
         view.SetBackend(viewMemPool);
 
         // Do all inputs exist?
         for (const CTxIn &txin : tx.vin) {
             if (!coins_cache.HaveCoinInCache(txin.prevout)) {
                 coins_to_uncache.push_back(txin.prevout);
             }
 
             // Note: this call may add txin.prevout to the coins cache
             // (CoinsTip().cacheCoins) by way of FetchCoin(). It should be
             // removed later (via coins_to_uncache) if this tx turns out to be
             // invalid.
             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 (coins_cache.HaveCoinInCache(COutPoint(txid, out))) {
                         return state.Invalid(TxValidationResult::TX_CONFLICT,
                                              "txn-already-known");
                     }
                 }
 
                 // Otherwise assume this might be an orphan tx for which we just
                 // haven't seen parents yet.
                 return state.Invalid(TxValidationResult::TX_MISSING_INPUTS,
                                      "bad-txns-inputs-missingorspent");
             }
         }
 
         // Are the actual inputs available?
         if (!view.HaveInputs(tx)) {
             return state.Invalid(TxValidationResult::TX_MEMPOOL_POLICY,
                                  "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.Invalid(TxValidationResult::TX_PREMATURE_SPEND,
                                  "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(), state.ToString());
         }
 
         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(TxValidationResult::TX_NOT_STANDARD,
                                  "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.Invalid(TxValidationResult::TX_MEMPOOL_POLICY,
                                  "min relay fee not met");
         }
 
         if (nAbsurdFee != Amount::zero() && nFees > nAbsurdFee) {
             return state.Invalid(TxValidationResult::TX_NOT_STANDARD,
                                  "absurdly-high-fee",
                                  strprintf("%d > %d", nFees, nAbsurdFee));
         }
 
         // Validate input scripts against standard script flags.
         const uint32_t scriptVerifyFlags =
             nextBlockScriptVerifyFlags | STANDARD_SCRIPT_VERIFY_FLAGS;
         PrecomputedTransactionData txdata(tx);
         int nSigChecksStandard;
         if (!CheckInputs(tx, state, view, 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.Invalid(
                 TxValidationResult::TX_MEMPOOL_POLICY,
                 "mempool min fee not met",
                 strprintf("%d < %d", nModifiedFees, mempoolRejectFee));
         }
 
         // Calculate in-mempool ancestors, up to a limit.
         CTxMemPool::setEntries setAncestors;
         size_t nLimitAncestors =
             gArgs.GetArg("-limitancestorcount", DEFAULT_ANCESTOR_LIMIT);
         size_t nLimitAncestorSize =
             gArgs.GetArg("-limitancestorsize", DEFAULT_ANCESTOR_SIZE_LIMIT) *
             1000;
         size_t nLimitDescendants =
             gArgs.GetArg("-limitdescendantcount", DEFAULT_DESCENDANT_LIMIT);
         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.Invalid(TxValidationResult::TX_MEMPOOL_POLICY,
                                  "too-long-mempool-chain", 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(), state.ToString());
         }
 
         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,
                 std::chrono::hours{
                     gArgs.GetArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY)});
             if (!pool.exists(txid)) {
                 return state.Invalid(TxValidationResult::TX_MEMPOOL_POLICY,
                                      "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,
                            TxValidationState &state, const CTransactionRef &tx,
                            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, nAcceptTime,
                                         bypass_limits, nAbsurdFee,
                                         coins_to_uncache, test_accept);
     if (!res) {
         // Remove coins that were not present in the coins cache before calling
         // ATMPW; this is to prevent memory DoS in case we receive a large
         // number of invalid transactions that attempt to overrun the in-memory
         // coins cache
         // (`CCoinsViewCache::cacheCoins`).
 
         for (const COutPoint &outpoint : coins_to_uncache) {
             ::ChainstateActive().CoinsTip().Uncache(outpoint);
         }
     }
 
     // After we've (potentially) uncached entries, ensure our coins cache is
     // still within its size limits
     BlockValidationState stateDummy;
     ::ChainstateActive().FlushStateToDisk(config.GetChainParams(), stateDummy,
                                           FlushStateMode::PERIODIC);
     return res;
 }
 
 bool AcceptToMemoryPool(const Config &config, CTxMemPool &pool,
                         TxValidationState &state, const CTransactionRef &tx,
                         bool bypass_limits, const Amount nAbsurdFee,
                         bool test_accept) {
     return AcceptToMemoryPoolWithTime(config, pool, state, tx, 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;
 }
 
 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;
 }
 
 CoinsViews::CoinsViews(std::string ldb_name, size_t cache_size_bytes,
                        bool in_memory, bool should_wipe)
     : m_dbview(GetDataDir() / ldb_name, cache_size_bytes, in_memory,
                should_wipe),
       m_catcherview(&m_dbview) {}
 
 void CoinsViews::InitCache() {
     m_cacheview = std::make_unique<CCoinsViewCache>(&m_catcherview);
 }
 
 // NOTE: for now m_blockman is set to a global, but this will be changed
 // in a future commit.
 CChainState::CChainState() : m_blockman(g_blockman) {}
 
 void CChainState::InitCoinsDB(size_t cache_size_bytes, bool in_memory,
                               bool should_wipe, std::string leveldb_name) {
     m_coins_views = std::make_unique<CoinsViews>(leveldb_name, cache_size_bytes,
                                                  in_memory, should_wipe);
 }
 
 void CChainState::InitCoinsCache() {
     assert(m_coins_views != nullptr);
     m_coins_views->InitCache();
 }
 
 // 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;
 }
 
 static CBlockIndex const *pindexBestForkTip = nullptr;
 static CBlockIndex const *pindexBestForkBase = nullptr;
 
 BlockMap &BlockIndex() {
     return g_blockman.m_block_index;
 }
 
 static void AlertNotify(const std::string &strMessage) {
     uiInterface.NotifyAlertChanged();
 #if defined(HAVE_SYSTEM)
     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();
 #endif
 }
 
 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();
 }
 
 void CChainState::InvalidChainFound(CBlockIndex *pindexNew) {
     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)) {
         m_finalizedBlockIndex = 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 BlockValidationState &state) {
     if (state.GetResult() != BlockValidationResult::BLOCK_MUTATED) {
         pindex->nStatus = pindex->nStatus.withFailed();
         m_blockman.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, m_tx_out.scriptPubKey, nFlags,
                       CachingTransactionSignatureChecker(
                           ptxTo, nIn, m_tx_out.nValue, 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, TxValidationState &state,
                  const CCoinsViewCache &inputs, 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());
     }
 
     // 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(TxValidationResult::TX_CONSENSUS,
                                  "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.
 
