diff --git a/doc/files.md b/doc/files.md
index a74cbd28e3..8e15fccec9 100644
--- a/doc/files.md
+++ b/doc/files.md
@@ -1,33 +1,34 @@
 
 * banlist.dat: stores the IPs/Subnets of banned nodes
 * bitcoin.conf: contains configuration settings for bitcoind or bitcoin-qt
 * bitcoind.pid: stores the process id of bitcoind while running
 * blocks/blk000??.dat: block data (custom, 128 MiB per file); since 0.8.0
 * blocks/rev000??.dat; block undo data (custom); since 0.8.0 (format changed since pre-0.8)
 * blocks/index/*; block index (LevelDB); since 0.8.0
 * chainstate/*; block chain state database (LevelDB); since 0.8.0
 * database/*: BDB database environment; only used for wallet since 0.8.0; moved to wallets/ directory on new installs since 0.18.7
 * db.log: wallet database log file; moved to wallets/ directory on new installs since 0.18.7
 * debug.log: contains debug information and general logging generated by bitcoind or bitcoin-qt
+* indexes/txindex/*: optional transaction index database (LevelDB); since 0.19.7
 * mempool.dat: dump of the mempool's transactions; since 0.14.0.
 * peers.dat: peer IP address database (custom format); since 0.7.0
 * wallet.dat: personal wallet (BDB) with keys and transactions; moved to wallets/ directory on new installs since 0.18.7
 * wallets/database/*: BDB database environment; used for wallets since 0.18.7
 * wallets/db.log: wallet database log file; since 0.18.7
 * wallets/wallet.dat: personal wallet (BDB) with keys and transactions; since 0.18.7
 * .cookie: session RPC authentication cookie (written at start when cookie authentication is used, deleted on shutdown): since 0.12.0
 * onion_private_key: cached Tor hidden service private key for `-listenonion`: since 0.12.0
 
 Only used in pre-0.8.0
 ---------------------
 * blktree/*; block chain index (LevelDB); since pre-0.8, replaced by blocks/index/* in 0.8.0
 * coins/*; unspent transaction output database (LevelDB); since pre-0.8, replaced by chainstate/* in 0.8.0
 
 Only used before 0.8.0
 ---------------------
 * blkindex.dat: block chain index database (BDB); replaced by {chainstate/*,blocks/index/*,blocks/rev000??.dat} in 0.8.0
 * blk000?.dat: block data (custom, 2 GiB per file); replaced by blocks/blk000??.dat in 0.8.0
 
 Only used before 0.7.0
 ---------------------
 * addr.dat: peer IP address database (BDB); replaced by peers.dat in 0.7.0
diff --git a/doc/release-notes.md b/doc/release-notes.md
index 8e8ff46bab..b3de6650b4 100644
--- a/doc/release-notes.md
+++ b/doc/release-notes.md
@@ -1,16 +1,28 @@
 Bitcoin ABC version 0.19.7 is now available from:
 
   <https://download.bitcoinabc.org/0.19.7/>
 
 This release includes the following features and fixes:
  - `-includeconf=<file>` can be used to include additional configuration files.
   Only works inside the `bitcoin.conf` file, not inside included files or from
   command-line. Multiple files may be included. Can be disabled from command-
   line via `-noincludeconf`. Note that multi-argument commands like
   `-includeconf` will override preceding `-noincludeconf`, i.e.
     noincludeconf=1
     includeconf=relative.conf
   as bitcoin.conf will still include `relative.conf`.
  - The `createrawtransaction` RPC will now accept an array or dictionary (kept for compatibility) for the `outputs` parameter. This means the order of transaction outputs can be specified by the client.
  - The new RPC `testmempoolaccept` can be used to test acceptance of a transaction to the mempool without adding it.
  - An `initialblockdownload` boolean has been added to the `getblockchaininfo` RPC to indicate whether the node is currently in IBD or not.
+
+Transaction index changes
+-------------------------
+
+The transaction index is now built separately from the main node procedure,
+meaning the `-txindex` flag can be toggled without a full reindex. If bitcoind
+is run with `-txindex` on a node that is already partially or fully synced
+without one, the transaction index will be built in the background and become
+available once caught up. When switching from running `-txindex` to running
+without the flag, the transaction index database will *not* be deleted
+automatically, meaning it could be turned back on at a later time without a full
+resync.
diff --git a/src/Makefile.test.include b/src/Makefile.test.include
index 7d23b34a7f..0ebd3c9cd8 100644
--- a/src/Makefile.test.include
+++ b/src/Makefile.test.include
@@ -1,206 +1,207 @@
 # Copyright (c) 2013-2016 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 TESTS += test/test_bitcoin
 LOG_DRIVER = $(srcdir)/test/test-bitcoin-driver
 EXTRA_DIST += test/test-bitcoin-driver
 bin_PROGRAMS += test/test_bitcoin
 noinst_PROGRAMS += test/test_bitcoin_fuzzy
 TEST_SRCDIR = test
 TEST_BINARY=test/test_bitcoin$(EXEEXT)
 
 JSON_TEST_FILES = \
   test/data/script_tests.json \
   test/data/base58_keys_valid.json \
   test/data/base58_encode_decode.json \
   test/data/base58_keys_invalid.json \
   test/data/blockfilters.json \
   test/data/tx_invalid.json \
   test/data/tx_valid.json \
   test/data/sighash.json
 
 RAW_TEST_FILES =
 
 GENERATED_TEST_FILES = $(JSON_TEST_FILES:.json=.json.h) $(RAW_TEST_FILES:.raw=.raw.h)
 
 # test_bitcoin binary #
 BITCOIN_TESTS =\
   test/scriptnum10.h \
   test/activation_tests.cpp \
   test/addrman_tests.cpp \
   test/allocator_tests.cpp \
   test/amount_tests.cpp \
   test/arith_uint256_tests.cpp \
   test/avalanche_tests.cpp \
   test/base32_tests.cpp \
   test/base58_tests.cpp \
   test/base64_tests.cpp \
   test/bip32_tests.cpp \
   test/blockcheck_tests.cpp \
   test/blockencodings_tests.cpp \
   test/blockfilter_tests.cpp \
   test/blockindex_tests.cpp \
   test/blockstatus_tests.cpp \
   test/bloom_tests.cpp \
   test/bswap_tests.cpp \
   test/cashaddr_tests.cpp \
   test/cashaddrenc_tests.cpp \
   test/checkdatasig_tests.cpp \
   test/checkpoints_tests.cpp \
   test/checkqueue_tests.cpp \
   test/coins_tests.cpp \
   test/compress_tests.cpp \
   test/config_tests.cpp \
   test/core_io_tests.cpp \
   test/crypto_tests.cpp \
   test/cuckoocache_tests.cpp \
   test/dbwrapper_tests.cpp \
   test/DoS_tests.cpp \
   test/dstencode_tests.cpp \
   test/excessiveblock_tests.cpp \
   test/feerate_tests.cpp \
   test/finalization_tests.cpp \
   test/getarg_tests.cpp \
   test/hash_tests.cpp \
   test/inv_tests.cpp \
   test/jsonutil.cpp \
   test/jsonutil.h \
   test/key_tests.cpp \
   test/lcg_tests.cpp \
   test/lcg.h \
   test/limitedmap_tests.cpp \
   test/main_tests.cpp \
   test/mempool_tests.cpp \
   test/merkle_tests.cpp \
   test/miner_tests.cpp \
   test/monolith_opcodes_tests.cpp \
   test/multisig_tests.cpp \
   test/net_tests.cpp \
   test/netbase_tests.cpp \
   test/pmt_tests.cpp \
   test/policyestimator_tests.cpp \
   test/pow_tests.cpp \
   test/prevector_tests.cpp \
   test/radix_tests.cpp \
   test/raii_event_tests.cpp \
   test/random_tests.cpp \
   test/rcu_tests.cpp \
   test/reverselock_tests.cpp \
   test/rpc_tests.cpp \
   test/rpc_server_tests.cpp \
   test/rwcollection_tests.cpp \
   test/sanity_tests.cpp \
   test/scheduler_tests.cpp \
   test/schnorr_tests.cpp \
   test/script_commitment_tests.cpp \
   test/script_P2SH_tests.cpp \
   test/script_tests.cpp \
   test/scriptflags.cpp \
   test/scriptflags.h \
   test/scriptnum_tests.cpp \
   test/serialize_tests.cpp \
   test/sigcache_tests.cpp \
   test/sigencoding_tests.cpp \
   test/sighash_tests.cpp \
   test/sighashtype_tests.cpp \
   test/sigopcount_tests.cpp \
   test/sigutil.cpp \
   test/sigutil.h \
   test/skiplist_tests.cpp \
   test/streams_tests.cpp \
   test/sync_tests.cpp \
   test/test_bitcoin.cpp \
   test/test_bitcoin.h \
   test/test_bitcoin_main.cpp \
   test/timedata_tests.cpp \
   test/transaction_tests.cpp \
+  test/txindex_tests.cpp \
   test/txvalidationcache_tests.cpp \
   test/uint256_tests.cpp \
   test/undo_tests.cpp \
   test/univalue_tests.cpp \
   test/util_tests.cpp \
   test/validation_tests.cpp \
   test/work_comparator_tests.cpp \
   rpc/test/server_tests.cpp
 
 if ENABLE_WALLET
 BITCOIN_TESTS += \
   wallet/test/wallet_test_fixture.cpp \
   wallet/test/wallet_test_fixture.h \
   wallet/test/accounting_tests.cpp \
   wallet/test/wallet_tests.cpp \
   wallet/test/walletdb_tests.cpp \
   wallet/test/wallet_crypto_tests.cpp
 endif
 
 test_test_bitcoin_SOURCES = $(BITCOIN_TESTS) $(JSON_TEST_FILES) $(RAW_TEST_FILES)
 test_test_bitcoin_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(TESTDEFS) $(EVENT_CFLAGS)
 test_test_bitcoin_LDADD =
 if ENABLE_WALLET
 test_test_bitcoin_LDADD += $(LIBBITCOIN_WALLET)
 endif
 
 test_test_bitcoin_LDADD += $(LIBBITCOIN_SERVER) $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL) $(LIBBITCOIN_CONSENSUS) $(LIBBITCOIN_CRYPTO) $(LIBUNIVALUE) \
   $(LIBLEVELDB) $(LIBLEVELDB_SSE42) $(LIBMEMENV) $(BOOST_LIBS) $(BOOST_UNIT_TEST_FRAMEWORK_LIB) $(LIBSECP256K1) $(EVENT_LIBS) $(EVENT_PTHREADS_LIBS)
 test_test_bitcoin_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 
 test_test_bitcoin_LDADD += $(LIBBITCOIN_CONSENSUS) $(BDB_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS) $(MINIUPNPC_LIBS)
 test_test_bitcoin_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS) -static
 
 if ENABLE_ZMQ
 test_test_bitcoin_LDADD += $(ZMQ_LIBS)
 endif
 #
 
 # test_bitcoin_fuzzy binary #
 test_test_bitcoin_fuzzy_SOURCES = test/test_bitcoin_fuzzy.cpp
 test_test_bitcoin_fuzzy_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
 test_test_bitcoin_fuzzy_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 test_test_bitcoin_fuzzy_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 
 test_test_bitcoin_fuzzy_LDADD = \
   $(LIBUNIVALUE) \
   $(LIBBITCOIN_SERVER) \
   $(LIBBITCOIN_COMMON) \
   $(LIBBITCOIN_UTIL) \
   $(LIBBITCOIN_CONSENSUS) \
   $(LIBBITCOIN_CRYPTO) \
   $(LIBSECP256K1)
 
 test_test_bitcoin_fuzzy_LDADD += $(BOOST_LIBS) $(CRYPTO_LIBS)
 #
 
 nodist_test_test_bitcoin_SOURCES = $(GENERATED_TEST_FILES)
 
 $(BITCOIN_TESTS): $(GENERATED_TEST_FILES)
 
 CLEAN_BITCOIN_TEST = test/*.gcda test/*.gcno $(GENERATED_TEST_FILES)
 
 CLEANFILES += $(CLEAN_BITCOIN_TEST)
 
 bitcoin_test: $(TEST_BINARY)
 
 bitcoin_test_check: $(TEST_BINARY) FORCE
 	$(MAKE) check-TESTS TESTS=$^
 
 bitcoin_test_clean : FORCE
 	rm -f $(CLEAN_BITCOIN_TEST) $(test_test_bitcoin_OBJECTS) $(TEST_BINARY)
 
 check-local:
 	@echo "Running test/util/bitcoin-util-test.py..."
 	$(top_builddir)/test/util/bitcoin-util-test.py
 	$(AM_V_at)$(MAKE) $(AM_MAKEFLAGS) -C secp256k1 check
 if EMBEDDED_UNIVALUE
 	$(AM_V_at)$(MAKE) $(AM_MAKEFLAGS) -C univalue check
 endif
 
 %.json.h: %.json
 	@$(MKDIR_P) $(@D)
 	@{ \
 	 echo "namespace json_tests{" && \
 	 echo "static unsigned const char $(*F)[] = {" && \
 	 $(HEXDUMP) -v -e '8/1 "0x%02x, "' -e '"\n"' $< | $(SED) -e 's/0x  ,//g' && \
 	 echo "};};"; \
 	} > "$@.new" && mv -f "$@.new" "$@"
 	@echo "Generated $@"
diff --git a/src/index/txindex.cpp b/src/index/txindex.cpp
index 356de099e5..844412465c 100644
--- a/src/index/txindex.cpp
+++ b/src/index/txindex.cpp
@@ -1,281 +1,305 @@
 // Copyright (c) 2017-2018 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 <config.h>
 #include <index/txindex.h>
 #include <init.h>
 #include <tinyformat.h>
 #include <ui_interface.h>
 #include <util.h>
 #include <validation.h>
 #include <warnings.h>
 
 constexpr int64_t SYNC_LOG_INTERVAL = 30;           // seconds
 constexpr int64_t SYNC_LOCATOR_WRITE_INTERVAL = 30; // seconds
 
+std::unique_ptr<TxIndex> g_txindex;
+
 template <typename... Args>
 static void FatalError(const char *fmt, const Args &... args) {
     std::string strMessage = tfm::format(fmt, args...);
     SetMiscWarning(strMessage);
     LogPrintf("*** %s\n", strMessage);
     uiInterface.ThreadSafeMessageBox(
         "Error: A fatal internal error occurred, see debug.log for details", "",
         CClientUIInterface::MSG_ERROR);
     StartShutdown();
 }
 
 TxIndex::TxIndex(std::unique_ptr<TxIndexDB> db)
     : m_db(std::move(db)), m_synced(false), m_best_block_index(nullptr) {}
 
 TxIndex::~TxIndex() {
     Interrupt();
     Stop();
 }
 
 bool TxIndex::Init() {
     LOCK(cs_main);
 
     // Attempt to migrate txindex from the old database to the new one. Even if
     // chain_tip is null, the node could be reindexing and we still want to
     // delete txindex records in the old database.
     if (!m_db->MigrateData(*pblocktree, chainActive.GetLocator())) {
         return false;
     }
 
     CBlockLocator locator;
     if (!m_db->ReadBestBlock(locator)) {
         locator.SetNull();
     }
 
     m_best_block_index = FindForkInGlobalIndex(chainActive, locator);
     m_synced = m_best_block_index.load() == chainActive.Tip();
     return true;
 }
 
 static const CBlockIndex *NextSyncBlock(const CBlockIndex *pindex_prev) {
     AssertLockHeld(cs_main);
 
     if (!pindex_prev) {
         return chainActive.Genesis();
     }
 
     const CBlockIndex *pindex = chainActive.Next(pindex_prev);
     if (pindex) {
         return pindex;
     }
 
     return chainActive.Next(chainActive.FindFork(pindex_prev));
 }
 
 void TxIndex::ThreadSync() {
     const CBlockIndex *pindex = m_best_block_index.load();
     if (!m_synced) {
         auto &config = GetConfig();
 
         int64_t last_log_time = 0;
         int64_t last_locator_write_time = 0;
         while (true) {
             if (m_interrupt) {
                 WriteBestBlock(pindex);
                 return;
             }
 
             {
                 LOCK(cs_main);
                 const CBlockIndex *pindex_next = NextSyncBlock(pindex);
                 if (!pindex_next) {
                     WriteBestBlock(pindex);
                     m_best_block_index = pindex;
                     m_synced = true;
                     break;
                 }
                 pindex = pindex_next;
             }
 
             int64_t current_time = GetTime();
             if (last_log_time + SYNC_LOG_INTERVAL < current_time) {
                 LogPrintf("Syncing txindex with block chain from height %d\n",
                           pindex->nHeight);
                 last_log_time = current_time;
             }
 
             if (last_locator_write_time + SYNC_LOCATOR_WRITE_INTERVAL <
                 current_time) {
                 WriteBestBlock(pindex);
                 last_locator_write_time = current_time;
             }
 
             CBlock block;
             if (!ReadBlockFromDisk(block, pindex, config)) {
                 FatalError("%s: Failed to read block %s from disk", __func__,
                            pindex->GetBlockHash().ToString());
                 return;
             }
             if (!WriteBlock(block, pindex)) {
                 FatalError("%s: Failed to write block %s to tx index database",
                            __func__, pindex->GetBlockHash().ToString());
                 return;
             }
         }
     }
 
     if (pindex) {
         LogPrintf("txindex is enabled at height %d\n", pindex->nHeight);
     } else {
         LogPrintf("txindex is enabled\n");
     }
 }
 
 bool TxIndex::WriteBlock(const CBlock &block, const CBlockIndex *pindex) {
     CDiskTxPos pos(pindex->GetBlockPos(),
                    GetSizeOfCompactSize(block.vtx.size()));
     std::vector<std::pair<uint256, CDiskTxPos>> vPos;
     vPos.reserve(block.vtx.size());
     for (const auto &tx : block.vtx) {
         vPos.emplace_back(tx->GetHash(), pos);
         pos.nTxOffset += ::GetSerializeSize(*tx, SER_DISK, CLIENT_VERSION);
     }
     return m_db->WriteTxs(vPos);
 }
 
 bool TxIndex::WriteBestBlock(const CBlockIndex *block_index) {
     LOCK(cs_main);
     if (!m_db->WriteBestBlock(chainActive.GetLocator(block_index))) {
         return error("%s: Failed to write locator to disk", __func__);
     }
     return true;
 }
 
 void TxIndex::BlockConnected(
     const std::shared_ptr<const CBlock> &block, const CBlockIndex *pindex,
     const std::vector<CTransactionRef> &txn_conflicted) {
     if (!m_synced) {
         return;
     }
 
     const CBlockIndex *best_block_index = m_best_block_index.load();
     if (!best_block_index) {
         if (pindex->nHeight != 0) {
             FatalError("%s: First block connected is not the genesis block "
                        "(height=%d)",
                        __func__, pindex->nHeight);
             return;
         }
     } else {
         // Ensure block connects to an ancestor of the current best block. This
         // should be the case most of the time, but may not be immediately after
         // the the sync thread catches up and sets m_synced. Consider the case
         // where there is a reorg and the blocks on the stale branch are in the
         // ValidationInterface queue backlog even after the sync thread has
         // caught up to the new chain tip. In this unlikely event, log a warning
         // and let the queue clear.
         if (best_block_index->GetAncestor(pindex->nHeight - 1) !=
             pindex->pprev) {
             LogPrintf("%s: WARNING: Block %s does not connect to an ancestor "
                       "of known best chain (tip=%s); not updating txindex\n",
                       __func__, pindex->GetBlockHash().ToString(),
                       best_block_index->GetBlockHash().ToString());
             return;
         }
     }
 
     if (WriteBlock(*block, pindex)) {
         m_best_block_index = pindex;
     } else {
         FatalError("%s: Failed to write block %s to txindex", __func__,
                    pindex->GetBlockHash().ToString());
         return;
     }
 }
 
 void TxIndex::ChainStateFlushed(const CBlockLocator &locator) {
     if (!m_synced) {
         return;
     }
 
     const uint256 &locator_tip_hash = locator.vHave.front();
     const CBlockIndex *locator_tip_index;
     {
         LOCK(cs_main);
         locator_tip_index = LookupBlockIndex(locator_tip_hash);
     }
 
     if (!locator_tip_index) {
         FatalError("%s: First block (hash=%s) in locator was not found",
                    __func__, locator_tip_hash.ToString());
         return;
     }
 