         // Verify signature
         CScriptCheck check(coin.GetTxOut(), tx, i, flags, sigCacheStore, txdata,
                            &txLimitSigChecks, pBlockLimitSigChecks);
 
         // If pvChecks is not null, defer the check execution to the caller.
         if (pvChecks) {
             pvChecks->push_back(std::move(check));
             continue;
         }
 
         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, ensure we return
                 // NOT_STANDARD instead of CONSENSUS to avoid downstream users
                 // splitting the network between upgraded and non-upgraded nodes
                 // by banning CONSENSUS-failing data providers.
                 CScriptCheck check2(coin.GetTxOut(), tx, i, mandatoryFlags,
                                     sigCacheStore, txdata);
                 if (check2()) {
                     return state.Invalid(
                         TxValidationResult::TX_NOT_STANDARD,
                         strprintf("non-mandatory-script-verify-flag (%s)",
                                   ScriptErrorString(scriptError)));
                 }
                 // update the error message to reflect the mandatory violation.
                 scriptError = check2.GetScriptError();
             }
 
             // MANDATORY flag failures correspond to
             // TxValidationResult::TX_CONSENSUS. Because CONSENSUS failures are
             // the most serious case of validation failures, we may need to
             // consider using RECENT_CONSENSUS_CHANGE for any script failure
             // that could be due to non-upgraded nodes which we may want to
             // support, to avoid splitting the network (but this depends on the
             // details of how net_processing handles such errors).
             return state.Invalid(
                 TxValidationResult::TX_CONSENSUS,
                 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;
 }
 
 static bool UndoWriteToDisk(const CBlockUndo &blockundo, FlatFilePos &pos,
                             const BlockHash &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;
 }
 
 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 = "",
                       unsigned int prefix = 0) {
     SetMiscWarning(strMessage);
     LogPrintf("*** %s\n", strMessage);
     if (!userMessage.empty()) {
         uiInterface.ThreadSafeMessageBox(Untranslated(userMessage), "",
                                          CClientUIInterface::MSG_ERROR |
                                              prefix);
     } else {
         uiInterface.ThreadSafeMessageBox(
             _("Error: A fatal internal error occurred, see debug.log for "
               "details"),
             "",
             CClientUIInterface::MSG_ERROR | CClientUIInterface::MSG_NOPREFIX);
     }
     StartShutdown();
     return false;
 }
 
 static bool AbortNode(BlockValidationState &state,
                       const std::string &strMessage,
                       const std::string &userMessage = "",
                       unsigned int prefix = 0) {
     AbortNode(strMessage, userMessage, prefix);
     return state.Error(strMessage);
 }
 
 /** 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(BlockValidationState &state, int nFile,
                         FlatFilePos &pos, unsigned int nAddSize);
 
 static bool WriteUndoDataForBlock(const CBlockUndo &blockundo,
                                   BlockValidationState &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_ENFORCE_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, BlockValidationState &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.GetResult() == BlockValidationResult::BLOCK_MUTATED) {
             // 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__,
                      state.ToString());
     }
 
     // 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 =
             m_blockman.m_block_index.find(hashAssumeValid);
         if (it != m_blockman.m_block_index.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.
                 // Script verification is skipped 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.
                 // 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, CVE-2012-1909, 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.
 
     // BIP34 requires that a block at height X (block X) has its coinbase
     // scriptSig start with a CScriptNum of X (indicated height X).  The above
     // logic of no longer requiring BIP30 once BIP34 activates is flawed in the
     // case that there is a block X before the BIP34 height of 227,931 which has
     // an indicated height Y where Y is greater than X.  The coinbase for block
     // X would also be a valid coinbase for block Y, which could be a BIP30
     // violation.  An exhaustive search of all mainnet coinbases before the
     // BIP34 height which have an indicated height greater than the block height
     // reveals many occurrences. The 3 lowest indicated heights found are
     // 209,921, 490,897, and 1,983,702 and thus coinbases for blocks at these 3
     // heights would be the first opportunity for BIP30 to be violated.
 
     // The search reveals a great many blocks which have an indicated height
     // greater than 1,983,702, so we simply remove the optimization to skip
     // BIP30 checking for blocks at height 1,983,702 or higher.  Before we reach
     // that block in another 25 years or so, we should take advantage of a
     // future consensus change to do a new and improved version of BIP34 that
     // will actually prevent ever creating any duplicate coinbases in the
     // future.
     static constexpr int BIP34_IMPLIES_BIP30_LIMIT = 1983702;
 
     // There is no potential to create a duplicate coinbase at block 209,921
     // because this is still before the BIP34 height and so explicit BIP30
     // checking is still active.
 
     // The final case is block 176,684 which has an indicated height of
     // 490,897. Unfortunately, this issue was not discovered until about 2 weeks
     // before block 490,897 so there was not much opportunity to address this
     // case other than to carefully analyze it and determine it would not be a
     // problem. Block 490,897 was, in fact, mined with a different coinbase than
     // block 176,684, but it is important to note that even if it hadn't been or
     // is remined on an alternate fork with a duplicate coinbase, we would still
     // not run into a BIP30 violation.  This is because the coinbase for 176,684
     // is spent in block 185,956 in transaction
     // d4f7fbbf92f4a3014a230b2dc70b8058d02eb36ac06b4a0736d9d60eaa9e8781.  This
     // spending transaction can't be duplicated because it also spends coinbase
     // 0328dd85c331237f18e781d692c92de57649529bd5edf1d01036daea32ffde29.  This
     // coinbase has an indicated height of over 4.2 billion, and wouldn't be
     // duplicatable until that height, and it's currently impossible to create a
     // chain that long. Nevertheless we may wish to consider a future soft fork
     // which retroactively prevents block 490,897 from creating a duplicate
     // coinbase. The two historical BIP30 violations often provide a confusing
     // edge case when manipulating the UTXO and it would be simpler not to have
     // another edge case to deal with.
 