     // This checks that ChainStateFlushed callbacks are received after
     // BlockConnected. The check may fail immediately after the the sync thread
     // catches up and sets m_synced. Consider the case where there is a reorg
     // and the blocks on the stale branch are in the ValidationInterface queue
     // backlog even after the sync thread has caught up to the new chain tip. In
     // this unlikely event, log a warning and let the queue clear.
     const CBlockIndex *best_block_index = m_best_block_index.load();
     if (best_block_index->GetAncestor(locator_tip_index->nHeight) !=
         locator_tip_index) {
         LogPrintf("%s: WARNING: Locator contains block (hash=%s) not on known "
                   "best chain (tip=%s); not writing txindex locator\n",
                   __func__, locator_tip_hash.ToString(),
                   best_block_index->GetBlockHash().ToString());
         return;
     }
 
     if (!m_db->WriteBestBlock(locator)) {
         error("%s: Failed to write locator to disk", __func__);
     }
 }
 
 bool TxIndex::BlockUntilSyncedToCurrentChain() {
     AssertLockNotHeld(cs_main);
 
     if (!m_synced) {
         return false;
     }
 
     {
         // Skip the queue-draining stuff if we know we're caught up with
         // chainActive.Tip().
         LOCK(cs_main);
         const CBlockIndex *chain_tip = chainActive.Tip();
         const CBlockIndex *best_block_index = m_best_block_index.load();
         if (best_block_index->GetAncestor(chain_tip->nHeight) == chain_tip) {
             return true;
         }
     }
 
     LogPrintf("%s: txindex is catching up on block notifications\n", __func__);
     SyncWithValidationInterfaceQueue();
     return true;
 }
 
-bool TxIndex::FindTx(const uint256 &txid, CDiskTxPos &pos) const {
-    return m_db->ReadTxPos(txid, pos);
+bool TxIndex::FindTx(const uint256 &tx_hash, uint256 &block_hash,
+                     CTransactionRef &tx) const {
+    CDiskTxPos postx;
+    if (!m_db->ReadTxPos(tx_hash, postx)) {
+        return false;
+    }
+
+    CAutoFile file(OpenBlockFile(postx, true), SER_DISK, CLIENT_VERSION);
+    if (file.IsNull()) {
+        return error("%s: OpenBlockFile failed", __func__);
+    }
+    CBlockHeader header;
+    try {
+        file >> header;
+        fseek(file.Get(), postx.nTxOffset, SEEK_CUR);
+        file >> tx;
+    } catch (const std::exception &e) {
+        return error("%s: Deserialize or I/O error - %s", __func__, e.what());
+    }
+    if (tx->GetHash() != tx_hash) {
+        return error("%s: txid mismatch", __func__);
+    }
+    block_hash = header.GetHash();
+    return true;
 }
 
 void TxIndex::Interrupt() {
     m_interrupt();
 }
 
 void TxIndex::Start() {
     // Need to register this ValidationInterface before running Init(), so that
     // callbacks are not missed if Init sets m_synced to true.
     RegisterValidationInterface(this);
     if (!Init()) {
         FatalError("%s: txindex failed to initialize", __func__);
         return;
     }
 
     m_thread_sync = std::thread(&TraceThread<std::function<void()>>, "txindex",
                                 std::bind(&TxIndex::ThreadSync, this));
 }
 
 void TxIndex::Stop() {
     UnregisterValidationInterface(this);
 
     if (m_thread_sync.joinable()) {
         m_thread_sync.join();
     }
 }
diff --git a/src/index/txindex.h b/src/index/txindex.h
index 43db34e5ce..22db753a20 100644
--- a/src/index/txindex.h
+++ b/src/index/txindex.h
@@ -1,87 +1,98 @@
 // Copyright (c) 2017-2018 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_INDEX_TXINDEX_H
 #define BITCOIN_INDEX_TXINDEX_H
 
 #include <primitives/block.h>
+#include <primitives/transaction.h>
 #include <threadinterrupt.h>
 #include <txdb.h>
 #include <uint256.h>
 #include <validationinterface.h>
 
 class CBlockIndex;
 
 /**
  * TxIndex is used to look up transactions included in the blockchain by hash.
  * The index is written to a LevelDB database and records the filesystem
  * location of each transaction by transaction hash.
  */
 class TxIndex final : public CValidationInterface {
 private:
     const std::unique_ptr<TxIndexDB> m_db;
 
     /// Whether the index is in sync with the main chain. The flag is flipped
     /// from false to true once, after which point this starts processing
     /// ValidationInterface notifications to stay in sync.
     std::atomic<bool> m_synced;
 
     /// The last block in the chain that the TxIndex is in sync with.
     std::atomic<const CBlockIndex *> m_best_block_index;
 
     std::thread m_thread_sync;
     CThreadInterrupt m_interrupt;
 
     /// Initialize internal state from the database and block index.
     bool Init();
 
     /// Sync the tx index with the block index starting from the current best
     /// block. Intended to be run in its own thread, m_thread_sync, and can be
     /// interrupted with m_interrupt. Once the txindex gets in sync, the
     /// m_synced flag is set and the BlockConnected ValidationInterface callback
     /// takes over and the sync thread exits.
     void ThreadSync();
 
     /// Write update index entries for a newly connected block.
     bool WriteBlock(const CBlock &block, const CBlockIndex *pindex);
 
     /// Write the current chain block locator to the DB.
     bool WriteBestBlock(const CBlockIndex *block_index);
 
 protected:
     void
     BlockConnected(const std::shared_ptr<const CBlock> &block,
                    const CBlockIndex *pindex,
                    const std::vector<CTransactionRef> &txn_conflicted) override;
 
     void ChainStateFlushed(const CBlockLocator &locator) override;
 
 public:
     /// Constructs the TxIndex, which becomes available to be queried.
     explicit TxIndex(std::unique_ptr<TxIndexDB> db);
 
     /// Destructor interrupts sync thread if running and blocks until it exits.
     ~TxIndex();
 
     /// Blocks the current thread until the transaction index is caught up to
     /// the current state of the block chain. This only blocks if the index has
     /// gotten in sync once and only needs to process blocks in the
     /// ValidationInterface queue. If the index is catching up from far behind,
     /// this method does not block and immediately returns false.
     bool BlockUntilSyncedToCurrentChain();
 
-    /// Look up the on-disk location of a transaction by hash.
-    bool FindTx(const uint256 &txid, CDiskTxPos &pos) const;
+    /// Look up a transaction by hash.
+    ///
+    /// @param[in]   tx_hash  The hash of the transaction to be returned.
+    /// @param[out]  block_hash  The hash of the block the transaction is found
+    /// in.
+    /// @param[out]  tx  The transaction itself.
+    /// @return  true if transaction is found, false otherwise
+    bool FindTx(const uint256 &tx_hash, uint256 &block_hash,
+                CTransactionRef &tx) const;
 
     void Interrupt();
 
     /// Start initializes the sync state and registers the instance as a
     /// ValidationInterface so that it stays in sync with blockchain updates.
     void Start();
 
     /// Stops the instance from staying in sync with blockchain updates.
     void Stop();
 };
 
+/// The global transaction index, used in GetTransaction. May be null.
+extern std::unique_ptr<TxIndex> g_txindex;
+
 #endif // BITCOIN_INDEX_TXINDEX_H
diff --git a/src/init.cpp b/src/init.cpp
index 4ebb4c1449..13d59edbd9 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -1,2455 +1,2467 @@
 // 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.
 
 #if defined(HAVE_CONFIG_H)
 #include <config/bitcoin-config.h>
 #endif
 
 #include <init.h>
 
 #include <addrman.h>
 #include <amount.h>
 #include <chain.h>
 #include <chainparams.h>
 #include <checkpoints.h>
 #include <compat/sanity.h>
 #include <config.h>
 #include <consensus/validation.h>
 #include <diskblockpos.h>
 #include <fs.h>
 #include <httprpc.h>
 #include <httpserver.h>
+#include <index/txindex.h>
 #include <key.h>
 #include <miner.h>
 #include <net.h>
 #include <net_processing.h>
 #include <netbase.h>
 #include <policy/policy.h>
 #include <rpc/blockchain.h>
 #include <rpc/register.h>
 #include <rpc/server.h>
 #include <scheduler.h>
 #include <script/scriptcache.h>
 #include <script/sigcache.h>
 #include <script/standard.h>
 #include <timedata.h>
 #include <torcontrol.h>
 #include <txdb.h>
 #include <txmempool.h>
 #include <ui_interface.h>
 #include <util.h>
 #include <utilmoneystr.h>
 #include <validation.h>
 #include <validationinterface.h>
 #include <walletinitinterface.h>
 #include <warnings.h>
 
 #include <boost/algorithm/string/classification.hpp>
 #include <boost/algorithm/string/replace.hpp>
 #include <boost/algorithm/string/split.hpp>
 #include <boost/bind.hpp>
 #include <boost/interprocess/sync/file_lock.hpp>
 #include <boost/thread.hpp>
 
 #if ENABLE_ZMQ
 #include <zmq/zmqnotificationinterface.h>
 #endif
 
 #ifndef WIN32
 #include <csignal>
 #endif
 #include <cstdint>
 #include <cstdio>
 #include <memory>
 
 static const bool DEFAULT_PROXYRANDOMIZE = true;
 static const bool DEFAULT_REST_ENABLE = false;
 static const bool DEFAULT_STOPAFTERBLOCKIMPORT = false;
 
 std::unique_ptr<CConnman> g_connman;
 std::unique_ptr<PeerLogicValidation> peerLogic;
 
 #if !(ENABLE_WALLET)
 class DummyWalletInit : public WalletInitInterface {
 public:
     void AddWalletOptions() const override {}
     bool ParameterInteraction() const override { return true; }
     void RegisterRPC(CRPCTable &) const override {}
     bool Verify(const CChainParams &chainParams) const override { return true; }
     bool Open(const CChainParams &chainParams) const override {
         LogPrintf("No wallet support compiled in!\n");
         return true;
     }
     void Start(CScheduler &scheduler) const override {}
     void Flush() const override {}
     void Stop() const override {}
     void Close() const override {}
 };
 
 const WalletInitInterface &g_wallet_init_interface = DummyWalletInit();
 #endif
 
 #if ENABLE_ZMQ
 static CZMQNotificationInterface *pzmqNotificationInterface = nullptr;
 #endif
 
 #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
 
 //////////////////////////////////////////////////////////////////////////////
 //
 // 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 triggers the DetectShutdownThread(), which interrupts
 // the main thread group. DetectShutdownThread() then exits, which causes
 // AppInit() to continue (it .joins the shutdown 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
 // fRequestShutdown getting set, and then does the normal Qt shutdown thing.
 //
 
 std::atomic<bool> fRequestShutdown(false);
 
 void StartShutdown() {
     fRequestShutdown = true;
 }
 bool ShutdownRequested() {
     return fRequestShutdown;
 }
 
 /**
  * This is a minimally invasive approach to shutdown on LevelDB read errors from
  * the chainstate, while keeping user interface out of the common library, which
  * is shared between bitcoind, and bitcoin-qt and non-server tools.
  */
 class CCoinsViewErrorCatcher final : public CCoinsViewBacked {
 public:
     explicit CCoinsViewErrorCatcher(CCoinsView *view)
         : CCoinsViewBacked(view) {}
     bool GetCoin(const COutPoint &outpoint, Coin &coin) const override {
         try {
             return CCoinsViewBacked::GetCoin(outpoint, coin);
         } catch (const std::runtime_error &e) {
             uiInterface.ThreadSafeMessageBox(
                 _("Error reading from database, shutting down."), "",
                 CClientUIInterface::MSG_ERROR);
             LogPrintf("Error reading from database: %s\n", e.what());
             // Starting the shutdown sequence and returning false to the caller
             // would be interpreted as 'entry not found' (as opposed to unable
             // to read data), and could lead to invalid interpretation. Just
             // exit immediately, as we can't continue anyway, and all writes
             // should be atomic.
             abort();
         }
     }
     // Writes do not need similar protection, as failure to write is handled by
     // the caller.
 };
 
 static std::unique_ptr<CCoinsViewErrorCatcher> pcoinscatcher;
 static std::unique_ptr<ECCVerifyHandle> globalVerifyHandle;
 
 static boost::thread_group threadGroup;
 static CScheduler scheduler;
 
 void Interrupt() {
     InterruptHTTPServer();
     InterruptHTTPRPC();
     InterruptRPC();
     InterruptREST();
     InterruptTorControl();
     InterruptMapPort();
     if (g_connman) {
         g_connman->Interrupt();
     }
+    if (g_txindex) {
+        g_txindex->Interrupt();
+    }
 }
 
 void Shutdown() {
     LogPrintf("%s: In progress...\n", __func__);
     static CCriticalSection 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.
     RenameThread("bitcoin-shutoff");
     g_mempool.AddTransactionsUpdated(1);
 
     StopHTTPRPC();
     StopREST();
     StopRPC();
     StopHTTPServer();
     g_wallet_init_interface.Flush();
     StopMapPort();
 
     // Because these depend on each-other, we make sure that neither can be
     // using the other before destroying them.
     if (peerLogic) {
         UnregisterValidationInterface(peerLogic.get());
     }
     if (g_connman) {
         g_connman->Stop();
     }
     peerLogic.reset();
     g_connman.reset();
+    if (g_txindex) {
+        g_txindex.reset();
+    }
 
     StopTorControl();
 
     // After everything has been shut down, but before things get flushed, stop
     // the CScheduler/checkqueue threadGroup
     threadGroup.interrupt_all();
     threadGroup.join_all();
 
     if (g_is_mempool_loaded &&
         gArgs.GetArg("-persistmempool", DEFAULT_PERSIST_MEMPOOL)) {
         DumpMempool();
     }
 
     // FlushStateToDisk generates a ChainStateFlushed callback, which we should
     // avoid missing
     if (pcoinsTip != nullptr) {
         FlushStateToDisk();
     }
 
     // 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 (pcoinsTip != nullptr) {
             FlushStateToDisk();
         }
         pcoinsTip.reset();
         pcoinscatcher.reset();
         pcoinsdbview.reset();
         pblocktree.reset();
     }
     g_wallet_init_interface.Stop();
 
 #if ENABLE_ZMQ
     if (pzmqNotificationInterface) {
         UnregisterValidationInterface(pzmqNotificationInterface);
         delete pzmqNotificationInterface;
         pzmqNotificationInterface = nullptr;
     }
 #endif
 
 #ifndef WIN32
     try {
         fs::remove(GetPidFile());
     } catch (const fs::filesystem_error &e) {
         LogPrintf("%s: Unable to remove pidfile: %s\n", __func__, e.what());
     }
 #endif
     UnregisterAllValidationInterfaces();
     GetMainSignals().UnregisterBackgroundSignalScheduler();
     GetMainSignals().UnregisterWithMempoolSignals(g_mempool);
     g_wallet_init_interface.Close();
     globalVerifyHandle.reset();
     ECC_Stop();
     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:
  */
 static void HandleSIGTERM(int) {
     fRequestShutdown = true;
 }
 
 static void HandleSIGHUP(int) {
     GetLogger().m_reopen_file = true;
 }
 
 #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
 
 void OnRPCStarted() {
     uiInterface.NotifyBlockTip.connect(&RPCNotifyBlockChange);
 }
 
 void OnRPCStopped() {
     uiInterface.NotifyBlockTip.disconnect(&RPCNotifyBlockChange);
     RPCNotifyBlockChange(false, nullptr);
     g_best_block_cv.notify_all();
     LogPrint(BCLog::RPC, "RPC stopped.\n");
 }
 
 void SetupServerArgs() {
     const auto defaultBaseParams =
         CreateBaseChainParams(CBaseChainParams::MAIN);
     const auto testnetBaseParams =
         CreateBaseChainParams(CBaseChainParams::TESTNET);
     const auto defaultChainParams = CreateChainParams(CBaseChainParams::MAIN);
     const auto testnetChainParams =
         CreateChainParams(CBaseChainParams::TESTNET);
 
     // 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("-?", _("Print this help message and exit"), false,
                  OptionsCategory::OPTIONS);
     gArgs.AddArg("-version", _("Print version and exit"), false,
                  OptionsCategory::OPTIONS);
     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)"),
                  false, OptionsCategory::OPTIONS);
     gArgs.AddArg("-blocksdir=<dir>",
                  _("Specify directory to hold blocks subdirectory for *.dat "
                    "files (default: <datadir>)"),
                  false, OptionsCategory::OPTIONS);
     gArgs.AddArg("-blocknotify=<cmd>",
                  _("Execute command when the best block changes (%s in cmd is "
                    "replaced by block hash)"),
                  false, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-blocksonly",
         strprintf(_("Whether to operate in a blocks only mode (default: %d)"),
                   DEFAULT_BLOCKSONLY),
         true, OptionsCategory::OPTIONS);
     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()),
         false, OptionsCategory::OPTIONS);
     gArgs.AddArg("-conf=<file>",
                  strprintf(_("Specify configuration file (default: %s)"),
                            BITCOIN_CONF_FILENAME),
                  false, OptionsCategory::OPTIONS);
     gArgs.AddArg("-datadir=<dir>", _("Specify data directory"), false,
                  OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-dbbatchsize",
         strprintf("Maximum database write batch size in bytes (default: %u)",
                   nDefaultDbBatchSize),
         true, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-dbcache=<n>",
         strprintf(
             _("Set database cache size in megabytes (%d to %d, default: %d)"),
             nMinDbCache, nMaxDbCache, nDefaultDbCache),
         false, OptionsCategory::OPTIONS);
     gArgs.AddArg("-feefilter",
                  strprintf("Tell other nodes to filter invs to us by "
                            "our mempool min fee (default: %d)",
                            DEFAULT_FEEFILTER),
                  true, 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),
                  false, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-includeconf=<file>",
         _("Specify additional configuration file, relative to the -datadir "
           "path (only useable from configuration file, not command line)"),
         false, 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),
         false, OptionsCategory::OPTIONS);
     gArgs.AddArg("-loadblock=<file>",
                  _("Imports blocks from external blk000??.dat file on startup"),
                  false, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-debuglogfile=<file>",
         strprintf(
             _("Specify location of debug log file: this can be an absolute "
               "path or a path relative to the data directory (default: %s)"),
             DEFAULT_DEBUGLOGFILE),
         false, OptionsCategory::OPTIONS);
     gArgs.AddArg("-maxorphantx=<n>",
                  strprintf(_("Keep at most <n> unconnectable "
                              "transactions in memory (default: %u)"),
                            DEFAULT_MAX_ORPHAN_TRANSACTIONS),
                  false, OptionsCategory::OPTIONS);
     gArgs.AddArg("-maxmempool=<n>",
                  strprintf(_("Keep the transaction memory pool "
                              "below <n> megabytes (default: %u)"),
                            DEFAULT_MAX_MEMPOOL_SIZE),
                  false, OptionsCategory::OPTIONS);
     gArgs.AddArg("-mempoolexpiry=<n>",
                  strprintf(_("Do not keep transactions in the mempool "
                              "longer than <n> hours (default: %u)"),
                            DEFAULT_MEMPOOL_EXPIRY),
                  false, 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()),
         true, OptionsCategory::OPTIONS);
     gArgs.AddArg("-persistmempool",
                  strprintf(_("Whether to save the mempool on shutdown "
                              "and load on restart (default: %u)"),
                            DEFAULT_PERSIST_MEMPOOL),
                  false, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-blockreconstructionextratxn=<n>",
         strprintf(_("Extra transactions to keep in memory for compact block "
                     "reconstructions (default: %u)"),
                   DEFAULT_BLOCK_RECONSTRUCTION_EXTRA_TXN),
         false, 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),
         false, OptionsCategory::OPTIONS);
 #ifndef WIN32
     gArgs.AddArg(
         "-pid=<file>",
         strprintf(_("Specify pid file (default: %s)"), BITCOIN_PID_FILENAME),
         false, OptionsCategory::OPTIONS);
 #endif
     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),
         false, OptionsCategory::OPTIONS);
     gArgs.AddArg("-reindex-chainstate",
                  _("Rebuild chain state from the currently indexed blocks"),
                  false, OptionsCategory::OPTIONS);
     gArgs.AddArg("-reindex",
                  _("Rebuild chain state and block index from the blk*.dat "
                    "files on disk"),
                  false, OptionsCategory::OPTIONS);
 #ifndef WIN32
     gArgs.AddArg(
         "-sysperms",
         _("Create new files with system default permissions, instead of umask "
           "077 (only effective with disabled wallet functionality)"),
         false, OptionsCategory::OPTIONS);
 #endif
     gArgs.AddArg("-txindex",
                  strprintf(_("Maintain a full transaction index, used by the "
                              "getrawtransaction rpc call (default: %d)"),
                            DEFAULT_TXINDEX),
                  false, OptionsCategory::OPTIONS);
     gArgs.AddArg("-usecashaddr",
                  _("Use Cash Address for destination encoding instead "
                    "of base58 (activate by default on Jan, 14)"),
                  false, 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)"),
         false, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-banscore=<n>",
         strprintf(
             _("Threshold for disconnecting misbehaving peers (default: %u)"),
             DEFAULT_BANSCORE_THRESHOLD),
         false, OptionsCategory::CONNECTION);
     gArgs.AddArg("-bantime=<n>",
                  strprintf(_("Number of seconds to keep misbehaving peers from "
                              "reconnecting (default: %u)"),
                            DEFAULT_MISBEHAVING_BANTIME),
                  false, OptionsCategory::CONNECTION);
     gArgs.AddArg("-bind=<addr>",
                  _("Bind to given address and always listen on it. Use "
                    "[host]:port notation for IPv6"),
                  false, 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)"),
                  false, OptionsCategory::CONNECTION);
     gArgs.AddArg("-discover",
                  _("Discover own IP addresses (default: 1 when listening and "
                    "no -externalip or -proxy)"),
                  false, OptionsCategory::CONNECTION);
     gArgs.AddArg("-dns",
                  _("Allow DNS lookups for -addnode, -seednode and -connect") +
                      " " + strprintf(_("(default: %d)"), DEFAULT_NAME_LOOKUP),
                  false, OptionsCategory::CONNECTION);
     gArgs.AddArg("-dnsseed",
                  _("Query for peer addresses via DNS lookup, if low on "
                    "addresses (default: 1 unless -connect/-noconnect)"),
                  false, OptionsCategory::CONNECTION);
     gArgs.AddArg("-externalip=<ip>", _("Specify your own public address"),
                  false, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-forcednsseed",
         strprintf(
             _("Always query for peer addresses via DNS lookup (default: %d)"),
             DEFAULT_FORCEDNSSEED),
         false, OptionsCategory::CONNECTION);
     gArgs.AddArg("-listen",
                  _("Accept connections from outside (default: 1 if no -proxy "
                    "or -connect/-noconnect)"),
                  false, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-listenonion",
         strprintf(_("Automatically create Tor hidden service (default: %d)"),
                   DEFAULT_LISTEN_ONION),
         false, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-maxconnections=<n>",
         strprintf(_("Maintain at most <n> connections to peers (default: %u)"),
                   DEFAULT_MAX_PEER_CONNECTIONS),
         false, OptionsCategory::CONNECTION);
     gArgs.AddArg("-maxreceivebuffer=<n>",
                  strprintf(_("Maximum per-connection receive buffer, <n>*1000 "
                              "bytes (default: %u)"),
                            DEFAULT_MAXRECEIVEBUFFER),
                  false, OptionsCategory::CONNECTION);
     gArgs.AddArg("-maxsendbuffer=<n>",
                  strprintf(_("Maximum per-connection send buffer, <n>*1000 "
                              "bytes (default: %u)"),
                            DEFAULT_MAXSENDBUFFER),
                  false, 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),
         false, OptionsCategory::CONNECTION);
     gArgs.AddArg("-onion=<ip:port>",
                  strprintf(_("Use separate SOCKS5 proxy to reach peers via Tor "
                              "hidden services (default: %s)"),
                            "-proxy"),
                  false, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-onlynet=<net>",
         _("Only connect to nodes in network <net> (ipv4, ipv6 or onion)"),
         false, OptionsCategory::CONNECTION);
     gArgs.AddArg("-permitbaremultisig",
                  strprintf(_("Relay non-P2SH multisig (default: %d)"),
                            DEFAULT_PERMIT_BAREMULTISIG),
                  false, OptionsCategory::CONNECTION);
     gArgs.AddArg("-peerbloomfilters",
                  strprintf(_("Support filtering of blocks and transaction with "
                              "bloom filters (default: %d)"),
                            DEFAULT_PEERBLOOMFILTERS),
                  false, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-port=<port>",
         strprintf(
             _("Listen for connections on <port> (default: %u or testnet: %u)"),
             defaultChainParams->GetDefaultPort(),
             testnetChainParams->GetDefaultPort()),
         false, OptionsCategory::CONNECTION);
     gArgs.AddArg("-proxy=<ip:port>", _("Connect through SOCKS5 proxy"), false,
                  OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-proxyrandomize",
         strprintf(_("Randomize credentials for every proxy connection. This "
                     "enables Tor stream isolation (default: %d)"),
                   DEFAULT_PROXYRANDOMIZE),
         false, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-seednode=<ip>",
         _("Connect to a node to retrieve peer addresses, and disconnect"),
         false, OptionsCategory::CONNECTION);
     gArgs.AddArg("-timeout=<n>",
                  strprintf(_("Specify connection timeout in milliseconds "
                              "(minimum: 1, default: %d)"),
                            DEFAULT_CONNECT_TIMEOUT),
                  false, OptionsCategory::CONNECTION);
     gArgs.AddArg("-torcontrol=<ip>:<port>",
                  strprintf(_("Tor control port to use if onion listening "
                              "enabled (default: %s)"),
                            DEFAULT_TOR_CONTROL),
                  false, OptionsCategory::CONNECTION);
     gArgs.AddArg("-torpassword=<pass>",
                  _("Tor control port password (default: empty)"), false,
                  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)"),
                  false, OptionsCategory::CONNECTION);
 #else
     gArgs.AddArg(
         "-upnp",
         strprintf(_("Use UPnP to map the listening port (default: %u)"), 0),
         false, OptionsCategory::CONNECTION);
 #endif
 #endif
     gArgs.AddArg("-whitebind=<addr>",
                  _("Bind to given address and whitelist peers connecting to "
                    "it. Use [host]:port notation for IPv6"),
                  false, OptionsCategory::CONNECTION);
     gArgs.AddArg("-whitelist=<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). Can be "
                    "specified multiple times.") +
                      " " +
                      _("Whitelisted peers cannot be DoS banned and their "
                        "transactions are always relayed, even if they are "
                        "already in the mempool, useful e.g. for a gateway"),
                  false, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-whitelistrelay",
         strprintf(_("Accept relayed transactions received from whitelisted "
                     "peers even when not relaying transactions (default: %d)"),
                   DEFAULT_WHITELISTRELAY),
         false, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-whitelistforcerelay",
         strprintf(_("Force relay of transactions from whitelisted peers even "
                     "if they violate local relay policy (default: %d)"),
                   DEFAULT_WHITELISTFORCERELAY),
         false, 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),
         false, OptionsCategory::CONNECTION);
 
     g_wallet_init_interface.AddWalletOptions();
 
 #if ENABLE_ZMQ
     gArgs.AddArg("-zmqpubhashblock=<address>",
                  _("Enable publish hash block in <address>"), false,
                  OptionsCategory::ZMQ);
     gArgs.AddArg("-zmqpubhashtx=<address>",
                  _("Enable publish hash transaction in <address>"), false,
                  OptionsCategory::ZMQ);
     gArgs.AddArg("-zmqpubrawblock=<address>",
                  _("Enable publish raw block in <address>"), false,
                  OptionsCategory::ZMQ);
     gArgs.AddArg("-zmqpubrawtx=<address>",
                  _("Enable publish raw transaction in <address>"), false,
                  OptionsCategory::ZMQ);
 #endif
 
     gArgs.AddArg(
         "-checkblocks=<n>",
         strprintf(
             _("How many blocks to check at startup (default: %u, 0 = all)"),
             DEFAULT_CHECKBLOCKS),
         true, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-checklevel=<n>",
                  strprintf(_("How thorough the block verification of "
                              "-checkblocks is (0-4, default: %u)"),
                            DEFAULT_CHECKLEVEL),
                  true, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-checkblockindex",
         strprintf("Do a full consistency check for mapBlockIndex, "
                   "setBlockIndexCandidates, chainActive and mapBlocksUnlinked "
                   "occasionally. Also sets -checkmempool (default: %u)",
                   defaultChainParams->DefaultConsistencyChecks()),
         true, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-checkmempool=<n>",
                  strprintf("Run checks every <n> transactions (default: %u)",
                            defaultChainParams->DefaultConsistencyChecks()),
                  true, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-checkpoints",
                  strprintf("Only accept block chain matching built-in "
                            "checkpoints (default: %d)",
                            DEFAULT_CHECKPOINTS_ENABLED),
                  true, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-deprecatedrpc=<method>",
                  "Allows deprecated RPC method(s) to be used", true,
                  OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-dropmessagestest=<n>",
                  "Randomly drop 1 of every <n> network messages", true,
                  OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-stopafterblockimport",
         strprintf("Stop running after importing blocks from disk (default: %d)",
                   DEFAULT_STOPAFTERBLOCKIMPORT),
         true, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-stopatheight",
                  strprintf("Stop running after reaching the given height in "
                            "the main chain (default: %u)",
                            DEFAULT_STOPATHEIGHT),
                  true, 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),
                  true, 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),
         true, 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),
         true, 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),
         true, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-addrmantest", "Allows to test address relay on localhost",
                  true, 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() + ".",
                  false, 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.")),
         false, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-help-debug",
                  _("Show all debugging options (usage: --help -help-debug)"),
                  false, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-logips",
         strprintf(_("Include IP addresses in debug output (default: %d)"),
                   DEFAULT_LOGIPS),
         false, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-logtimestamps",
         strprintf(_("Prepend debug output with timestamp (default: %d)"),
                   DEFAULT_LOGTIMESTAMPS),
         false, OptionsCategory::DEBUG_TEST);
 
     gArgs.AddArg(
         "-logtimemicros",
         strprintf("Add microsecond precision to debug timestamps (default: %d)",
                   DEFAULT_LOGTIMEMICROS),
         true, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-mocktime=<n>",
         "Replace actual time with <n> seconds since epoch (default: 0)", true,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-maxsigcachesize=<n>",
         strprintf("Limit size of signature cache to <n> MiB (default: %u)",
                   DEFAULT_MAX_SIG_CACHE_SIZE),
         true, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-maxscriptcachesize=<n>",
         strprintf("Limit size of script cache to <n> MiB (default: %u)",
                   DEFAULT_MAX_SCRIPT_CACHE_SIZE),
         true, 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),
                  true, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-maxtxfee=<amt>",
         strprintf(_("Maximum total fees (in %s) to use in a single wallet "
                     "transaction or raw transaction; setting this too low may "
                     "abort large transactions (default: %s)"),
                   CURRENCY_UNIT, FormatMoney(DEFAULT_TRANSACTION_MAXFEE)),
         false, OptionsCategory::DEBUG_TEST);
 
     gArgs.AddArg(
         "-printtoconsole",
         _("Send trace/debug info to console instead of debug.log file"), false,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-printpriority",
                  strprintf("Log transaction priority and fee per kB when "
                            "mining blocks (default: %d)",
                            DEFAULT_PRINTPRIORITY),
                  true, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-shrinkdebugfile",
                  _("Shrink debug.log file on client startup (default: 1 when "
                    "no -debug)"),
                  false, OptionsCategory::DEBUG_TEST);
 
     gArgs.AddArg("-uacomment=<cmt>",
                  _("Append comment to the user agent string"), false,
                  OptionsCategory::DEBUG_TEST);
 
     SetupChainParamsBaseOptions();
 
     gArgs.AddArg(
         "-acceptnonstdtxn",
         strprintf(
             "Relay and mine \"non-standard\" transactions (%sdefault: %u)",
             "testnet/regtest only; ", defaultChainParams->RequireStandard()),
         true, OptionsCategory::NODE_RELAY);
     gArgs.AddArg("-excessiveblocksize=<n>",
                  strprintf(_("Do not accept blocks larger than this limit, in "
                              "bytes (default: %d)"),
                            DEFAULT_MAX_BLOCK_SIZE),
                  true, OptionsCategory::NODE_RELAY);
     gArgs.AddArg(
         "-dustrelayfee=<amt>",
         strprintf("Fee rate (in %s/kB) used to defined 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)),
         true, OptionsCategory::NODE_RELAY);
     gArgs.AddArg("-limitfreerelay=<n>",
                  strprintf("Continuously rate-limit free transactions to "
                            "<n>*1000 bytes per minute (default: %u)",
                            DEFAULT_LIMITFREERELAY),
                  true, OptionsCategory::NODE_RELAY);
     gArgs.AddArg("-relaypriority",
                  strprintf("Require high priority for relaying free or low-fee "
                            "transactions (default: %d)",
                            DEFAULT_RELAYPRIORITY),
                  true, OptionsCategory::NODE_RELAY);
 
     gArgs.AddArg("-bytespersigop",
                  strprintf(_("Equivalent bytes per sigop in transactions for "
                              "relay and mining (default: %u)"),
                            DEFAULT_BYTES_PER_SIGOP),
                  false, OptionsCategory::NODE_RELAY);
     gArgs.AddArg(
         "-datacarrier",
         strprintf(_("Relay and mine data carrier transactions (default: %d)"),
                   DEFAULT_ACCEPT_DATACARRIER),
         false, 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),
                  false, OptionsCategory::NODE_RELAY);
     gArgs.AddArg(
         "-minrelaytxfee=<amt>",
         strprintf(
             _("Fees (in %s/kB) smaller than this are considered zero fee for "
               "relaying, mining and transaction creation (default: %s)"),
             CURRENCY_UNIT, FormatMoney(DEFAULT_MIN_RELAY_TX_FEE_PER_KB)),
         false, 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)),
                  true, OptionsCategory::NODE_RELAY);
 
     gArgs.AddArg("-blockmaxsize=<n>",
                  strprintf(_("Set maximum block size in bytes (default: %d)"),
                            DEFAULT_MAX_GENERATED_BLOCK_SIZE),
                  false, OptionsCategory::BLOCK_CREATION);
     gArgs.AddArg(
         "-blockprioritypercentage=<n>",
         strprintf(_("Set maximum percentage of a block reserved to "
                     "high-priority/low-fee transactions (default: %d)"),
                   DEFAULT_BLOCK_PRIORITY_PERCENTAGE),
         false, 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)),
         false, OptionsCategory::BLOCK_CREATION);
 
     gArgs.AddArg("-blockversion=<n>",
                  "Override block version to test forking scenarios", true,
                  OptionsCategory::BLOCK_CREATION);
 
     gArgs.AddArg("-server", _("Accept command line and JSON-RPC commands"),
                  false, OptionsCategory::RPC);
     gArgs.AddArg("-rest",
                  strprintf(_("Accept public REST requests (default: %d)"),
                            DEFAULT_REST_ENABLE),
                  false, OptionsCategory::RPC);
     gArgs.AddArg(
         "-rpcbind=<addr>",
         _("Bind to given address to listen for JSON-RPC connections. Use "
           "[host]:port notation for IPv6. This option can be specified "
           "multiple times (default: bind to all interfaces)"),
         false, OptionsCategory::RPC);
     gArgs.AddArg("-rpccookiefile=<loc>",
                  _("Location of the auth cookie (default: data dir)"), false,
                  OptionsCategory::RPC);
     gArgs.AddArg("-rpcuser=<user>", _("Username for JSON-RPC connections"),
                  false, OptionsCategory::RPC);
     gArgs.AddArg("-rpcpassword=<pw>", _("Password for JSON-RPC connections"),
                  false, OptionsCategory::RPC);
     gArgs.AddArg(
         "-rpcauth=<userpw>",
         _("Username and hashed password for JSON-RPC connections. The field "
           "<userpw> comes in the format: <USERNAME>:<SALT>$<HASH>. A canonical "
           "python script is included in share/rpcuser. The client then "
           "connects normally using the "
           "rpcuser=<USERNAME>/rpcpassword=<PASSWORD> pair of arguments. This "
           "option can be specified multiple times"),
         false, OptionsCategory::RPC);
     gArgs.AddArg(
         "-rpcport=<port>",
         strprintf(_("Listen for JSON-RPC connections on <port> (default: %u or "
                     "testnet: %u)"),
                   defaultBaseParams->RPCPort(), testnetBaseParams->RPCPort()),
         false, 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"),
                  false, OptionsCategory::RPC);
     gArgs.AddArg(
         "-rpcthreads=<n>",
         strprintf(
             _("Set the number of threads to service RPC calls (default: %d)"),
             DEFAULT_HTTP_THREADS),
         false, OptionsCategory::RPC);
     gArgs.AddArg(
         "-rpccorsdomain=value",
         "Domain from which to accept cross origin requests (browser enforced)",
         false, OptionsCategory::RPC);
 
     gArgs.AddArg("-rpcworkqueue=<n>",
                  strprintf("Set the depth of the work queue to service RPC "
                            "calls (default: %d)",
                            DEFAULT_HTTP_WORKQUEUE),
                  true, OptionsCategory::RPC);
     gArgs.AddArg("-rpcservertimeout=<n>",
                  strprintf("Timeout during HTTP requests (default: %d)",
                            DEFAULT_HTTP_SERVER_TIMEOUT),
                  true, OptionsCategory::RPC);
 }
 