     // testnet3 has no blocks before the BIP34 height with indicated heights
     // post BIP34 before approximately height 486,000,000 and presumably will
     // be reset before it reaches block 1,983,702 and starts doing unnecessary
     // BIP30 checking again.
     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));
 
     // TODO: Remove BIP30 checking from block height 1,983,702 on, once we have
     // a consensus change that ensures coinbases at those heights can not
     // duplicate earlier coinbases.
     if (fEnforceBIP30 || pindex->nHeight >= BIP34_IMPLIES_BIP30_LIMIT) {
         for (const auto &tx : block.vtx) {
             for (size_t o = 0; o < tx->vout.size(); o++) {
                 if (view.HaveCoin(COutPoint(tx->GetId(), o))) {
                     LogPrintf("ERROR: ConnectBlock(): tried to overwrite "
                               "transaction\n");
                     return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
                                          "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.
         LogPrintf("ERROR: ConnectBlock(): tried to overwrite transaction\n");
         return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
                              "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();
             TxValidationState tx_state;
             if (!isCoinBase &&
                 !Consensus::CheckTxInputs(tx, tx_state, view, pindex->nHeight,
                                           txfee)) {
                 // Any transaction validation failure in ConnectBlock is a block
                 // consensus failure.
                 state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
                               tx_state.GetRejectReason(),
                               tx_state.GetDebugMessage());
 
                 return error("%s: Consensus::CheckTxInputs: %s, %s", __func__,
                              tx.GetId().ToString(), state.ToString());
             }
             nFees += txfee;
         }
 
         if (!MoneyRange(nFees)) {
             LogPrintf("ERROR: %s: accumulated fee in the block out of range.\n",
                       __func__);
             return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
                                  "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)) {
             LogPrintf("ERROR: %s: contains a non-BIP68-final transaction\n",
                       __func__);
             return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
                                  "bad-txns-nonfinal");
         }
 
         // Don't cache results if we're actually connecting blocks (still
         // consult the cache, though).
         bool fCacheResults = fJustCheck;
 
         const bool fEnforceSigCheck = flags & SCRIPT_ENFORCE_SIGCHECKS;
         if (!fEnforceSigCheck) {
             // Historically, there has been transactions with a very high
             // sigcheck count, so we need to disable this check for such
             // transactions.
             nSigChecksTxLimiters[txIndex] = TxSigCheckLimiter::getDisabled();
         }
 
         std::vector<CScriptCheck> vChecks;
         // nSigChecksRet may be accurate (found in cache) or 0 (checks were
         // deferred into vChecks).
         int nSigChecksRet;
         TxValidationState tx_state;
         if (fScriptChecks &&
             !CheckInputs(tx, tx_state, view, flags, fCacheResults,
                          fCacheResults, PrecomputedTransactionData(tx),
                          nSigChecksRet, nSigChecksTxLimiters[txIndex],
                          &nSigChecksBlockLimiter, &vChecks)) {
             // Any transaction validation failure in ConnectBlock is a block
             // consensus failure
             state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
                           tx_state.GetRejectReason(),
                           tx_state.GetDebugMessage());
             return error("ConnectBlock(): CheckInputs on %s failed with %s",
                          tx.GetId().ToString(), state.ToString());
         }
 
         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) {
         LogPrintf("ERROR: ConnectBlock(): coinbase pays too much (actual=%d vs "
                   "limit=%d)\n",
                   block.vtx[0]->GetValueOut(), blockReward);
         return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
                              "bad-cb-amount");
     }
 
     const std::vector<CTxDestination> whitelist =
         GetMinerFundWhitelist(consensusParams, pindex->pprev);
     if (!whitelist.empty()) {
         const Amount required = GetMinerFundAmount(blockReward);
 
         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.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
                              "bad-cb-minerfund");
     }
 
 MinerFundSuccess:
 
     if (!control.Wait()) {
         return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
                              "blk-bad-inputs", "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,
                                    BlockValidationState &state,
                                    FlushStateMode mode,
                                    int nManualPruneHeight) {
     int64_t nMempoolUsage = g_mempool.DynamicMemoryUsage();
     LOCK(cs_main);
     assert(this->CanFlushToDisk());
     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 = CoinsTip().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 too low!",
                         _("Error: Disk space is too low!").translated,
                         CClientUIInterface::MSG_NOPREFIX);
                 }
 
                 // 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 && !CoinsTip().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 * CoinsTip().GetCacheSize())) {
                     return AbortNode(
                         state, "Disk space is too low!",
                         _("Error: Disk space is too low!").translated,
                         CClientUIInterface::MSG_NOPREFIX);
                 }
 
                 // Flush the chainstate (which may refer to block index
                 // entries).
                 if (!CoinsTip().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() {
     BlockValidationState state;
     const CChainParams &chainparams = Params();
     if (!this->FlushStateToDisk(chainparams, state, FlushStateMode::ALWAYS)) {
         LogPrintf("%s: failed to flush state (%s)\n", __func__,
                   state.ToString());
     }
 }
 
 void CChainState::PruneAndFlush() {
     BlockValidationState state;
     fCheckForPruning = true;
     const CChainParams &chainparams = Params();
     if (!this->FlushStateToDisk(chainparams, state, FlushStateMode::NONE)) {
         LogPrintf("%s: failed to flush state (%s)\n", __func__,
                   state.ToString());
     }
 }
 
 /** Check warning conditions and do some notifications on new chain tip set. */
 static void UpdateTip(const CChainParams &params, CBlockIndex *pindexNew)
     EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
     // 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=%ld "
               "date='%s' progress=%f cache=%.1fMiB(%utxo)\n",
               __func__, pindexNew->GetBlockHash().ToString(),
               pindexNew->nHeight, pindexNew->nVersion,
               log(pindexNew->nChainWork.getdouble()) / log(2.0),
               pindexNew->GetChainTxCount(),
               FormatISO8601DateTime(pindexNew->GetBlockTime()),
               GuessVerificationProgress(params.TxData(), pindexNew),
               ::ChainstateActive().CoinsTip().DynamicMemoryUsage() *
                   (1.0 / (1 << 20)),
               ::ChainstateActive().CoinsTip().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,
                                 BlockValidationState &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 error("DisconnectTip(): Failed to read block");
     }
 
     // Apply the block atomically to the chain state.
     int64_t nStart = GetTimeMicros();
     {
         CCoinsViewCache view(&CoinsTip());
         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, g_mempool);
     }
 
     // If the tip is finalized, then undo it.
     if (m_finalizedBlockIndex == pindexDelete) {
         m_finalizedBlockIndex = 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, pindexDelete);
     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));
         }
     }
 };
 
 bool CChainState::MarkBlockAsFinal(const Config &config,
                                    BlockValidationState &state,
                                    const CBlockIndex *pindex) {
     AssertLockHeld(cs_main);
     if (pindex->nStatus.isInvalid()) {
         // We try to finalize an invalid block.
         LogPrintf("ERROR: %s: Trying to finalize invalid block %s\n", __func__,
                   pindex->GetBlockHash().ToString());
         return state.Invalid(BlockValidationResult::BLOCK_CACHED_INVALID,
                              "finalize-invalid-block");
     }
 