 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"), 2009, COPYRIGHT_YEAR) +
                " ") +
            "\n" + "\n" +
            strprintf(_("Please contribute if you find %s useful. "
                        "Visit %s for further information about the software."),
                      PACKAGE_NAME, URL_WEBSITE) +
            "\n" +
            strprintf(_("The source code is available from %s."),
                      URL_SOURCE_CODE) +
            "\n" + "\n" + _("This is experimental software.") + "\n" +
            strprintf(_("Distributed under the MIT software license, see the "
                        "accompanying file %s or %s"),
                      "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."),
                      "<https://www.openssl.org>") +
            "\n";
 }
 
 static void BlockNotifyCallback(bool initialSync,
                                 const CBlockIndex *pBlockIndex) {
     if (initialSync || !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();
     }
 }
 
 static bool fHaveGenesis = false;
 static Mutex g_genesis_wait_mutex;
 static std::condition_variable g_genesis_wait_cv;
 
 static void BlockNotifyGenesisWait(bool, 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.
 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");
     fs::path blocksdir = GetBlocksDir();
     for (fs::directory_iterator it(blocksdir); it != fs::directory_iterator();
          it++) {
         if (is_regular_file(*it) &&
             it->path().filename().string().length() == 12 &&
             it->path().filename().string().substr(8, 4) == ".dat") {
             if (it->path().filename().string().substr(0, 3) == "blk") {
                 mapBlockFiles[it->path().filename().string().substr(3, 5)] =
                     it->path();
             } else if (it->path().filename().string().substr(0, 3) == "rev") {
                 remove(it->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 nContigCounter = 0;
     for (const std::pair<std::string, fs::path> &item : mapBlockFiles) {
         if (atoi(item.first) == nContigCounter) {
             nContigCounter++;
             continue;
         }
         remove(item.second);
     }
 }
 
 void ThreadImport(const Config &config, std::vector<fs::path> vImportFiles) {
     RenameThread("bitcoin-loadblk");
 
     {
         CImportingNow imp;
 
         // -reindex
         if (fReindex) {
             int nFile = 0;
             while (true) {
                 CDiskBlockPos pos(nFile, 0);
                 if (!fs::exists(GetBlockPosFilename(pos, "blk"))) {
                     // 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(config.GetChainParams());
         }
 
         // hardcoded $DATADIR/bootstrap.dat
         fs::path pathBootstrap = GetDataDir() / "bootstrap.dat";
         if (fs::exists(pathBootstrap)) {
             FILE *file = fsbridge::fopen(pathBootstrap, "rb");
             if (file) {
                 fs::path pathBootstrapOld = GetDataDir() / "bootstrap.dat.old";
                 LogPrintf("Importing bootstrap.dat...\n");
                 LoadExternalBlockFile(config, file);
                 RenameOver(pathBootstrap, pathBootstrapOld);
             } else {
                 LogPrintf("Warning: Could not open bootstrap file %s\n",
                           pathBootstrap.string());
             }
         }
 
         // -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());
             }
         }
 
         // scan for better chains in the block chain database, that are not yet
         // connected in the active best chain
         CValidationState state;
         if (!ActivateBestChain(config, state)) {
             LogPrintf("Failed to connect best block");
             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_is_mempool_loaded = !fRequestShutdown;
 }
 
 /** Sanity checks
  *  Ensure that Bitcoin is running in a usable environment with all
  *  necessary library support.
  */
 bool InitSanityCheck(void) {
     if (!ECC_InitSanityCheck()) {
         InitError(
             "Elliptic curve cryptography sanity check failure. Aborting.");
         return false;
     }
 
     if (!glibc_sanity_test() || !glibcxx_sanity_test()) {
         return false;
     }
 
     if (!Random_SanityCheck()) {
         InitError("OS cryptographic RNG sanity check failure. Aborting.");
         return false;
     }
 
     return true;
 }
 
 static bool AppInitServers(Config &config,
                            HTTPRPCRequestProcessor &httpRPCRequestProcessor) {
     RPCServerSignals::OnStarted(&OnRPCStarted);
     RPCServerSignals::OnStopped(&OnRPCStopped);
     if (!InitHTTPServer(config)) {
         return false;
     }
     if (!StartRPC()) {
         return false;
     }
     if (!StartHTTPRPC(config, httpRPCRequestProcessor)) {
         return false;
     }
     if (gArgs.GetBoolArg("-rest", DEFAULT_REST_ENABLE) && !StartREST()) {
         return false;
     }
     if (!StartHTTPServer()) {
         return false;
     }
     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__);
         }
     }
 
     // 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.
     gArgs.WarnForSectionOnlyArgs();
 }
 
 static std::string ResolveErrMsg(const char *const optname,
                                  const std::string &strBind) {
     return strprintf(_("Cannot resolve -%s address: '%s'"), optname, strBind);
 }
 
 void InitLogging() {
     BCLog::Logger &logger = GetLogger();
     logger.m_print_to_console = gArgs.GetBoolArg("-printtoconsole", false);
     logger.m_log_timestamps =
         gArgs.GetBoolArg("-logtimestamps", DEFAULT_LOGTIMESTAMPS);
     logger.m_log_time_micros =
         gArgs.GetBoolArg("-logtimemicros", DEFAULT_LOGTIMEMICROS);
 
     fLogIPs = gArgs.GetBoolArg("-logips", DEFAULT_LOGIPS);
 
     LogPrintf("\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n");
     LogPrintf("%s version %s\n", CLIENT_NAME, FormatFullVersion());
 }
 
 namespace { // Variables internal to initialization process only
 
 int nMaxConnections;
 int nUserMaxConnections;
 int nFD;
 ServiceFlags nLocalServices = ServiceFlags(NODE_NETWORK | NODE_NETWORK_LIMITED);
 } // 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));
 #endif
 #if _MSC_VER >= 1400
     // 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)
 // Minimum supported OS versions: WinXP SP3, WinVista >= SP1, Win Server 2008
 // A failure is non-critical and needs no further attention!
 #ifndef PROCESS_DEP_ENABLE
 // We define this here, because GCCs winbase.h limits this to _WIN32_WINNT >=
 // 0x0601 (Windows 7), which is not correct. Can be removed, when GCCs winbase.h
 // is fixed!
 #define PROCESS_DEP_ENABLE 0x00000001
 #endif
     typedef BOOL(WINAPI * PSETPROCDEPPOL)(DWORD);
     PSETPROCDEPPOL setProcDEPPol = (PSETPROCDEPPOL)GetProcAddress(
         GetModuleHandleA("Kernel32.dll"), "SetProcessDEPPolicy");
     if (setProcDEPPol != nullptr) {
         setProcDEPPol(PROCESS_DEP_ENABLE);
     }
 #endif
 
     if (!SetupNetworking()) {
         return InitError("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);
 #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()
 
     if (!fs::is_directory(GetBlocksDir(false))) {
         return InitError(
             strprintf(_("Specified blocks directory \"%s\" does not exist.\n"),
                       gArgs.GetArg("-blocksdir", "").c_str()));
     }
 
     // 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 space reserved for high priority transactions is misconfigured
     // stop program execution and warn the user with a proper error message
     const int64_t blkprio = gArgs.GetArg("-blockprioritypercentage",
                                          DEFAULT_BLOCK_PRIORITY_PERCENTAGE);
     if (!config.SetBlockPriorityPercentage(blkprio)) {
         return InitError(_("Block priority percentage has to belong to the "
                            "[0..100] interval."));
     }
 
     // -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(
             "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
     nMaxConnections =
         std::max(std::min(nMaxConnections,
                           (int)(FD_SETSIZE - nBind - MIN_CORE_FILEDESCRIPTORS -
                                 MAX_ADDNODE_CONNECTIONS)),
                  0);
     nFD = RaiseFileDescriptorLimit(nMaxConnections + MIN_CORE_FILEDESCRIPTORS +
                                    MAX_ADDNODE_CONNECTIONS);
     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."),
                               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 (find(categories.begin(), categories.end(), std::string("0")) ==
             categories.end()) {
             for (const auto &cat : categories) {
                 BCLog::LogFlags flag;
                 if (!GetLogCategory(flag, cat)) {
                     InitWarning(
                         strprintf(_("Unsupported logging category %s=%s."),
                                   "-debug", cat));
                 }
                 GetLogger().EnableCategory(flag);
             }
         }
     }
 
     // Now remove the logging categories which were explicitly excluded
     for (const std::string &cat : gArgs.GetArgs("-debugexclude")) {
         BCLog::LogFlags flag;
         if (!GetLogCategory(flag, cat)) {
             InitWarning(strprintf(_("Unsupported logging category %s=%s."),
                                   "-debugexclude", cat));
         }
         GetLogger().DisableCategory(flag);
     }
 
     // Check for -debugnet
     if (gArgs.GetBoolArg("-debugnet", false)) {
         InitWarning(
             _("Unsupported argument -debugnet ignored, use -debug=net."));
     }
     // Check for -socks - as this is a privacy risk to continue, exit here
     if (gArgs.IsArgSet("-socks")) {
         return InitError(
             _("Unsupported argument -socks found. Setting SOCKS version isn't "
               "possible anymore, only SOCKS5 proxies are supported."));
     }
     // Check for -tor - as this is a privacy risk to continue, exit here
     if (gArgs.GetBoolArg("-tor", false)) {
         return InitError(_("Unsupported argument -tor found, use -onion."));
     }
 
     if (gArgs.GetBoolArg("-benchmark", false)) {
         InitWarning(
             _("Unsupported argument -benchmark ignored, use -debug=bench."));
     }
 
     if (gArgs.GetBoolArg("-whitelistalwaysrelay", false)) {
         InitWarning(_("Unsupported argument -whitelistalwaysrelay ignored, use "
                       "-whitelistrelay and/or -whitelistforcerelay."));
     }
 
     if (gArgs.IsArgSet("-blockminsize")) {
         InitWarning("Unsupported argument -blockminsize ignored.");
     }
 
     // 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 = uint256S(
         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(
                 "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)));
     }
 
     // -par=0 means autodetect, but nScriptCheckThreads==0 means no concurrency
     nScriptCheckThreads = gArgs.GetArg("-par", DEFAULT_SCRIPTCHECK_THREADS);
     if (nScriptCheckThreads <= 0) {
         nScriptCheckThreads += GetNumCores();
     }
     if (nScriptCheckThreads <= 1) {
         nScriptCheckThreads = 0;
     } else if (nScriptCheckThreads > MAX_SCRIPTCHECK_THREADS) {
         nScriptCheckThreads = MAX_SCRIPTCHECK_THREADS;
     }
 
     // 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 %uMiB 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;
     }
 
     // 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);
     }
 
     // Fee-per-kilobyte amount considered the same as "free". If you are mining,
     // be careful setting this: if you set it to zero then a transaction spammer
     // can cheaply fill blocks using 1-satoshi-fee transactions. It should be
     // set above the real cost to you of processing a transaction.
     if (gArgs.IsArgSet("-minrelaytxfee")) {
         Amount n = Amount::zero();
         auto parsed = ParseMoney(gArgs.GetArg("-minrelaytxfee", ""), n);
         if (!parsed || Amount::zero() == n) {
             return InitError(AmountErrMsg("minrelaytxfee",
                                           gArgs.GetArg("-minrelaytxfee", "")));
         }
         // High fee check is done afterward in WalletParameterInteraction()
         config.SetMinFeePerKB(CFeeRate(n));
     } else {
         config.SetMinFeePerKB(CFeeRate(DEFAULT_MIN_RELAY_TX_FEE_PER_KB));
     }
 
     // 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.RequireStandard() && !fRequireStandard) {
         return InitError(
             strprintf("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) {
     // Step 4a: application initialization
     const CChainParams &chainparams = config.GetChainParams();
 
 #ifndef WIN32
     CreatePidFile(GetPidFile(), getpid());
 #endif
 
     BCLog::Logger &logger = GetLogger();
 
     bool default_shrinkdebugfile = logger.DefaultShrinkDebugFile();
     if (gArgs.GetBoolArg("-shrinkdebugfile", default_shrinkdebugfile)) {
         // 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.m_print_to_file) {
         if (!logger.OpenDebugLog()) {
             return InitError(strprintf("Could not open debug log file %s",
                                        logger.GetDebugLogPath().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());
     LogPrintf(
         "Using config file %s\n",
         GetConfigFile(gArgs.GetArg("-conf", BITCOIN_CONF_FILENAME)).string());
     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();
 
     LogPrintf("Using %u threads for script verification\n",
               nScriptCheckThreads);
     if (nScriptCheckThreads) {
         for (int i = 0; i < nScriptCheckThreads - 1; i++) {
             threadGroup.create_thread(&ThreadScriptCheck);
         }
     }
 
     // Start the lightweight task scheduler thread
     CScheduler::Function serviceLoop =
         boost::bind(&CScheduler::serviceQueue, &scheduler);
     threadGroup.create_thread(boost::bind(&TraceThread<CScheduler::Function>,
                                           "scheduler", serviceLoop));
 
     GetMainSignals().RegisterBackgroundSignalScheduler(scheduler);
     GetMainSignals().RegisterWithMempoolSignals(g_mempool);
 
     /**
      * 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);
     g_wallet_init_interface.RegisterRPC(tableRPC);
 
     /**
      * 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
     if (!g_wallet_init_interface.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(!g_connman);
     g_connman = std::unique_ptr<CConnman>(
         new CConnman(config, GetRand(std::numeric_limits<uint64_t>::max()),
                      GetRand(std::numeric_limits<uint64_t>::max())));
     CConnman &connman = *g_connman;
 
     peerLogic.reset(new PeerLogicValidation(&connman, scheduler));
     RegisterValidationInterface(peerLogic.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)) SetLimited(net);
         }
     }
 
     // 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", "");
     SetLimited(NET_ONION);
     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
         SetLimited(NET_ONION, false);
     }
 
     // -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
             SetLimited(NET_ONION); // set onions as unreachable
         } 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);
             SetLimited(NET_ONION, false);
         }
     }
 
     // see Step 2: parameter interactions for more information about these
     fListen = gArgs.GetBoolArg("-listen", DEFAULT_LISTEN);
     fDiscover = gArgs.GetBoolArg("-discover", true);
     fRelayTxes = !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(ResolveErrMsg("externalip", strAddr));
         }
     }
 
 #if ENABLE_ZMQ
     pzmqNotificationInterface = CZMQNotificationInterface::Create();
 
     if (pzmqNotificationInterface) {
         RegisterValidationInterface(pzmqNotificationInterface);
     }
 #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 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", nDefaultDbCache) << 20);
     // total cache cannot be less than nMinDbCache
     nTotalCache = std::max(nTotalCache, nMinDbCache << 20);
     // total cache cannot be greater than nMaxDbcache
     nTotalCache = std::min(nTotalCache, nMaxDbCache << 20);
-    int64_t nBlockTreeDBCache = nTotalCache / 8;
-    nBlockTreeDBCache = std::min(nBlockTreeDBCache,
-                                 (gArgs.GetBoolArg("-txindex", DEFAULT_TXINDEX)
-                                      ? nMaxBlockDBAndTxIndexCache
-                                      : nMaxBlockDBCache)
-                                     << 20);
+    int64_t nBlockTreeDBCache =
+        std::min(nTotalCache / 8, nMaxBlockDBCache << 20);
     nTotalCache -= nBlockTreeDBCache;
+    int64_t nTxIndexCache =
+        std::min(nTotalCache / 8, gArgs.GetBoolArg("-txindex", DEFAULT_TXINDEX)
+                                      ? nMaxTxIndexCache << 20
+                                      : 0);
+    nTotalCache -= nTxIndexCache;
     // 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, nMaxCoinsDBCache << 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 %.1fMiB for block index database\n",
               nBlockTreeDBCache * (1.0 / 1024 / 1024));
+    if (gArgs.GetBoolArg("-txindex", DEFAULT_TXINDEX)) {
+        LogPrintf("* Using %.1fMiB for transaction index database\n",
+                  nTxIndexCache * (1.0 / 1024 / 1024));
+    }
     LogPrintf("* Using %.1fMiB for chain state database\n",
               nCoinDBCache * (1.0 / 1024 / 1024));
     LogPrintf("* Using %.1fMiB for in-memory UTXO set (plus up to %.1fMiB of "
               "unused mempool space)\n",
               nCoinCacheUsage * (1.0 / 1024 / 1024),
               nMempoolSizeMax * (1.0 / 1024 / 1024));
 
     int64_t nStart = 0;
     bool fLoaded = false;
     while (!fLoaded && !fRequestShutdown) {
         bool fReset = fReindex;
         std::string strLoadError;
 
         uiInterface.InitMessage(_("Loading block index..."));
 
         LOCK(cs_main);
 
         nStart = GetTimeMillis();
         do {
             try {
                 UnloadBlockIndex();
                 pcoinsTip.reset();
                 pcoinsdbview.reset();
                 pcoinscatcher.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 (fRequestShutdown) {
                     break;
                 }
 
-                // LoadBlockIndex will load fTxIndex from the db, or set it if
-                // we're reindexing. It will also load fHavePruned if we've
-                // ever removed a block file from disk.
+                // 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(config)) {
                     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 (!mapBlockIndex.empty() &&
                     !LookupBlockIndex(
                         chainparams.GetConsensus().hashGenesisBlock)) {
                     return InitError(_("Incorrect or no genesis block found. "
                                        "Wrong datadir for network?"));
                 }
 
-                // Check for changed -txindex state
-                if (fTxIndex != gArgs.GetBoolArg("-txindex", DEFAULT_TXINDEX)) {
-                    strLoadError = _("You need to rebuild the database using "
-                                     "-reindex-chainstate to change -txindex");
-                    break;
-                }
-
                 // 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 mapBlockIndex!
 
                 pcoinsdbview.reset(new CCoinsViewDB(
                     nCoinDBCache, false, fReset || fReindexChainState));
                 pcoinscatcher.reset(
                     new CCoinsViewErrorCatcher(pcoinsdbview.get()));
 
                 // If necessary, upgrade from older database format.
                 // This is a no-op if we cleared the coinsviewdb with -reindex
                 // or -reindex-chainstate
                 if (!pcoinsdbview->Upgrade()) {
                     strLoadError = _("Error upgrading chainstate database");
                     break;
                 }
 
                 // ReplayBlocks is a no-op if we cleared the coinsviewdb with
                 // -reindex or -reindex-chainstate
                 if (!ReplayBlocks(config, pcoinsdbview.get())) {
                     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
                 pcoinsTip.reset(new CCoinsViewCache(pcoinscatcher.get()));
 
                 bool is_coinsview_empty = fReset || fReindexChainState ||
                                           pcoinsTip->GetBestBlock().IsNull();
                 if (!is_coinsview_empty) {
                     // LoadChainTip sets chainActive based on pcoinsTip's best
                     // block
                     if (!LoadChainTip(config)) {
                         strLoadError = _("Error initializing block database");
                         break;
                     }
                     assert(chainActive.Tip() != nullptr);
                 }
 
                 if (!fReset) {
                     // Note that RewindBlockIndex MUST run even if we're about
                     // to -reindex-chainstate. It both disconnects blocks based
                     // on chainActive, and drops block data in mapBlockIndex
                     // based on lack of available witness data.
                     uiInterface.InitMessage(_("Rewinding blocks..."));
                     if (!RewindBlockIndex(config)) {
                         strLoadError = _("Unable to rewind the database to a "
                                          "pre-fork state. You will need to "
                                          "redownload the blockchain");
                         break;
                     }
                 }
 
                 if (!is_coinsview_empty) {
                     uiInterface.InitMessage(_("Verifying blocks..."));
                     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(true, 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, pcoinsdbview.get(),
                             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;
         } while (false);
 
         if (!fLoaded && !fRequestShutdown) {
             // first suggest a reindex
             if (!fReset) {
                 bool fRet = uiInterface.ThreadSafeQuestion(
                     strLoadError + ".\n\n" +
                         _("Do you want to rebuild the block database now?"),
                     strLoadError + ".\nPlease restart with -reindex or "
                                    "-reindex-chainstate to recover.",
                     "",
                     CClientUIInterface::MSG_ERROR |
                         CClientUIInterface::BTN_ABORT);
                 if (fRet) {
                     fReindex = true;
                     fRequestShutdown = false;
                 } 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 (fRequestShutdown) {
         LogPrintf("Shutdown requested. Exiting.\n");
         return false;
     }
     LogPrintf(" block index %15dms\n", GetTimeMillis() - nStart);
 