     // Check that the request is consistent with current finalization.
     if (m_finalizedBlockIndex &&
         !AreOnTheSameFork(pindex, m_finalizedBlockIndex)) {
         LogPrintf("ERROR: %s: Trying to finalize block %s which conflicts with "
                   "already finalized block\n",
                   __func__, pindex->GetBlockHash().ToString());
         return state.Invalid(BlockValidationResult::BLOCK_FINALIZATION,
                              "bad-fork-prior-finalized");
     }
 
     if (IsBlockFinalized(pindex)) {
         // The block is already finalized.
         return true;
     }
 
     // We have a new block to finalize.
     m_finalizedBlockIndex = 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 != ::ChainstateActive().GetFinalizedBlock())) {
         // 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, BlockValidationState &state,
                              CBlockIndex *pindexNew,
                              const std::shared_ptr<const CBlock> &pblock,
                              ConnectTrace &connectTrace,
                              DisconnectedBlockTransactions &disconnectpool) {
     AssertLockHeld(cs_main);
     AssertLockHeld(g_mempool.cs);
 
     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(&CoinsTip());
         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(),
                          state.ToString());
         }
 
         // Update the finalized block.
         const CBlockIndex *pindexToFinalize =
             FindBlockToFinalize(config, pindexNew);
         if (pindexToFinalize &&
             !MarkBlockAsFinal(config, state, pindexToFinalize)) {
             return error("ConnectTip(): MarkBlockAsFinal %s failed (%s)",
                          pindexNew->GetBlockHash().ToString(),
                          state.ToString());
         }
 
         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 (m_finalizedBlockIndex &&
             !AreOnTheSameFork(pindexNew, m_finalizedBlockIndex)) {
             LogPrintf("Mark block %s invalid because it forks prior to the "
                       "finalization point %d.\n",
                       pindexNew->GetBlockHash().ToString(),
                       m_finalizedBlockIndex->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
                     // m_blocks_unlinked, so that if the block arrives in the
                     // future we can try adding to setBlockIndexCandidates
                     // again.
                     m_blockman.m_blocks_unlinked.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 &&
             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.
  *
  * @returns true unless a system error occurred
  */
 bool CChainState::ActivateBestChainStep(
     const Config &config, BlockValidationState &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, g_mempool);
 
             // If we're unable to disconnect a block during normal operation,
             // then that is a failure of our local system -- we should abort
             // rather than stay on a less work chain.
             AbortNode(state,
                       "Failed to disconnect block; see debug.log for details");
             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.GetResult() !=
                         BlockValidationResult::BLOCK_MUTATED) {
                         InvalidChainFound(vpindexToConnect.back());
                     }
                     state = BlockValidationState();
                     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, g_mempool);
                 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);
     }
 
     g_mempool.check(&CoinsTip());
 
     // Callbacks/notifications for a new best chain.
     if (fInvalidFound) {
         CheckForkWarningConditionsOnNewFork(pindexMostWork);
     } else {
         CheckForkWarningConditions();
     }
 
     return true;
 }
 
 static SynchronizationState GetSynchronizationState(bool init) {
     if (!init) {
         return SynchronizationState::POST_INIT;
     }
     if (::fReindex) {
         return SynchronizationState::INIT_REINDEX;
     }
     return SynchronizationState::INIT_DOWNLOAD;
 }
 
 static bool 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(
             GetSynchronizationState(fInitialBlockDownload), pindexHeader);
     }
     return fNotify;
 }
 
 static void LimitValidationInterfaceQueue() LOCKS_EXCLUDED(cs_main) {
     AssertLockNotHeld(cs_main);
 
     if (GetMainSignals().CallbacksPending() > 10) {
         SyncWithValidationInterfaceQueue();
     }
 }
 
 bool CChainState::ActivateBestChain(const Config &config,
                                     BlockValidationState &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();
 
         // 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.
         LimitValidationInterfaceQueue();
 
         {
             // Lock transaction pool for at least as long as it takes for
             // connectTrace to be consumed
             LOCK2(cs_main, ::g_mempool.cs);
             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)) {
                     // A system error occurred
                     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(
                     GetSynchronizationState(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, BlockValidationState &state,
                        std::shared_ptr<const CBlock> pblock) {
     return ::ChainstateActive().ActivateBestChain(config, state,
                                                   std::move(pblock));
 }
 
 bool CChainState::PreciousBlock(const Config &config,
                                 BlockValidationState &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, BlockValidationState &state,
                    CBlockIndex *pindex) {
     return ::ChainstateActive().PreciousBlock(config, state, pindex);
 }
 
 bool CChainState::UnwindBlock(const Config &config, BlockValidationState &state,
                               CBlockIndex *pindex, bool invalidate) {
     CBlockIndex *to_mark_failed_or_parked = pindex;
     bool pindex_was_in_chain = false;
     int disconnected = 0;
     const CChainParams &chainparams = config.GetChainParams();
 
     // We do not allow ActivateBestChain() to run while UnwindBlock() is
     // running, as that could cause the tip to change while we disconnect
     // blocks. (Note for backport of Core PR16849: we acquire
     // LOCK(m_cs_chainstate) in the Park, Invalidate and FinalizeBlock functions
     // due to differences in our code)
     AssertLockHeld(m_cs_chainstate);
 
     // We'll be acquiring and releasing cs_main below, to allow the validation
     // callbacks to run. However, we should keep the block index in a
     // consistent state as we disconnect blocks -- in particular we need to
     // add equal-work blocks to setBlockIndexCandidates as we disconnect.
     // To avoid walking the block index repeatedly in search of candidates,
     // build a map once so that we can look up candidate blocks by chain
     // work as we go.
     std::multimap<const arith_uint256, CBlockIndex *> candidate_blocks_by_work;
 
     {
         LOCK(cs_main);
         for (const auto &entry : m_blockman.m_block_index) {
             CBlockIndex *candidate = entry.second;
             // We don't need to put anything in our active chain into the
             // multimap, because those candidates will be found and considered
             // as we disconnect.
             // Instead, consider only non-active-chain blocks that have at
             // least as much work as where we expect the new tip to end up.
             if (!m_chain.Contains(candidate) &&
                 !CBlockIndexWorkComparator()(candidate, pindex->pprev) &&
                 candidate->IsValid(BlockValidity::TRANSACTIONS) &&
                 candidate->HaveTxsDownloaded()) {
                 candidate_blocks_by_work.insert(
                     std::make_pair(candidate->nChainWork, candidate));
             }
         }
     }
 
     // Disconnect (descendants of) pindex, and mark them invalid.
     while (true) {
         if (ShutdownRequested()) {
             break;
         }
 
         // Make sure the queue of validation callbacks doesn't grow unboundedly.
         LimitValidationInterfaceQueue();
 
         LOCK(cs_main);
         // Lock for as long as disconnectpool is in scope to make sure
         // UpdateMempoolForReorg is called after DisconnectTip without unlocking
         // in between
         LOCK(::g_mempool.cs);
 
         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(chainparams, 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,
             ::g_mempool);
 
         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);
         }
 
         // Add any equal or more work headers to setBlockIndexCandidates
         auto candidate_it = candidate_blocks_by_work.lower_bound(
             invalid_walk_tip->pprev->nChainWork);
         while (candidate_it != candidate_blocks_by_work.end()) {
             if (!CBlockIndexWorkComparator()(candidate_it->second,
                                              invalid_walk_tip->pprev)) {
                 setBlockIndexCandidates.insert(candidate_it->second);
                 candidate_it = candidate_blocks_by_work.erase(candidate_it);
             } else {
                 ++candidate_it;
             }
         }
 
         // 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;
     }
 
     CheckBlockIndex(chainparams.GetConsensus());
 
     {
         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_blockman.m_failed_blocks.insert(to_mark_failed_or_parked);
         }
 
         // If any new blocks somehow arrived while we were disconnecting
         // (above), then the pre-calculation of what should go into
         // setBlockIndexCandidates may have missed entries. This would
         // technically be an inconsistency in the block index, but if we clean
         // it up here, this should be an essentially unobservable error.
         // Loop back over all block index entries and add any missing entries
         // to setBlockIndexCandidates.
         for (const std::pair<const BlockHash, CBlockIndex *> &it :
              m_blockman.m_block_index) {
             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(
             GetSynchronizationState(IsInitialBlockDownload()),
             to_mark_failed_or_parked->pprev);
     }
     return true;
 }
 
 bool CChainState::InvalidateBlock(const Config &config,
                                   BlockValidationState &state,
                                   CBlockIndex *pindex) {
     AssertLockNotHeld(m_cs_chainstate);
     // See 'Note for backport of Core PR16849' in CChainState::UnwindBlock
     LOCK(m_cs_chainstate);
 
     return UnwindBlock(config, state, pindex, true);
 }
 
 bool CChainState::ParkBlock(const Config &config, BlockValidationState &state,
                             CBlockIndex *pindex) {
     AssertLockNotHeld(m_cs_chainstate);
     // See 'Note for backport of Core PR16849' in CChainState::UnwindBlock
     LOCK(m_cs_chainstate);
 
     return UnwindBlock(config, state, pindex, false);
 }
 
 bool CChainState::FinalizeBlock(const Config &config,
                                 BlockValidationState &state,
                                 CBlockIndex *pindex) {
     AssertLockNotHeld(m_cs_chainstate);
     // See 'Note for backport of Core PR16849' in CChainState::UnwindBlock
     LOCK(m_cs_chainstate);
 
     AssertLockNotHeld(cs_main);
     CBlockIndex *pindexToInvalidate = nullptr;
     {
         LOCK(cs_main);
         if (!MarkBlockAsFinal(config, state, pindex)) {
             // state is set by MarkBlockAsFinal.
             return false;
         }
 
         // We have a valid candidate, make sure it is not parked.
         if (pindex->nStatus.isOnParkedChain()) {
             UnparkBlock(pindex);
         }
 
         // If the finalized block is on the active chain, there is no need to
         // rewind.
         if (::ChainActive().Contains(pindex)) {
             return true;
         }
 
         // If the finalized block is not on the active chain, that chain is
         // invalid
         // ...
         const CBlockIndex *pindexFork = ::ChainActive().FindFork(pindex);
         pindexToInvalidate = ::ChainActive().Next(pindexFork);
         if (!pindexToInvalidate) {
             return false;
         }
     } // end of locked cs_main scope
 
     // ... therefore, we invalidate the block on the active chain that comes
     // immediately after it
     return UnwindBlock(config, state, pindexToInvalidate,
                        true /* invalidating */);
 }
 
 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_blockman.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 = m_blockman.m_block_index.begin();
     while (it != m_blockman.m_block_index.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 (m_finalizedBlockIndex) {
         m_finalizedBlockIndex =
             LastCommonAncestor(pindex, m_finalizedBlockIndex);
     }
 
     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);
 }
 
 bool CChainState::IsBlockFinalized(const CBlockIndex *pindex) const {
     AssertLockHeld(cs_main);
     return m_finalizedBlockIndex &&
            m_finalizedBlockIndex->GetAncestor(pindex->nHeight) == pindex;
 }
 
 /** Return the currently finalized block index. */
 const CBlockIndex *CChainState::GetFinalizedBlock() const {
     AssertLockHeld(cs_main);
     return m_finalizedBlockIndex;
 }
 
 CBlockIndex *BlockManager::AddToBlockIndex(const CBlockHeader &block) {
     AssertLockHeld(cs_main);
 
     // Check for duplicate
     BlockHash hash = block.GetHash();
     BlockMap::iterator it = m_block_index.find(hash);
     if (it != m_block_index.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 =
         m_block_index.insert(std::make_pair(hash, pindexNew)).first;
     pindexNew->phashBlock = &((*mi).first);
     BlockMap::iterator miPrev = m_block_index.find(block.hashPrevBlock);
     if (miPrev != m_block_index.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->nSize = ::GetSerializeSize(block, PROTOCOL_VERSION);
     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->UpdateChainStats()) {
         // 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->UpdateChainStats();
             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 = m_blockman.m_blocks_unlinked.equal_range(pindex);
             while (range.first != range.second) {
                 std::multimap<CBlockIndex *, CBlockIndex *>::iterator it =
                     range.first;
                 queue.push_back(it->second);
                 range.first++;
                 m_blockman.m_blocks_unlinked.erase(it);
             }
         }
     } else if (pindexNew->pprev &&
                pindexNew->pprev->IsValid(BlockValidity::TREE)) {
         m_blockman.m_blocks_unlinked.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 too low!",
                              _("Error: Disk space is too low!").translated,
                              CClientUIInterface::MSG_NOPREFIX);
         }
         if (bytes_allocated != 0 && fPruneMode) {
             fCheckForPruning = true;
         }
     }
 
     setDirtyFileInfo.insert(nFile);
     return true;
 }
 
 static bool FindUndoPos(BlockValidationState &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 too low!",
                          _("Error: Disk space is too low!").translated,
                          CClientUIInterface::MSG_NOPREFIX);
     }
     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,
                              BlockValidationState &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.Invalid(BlockValidationResult::BLOCK_INVALID_HEADER,
                              "high-hash", "proof of work failed");
     }
 
     return true;
 }
 
 bool CheckBlock(const CBlock &block, BlockValidationState &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.Invalid(BlockValidationResult::BLOCK_MUTATED,
                                  "bad-txnmrklroot", "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.Invalid(BlockValidationResult::BLOCK_MUTATED,
                                  "bad-txns-duplicate", "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.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
                              "bad-cb-missing", "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.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
                              "bad-blk-length", "size limits failed");
     }
 
     auto currentBlockSize = ::GetSerializeSize(block, PROTOCOL_VERSION);
     if (currentBlockSize > nMaxBlockSize) {
         return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
                              "bad-blk-length", "size limits failed");
     }
 