     // Encoded addresses using cashaddr instead of base58
     // Activates by default on Jan, 14
     config.SetCashAddrEncoding(
         gArgs.GetBoolArg("-usecashaddr", GetAdjustedTime() > 1515900000));
 
-    // Step 8: load wallet
+    // Step 8: load indexers
+    if (gArgs.GetBoolArg("-txindex", DEFAULT_TXINDEX)) {
+        auto txindex_db =
+            std::make_unique<TxIndexDB>(nTxIndexCache, false, fReindex);
+        g_txindex = std::make_unique<TxIndex>(std::move(txindex_db));
+        g_txindex->Start();
+    }
+
+    // Step 9: load wallet
     if (!g_wallet_init_interface.Open(chainparams)) {
         return false;
     }
 
-    // Step 9: data directory maintenance
+    // 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..."));
             PruneAndFlush();
         }
     }
 
-    // Step 10: import blocks
+    // Step 11: import blocks
     if (!CheckDiskSpace(/* additional_bytes */ 0, /* blocks_dir */ false)) {
         InitError(
             strprintf(_("Error: Disk space is low for %s"), GetDataDir()));
         return false;
     }
     if (!CheckDiskSpace(/* additional_bytes */ 0, /* blocks_dir */ true)) {
         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.
     if (chainActive.Tip() == nullptr) {
         uiInterface.NotifyBlockTip.connect(BlockNotifyGenesisWait);
     } else {
         fHaveGenesis = true;
     }
 
     if (gArgs.IsArgSet("-blocknotify")) {
         uiInterface.NotifyBlockTip.connect(BlockNotifyCallback);
     }
 
     std::vector<fs::path> vImportFiles;
     for (const std::string &strFile : gArgs.GetArgs("-loadblock")) {
         vImportFiles.push_back(strFile);
     }
 
     threadGroup.create_thread(
         boost::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));
         }
         uiInterface.NotifyBlockTip.disconnect(BlockNotifyGenesisWait);
     }
 
     if (ShutdownRequested()) {
         return false;
     }
 
-    // Step 11: start node
+    // Step 12: start node
 
     int chain_active_height;
 
     //// debug print
     {
         LOCK(cs_main);
         LogPrintf("mapBlockIndex.size() = %u\n", mapBlockIndex.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.nMaxOutbound =
         std::min(MAX_OUTBOUND_CONNECTIONS, connOptions.nMaxConnections);
     connOptions.nMaxAddnode = MAX_ADDNODE_CONNECTIONS;
     connOptions.nMaxFeeler = 1;
     connOptions.nBestHeight = chain_active_height;
     connOptions.uiInterface = &uiInterface;
     connOptions.m_msgproc = peerLogic.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;
 
     for (const std::string &strBind : gArgs.GetArgs("-bind")) {
         CService addrBind;
         if (!Lookup(strBind.c_str(), addrBind, GetListenPort(), false)) {
             return InitError(ResolveErrMsg("bind", strBind));
         }
         connOptions.vBinds.push_back(addrBind);
     }
 
     for (const std::string &strBind : gArgs.GetArgs("-whitebind")) {
         CService addrBind;
         if (!Lookup(strBind.c_str(), addrBind, 0, false)) {
             return InitError(ResolveErrMsg("whitebind", strBind));
         }
         if (addrBind.GetPort() == 0) {
             return InitError(strprintf(
                 _("Need to specify a port with -whitebind: '%s'"), strBind));
         }
         connOptions.vWhiteBinds.push_back(addrBind);
     }
 
     for (const auto &net : gArgs.GetArgs("-whitelist")) {
         CSubNet subnet;
         LookupSubNet(net.c_str(), subnet);
         if (!subnet.IsValid()) {
             return InitError(strprintf(
                 _("Invalid netmask specified in -whitelist: '%s'"), net));
         }
         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 (!connman.Start(scheduler, connOptions)) {
         return false;
     }
 
-    // Step 12: finished
+    // Step 13: finished
 
     SetRPCWarmupFinished();
     uiInterface.InitMessage(_("Done loading"));
 
     g_wallet_init_interface.Start(scheduler);
 
     return true;
 }
diff --git a/src/rest.cpp b/src/rest.cpp
index f7920a49e2..64f8b3dbb9 100644
--- a/src/rest.cpp
+++ b/src/rest.cpp
@@ -1,700 +1,705 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <chain.h>
 #include <chainparams.h>
 #include <config.h>
 #include <core_io.h>
 #include <httpserver.h>
+#include <index/txindex.h>
 #include <primitives/block.h>
 #include <primitives/transaction.h>
 #include <rpc/blockchain.h>
 #include <rpc/server.h>
 #include <streams.h>
 #include <sync.h>
 #include <txmempool.h>
 #include <utilstrencodings.h>
 #include <validation.h>
 #include <version.h>
 
 #include <boost/algorithm/string.hpp>
 
 #include <univalue.h>
 
 // Allow a max of 15 outpoints to be queried at once.
 static const size_t MAX_GETUTXOS_OUTPOINTS = 15;
 
 enum class RetFormat {
     UNDEF,
     BINARY,
     HEX,
     JSON,
 };
 
 static const struct {
     enum RetFormat rf;
     const char *name;
 } rf_names[] = {
     {RetFormat::UNDEF, ""},
     {RetFormat::BINARY, "bin"},
     {RetFormat::HEX, "hex"},
     {RetFormat::JSON, "json"},
 };
 
 struct CCoin {
     uint32_t nHeight;
     CTxOut out;
 
     CCoin() : nHeight(0) {}
     explicit CCoin(Coin in)
         : nHeight(in.GetHeight()), out(std::move(in.GetTxOut())) {}
 
     ADD_SERIALIZE_METHODS;
 
     template <typename Stream, typename Operation>
     inline void SerializationOp(Stream &s, Operation ser_action) {
         uint32_t nTxVerDummy = 0;
         READWRITE(nTxVerDummy);
         READWRITE(nHeight);
         READWRITE(out);
     }
 };
 
 static bool RESTERR(HTTPRequest *req, enum HTTPStatusCode status,
                     std::string message) {
     req->WriteHeader("Content-Type", "text/plain");
     req->WriteReply(status, message + "\r\n");
     return false;
 }
 
 static enum RetFormat ParseDataFormat(std::string &param,
                                       const std::string &strReq) {
     const std::string::size_type pos = strReq.rfind('.');
     if (pos == std::string::npos) {
         param = strReq;
         return rf_names[0].rf;
     }
 
     param = strReq.substr(0, pos);
     const std::string suff(strReq, pos + 1);
 
     for (size_t i = 0; i < ARRAYLEN(rf_names); i++) {
         if (suff == rf_names[i].name) {
             return rf_names[i].rf;
         }
     }
 
     /* If no suffix is found, return original string.  */
     param = strReq;
     return rf_names[0].rf;
 }
 
 static std::string AvailableDataFormatsString() {
     std::string formats;
     for (size_t i = 0; i < ARRAYLEN(rf_names); i++) {
         if (strlen(rf_names[i].name) > 0) {
             formats.append(".");
             formats.append(rf_names[i].name);
             formats.append(", ");
         }
     }
 
     if (formats.length() > 0) {
         return formats.substr(0, formats.length() - 2);
     }
 
     return formats;
 }
 
 static bool ParseHashStr(const std::string &strReq, uint256 &v) {
     if (!IsHex(strReq) || (strReq.size() != 64)) {
         return false;
     }
 
     v.SetHex(strReq);
     return true;
 }
 
 static bool CheckWarmup(HTTPRequest *req) {
     std::string statusmessage;
     if (RPCIsInWarmup(&statusmessage)) {
         return RESTERR(req, HTTP_SERVICE_UNAVAILABLE,
                        "Service temporarily unavailable: " + statusmessage);
     }
 
     return true;
 }
 
 static bool rest_headers(Config &config, HTTPRequest *req,
                          const std::string &strURIPart) {
     if (!CheckWarmup(req)) {
         return false;
     }
 
     std::string param;
     const RetFormat rf = ParseDataFormat(param, strURIPart);
     std::vector<std::string> path;
     boost::split(path, param, boost::is_any_of("/"));
 
     if (path.size() != 2) {
         return RESTERR(req, HTTP_BAD_REQUEST,
                        "No header count specified. Use "
                        "/rest/headers/<count>/<hash>.<ext>.");
     }
 
     long count = strtol(path[0].c_str(), nullptr, 10);
     if (count < 1 || count > 2000) {
         return RESTERR(req, HTTP_BAD_REQUEST,
                        "Header count out of range: " + path[0]);
     }
 
     std::string hashStr = path[1];
     uint256 hash;
     if (!ParseHashStr(hashStr, hash)) {
         return RESTERR(req, HTTP_BAD_REQUEST, "Invalid hash: " + hashStr);
     }
 
     const CBlockIndex *tip = nullptr;
     std::vector<const CBlockIndex *> headers;
     headers.reserve(count);
     {
         LOCK(cs_main);
         tip = chainActive.Tip();
         const CBlockIndex *pindex = LookupBlockIndex(hash);
         while (pindex != nullptr && chainActive.Contains(pindex)) {
             headers.push_back(pindex);
             if (headers.size() == size_t(count)) {
                 break;
             }
             pindex = chainActive.Next(pindex);
         }
     }
 
     CDataStream ssHeader(SER_NETWORK, PROTOCOL_VERSION);
     for (const CBlockIndex *pindex : headers) {
         ssHeader << pindex->GetBlockHeader();
     }
 
     switch (rf) {
         case RetFormat::BINARY: {
             std::string binaryHeader = ssHeader.str();
             req->WriteHeader("Content-Type", "application/octet-stream");
             req->WriteReply(HTTP_OK, binaryHeader);
             return true;
         }
 
         case RetFormat::HEX: {
             std::string strHex =
                 HexStr(ssHeader.begin(), ssHeader.end()) + "\n";
             req->WriteHeader("Content-Type", "text/plain");
             req->WriteReply(HTTP_OK, strHex);
             return true;
         }
         case RetFormat::JSON: {
             UniValue jsonHeaders(UniValue::VARR);
             for (const CBlockIndex *pindex : headers) {
                 jsonHeaders.push_back(blockheaderToJSON(tip, pindex));
             }
             std::string strJSON = jsonHeaders.write() + "\n";
             req->WriteHeader("Content-Type", "application/json");
             req->WriteReply(HTTP_OK, strJSON);
             return true;
         }
         default: {
             return RESTERR(req, HTTP_NOT_FOUND,
                            "output format not found (available: .bin, .hex)");
         }
     }
 
     // not reached
     // continue to process further HTTP reqs on this cxn
     return true;
 }
 
 static bool rest_block(const Config &config, HTTPRequest *req,
                        const std::string &strURIPart, bool showTxDetails) {
     if (!CheckWarmup(req)) {
         return false;
     }
 
     std::string hashStr;
     const RetFormat rf = ParseDataFormat(hashStr, strURIPart);
 
     uint256 hash;
     if (!ParseHashStr(hashStr, hash)) {
         return RESTERR(req, HTTP_BAD_REQUEST, "Invalid hash: " + hashStr);
     }
 
     CBlock block;
     CBlockIndex *pblockindex = nullptr;
     CBlockIndex *tip = nullptr;
     {
         LOCK(cs_main);
         tip = chainActive.Tip();
         pblockindex = LookupBlockIndex(hash);
         if (!pblockindex) {
             return RESTERR(req, HTTP_NOT_FOUND, hashStr + " not found");
         }
 
         if (fHavePruned && !pblockindex->nStatus.hasData() &&
             pblockindex->nTx > 0) {
             return RESTERR(req, HTTP_NOT_FOUND,
                            hashStr + " not available (pruned data)");
         }
 
         if (!ReadBlockFromDisk(block, pblockindex, config)) {
             return RESTERR(req, HTTP_NOT_FOUND, hashStr + " not found");
         }
     }
 
     CDataStream ssBlock(SER_NETWORK,
                         PROTOCOL_VERSION | RPCSerializationFlags());
     ssBlock << block;
 
     switch (rf) {
         case RetFormat::BINARY: {
             std::string binaryBlock = ssBlock.str();
             req->WriteHeader("Content-Type", "application/octet-stream");
             req->WriteReply(HTTP_OK, binaryBlock);
             return true;
         }
 
         case RetFormat::HEX: {
             std::string strHex = HexStr(ssBlock.begin(), ssBlock.end()) + "\n";
             req->WriteHeader("Content-Type", "text/plain");
             req->WriteReply(HTTP_OK, strHex);
             return true;
         }
 
         case RetFormat::JSON: {
             UniValue objBlock =
                 blockToJSON(block, tip, pblockindex, showTxDetails);
             std::string strJSON = objBlock.write() + "\n";
             req->WriteHeader("Content-Type", "application/json");
             req->WriteReply(HTTP_OK, strJSON);
             return true;
         }
 
         default: {
             return RESTERR(req, HTTP_NOT_FOUND,
                            "output format not found (available: " +
                                AvailableDataFormatsString() + ")");
         }
     }
 
     // not reached
     // continue to process further HTTP reqs on this cxn
     return true;
 }
 
 static bool rest_block_extended(Config &config, HTTPRequest *req,
                                 const std::string &strURIPart) {
     return rest_block(config, req, strURIPart, true);
 }
 
 static bool rest_block_notxdetails(Config &config, HTTPRequest *req,
                                    const std::string &strURIPart) {
     return rest_block(config, req, strURIPart, false);
 }
 
 static bool rest_chaininfo(Config &config, HTTPRequest *req,
                            const std::string &strURIPart) {
     if (!CheckWarmup(req)) {
         return false;
     }
 
     std::string param;
     const RetFormat rf = ParseDataFormat(param, strURIPart);
 
     switch (rf) {
         case RetFormat::JSON: {
             JSONRPCRequest jsonRequest;
             jsonRequest.params = UniValue(UniValue::VARR);
             UniValue chainInfoObject = getblockchaininfo(config, jsonRequest);
             std::string strJSON = chainInfoObject.write() + "\n";
             req->WriteHeader("Content-Type", "application/json");
             req->WriteReply(HTTP_OK, strJSON);
             return true;
         }
         default: {
             return RESTERR(req, HTTP_NOT_FOUND,
                            "output format not found (available: json)");
         }
     }
 
     // not reached
     // continue to process further HTTP reqs on this cxn
     return true;
 }
 
 static bool rest_mempool_info(Config &config, HTTPRequest *req,
                               const std::string &strURIPart) {
     if (!CheckWarmup(req)) {
         return false;
     }
 
     std::string param;
     const RetFormat rf = ParseDataFormat(param, strURIPart);
 
     switch (rf) {
         case RetFormat::JSON: {
             UniValue mempoolInfoObject = mempoolInfoToJSON();
 
             std::string strJSON = mempoolInfoObject.write() + "\n";
             req->WriteHeader("Content-Type", "application/json");
             req->WriteReply(HTTP_OK, strJSON);
             return true;
         }
         default: {
             return RESTERR(req, HTTP_NOT_FOUND,
                            "output format not found (available: json)");
         }
     }
 
     // not reached
     // continue to process further HTTP reqs on this cxn
     return true;
 }
 
 static bool rest_mempool_contents(Config &config, HTTPRequest *req,
                                   const std::string &strURIPart) {
     if (!CheckWarmup(req)) {
         return false;
     }
 
     std::string param;
     const RetFormat rf = ParseDataFormat(param, strURIPart);
 
     switch (rf) {
         case RetFormat::JSON: {
             UniValue mempoolObject = mempoolToJSON(true);
 
             std::string strJSON = mempoolObject.write() + "\n";
             req->WriteHeader("Content-Type", "application/json");
             req->WriteReply(HTTP_OK, strJSON);
             return true;
         }
         default: {
             return RESTERR(req, HTTP_NOT_FOUND,
                            "output format not found (available: json)");
         }
     }
 
     // not reached
     // continue to process further HTTP reqs on this cxn
     return true;
 }
 
 static bool rest_tx(Config &config, HTTPRequest *req,
                     const std::string &strURIPart) {
     if (!CheckWarmup(req)) {
         return false;
     }
 
     std::string hashStr;
     const RetFormat rf = ParseDataFormat(hashStr, strURIPart);
 
     uint256 hash;
     if (!ParseHashStr(hashStr, hash)) {
         return RESTERR(req, HTTP_BAD_REQUEST, "Invalid hash: " + hashStr);
     }
 
     const TxId txid(hash);
 
+    if (g_txindex) {
+        g_txindex->BlockUntilSyncedToCurrentChain();
+    }
+
     CTransactionRef tx;
     uint256 hashBlock = uint256();
     if (!GetTransaction(config, txid, tx, hashBlock, true)) {
         return RESTERR(req, HTTP_NOT_FOUND, hashStr + " not found");
     }
 
     CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION | RPCSerializationFlags());
     ssTx << tx;
 
     switch (rf) {
         case RetFormat::BINARY: {
             std::string binaryTx = ssTx.str();
             req->WriteHeader("Content-Type", "application/octet-stream");
             req->WriteReply(HTTP_OK, binaryTx);
             return true;
         }
 
         case RetFormat::HEX: {
             std::string strHex = HexStr(ssTx.begin(), ssTx.end()) + "\n";
             req->WriteHeader("Content-Type", "text/plain");
             req->WriteReply(HTTP_OK, strHex);
             return true;
         }
 
         case RetFormat::JSON: {
             UniValue objTx(UniValue::VOBJ);
             TxToUniv(*tx, hashBlock, objTx);
             std::string strJSON = objTx.write() + "\n";
             req->WriteHeader("Content-Type", "application/json");
             req->WriteReply(HTTP_OK, strJSON);
             return true;
         }
 
         default: {
             return RESTERR(req, HTTP_NOT_FOUND,
                            "output format not found (available: " +
                                AvailableDataFormatsString() + ")");
         }
     }
 
     // not reached
     // continue to process further HTTP reqs on this cxn
     return true;
 }
 
 static bool rest_getutxos(Config &config, HTTPRequest *req,
                           const std::string &strURIPart) {
     if (!CheckWarmup(req)) {
         return false;
     }
 
     std::string param;
     const RetFormat rf = ParseDataFormat(param, strURIPart);
 
     std::vector<std::string> uriParts;
     if (param.length() > 1) {
         std::string strUriParams = param.substr(1);
         boost::split(uriParts, strUriParams, boost::is_any_of("/"));
     }
 
     // throw exception in case of a empty request
     std::string strRequestMutable = req->ReadBody();
     if (strRequestMutable.length() == 0 && uriParts.size() == 0) {
         return RESTERR(req, HTTP_BAD_REQUEST, "Error: empty request");
     }
 
     bool fInputParsed = false;
     bool fCheckMemPool = false;
     std::vector<COutPoint> vOutPoints;
 
     // parse/deserialize input
     // input-format = output-format, rest/getutxos/bin requires binary input,
     // gives binary output, ...
 
     if (uriParts.size() > 0) {
         // inputs is sent over URI scheme
         // (/rest/getutxos/checkmempool/txid1-n/txid2-n/...)
         if (uriParts[0] == "checkmempool") {
             fCheckMemPool = true;
         }
 
         for (size_t i = (fCheckMemPool) ? 1 : 0; i < uriParts.size(); i++) {
             uint256 txid;
             int32_t nOutput;
             std::string strTxid = uriParts[i].substr(0, uriParts[i].find("-"));
             std::string strOutput =
                 uriParts[i].substr(uriParts[i].find("-") + 1);
 
             if (!ParseInt32(strOutput, &nOutput) || !IsHex(strTxid)) {
                 return RESTERR(req, HTTP_BAD_REQUEST, "Parse error");
             }
 
             txid.SetHex(strTxid);
             vOutPoints.push_back(COutPoint(txid, (uint32_t)nOutput));
         }
 
         if (vOutPoints.size() > 0) {
             fInputParsed = true;
         } else {
             return RESTERR(req, HTTP_BAD_REQUEST, "Error: empty request");
         }
     }
 
     switch (rf) {
         case RetFormat::HEX: {
             // convert hex to bin, continue then with bin part
             std::vector<uint8_t> strRequestV = ParseHex(strRequestMutable);
             strRequestMutable.assign(strRequestV.begin(), strRequestV.end());
         }
         // FALLTHROUGH
         case RetFormat::BINARY: {
             try {
                 // deserialize only if user sent a request
                 if (strRequestMutable.size() > 0) {
                     // don't allow sending input over URI and HTTP RAW DATA
                     if (fInputParsed) {
                         return RESTERR(req, HTTP_BAD_REQUEST,
                                        "Combination of URI scheme inputs and "
                                        "raw post data is not allowed");
                     }
 
                     CDataStream oss(SER_NETWORK, PROTOCOL_VERSION);
                     oss << strRequestMutable;
                     oss >> fCheckMemPool;
                     oss >> vOutPoints;
                 }
             } catch (const std::ios_base::failure &e) {
                 // abort in case of unreadable binary data
                 return RESTERR(req, HTTP_BAD_REQUEST, "Parse error");
             }
             break;
         }
 
         case RetFormat::JSON: {
             if (!fInputParsed) {
                 return RESTERR(req, HTTP_BAD_REQUEST, "Error: empty request");
             }
             break;
         }
         default: {
             return RESTERR(req, HTTP_NOT_FOUND,
                            "output format not found (available: " +
                                AvailableDataFormatsString() + ")");
         }
     }
 
     // limit max outpoints
     if (vOutPoints.size() > MAX_GETUTXOS_OUTPOINTS) {
         return RESTERR(
             req, HTTP_BAD_REQUEST,
             strprintf("Error: max outpoints exceeded (max: %d, tried: %d)",
                       MAX_GETUTXOS_OUTPOINTS, vOutPoints.size()));
     }
 
     // check spentness and form a bitmap (as well as a JSON capable
     // human-readable string representation)
     std::vector<uint8_t> bitmap;
     std::vector<CCoin> outs;
     std::string bitmapStringRepresentation;
     std::vector<bool> hits;
     bitmap.resize((vOutPoints.size() + 7) / 8);
     {
         LOCK2(cs_main, g_mempool.cs);
 
         CCoinsView viewDummy;
         CCoinsViewCache view(&viewDummy);
 
         CCoinsViewCache &viewChain = *pcoinsTip;
         CCoinsViewMemPool viewMempool(&viewChain, g_mempool);
 
         if (fCheckMemPool) {
             // switch cache backend to db+mempool in case user likes to query
             // mempool.
             view.SetBackend(viewMempool);
         }
 
         for (size_t i = 0; i < vOutPoints.size(); i++) {
             Coin coin;
             bool hit = false;
             if (view.GetCoin(vOutPoints[i], coin) &&
                 !g_mempool.isSpent(vOutPoints[i])) {
                 hit = true;
                 outs.emplace_back(std::move(coin));
             }
 
             hits.push_back(hit);
             // form a binary string representation (human-readable for json
             // output)
             bitmapStringRepresentation.append(hit ? "1" : "0");
             bitmap[i / 8] |= ((uint8_t)hit) << (i % 8);
         }
     }
 
     switch (rf) {
         case RetFormat::BINARY: {
             // serialize data
             // use exact same output as mentioned in Bip64
             CDataStream ssGetUTXOResponse(SER_NETWORK, PROTOCOL_VERSION);
             ssGetUTXOResponse << chainActive.Height()
                               << chainActive.Tip()->GetBlockHash() << bitmap
                               << outs;
             std::string ssGetUTXOResponseString = ssGetUTXOResponse.str();
 
             req->WriteHeader("Content-Type", "application/octet-stream");
             req->WriteReply(HTTP_OK, ssGetUTXOResponseString);
             return true;
         }
 
         case RetFormat::HEX: {
             CDataStream ssGetUTXOResponse(SER_NETWORK, PROTOCOL_VERSION);
             ssGetUTXOResponse << chainActive.Height()
                               << chainActive.Tip()->GetBlockHash() << bitmap
                               << outs;
             std::string strHex =
                 HexStr(ssGetUTXOResponse.begin(), ssGetUTXOResponse.end()) +
                 "\n";
 
             req->WriteHeader("Content-Type", "text/plain");
             req->WriteReply(HTTP_OK, strHex);
             return true;
         }
 
         case RetFormat::JSON: {
             UniValue objGetUTXOResponse(UniValue::VOBJ);
 
             // pack in some essentials
             // use more or less the same output as mentioned in Bip64
             objGetUTXOResponse.pushKV("chainHeight", chainActive.Height());
             objGetUTXOResponse.pushKV(
                 "chaintipHash", chainActive.Tip()->GetBlockHash().GetHex());
             objGetUTXOResponse.pushKV("bitmap", bitmapStringRepresentation);
 
             UniValue utxos(UniValue::VARR);
             for (const CCoin &coin : outs) {
                 UniValue utxo(UniValue::VOBJ);
                 utxo.pushKV("height", int32_t(coin.nHeight));
                 utxo.pushKV("value", ValueFromAmount(coin.out.nValue));
 
                 // include the script in a json output
                 UniValue o(UniValue::VOBJ);
                 ScriptPubKeyToUniv(coin.out.scriptPubKey, o, true);
                 utxo.pushKV("scriptPubKey", o);
                 utxos.push_back(utxo);
             }
             objGetUTXOResponse.pushKV("utxos", utxos);
 
             // return json string
             std::string strJSON = objGetUTXOResponse.write() + "\n";
             req->WriteHeader("Content-Type", "application/json");
             req->WriteReply(HTTP_OK, strJSON);
             return true;
         }
         default: {
             return RESTERR(req, HTTP_NOT_FOUND,
                            "output format not found (available: " +
                                AvailableDataFormatsString() + ")");
         }
     }
 
     // not reached
     // continue to process further HTTP reqs on this cxn
     return true;
 }
 
 static const struct {
     const char *prefix;
     bool (*handler)(Config &config, HTTPRequest *req,
                     const std::string &strReq);
 } uri_prefixes[] = {
     {"/rest/tx/", rest_tx},
     {"/rest/block/notxdetails/", rest_block_notxdetails},
     {"/rest/block/", rest_block_extended},
     {"/rest/chaininfo", rest_chaininfo},
     {"/rest/mempool/info", rest_mempool_info},
     {"/rest/mempool/contents", rest_mempool_contents},
     {"/rest/headers/", rest_headers},
     {"/rest/getutxos", rest_getutxos},
 };
 
 bool StartREST() {
     for (size_t i = 0; i < ARRAYLEN(uri_prefixes); i++) {
         RegisterHTTPHandler(uri_prefixes[i].prefix, false,
                             uri_prefixes[i].handler);
     }
 
     return true;
 }
 
 void InterruptREST() {}
 
 void StopREST() {
     for (size_t i = 0; i < ARRAYLEN(uri_prefixes); i++) {
         UnregisterHTTPHandler(uri_prefixes[i].prefix, false);
     }
 }
diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index 653c095050..d86ea39510 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -1,1456 +1,1476 @@
 // Copyright (c) 2010 Satoshi Nakamoto
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <base58.h>
 #include <chain.h>
 #include <coins.h>
 #include <config.h>
 #include <consensus/validation.h>
 #include <core_io.h>
 #include <dstencode.h>
+#include <index/txindex.h>
 #include <init.h>
 #include <keystore.h>
 #include <merkleblock.h>
 #include <net.h>
 #include <policy/policy.h>
 #include <primitives/transaction.h>
 #include <rpc/rawtransaction.h>
 #include <rpc/server.h>
 #include <script/script.h>
 #include <script/script_error.h>
 #include <script/sign.h>
 #include <script/standard.h>
 #include <txmempool.h>
 #include <uint256.h>
 #include <utilstrencodings.h>
 #include <validation.h>
 #ifdef ENABLE_WALLET
 #include <wallet/rpcwallet.h>
 #endif
 
 #include <cstdint>
 
 #include <univalue.h>
 
 static void TxToJSON(const CTransaction &tx, const uint256 hashBlock,
                      UniValue &entry) {
     // Call into TxToUniv() in bitcoin-common to decode the transaction hex.
     //
     // Blockchain contextual information (confirmations and blocktime) is not
     // available to code in bitcoin-common, so we query them here and push the
     // data into the returned UniValue.
     TxToUniv(tx, uint256(), entry, true, RPCSerializationFlags());
 
     if (!hashBlock.IsNull()) {
+        LOCK(cs_main);
+
         entry.pushKV("blockhash", hashBlock.GetHex());
         CBlockIndex *pindex = LookupBlockIndex(hashBlock);
         if (pindex) {
             if (chainActive.Contains(pindex)) {
                 entry.pushKV("confirmations",
                              1 + chainActive.Height() - pindex->nHeight);
                 entry.pushKV("time", pindex->GetBlockTime());
                 entry.pushKV("blocktime", pindex->GetBlockTime());
             } else {
                 entry.pushKV("confirmations", 0);
             }
         }
     }
 }
 
 static UniValue getrawtransaction(const Config &config,
                                   const JSONRPCRequest &request) {
     if (request.fHelp || request.params.size() < 1 ||
         request.params.size() > 3) {
         throw std::runtime_error(
             "getrawtransaction \"txid\" ( verbose \"blockhash\" )\n"
 
             "\nNOTE: By default this function only works for mempool "
             "transactions. If the -txindex option is\n"
             "enabled, it also works for blockchain transactions. If the block "
             "which contains the transaction\n"
             "is known, its hash can be provided even for nodes without "
             "-txindex. Note that if a blockhash is\n"
             "provided, only that block will be searched and if the transaction "
             "is in the mempool or other\n"
             "blocks, or if this node does not have the given block available, "
             "the transaction will not be found.\n"
             "DEPRECATED: for now, it also works for transactions with unspent "
             "outputs.\n"
 
             "\nReturn the raw transaction data.\n"
             "\nIf verbose is 'true', returns an Object with information about "
             "'txid'.\n"
             "If verbose is 'false' or omitted, returns a string that is "
             "serialized, hex-encoded data for 'txid'.\n"
 
             "\nArguments:\n"
             "1. \"txid\"      (string, required) The transaction id\n"
             "2. verbose     (bool, optional, default=false) If false, return a "
             "string, otherwise return a json object\n"
             "3. \"blockhash\" (string, optional) The block in which to look "
             "for the transaction\n"
 
             "\nResult (if verbose is not set or set to false):\n"
             "\"data\"      (string) The serialized, hex-encoded data for "
             "'txid'\n"
 
             "\nResult (if verbose is set to true):\n"
             "{\n"
             "  \"in_active_chain\": b, (bool) Whether specified block is in "
             "the active chain or not (only present with explicit \"blockhash\" "
             "argument)\n"
             "  \"hex\" : \"data\",       (string) The serialized, hex-encoded "
             "data for 'txid'\n"
             "  \"txid\" : \"id\",        (string) The transaction id (same as "
             "provided)\n"
             "  \"hash\" : \"id\",        (string) The transaction hash "
             "(differs from txid for witness transactions)\n"
             "  \"size\" : n,             (numeric) The serialized transaction "
             "size\n"
             "  \"version\" : n,          (numeric) The version\n"
             "  \"locktime\" : ttt,       (numeric) The lock time\n"
             "  \"vin\" : [               (array of json objects)\n"
             "     {\n"
             "       \"txid\": \"id\",    (string) The transaction id\n"
             "       \"vout\": n,         (numeric) \n"
             "       \"scriptSig\": {     (json object) The script\n"
             "         \"asm\": \"asm\",  (string) asm\n"
             "         \"hex\": \"hex\"   (string) hex\n"
             "       },\n"
             "       \"sequence\": n      (numeric) The script sequence number\n"
             "     }\n"
             "     ,...\n"
             "  ],\n"
             "  \"vout\" : [              (array of json objects)\n"
             "     {\n"
             "       \"value\" : x.xxx,            (numeric) The value in " +
             CURRENCY_UNIT +
             "\n"
             "       \"n\" : n,                    (numeric) index\n"
             "       \"scriptPubKey\" : {          (json object)\n"
             "         \"asm\" : \"asm\",          (string) the asm\n"
             "         \"hex\" : \"hex\",          (string) the hex\n"
             "         \"reqSigs\" : n,            (numeric) The required sigs\n"
             "         \"type\" : \"pubkeyhash\",  (string) The type, eg "
             "'pubkeyhash'\n"
             "         \"addresses\" : [           (json array of string)\n"
             "           \"address\"        (string) bitcoin address\n"
             "           ,...\n"
             "         ]\n"
             "       }\n"
             "     }\n"
             "     ,...\n"
             "  ],\n"
             "  \"blockhash\" : \"hash\",   (string) the block hash\n"
             "  \"confirmations\" : n,      (numeric) The confirmations\n"
             "  \"time\" : ttt,             (numeric) The transaction time in "
             "seconds since epoch (Jan 1 1970 GMT)\n"
             "  \"blocktime\" : ttt         (numeric) The block time in seconds "
             "since epoch (Jan 1 1970 GMT)\n"
             "}\n"
 
             "\nExamples:\n" +
             HelpExampleCli("getrawtransaction", "\"mytxid\"") +
             HelpExampleCli("getrawtransaction", "\"mytxid\" true") +
             HelpExampleRpc("getrawtransaction", "\"mytxid\", true") +
             HelpExampleCli("getrawtransaction",
                            "\"mytxid\" false \"myblockhash\"") +
             HelpExampleCli("getrawtransaction",
                            "\"mytxid\" true \"myblockhash\""));
     }
 
-    LOCK(cs_main);
-
     bool in_active_chain = true;
     TxId txid = TxId(ParseHashV(request.params[0], "parameter 1"));
     CBlockIndex *blockindex = nullptr;
 
     if (txid == config.GetChainParams().GenesisBlock().hashMerkleRoot) {
         // Special exception for the genesis block coinbase transaction
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY,
                            "The genesis block coinbase is not considered an "
                            "ordinary transaction and cannot be retrieved");
     }
 
     // Accept either a bool (true) or a num (>=1) to indicate verbose output.
     bool fVerbose = false;
     if (!request.params[1].isNull()) {
         fVerbose = request.params[1].isNum()
                        ? (request.params[1].get_int() != 0)
                        : request.params[1].get_bool();
     }
 
     if (!request.params[2].isNull()) {
+        LOCK(cs_main);
+
         uint256 blockhash = ParseHashV(request.params[2], "parameter 3");
         blockindex = LookupBlockIndex(blockhash);
         if (!blockindex) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY,
                                "Block hash not found");
         }
         in_active_chain = chainActive.Contains(blockindex);
     }
 
+    bool f_txindex_ready = false;
+    if (g_txindex && !blockindex) {
+        f_txindex_ready = g_txindex->BlockUntilSyncedToCurrentChain();
+    }
+
     CTransactionRef tx;
     uint256 hash_block;
     if (!GetTransaction(config, txid, tx, hash_block, true, blockindex)) {
         std::string errmsg;
         if (blockindex) {
             if (!blockindex->nStatus.hasData()) {
                 throw JSONRPCError(RPC_MISC_ERROR, "Block not available");
             }
             errmsg = "No such transaction found in the provided block";
+        } else if (!g_txindex) {
+            errmsg = "No such mempool transaction. Use -txindex to enable "
+                     "blockchain transaction queries";
+        } else if (!f_txindex_ready) {
+            errmsg = "No such mempool transaction. Blockchain transactions are "
+                     "still in the process of being indexed";
         } else {
-            errmsg = fTxIndex ? "No such mempool or blockchain transaction"
-                              : "No such mempool transaction. Use -txindex to "
-                                "enable blockchain transaction queries";
+            errmsg = "No such mempool or blockchain transaction";
         }
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY,
                            errmsg +
                                ". Use gettransaction for wallet transactions.");
     }
 
     if (!fVerbose) {
         return EncodeHexTx(*tx, RPCSerializationFlags());
     }
 
     UniValue result(UniValue::VOBJ);
     if (blockindex) {
         result.pushKV("in_active_chain", in_active_chain);
     }
     TxToJSON(*tx, hash_block, result);
     return result;
 }
 
 static UniValue gettxoutproof(const Config &config,
                               const JSONRPCRequest &request) {
     if (request.fHelp ||
         (request.params.size() != 1 && request.params.size() != 2)) {
         throw std::runtime_error(
             "gettxoutproof [\"txid\",...] ( blockhash )\n"
             "\nReturns a hex-encoded proof that \"txid\" was included in a "
             "block.\n"
             "\nNOTE: By default this function only works sometimes. This is "
             "when there is an\n"
             "unspent output in the utxo for this transaction. To make it "
             "always work,\n"
             "you need to maintain a transaction index, using the -txindex "
             "command line option or\n"
             "specify the block in which the transaction is included manually "
             "(by blockhash).\n"
             "\nArguments:\n"
             "1. \"txids\"       (string) A json array of txids to filter\n"
             "    [\n"
             "      \"txid\"     (string) A transaction hash\n"
             "      ,...\n"
             "    ]\n"
             "2. \"blockhash\"   (string, optional) If specified, looks for "
             "txid in the block with this hash\n"
             "\nResult:\n"
             "\"data\"           (string) A string that is a serialized, "
             "hex-encoded data for the proof.\n");
     }
 
     std::set<TxId> setTxIds;
     TxId oneTxId;
     UniValue txids = request.params[0].get_array();
     for (unsigned int idx = 0; idx < txids.size(); idx++) {
         const UniValue &utxid = txids[idx];
         if (utxid.get_str().length() != 64 || !IsHex(utxid.get_str())) {
             throw JSONRPCError(RPC_INVALID_PARAMETER,
                                std::string("Invalid txid ") + utxid.get_str());
         }
 