     // And a valid coinbase.
     TxValidationState tx_state;
     if (!CheckCoinbase(*block.vtx[0], tx_state)) {
         return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
                              tx_state.GetRejectReason(),
                              strprintf("Coinbase check failed (txid %s) %s",
                                        block.vtx[0]->GetId().ToString(),
                                        tx_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, tx_state)) {
             return state.Invalid(
                 BlockValidationResult::BLOCK_CONSENSUS,
                 tx_state.GetRejectReason(),
                 strprintf("Transaction check failed (txid %s) %s",
                           tx->GetId().ToString(), tx_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,
                                        BlockValidationState &state,
                                        const CBlockIndex *pindexPrev,
                                        int64_t nAdjustedTime)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
     assert(pindexPrev != nullptr);
     const int nHeight = pindexPrev->nHeight + 1;
 
     // Check proof of work
     if (block.nBits != GetNextWorkRequired(pindexPrev, &block, params)) {
         LogPrintf("bad bits after height: %d\n", pindexPrev->nHeight);
         return state.Invalid(BlockValidationResult::BLOCK_INVALID_HEADER,
                              "bad-diffbits", "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())) {
             LogPrintf("ERROR: %s: rejected by checkpoint lock-in at %d\n",
                       __func__, nHeight);
             return state.Invalid(BlockValidationResult::BLOCK_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 g_blockman.m_block_index.
         CBlockIndex *pcheckpoint = Checkpoints::GetLastCheckpoint(checkpoints);
         if (pcheckpoint && nHeight < pcheckpoint->nHeight) {
             LogPrintf("ERROR: %s: forked chain older than last checkpoint "
                       "(height %d)\n",
                       __func__, nHeight);
             return state.Invalid(BlockValidationResult::BLOCK_CHECKPOINT,
                                  "bad-fork-prior-to-checkpoint");
         }
     }
 
     // Check timestamp against prev
     if (block.GetBlockTime() <= pindexPrev->GetMedianTimePast()) {
         return state.Invalid(BlockValidationResult::BLOCK_INVALID_HEADER,
                              "time-too-old", "block's timestamp is too early");
     }
 
     // Check timestamp
     if (block.GetBlockTime() > nAdjustedTime + MAX_FUTURE_BLOCK_TIME) {
         return state.Invalid(BlockValidationResult::BLOCK_TIME_FUTURE,
                              "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
     const Consensus::Params &consensusParams = params.GetConsensus();
     if ((block.nVersion < 2 && nHeight >= consensusParams.BIP34Height) ||
         (block.nVersion < 3 && nHeight >= consensusParams.BIP66Height) ||
         (block.nVersion < 4 && nHeight >= consensusParams.BIP65Height)) {
         return state.Invalid(
             BlockValidationResult::BLOCK_INVALID_HEADER,
             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,
                                                TxValidationState &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,
                                  BlockValidationState &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.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
                                          "tx-duplicate",
                                          strprintf("Duplicated transaction %s",
                                                    tx.GetId().ToString()));
                 }
 
                 return state.Invalid(
                     BlockValidationResult::BLOCK_CONSENSUS, "tx-ordering",
                     strprintf("Transaction order is invalid (%s < %s)",
                               tx.GetId().ToString(),
                               prevTx->GetId().ToString()));
             }
 
             if (prevTx || !tx.IsCoinBase()) {
                 prevTx = &tx;
             }
         }
 
         TxValidationState tx_state;
         if (!ContextualCheckTransaction(params, tx, tx_state, nHeight,
                                         nLockTimeCutoff, nMedianTimePast)) {
             return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
                                  tx_state.GetRejectReason(),
                                  tx_state.GetDebugMessage());
         }
     }
 
     // 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.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
                                  "bad-cb-height",
                                  "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 BlockManager::AcceptBlockHeader(const Config &config,
                                      const CBlockHeader &block,
                                      BlockValidationState &state,
                                      CBlockIndex **ppindex) {
     AssertLockHeld(cs_main);
     const CChainParams &chainparams = config.GetChainParams();
 
     // Check for duplicate
     BlockHash hash = block.GetHash();
     BlockMap::iterator miSelf = m_block_index.find(hash);
     CBlockIndex *pindex = nullptr;
     if (hash != chainparams.GetConsensus().hashGenesisBlock) {
         if (miSelf != m_block_index.end()) {
             // Block header is already known.
             pindex = miSelf->second;
             if (ppindex) {
                 *ppindex = pindex;
             }
 
             if (pindex->nStatus.isInvalid()) {
                 LogPrintf("ERROR: %s: block %s is marked invalid\n", __func__,
                           hash.ToString());
                 return state.Invalid(
                     BlockValidationResult::BLOCK_CACHED_INVALID, "duplicate");
             }
 
             return true;
         }
 
         if (!CheckBlockHeader(block, state, chainparams.GetConsensus(),
                               BlockValidationOptions(config))) {
             return error("%s: Consensus::CheckBlockHeader: %s, %s", __func__,
                          hash.ToString(), state.ToString());
         }
 
         // Get prev block index
         BlockMap::iterator mi = m_block_index.find(block.hashPrevBlock);
         if (mi == m_block_index.end()) {
             LogPrintf("ERROR: %s: prev block not found\n", __func__);
             return state.Invalid(BlockValidationResult::BLOCK_MISSING_PREV,
                                  "prev-blk-not-found");
         }
 
         CBlockIndex *pindexPrev = (*mi).second;
         assert(pindexPrev);
         if (pindexPrev->nStatus.isInvalid()) {
             LogPrintf("ERROR: %s: prev block invalid\n", __func__);
             return state.Invalid(BlockValidationResult::BLOCK_INVALID_PREV,
                                  "bad-prevblk");
         }
 
         if (!ContextualCheckBlockHeader(chainparams, block, state, pindexPrev,
                                         GetAdjustedTime())) {
             return error("%s: Consensus::ContextualCheckBlockHeader: %s, %s",
                          __func__, hash.ToString(), state.ToString());
         }
 