         TxId txid(uint256S(utxid.get_str()));
         if (setTxIds.count(txid)) {
             throw JSONRPCError(
                 RPC_INVALID_PARAMETER,
                 std::string("Invalid parameter, duplicated txid: ") +
                     utxid.get_str());
         }
 
         setTxIds.insert(txid);
         oneTxId = txid;
     }
 
-    LOCK(cs_main);
-
     CBlockIndex *pblockindex = nullptr;
 
     uint256 hashBlock;
     if (!request.params[1].isNull()) {
+        LOCK(cs_main);
         hashBlock = uint256S(request.params[1].get_str());
         pblockindex = LookupBlockIndex(hashBlock);
         if (!pblockindex) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found");
         }
     } else {
+        LOCK(cs_main);
         // Loop through txids and try to find which block they're in. Exit loop
         // once a block is found.
         for (const auto &txid : setTxIds) {
             const Coin &coin = AccessByTxid(*pcoinsTip, txid);
             if (!coin.IsSpent()) {
                 pblockindex = chainActive[coin.GetHeight()];
                 break;
             }
         }
     }
 
+    // Allow txindex to catch up if we need to query it and before we acquire
+    // cs_main.
+    if (g_txindex && !pblockindex) {
+        g_txindex->BlockUntilSyncedToCurrentChain();
+    }
+
+    LOCK(cs_main);
+
     if (pblockindex == nullptr) {
         CTransactionRef tx;
         if (!GetTransaction(config, oneTxId, tx, hashBlock, false) ||
             hashBlock.IsNull()) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY,
                                "Transaction not yet in block");
         }
 
         pblockindex = LookupBlockIndex(hashBlock);
         if (!pblockindex) {
             throw JSONRPCError(RPC_INTERNAL_ERROR, "Transaction index corrupt");
         }
     }
 
     CBlock block;
     if (!ReadBlockFromDisk(block, pblockindex, config)) {
         throw JSONRPCError(RPC_INTERNAL_ERROR, "Can't read block from disk");
     }
 
     unsigned int ntxFound = 0;
     for (const auto &tx : block.vtx) {
         if (setTxIds.count(tx->GetId())) {
             ntxFound++;
         }
     }
 
     if (ntxFound != setTxIds.size()) {
         throw JSONRPCError(
             RPC_INVALID_ADDRESS_OR_KEY,
             "Not all transactions found in specified or retrieved block");
     }
 
     CDataStream ssMB(SER_NETWORK, PROTOCOL_VERSION);
     CMerkleBlock mb(block, setTxIds);
     ssMB << mb;
     std::string strHex = HexStr(ssMB.begin(), ssMB.end());
     return strHex;
 }
 
 static UniValue verifytxoutproof(const Config &config,
                                  const JSONRPCRequest &request) {
     if (request.fHelp || request.params.size() != 1) {
         throw std::runtime_error(
             "verifytxoutproof \"proof\"\n"
             "\nVerifies that a proof points to a transaction in a block, "
             "returning the transaction it commits to\n"
             "and throwing an RPC error if the block is not in our best chain\n"
             "\nArguments:\n"
             "1. \"proof\"    (string, required) The hex-encoded proof "
             "generated by gettxoutproof\n"
             "\nResult:\n"
             "[\"txid\"]      (array, strings) The txid(s) which the proof "
             "commits to, or empty array if the proof is invalid\n");
     }
 
     CDataStream ssMB(ParseHexV(request.params[0], "proof"), SER_NETWORK,
                      PROTOCOL_VERSION);
     CMerkleBlock merkleBlock;
     ssMB >> merkleBlock;
 
     UniValue res(UniValue::VARR);
 
     std::vector<uint256> vMatch;
     std::vector<unsigned int> vIndex;
     if (merkleBlock.txn.ExtractMatches(vMatch, vIndex) !=
         merkleBlock.header.hashMerkleRoot) {
         return res;
     }
 
     LOCK(cs_main);
 
     const CBlockIndex *pindex = LookupBlockIndex(merkleBlock.header.GetHash());
     if (!pindex || !chainActive.Contains(pindex)) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY,
                            "Block not found in chain");
     }
 
     for (const uint256 &hash : vMatch) {
         res.push_back(hash.GetHex());
     }
 
     return res;
 }
 
 static UniValue createrawtransaction(const Config &config,
                                      const JSONRPCRequest &request) {
     if (request.fHelp || request.params.size() < 2 ||
         request.params.size() > 3) {
         throw std::runtime_error(
             // clang-format off
             "createrawtransaction [{\"txid\":\"id\",\"vout\":n},...] [{\"address\":amount},{\"data\":\"hex\"},...] ( locktime )\n"
             "\nCreate a transaction spending the given inputs and creating new outputs.\n"
             "Outputs can be addresses or data.\n"
             "Returns hex-encoded raw transaction.\n"
             "Note that the transaction's inputs are not signed, and\n"
             "it is not stored in the wallet or transmitted to the network.\n"
 
             "\nArguments:\n"
             "1. \"inputs\"                (array, required) A json array of "
             "json objects\n"
             "     [\n"
             "       {\n"
             "         \"txid\":\"id\",      (string, required) The transaction id\n"
             "         \"vout\":n,         (numeric, required) The output number\n"
             "         \"sequence\":n      (numeric, optional) The sequence number\n"
             "       } \n"
             "       ,...\n"
             "     ]\n"
             "2. \"outputs\"               (array, required) a json array with outputs (key-value pairs)\n"
             "   [\n"
             "    {\n"
             "      \"address\": x.xxx,    (obj, optional) A key-value pair. The key (string) is the bitcoin address, the value (float or string) is the amount in " + CURRENCY_UNIT + "\n"
             "    },\n"
             "    {\n"
             "      \"data\": \"hex\"        (obj, optional) A key-value pair. The key must be \"data\", the value is hex encoded data\n"
             "    }\n"
             "    ,...                     More key-value pairs of the above form. For compatibility reasons, a dictionary, which holds the key-value pairs directly, is also\n"
             "                             accepted as second parameter.\n"
             "   ]\n"
             "3. locktime                  (numeric, optional, default=0) Raw locktime. Non-0 value also locktime-activates inputs\n"
             "\nResult:\n"
             "\"transaction\"              (string) hex string of the transaction\n"
 
             "\nExamples:\n"
             + HelpExampleCli("createrawtransaction", "\"[{\\\"txid\\\":\\\"myid\\\",\\\"vout\\\":0}]\" \"[{\\\"address\\\":0.01}]\"")
             + HelpExampleCli("createrawtransaction", "\"[{\\\"txid\\\":\\\"myid\\\",\\\"vout\\\":0}]\" \"[{\\\"data\\\":\\\"00010203\\\"}]\"")
             + HelpExampleRpc("createrawtransaction", "\"[{\\\"txid\\\":\\\"myid\\\",\\\"vout\\\":0}]\", \"[{\\\"address\\\":0.01}]\"")
             + HelpExampleRpc("createrawtransaction", "\"[{\\\"txid\\\":\\\"myid\\\",\\\"vout\\\":0}]\", \"[{\\\"data\\\":\\\"00010203\\\"}]\"")
             // clang-format on
         );
     }
 
     RPCTypeCheck(request.params,
                  {UniValue::VARR,
                   UniValueType(), // ARR or OBJ, checked later
                   UniValue::VNUM, UniValue::VBOOL},
                  true);
     if (request.params[0].isNull() || request.params[1].isNull()) {
         throw JSONRPCError(
             RPC_INVALID_PARAMETER,
             "Invalid parameter, arguments 1 and 2 must be non-null");
     }
 
     UniValue inputs = request.params[0].get_array();
     const bool outputs_is_obj = request.params[1].isObject();
     UniValue outputs = outputs_is_obj ? request.params[1].get_obj()
                                       : request.params[1].get_array();
 
     CMutableTransaction rawTx;
 
     if (request.params.size() > 2 && !request.params[2].isNull()) {
         int64_t nLockTime = request.params[2].get_int64();
         if (nLockTime < 0 || nLockTime > std::numeric_limits<uint32_t>::max()) {
             throw JSONRPCError(RPC_INVALID_PARAMETER,
                                "Invalid parameter, locktime out of range");
         }
 
         rawTx.nLockTime = nLockTime;
     }
 
     for (size_t idx = 0; idx < inputs.size(); idx++) {
         const UniValue &input = inputs[idx];
         const UniValue &o = input.get_obj();
 
         uint256 txid = ParseHashO(o, "txid");
 
         const UniValue &vout_v = find_value(o, "vout");
         if (vout_v.isNull()) {
             throw JSONRPCError(RPC_INVALID_PARAMETER,
                                "Invalid parameter, missing vout key");
         }
 
         if (!vout_v.isNum()) {
             throw JSONRPCError(RPC_INVALID_PARAMETER,
                                "Invalid parameter, vout must be a number");
         }
 
         int nOutput = vout_v.get_int();
         if (nOutput < 0) {
             throw JSONRPCError(RPC_INVALID_PARAMETER,
                                "Invalid parameter, vout must be positive");
         }
 
         uint32_t nSequence =
             (rawTx.nLockTime ? std::numeric_limits<uint32_t>::max() - 1
                              : std::numeric_limits<uint32_t>::max());
 
         // Set the sequence number if passed in the parameters object.
         const UniValue &sequenceObj = find_value(o, "sequence");
         if (sequenceObj.isNum()) {
             int64_t seqNr64 = sequenceObj.get_int64();
             if (seqNr64 < 0 || seqNr64 > std::numeric_limits<uint32_t>::max()) {
                 throw JSONRPCError(
                     RPC_INVALID_PARAMETER,
                     "Invalid parameter, sequence number is out of range");
             }
 
             nSequence = uint32_t(seqNr64);
         }
 
         CTxIn in(COutPoint(txid, nOutput), CScript(), nSequence);
         rawTx.vin.push_back(in);
     }
 
     std::set<CTxDestination> destinations;
     if (!outputs_is_obj) {
         // Translate array of key-value pairs into dict
         UniValue outputs_dict = UniValue(UniValue::VOBJ);
         for (size_t i = 0; i < outputs.size(); ++i) {
             const UniValue &output = outputs[i];
             if (!output.isObject()) {
                 throw JSONRPCError(RPC_INVALID_PARAMETER,
                                    "Invalid parameter, key-value pair not an "
                                    "object as expected");
             }
             if (output.size() != 1) {
                 throw JSONRPCError(RPC_INVALID_PARAMETER,
                                    "Invalid parameter, key-value pair must "
                                    "contain exactly one key");
             }
             outputs_dict.pushKVs(output);
         }
         outputs = std::move(outputs_dict);
     }
     for (const std::string &name_ : outputs.getKeys()) {
         if (name_ == "data") {
             std::vector<uint8_t> data =
                 ParseHexV(outputs[name_].getValStr(), "Data");
 
             CTxOut out(Amount::zero(), CScript() << OP_RETURN << data);
             rawTx.vout.push_back(out);
         } else {
             CTxDestination destination =
                 DecodeDestination(name_, config.GetChainParams());
             if (!IsValidDestination(destination)) {
                 throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY,
                                    std::string("Invalid Bitcoin address: ") +
                                        name_);
             }
 
             if (!destinations.insert(destination).second) {
                 throw JSONRPCError(
                     RPC_INVALID_PARAMETER,
                     std::string("Invalid parameter, duplicated address: ") +
                         name_);
             }
 
             CScript scriptPubKey = GetScriptForDestination(destination);
             Amount nAmount = AmountFromValue(outputs[name_]);
 
             CTxOut out(nAmount, scriptPubKey);
             rawTx.vout.push_back(out);
         }
     }
 
     return EncodeHexTx(CTransaction(rawTx));
 }
 
 static UniValue decoderawtransaction(const Config &config,
                                      const JSONRPCRequest &request) {
     if (request.fHelp || request.params.size() != 1) {
         throw std::runtime_error(
             "decoderawtransaction \"hexstring\"\n"
             "\nReturn a JSON object representing the serialized, hex-encoded "
             "transaction.\n"
 
             "\nArguments:\n"
             "1. \"hexstring\"      (string, required) The transaction hex "
             "string\n"
 
             "\nResult:\n"
             "{\n"
             "  \"txid\" : \"id\",        (string) The transaction id\n"
             "  \"hash\" : \"id\",        (string) The transaction hash "
             "(differs from txid for witness transactions)\n"
             "  \"size\" : n,             (numeric) The transaction size\n"
             "  \"version\" : n,          (numeric) The version\n"
             "  \"locktime\" : ttt,       (numeric) The lock time\n"
             "  \"vin\" : [               (array of json objects)\n"
             "     {\n"
             "       \"txid\": \"id\",    (string) The transaction id\n"
             "       \"vout\": n,         (numeric) The output number\n"
             "       \"scriptSig\": {     (json object) The script\n"
             "         \"asm\": \"asm\",  (string) asm\n"
             "         \"hex\": \"hex\"   (string) hex\n"
             "       },\n"
             "       \"sequence\": n     (numeric) The script sequence number\n"
             "     }\n"
             "     ,...\n"
             "  ],\n"
             "  \"vout\" : [             (array of json objects)\n"
             "     {\n"
             "       \"value\" : x.xxx,            (numeric) The value in " +
             CURRENCY_UNIT +
             "\n"
             "       \"n\" : n,                    (numeric) index\n"
             "       \"scriptPubKey\" : {          (json object)\n"
             "         \"asm\" : \"asm\",          (string) the asm\n"
             "         \"hex\" : \"hex\",          (string) the hex\n"
             "         \"reqSigs\" : n,            (numeric) The required sigs\n"
             "         \"type\" : \"pubkeyhash\",  (string) The type, eg "
             "'pubkeyhash'\n"
             "         \"addresses\" : [           (json array of string)\n"
             "           \"12tvKAXCxZjSmdNbao16dKXC8tRWfcF5oc\"   (string) "
             "bitcoin address\n"
             "           ,...\n"
             "         ]\n"
             "       }\n"
             "     }\n"
             "     ,...\n"
             "  ],\n"
             "}\n"
 
             "\nExamples:\n" +
             HelpExampleCli("decoderawtransaction", "\"hexstring\"") +
             HelpExampleRpc("decoderawtransaction", "\"hexstring\""));
     }
 
     LOCK(cs_main);
     RPCTypeCheck(request.params, {UniValue::VSTR});
 
     CMutableTransaction mtx;
 
     if (!DecodeHexTx(mtx, request.params[0].get_str())) {
         throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "TX decode failed");
     }
 
     UniValue result(UniValue::VOBJ);
     TxToUniv(CTransaction(std::move(mtx)), uint256(), result, false);
 
     return result;
 }
 
 static UniValue decodescript(const Config &config,
                              const JSONRPCRequest &request) {
     if (request.fHelp || request.params.size() != 1) {
         throw std::runtime_error(
             "decodescript \"hexstring\"\n"
             "\nDecode a hex-encoded script.\n"
             "\nArguments:\n"
             "1. \"hexstring\"     (string) the hex encoded script\n"
             "\nResult:\n"
             "{\n"
             "  \"asm\":\"asm\",   (string) Script public key\n"
             "  \"hex\":\"hex\",   (string) hex encoded public key\n"
             "  \"type\":\"type\", (string) The output type\n"
             "  \"reqSigs\": n,    (numeric) The required signatures\n"
             "  \"addresses\": [   (json array of string)\n"
             "     \"address\"     (string) bitcoin address\n"
             "     ,...\n"
             "  ],\n"
             "  \"p2sh\",\"address\" (string) address of P2SH script wrapping "
             "this redeem script (not returned if the script is already a "
             "P2SH).\n"
             "}\n"
             "\nExamples:\n" +
             HelpExampleCli("decodescript", "\"hexstring\"") +
             HelpExampleRpc("decodescript", "\"hexstring\""));
     }
 
     RPCTypeCheck(request.params, {UniValue::VSTR});
 
     UniValue r(UniValue::VOBJ);
     CScript script;
     if (request.params[0].get_str().size() > 0) {
         std::vector<uint8_t> scriptData(
             ParseHexV(request.params[0], "argument"));
         script = CScript(scriptData.begin(), scriptData.end());
     } else {
         // Empty scripts are valid.
     }
 
     ScriptPubKeyToUniv(script, r, false);
 
     UniValue type;
     type = find_value(r, "type");
 
     if (type.isStr() && type.get_str() != "scripthash") {
         // P2SH cannot be wrapped in a P2SH. If this script is already a P2SH,
         // don't return the address for a P2SH of the P2SH.
         r.pushKV("p2sh", EncodeDestination(CScriptID(script)));
     }
 
     return r;
 }
 
 /**
  * Pushes a JSON object for script verification or signing errors to vErrorsRet.
  */
 static void TxInErrorToJSON(const CTxIn &txin, UniValue &vErrorsRet,
                             const std::string &strMessage) {
     UniValue entry(UniValue::VOBJ);
     entry.pushKV("txid", txin.prevout.GetTxId().ToString());
     entry.pushKV("vout", uint64_t(txin.prevout.GetN()));
     entry.pushKV("scriptSig",
                  HexStr(txin.scriptSig.begin(), txin.scriptSig.end()));
     entry.pushKV("sequence", uint64_t(txin.nSequence));
     entry.pushKV("error", strMessage);
     vErrorsRet.push_back(entry);
 }
 
 static UniValue combinerawtransaction(const Config &config,
                                       const JSONRPCRequest &request) {
 
     if (request.fHelp || request.params.size() != 1) {
         throw std::runtime_error(
             "combinerawtransaction [\"hexstring\",...]\n"
             "\nCombine multiple partially signed transactions into one "
             "transaction.\n"
             "The combined transaction may be another partially signed "
             "transaction or a \n"
             "fully signed transaction."
 