         /* 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 BlockValidity::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;
                     }
                     LogPrintf("ERROR: %s: prev block invalid\n", __func__);
                     return state.Invalid(
                         BlockValidationResult::BLOCK_INVALID_PREV,
                         "bad-prevblk");
                 }
             }
         }
     }
 
     if (pindex == nullptr) {
         pindex = AddToBlockIndex(block);
     }
 
     if (ppindex) {
         *ppindex = pindex;
     }
 
     return true;
 }
 
 // Exposed wrapper for AcceptBlockHeader
 bool ProcessNewBlockHeaders(const Config &config,
                             const std::vector<CBlockHeader> &headers,
                             BlockValidationState &state,
                             const CBlockIndex **ppindex) {
     {
         LOCK(cs_main);
         for (const CBlockHeader &header : headers) {
             // Use a temp pindex instead of ppindex to avoid a const_cast
             CBlockIndex *pindex = nullptr;
             bool accepted =
                 g_blockman.AcceptBlockHeader(config, header, state, &pindex);
             ::ChainstateActive().CheckBlockIndex(
                 config.GetChainParams().GetConsensus());
 
             if (!accepted) {
                 return false;
             }
 
             if (ppindex) {
                 *ppindex = pindex;
             }
         }
     }
 
     if (NotifyHeaderTip()) {
         if (::ChainstateActive().IsInitialBlockDownload() && ppindex &&
             *ppindex) {
             LogPrintf("Synchronizing blockheaders, height: %d (~%.2f%%)\n",
                       (*ppindex)->nHeight,
                       100.0 /
                           ((*ppindex)->nHeight +
                            (GetAdjustedTime() - (*ppindex)->GetBlockTime()) /
                                Params().GetConsensus().nPowTargetSpacing) *
                           (*ppindex)->nHeight);
         }
     }
     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,
                               BlockValidationState &state, bool fRequested,
                               const FlatFilePos *dbp, bool *fNewBlock) {
     AssertLockHeld(cs_main);
 
     const CBlock &block = *pblock;
     if (fNewBlock) {
         *fNewBlock = false;
     }
 
     CBlockIndex *pindex = nullptr;
 
     bool accepted_header =
         m_blockman.AcceptBlockHeader(config, block, state, &pindex);
     CheckBlockIndex(config.GetChainParams().GetConsensus());
 
     if (!accepted_header) {
         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.GetResult() != BlockValidationResult::BLOCK_MUTATED) {
             pindex->nStatus = pindex->nStatus.withFailed();
             setDirtyBlockIndex.insert(pindex);
         }
 
         return error("%s: %s (block %s)", __func__, state.ToString(),
                      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;
         }
 
         BlockValidationState 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__,
                          state.ToString());
         }
     }
 
     NotifyHeaderTip();
 
     // Only used to report errors, not invalidity - ignore it
     BlockValidationState state;
     if (!::ChainstateActive().ActivateBestChain(config, state, pblock)) {
         return error("%s: ActivateBestChain failed (%s)", __func__,
                      state.ToString());
     }
 
     return true;
 }
 
 bool TestBlockValidity(BlockValidationState &state, const CChainParams &params,
                        const CBlock &block, CBlockIndex *pindexPrev,
                        BlockValidationOptions validationOptions) {
     AssertLockHeld(cs_main);
     assert(pindexPrev && pindexPrev == ::ChainActive().Tip());
     CCoinsViewCache viewNew(&::ChainstateActive().CoinsTip());
     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__,
                      state.ToString());
     }
 
     if (!CheckBlock(block, state, params.GetConsensus(), validationOptions)) {
         return error("%s: Consensus::CheckBlock: %s", __func__,
                      state.ToString());
     }
 
     if (!ContextualCheckBlock(block, state, params.GetConsensus(),
                               pindexPrev)) {
         return error("%s: Consensus::ContextualCheckBlock: %s", __func__,
                      state.ToString());
     }
 
     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 : g_blockman.m_block_index) {
         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 m_blocks_unlinked -- 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
             // m_blocks_unlinked or setBlockIndexCandidates.
             auto range =
                 g_blockman.m_blocks_unlinked.equal_range(pindex->pprev);
             while (range.first != range.second) {
                 std::multimap<CBlockIndex *, CBlockIndex *>::iterator _it =
                     range.first;
                 range.first++;
                 if (_it->second == pindex) {
                     g_blockman.m_blocks_unlinked.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) {
     BlockValidationState state;
     const CChainParams &chainparams = Params();
     if (!::ChainstateActive().FlushStateToDisk(
             chainparams, state, FlushStateMode::NONE, nManualPruneHeight)) {
         LogPrintf("%s: failed to flush state (%s)\n", __func__,
                   state.ToString());
     }
 }
 
 /**
  * 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);
 }
 
 CBlockIndex *BlockManager::InsertBlockIndex(const BlockHash &hash) {
     AssertLockHeld(cs_main);
 
     if (hash.IsNull()) {
         return nullptr;
     }
 
     // Return existing
     BlockMap::iterator mi = m_block_index.find(hash);
     if (mi != m_block_index.end()) {
         return (*mi).second;
     }
 
     // Create new
     CBlockIndex *pindexNew = new CBlockIndex();
     mi = m_block_index.insert(std::make_pair(hash, pindexNew)).first;
     pindexNew->phashBlock = &((*mi).first);
 
     return pindexNew;
 }
 
 bool BlockManager::LoadBlockIndex(
     const Consensus::Params &params, CBlockTreeDB &blocktree,
     std::set<CBlockIndex *, CBlockIndexWorkComparator>
         &block_index_candidates) {
     AssertLockHeld(cs_main);
     if (!blocktree.LoadBlockIndexGuts(
             params, [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(m_block_index.size());
     for (const std::pair<const BlockHash, CBlockIndex *> &item :
          m_block_index) {
         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) {
         if (ShutdownRequested()) {
             return false;
         }
         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->UpdateChainStats() && pindex->pprev) {
                 m_blocks_unlinked.insert(std::make_pair(pindex->pprev, pindex));
             }
         }
 
         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)) {
             block_index_candidates.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;
 }
 
 void BlockManager::Unload() {
     m_failed_blocks.clear();
     m_blocks_unlinked.clear();
 
     for (const BlockMap::value_type &entry : m_block_index) {
         delete entry.second;
     }
 
     m_block_index.clear();
 }
 
 static bool LoadBlockIndexDB(const Consensus::Params &params)
     EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
     if (!g_blockman.LoadBlockIndex(
             params, *pblocktree,
             ::ChainstateActive().setBlockIndexCandidates)) {
         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 :
          g_blockman.m_block_index) {
         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
     if (pblocktree->IsReindexing()) {
         fReindex = true;
     }
 
     return true;
 }
 
 bool CChainState::LoadChainTip(const CChainParams &chainparams) {
     AssertLockHeld(cs_main);
     const CCoinsViewCache &coins_cache = CoinsTip();
     // Never called when the coins view is empty
     assert(!coins_cache.GetBestBlock().IsNull());
     const CBlockIndex *tip = m_chain.Tip();
 
     if (tip && tip->GetBlockHash() == coins_cache.GetBestBlock()) {
         return true;
     }
 
     // Load pointer to end of best chain
     CBlockIndex *pindex = LookupBlockIndex(coins_cache.GetBestBlock());
     if (!pindex) {
         return false;
     }
     m_chain.SetTip(pindex);
     PruneBlockIndexCandidates();
 
     tip = m_chain.Tip();
     LogPrintf(
         "Loaded best chain: hashBestChain=%s height=%d date=%s progress=%f\n",
         tip->GetBlockHash().ToString(), m_chain.Height(),
         FormatISO8601DateTime(tip->GetBlockTime()),
         GuessVerificationProgress(chainparams.TxData(), 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;
     BlockValidationState state;
     int reportDone = 0;
     LogPrintfToBeContinued("[0%%]...");
     for (pindex = ::ChainActive().Tip(); pindex && pindex->pprev;
          pindex = pindex->pprev) {
         boost::this_thread::interruption_point();
         const 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(), state.ToString());
         }
 
         // 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() +
              ::ChainstateActive().CoinsTip().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();
             const int percentageDone = std::max(
                 1, std::min(99, 100 - int(double(::ChainActive().Height() -
                                                  pindex->nHeight) /
                                           double(nCheckDepth) * 50)));
             if (reportDone < percentageDone / 10) {
                 // report every 10% step
                 LogPrintfToBeContinued("[%d%%]...", percentageDone);
                 reportDone = percentageDone / 10;
             }
             uiInterface.ShowProgress(_("Verifying blocks...").translated,
                                      percentageDone, 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(),
                              state.ToString());
             }
         }
     }
 
     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) {
     LOCK(cs_main);
 
     CCoinsView &db = this->CoinsDB();
     CCoinsViewCache cache(&db);
 
     std::vector<BlockHash> hashHeads = db.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 (m_blockman.m_block_index.count(hashHeads[0]) == 0) {
         return error(
             "ReplayBlocks(): reorganization to unknown block requested");
     }
 
     pindexNew = m_blockman.m_block_index[hashHeads[0]];
 
     if (!hashHeads[1].IsNull()) {
         // The old tip is allowed to be 0, indicating it's the first flush.
         if (m_blockman.m_block_index.count(hashHeads[1]) == 0) {
             return error(
                 "ReplayBlocks(): reorganization from unknown block requested");
         }
 
         pindexOld = m_blockman.m_block_index[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);
         uiInterface.ShowProgress(_("Replaying blocks...").translated,
                                  (int)((nHeight - nForkHeight) * 100.0 /
                                        (pindexNew->nHeight - nForkHeight)),
                                  false);
         if (!RollforwardBlock(pindex, cache, params)) {
             return false;
         }
     }
 
     cache.SetBestBlock(pindexNew->GetBlockHash());
     cache.Flush();
     uiInterface.ShowProgress("", 100, false);
     return true;
 }
 
 // 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;
     setBlockIndexCandidates.clear();
 
     // Do not point to CBlockIndex that will be free'd
     m_finalizedBlockIndex = nullptr;
 }
 
 // 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);
     g_blockman.Unload();
     pindexBestInvalid = nullptr;
     pindexBestParked = nullptr;
     pindexBestHeader = nullptr;
     pindexBestForkTip = nullptr;
     pindexBestForkBase = nullptr;
     ResetASERTAnchorBlockCache();
     g_mempool.clear();
     vinfoBlockFile.clear();
     nLastBlockFile = 0;
     setDirtyBlockIndex.clear();
     setDirtyFileInfo.clear();
     fHavePruned = false;
 
     ::ChainstateActive().UnloadBlockIndex();
 }
 
 bool LoadBlockIndex(const Consensus::Params &params) {
     // Load block index from databases
     bool needs_init = fReindex;
     if (!fReindex) {
         bool ret = LoadBlockIndexDB(params);
         if (!ret) {
             return false;
         }
 
         needs_init = g_blockman.m_block_index.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
     // m_blockman.m_block_index. 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 (m_blockman.m_block_index.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 = m_blockman.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()) {
                         BlockValidationState 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) {
                     BlockValidationState 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);
                             BlockValidationState 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
     // m_blockman.m_block_index 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(m_blockman.m_block_index.size() <= 1);
         return;
     }
 
     // Build forward-pointing map of the entire block tree.
     std::multimap<CBlockIndex *, CBlockIndex *> forward;
     for (const auto &entry : m_blockman.m_block_index) {
         forward.emplace(entry.second->pprev, entry.second);
     }
 
     assert(forward.size() == m_blockman.m_block_index.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 m_blockman.m_block_index 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
                 // m_blocks_unlinked -- 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 m_blocks_unlinked.
         std::pair<std::multimap<CBlockIndex *, CBlockIndex *>::iterator,
                   std::multimap<CBlockIndex *, CBlockIndex *>::iterator>
             rangeUnlinked =
                 m_blockman.m_blocks_unlinked.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
             // m_blocks_unlinked.
             assert(foundInUnlinked);
         }
         if (!pindex->nStatus.hasData()) {
             // Can't be in m_blocks_unlinked if we don't HAVE_DATA
             assert(!foundInUnlinked);
         }
         if (pindexFirstMissing == nullptr) {
             // We aren't missing data for any parent -- cannot be in
             // m_blocks_unlinked.
             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 m_blocks_unlinked 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 m_blocks_unlinked.
             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);
             }
             TxValidationState state;
             if (nTime + nExpiryTimeout > nNow) {
                 LOCK(cs_main);
                 AcceptToMemoryPoolWithTime(
                     config, pool, state, tx, 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(count_seconds(i.m_time));
             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 the chain's
 //! transaction count 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->GetChainTxCount() <= data.nTxCount) {
         fTxTotal = data.nTxCount + (nNow - data.nTime) * data.dTxRate;
     } else {
         fTxTotal = pindex->GetChainTxCount() +
                    (nNow - pindex->GetBlockTime()) * data.dTxRate;
     }
 
     return pindex->GetChainTxCount() / fTxTotal;
 }
 
 class CMainCleanup {
 public:
     CMainCleanup() {}
     ~CMainCleanup() {
         // block headers
         for (const std::pair<const BlockHash, CBlockIndex *> &it :
              g_blockman.m_block_index) {
             delete it.second;
         }
         g_blockman.m_block_index.clear();
     }
 };
 static CMainCleanup instance_of_cmaincleanup;