             "\nArguments:\n"
             "1. \"txs\"         (string) A json array of hex strings of "
             "partially signed transactions\n"
             "    [\n"
             "      \"hexstring\"     (string) A transaction hash\n"
             "      ,...\n"
             "    ]\n"
 
             "\nResult:\n"
             "\"hex\" : \"value\",           (string) The hex-encoded raw "
             "transaction with signature(s)\n"
 
             "\nExamples:\n" +
             HelpExampleCli("combinerawtransaction",
                            "[\"myhex1\", \"myhex2\", \"myhex3\"]"));
     }
 
     UniValue txs = request.params[0].get_array();
     std::vector<CMutableTransaction> txVariants(txs.size());
 
     for (unsigned int idx = 0; idx < txs.size(); idx++) {
         if (!DecodeHexTx(txVariants[idx], txs[idx].get_str())) {
             throw JSONRPCError(RPC_DESERIALIZATION_ERROR,
                                strprintf("TX decode failed for tx %d", idx));
         }
     }
 
     if (txVariants.empty()) {
         throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "Missing transactions");
     }
 
     // mergedTx will end up with all the signatures; it
     // starts as a clone of the rawtx:
     CMutableTransaction mergedTx(txVariants[0]);
 
     // Fetch previous transactions (inputs):
     CCoinsView viewDummy;
     CCoinsViewCache view(&viewDummy);
     {
         LOCK(cs_main);
         LOCK(g_mempool.cs);
         CCoinsViewCache &viewChain = *pcoinsTip;
         CCoinsViewMemPool viewMempool(&viewChain, g_mempool);
         // temporarily switch cache backend to db+mempool view
         view.SetBackend(viewMempool);
 
         for (const CTxIn &txin : mergedTx.vin) {
             // Load entries from viewChain into view; can fail.
             view.AccessCoin(txin.prevout);
         }
 
         // switch back to avoid locking mempool for too long
         view.SetBackend(viewDummy);
     }
 
     // Use CTransaction for the constant parts of the
     // transaction to avoid rehashing.
     const CTransaction txConst(mergedTx);
     // Sign what we can:
     for (size_t i = 0; i < mergedTx.vin.size(); i++) {
         CTxIn &txin = mergedTx.vin[i];
         const Coin &coin = view.AccessCoin(txin.prevout);
         if (coin.IsSpent()) {
             throw JSONRPCError(RPC_VERIFY_ERROR,
                                "Input not found or already spent");
         }
         const CScript &prevPubKey = coin.GetTxOut().scriptPubKey;
         const Amount &amount = coin.GetTxOut().nValue;
 
         SignatureData sigdata;
 
         // ... and merge in other signatures:
         for (const CMutableTransaction &txv : txVariants) {
             if (txv.vin.size() > i) {
                 sigdata = CombineSignatures(
                     prevPubKey,
                     TransactionSignatureChecker(&txConst, i, amount), sigdata,
                     DataFromTransaction(txv, i));
             }
         }
 
         UpdateTransaction(mergedTx, i, sigdata);
     }
 
     return EncodeHexTx(CTransaction(mergedTx));
 }
 
 UniValue SignTransaction(CMutableTransaction &mtx,
                          const UniValue &prevTxsUnival,
                          CBasicKeyStore *keystore, bool is_temp_keystore,
                          const UniValue &hashType) {
     // Fetch previous transactions (inputs):
     CCoinsView viewDummy;
     CCoinsViewCache view(&viewDummy);
     {
         LOCK2(cs_main, g_mempool.cs);
         CCoinsViewCache &viewChain = *pcoinsTip;
         CCoinsViewMemPool viewMempool(&viewChain, g_mempool);
         // Temporarily switch cache backend to db+mempool view.
         view.SetBackend(viewMempool);
 
         for (const CTxIn &txin : mtx.vin) {
             // Load entries from viewChain into view; can fail.
             view.AccessCoin(txin.prevout);
         }
 
         // Switch back to avoid locking mempool for too long.
         view.SetBackend(viewDummy);
     }
 
     // Add previous txouts given in the RPC call:
     if (!prevTxsUnival.isNull()) {
         UniValue prevTxs = prevTxsUnival.get_array();
         for (size_t idx = 0; idx < prevTxs.size(); ++idx) {
             const UniValue &p = prevTxs[idx];
             if (!p.isObject()) {
                 throw JSONRPCError(RPC_DESERIALIZATION_ERROR,
                                    "expected object with "
                                    "{\"txid'\",\"vout\",\"scriptPubKey\"}");
             }
 
             UniValue prevOut = p.get_obj();
 
             RPCTypeCheckObj(prevOut,
                             {
                                 {"txid", UniValueType(UniValue::VSTR)},
                                 {"vout", UniValueType(UniValue::VNUM)},
                                 {"scriptPubKey", UniValueType(UniValue::VSTR)},
                                 // "amount" is also required but check is done
                                 // below due to UniValue::VNUM erroneously
                                 // not accepting quoted numerics
                                 // (which are valid JSON)
                             });
 
             uint256 txid = ParseHashO(prevOut, "txid");
 
             int nOut = find_value(prevOut, "vout").get_int();
             if (nOut < 0) {
                 throw JSONRPCError(RPC_DESERIALIZATION_ERROR,
                                    "vout must be positive");
             }
 
             COutPoint out(txid, nOut);
             std::vector<uint8_t> pkData(ParseHexO(prevOut, "scriptPubKey"));
             CScript scriptPubKey(pkData.begin(), pkData.end());
 
             {
                 const Coin &coin = view.AccessCoin(out);
                 if (!coin.IsSpent() &&
                     coin.GetTxOut().scriptPubKey != scriptPubKey) {
                     std::string err("Previous output scriptPubKey mismatch:\n");
                     err = err + ScriptToAsmStr(coin.GetTxOut().scriptPubKey) +
                           "\nvs:\n" + ScriptToAsmStr(scriptPubKey);
                     throw JSONRPCError(RPC_DESERIALIZATION_ERROR, err);
                 }
 
                 CTxOut txout;
                 txout.scriptPubKey = scriptPubKey;
                 txout.nValue = Amount::zero();
                 if (prevOut.exists("amount")) {
                     txout.nValue =
                         AmountFromValue(find_value(prevOut, "amount"));
                 } else {
                     // amount param is required in replay-protected txs.
                     // Note that we must check for its presence here rather
                     // than use RPCTypeCheckObj() above, since UniValue::VNUM
                     // parser incorrectly parses numerics with quotes, eg
                     // "3.12" as a string when JSON allows it to also parse
                     // as numeric. And we have to accept numerics with quotes
                     // because our own dogfood (our rpc results) always
                     // produces decimal numbers that are quoted
                     // eg getbalance returns "3.14152" rather than 3.14152
                     throw JSONRPCError(RPC_INVALID_PARAMETER, "Missing amount");
                 }
 
                 view.AddCoin(out, Coin(txout, 1, false), true);
             }
 
             // If redeemScript given and not using the local wallet (private
             // keys given), add redeemScript to the keystore so it can be
             // signed:
             if (is_temp_keystore && scriptPubKey.IsPayToScriptHash()) {
                 RPCTypeCheckObj(
                     prevOut, {
                                  {"txid", UniValueType(UniValue::VSTR)},
                                  {"vout", UniValueType(UniValue::VNUM)},
                                  {"scriptPubKey", UniValueType(UniValue::VSTR)},
                                  {"redeemScript", UniValueType(UniValue::VSTR)},
                              });
                 UniValue v = find_value(prevOut, "redeemScript");
                 if (!v.isNull()) {
                     std::vector<uint8_t> rsData(ParseHexV(v, "redeemScript"));
                     CScript redeemScript(rsData.begin(), rsData.end());
                     keystore->AddCScript(redeemScript);
                 }
             }
         }
     }
 
     SigHashType sigHashType = SigHashType().withForkId();
     if (!hashType.isNull()) {
         static std::map<std::string, int> mapSigHashValues = {
             {"ALL", SIGHASH_ALL},
             {"ALL|ANYONECANPAY", SIGHASH_ALL | SIGHASH_ANYONECANPAY},
             {"ALL|FORKID", SIGHASH_ALL | SIGHASH_FORKID},
             {"ALL|FORKID|ANYONECANPAY",
              SIGHASH_ALL | SIGHASH_FORKID | SIGHASH_ANYONECANPAY},
             {"NONE", SIGHASH_NONE},
             {"NONE|ANYONECANPAY", SIGHASH_NONE | SIGHASH_ANYONECANPAY},
             {"NONE|FORKID", SIGHASH_NONE | SIGHASH_FORKID},
             {"NONE|FORKID|ANYONECANPAY",
              SIGHASH_NONE | SIGHASH_FORKID | SIGHASH_ANYONECANPAY},
             {"SINGLE", SIGHASH_SINGLE},
             {"SINGLE|ANYONECANPAY", SIGHASH_SINGLE | SIGHASH_ANYONECANPAY},
             {"SINGLE|FORKID", SIGHASH_SINGLE | SIGHASH_FORKID},
             {"SINGLE|FORKID|ANYONECANPAY",
              SIGHASH_SINGLE | SIGHASH_FORKID | SIGHASH_ANYONECANPAY},
         };
         std::string strHashType = hashType.get_str();
         if (!mapSigHashValues.count(strHashType)) {
             throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid sighash param");
         }
 
         sigHashType = SigHashType(mapSigHashValues[strHashType]);
         if (!sigHashType.hasForkId()) {
             throw JSONRPCError(RPC_INVALID_PARAMETER,
                                "Signature must use SIGHASH_FORKID");
         }
     }
 
     // Script verification errors.
     UniValue vErrors(UniValue::VARR);
 
     // Use CTransaction for the constant parts of the transaction to avoid
     // rehashing.
     const CTransaction txConst(mtx);
     // Sign what we can:
     for (size_t i = 0; i < mtx.vin.size(); i++) {
         CTxIn &txin = mtx.vin[i];
         const Coin &coin = view.AccessCoin(txin.prevout);
         if (coin.IsSpent()) {
             TxInErrorToJSON(txin, vErrors, "Input not found or already spent");
             continue;
         }
 
         const CScript &prevPubKey = coin.GetTxOut().scriptPubKey;
         const Amount amount = coin.GetTxOut().nValue;
 
         SignatureData sigdata;
         // Only sign SIGHASH_SINGLE if there's a corresponding output:
         if ((sigHashType.getBaseType() != BaseSigHashType::SINGLE) ||
             (i < mtx.vout.size())) {
             ProduceSignature(MutableTransactionSignatureCreator(
                                  keystore, &mtx, i, amount, sigHashType),
                              prevPubKey, sigdata);
         }
         sigdata = CombineSignatures(
             prevPubKey, TransactionSignatureChecker(&txConst, i, amount),
             sigdata, DataFromTransaction(mtx, i));
 
         UpdateTransaction(mtx, i, sigdata);
 
         ScriptError serror = SCRIPT_ERR_OK;
         if (!VerifyScript(
                 txin.scriptSig, prevPubKey, STANDARD_SCRIPT_VERIFY_FLAGS,
                 TransactionSignatureChecker(&txConst, i, amount), &serror)) {
             if (serror == SCRIPT_ERR_INVALID_STACK_OPERATION) {
                 // Unable to sign input and verification failed (possible
                 // attempt to partially sign).
                 TxInErrorToJSON(txin, vErrors,
                                 "Unable to sign input, invalid "
                                 "stack size (possibly missing "
                                 "key)");
             } else {
                 TxInErrorToJSON(txin, vErrors, ScriptErrorString(serror));
             }
         }
     }
 
     bool fComplete = vErrors.empty();
 
     UniValue result(UniValue::VOBJ);
     result.pushKV("hex", EncodeHexTx(CTransaction(mtx)));
     result.pushKV("complete", fComplete);
     if (!vErrors.empty()) {
         result.pushKV("errors", vErrors);
     }
 
     return result;
 }
 
 static UniValue signrawtransactionwithkey(const Config &config,
                                           const JSONRPCRequest &request) {
     if (request.fHelp || request.params.size() < 2 ||
         request.params.size() > 4) {
         throw std::runtime_error(
             "signrawtransactionwithkey \"hexstring\" [\"privatekey1\",...] ( "
             "[{\"txid\":\"id\",\"vout\":n,\"scriptPubKey\":\"hex\","
             "\"redeemScript\":\"hex\"},...] sighashtype )\n"
             "\nSign inputs for raw transaction (serialized, hex-encoded).\n"
             "The second argument is an array of base58-encoded private\n"
             "keys that will be the only keys used to sign the transaction.\n"
             "The third optional argument (may be null) is an array of previous "
             "transaction outputs that\n"
             "this transaction depends on but may not yet be in the block "
             "chain.\n"
 
             "\nArguments:\n"
             "1. \"hexstring\"                      (string, required) The "
             "transaction hex string\n"
             "2. \"privkeys\"                       (string, required) A json "
             "array of base58-encoded private keys for signing\n"
             "    [                               (json array of strings)\n"
             "      \"privatekey\"                  (string) private key in "
             "base58-encoding\n"
             "      ,...\n"
             "    ]\n"
             "3. \"prevtxs\"                        (string, optional) An json "
             "array of previous dependent transaction outputs\n"
             "     [                              (json array of json objects, "
             "or 'null' if none provided)\n"
             "       {\n"
             "         \"txid\":\"id\",               (string, required) The "
             "transaction id\n"
             "         \"vout\":n,                  (numeric, required) The "
             "output number\n"
             "         \"scriptPubKey\": \"hex\",     (string, required) script "
             "key\n"
             "         \"redeemScript\": \"hex\",     (string, required for "
             "P2SH) redeem script\n"
             "         \"amount\": value            (numeric, required) The "
             "amount spent\n"
             "       }\n"
             "       ,...\n"
             "    ]\n"
             "4. \"sighashtype\"                    (string, optional, "
             "default=ALL) The signature hash type. Must be one of\n"
             "       \"ALL|FORKID\"\n"
             "       \"NONE|FORKID\"\n"
             "       \"SINGLE|FORKID\"\n"
             "       \"ALL|FORKID|ANYONECANPAY\"\n"
             "       \"NONE|FORKID|ANYONECANPAY\"\n"
             "       \"SINGLE|FORKID|ANYONECANPAY\"\n"
 
             "\nResult:\n"
             "{\n"
             "  \"hex\" : \"value\",                  (string) The hex-encoded "
             "raw transaction with signature(s)\n"
             "  \"complete\" : true|false,          (boolean) If the "
             "transaction has a complete set of signatures\n"
             "  \"errors\" : [                      (json array of objects) "
             "Script verification errors (if there are any)\n"
             "    {\n"
             "      \"txid\" : \"hash\",              (string) The hash of the "
             "referenced, previous transaction\n"
             "      \"vout\" : n,                   (numeric) The index of the "
             "output to spent and used as input\n"
             "      \"scriptSig\" : \"hex\",          (string) The hex-encoded "
             "signature script\n"
             "      \"sequence\" : n,               (numeric) Script sequence "
             "number\n"
             "      \"error\" : \"text\"              (string) Verification or "
             "signing error related to the input\n"
             "    }\n"
             "    ,...\n"
             "  ]\n"
             "}\n"
 
             "\nExamples:\n" +
             HelpExampleCli("signrawtransactionwithkey", "\"myhex\"") +
             HelpExampleRpc("signrawtransactionwithkey", "\"myhex\""));
     }
 
     RPCTypeCheck(
         request.params,
         {UniValue::VSTR, UniValue::VARR, UniValue::VARR, UniValue::VSTR}, true);
 
     CMutableTransaction mtx;
     if (!DecodeHexTx(mtx, request.params[0].get_str())) {
         throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "TX decode failed");
     }
 
     CBasicKeyStore keystore;
     const UniValue &keys = request.params[1].get_array();
     for (size_t idx = 0; idx < keys.size(); ++idx) {
         UniValue k = keys[idx];
         CBitcoinSecret vchSecret;
         if (!vchSecret.SetString(k.get_str())) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY,
                                "Invalid private key");
         }
         CKey key = vchSecret.GetKey();
         if (!key.IsValid()) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY,
                                "Private key outside allowed range");
         }
         keystore.AddKey(key);
     }
 
     return SignTransaction(mtx, request.params[2], &keystore, true,
                            request.params[3]);
 }
 
 static UniValue signrawtransaction(const Config &config,
                                    const JSONRPCRequest &request) {
 #ifdef ENABLE_WALLET
     CWallet *const pwallet = GetWalletForJSONRPCRequest(request);
 #endif
 
     if (request.fHelp || request.params.size() < 1 ||
         request.params.size() > 4) {
         throw std::runtime_error(
             "signrawtransaction \"hexstring\" ( "
             "[{\"txid\":\"id\",\"vout\":n,\"scriptPubKey\":\"hex\","
             "\"redeemScript\":\"hex\"},...] [\"privatekey1\",...] sighashtype "
             ")\n"
             "\nDEPRECATED.Sign inputs for raw transaction (serialized, "
             "hex-encoded).\n"
             "The second optional argument (may be null) is an array of "
             "previous transaction outputs that\n"
             "this transaction depends on but may not yet be in the block "
             "chain.\n"
             "The third optional argument (may be null) is an array of "
             "base58-encoded private\n"
             "keys that, if given, will be the only keys used to sign the "
             "transaction.\n"
 #ifdef ENABLE_WALLET
             + HelpRequiringPassphrase(pwallet) +
             "\n"
 #endif
             "\nArguments:\n"
             "1. \"hexstring\"     (string, required) The transaction hex "
             "string\n"
             "2. \"prevtxs\"       (string, optional) An json array of previous "
             "dependent transaction outputs\n"
             "     [               (json array of json objects, or 'null' if "
             "none provided)\n"
             "       {\n"
             "         \"txid\":\"id\",             (string, required) The "
             "transaction id\n"
             "         \"vout\":n,                  (numeric, required) The "
             "output number\n"
             "         \"scriptPubKey\": \"hex\",   (string, required) script "
             "key\n"
             "         \"redeemScript\": \"hex\",   (string, required for P2SH) "
             "redeem script\n"
             "         \"amount\": value            (numeric, required) The "
             "amount spent\n"
             "       }\n"
             "       ,...\n"
             "    ]\n"
             "3. \"privkeys\"     (string, optional) A json array of "
             "base58-encoded private keys for signing\n"
             "    [                  (json array of strings, or 'null' if none "
             "provided)\n"
             "      \"privatekey\"   (string) private key in base58-encoding\n"
             "      ,...\n"
             "    ]\n"
             "4. \"sighashtype\"     (string, optional, default=ALL) The "
             "signature hash type. Must be one of\n"
             "       \"ALL|FORKID\"\n"
             "       \"NONE|FORKID\"\n"
             "       \"SINGLE|FORKID\"\n"
             "       \"ALL|FORKID|ANYONECANPAY\"\n"
             "       \"NONE|FORKID|ANYONECANPAY\"\n"
             "       \"SINGLE|FORKID|ANYONECANPAY\"\n"
 
             "\nResult:\n"
             "{\n"
             "  \"hex\" : \"value\",           (string) The hex-encoded raw "
             "transaction with signature(s)\n"
             "  \"complete\" : true|false,   (boolean) If the transaction has a "
             "complete set of signatures\n"
             "  \"errors\" : [                 (json array of objects) Script "
             "verification errors (if there are any)\n"
             "    {\n"
             "      \"txid\" : \"hash\",           (string) The hash of the "
             "referenced, previous transaction\n"
             "      \"vout\" : n,                (numeric) The index of the "
             "output to spent and used as input\n"
             "      \"scriptSig\" : \"hex\",       (string) The hex-encoded "
             "signature script\n"
             "      \"sequence\" : n,            (numeric) Script sequence "
             "number\n"
             "      \"error\" : \"text\"           (string) Verification or "
             "signing error related to the input\n"
             "    }\n"
             "    ,...\n"
             "  ]\n"
             "}\n"
 
             "\nExamples:\n" +
             HelpExampleCli("signrawtransaction", "\"myhex\"") +
             HelpExampleRpc("signrawtransaction", "\"myhex\""));
     }
 
     if (!IsDeprecatedRPCEnabled(gArgs, "signrawtransaction")) {
         throw JSONRPCError(
             RPC_METHOD_DEPRECATED,
             "signrawtransaction is deprecated and will be fully removed in "
             "v0.20. "
             "To use signrawtransaction in v0.19, restart bitcoind with "
             "-deprecatedrpc=signrawtransaction.\n"
             "Projects should transition to using signrawtransactionwithkey and "
             "signrawtransactionwithwallet before upgrading to v0.20");
     }
 
     RPCTypeCheck(
         request.params,
         {UniValue::VSTR, UniValue::VARR, UniValue::VARR, UniValue::VSTR}, true);
 
     // Make a JSONRPCRequest to pass on to the right signrawtransaction* command
     JSONRPCRequest new_request;
     new_request.id = request.id;
     new_request.URI = std::move(request.URI);
     new_request.params.setArray();
 
     // For signing with private keys
     if (!request.params[2].isNull()) {
         new_request.params.push_back(request.params[0]);
         // Note: the prevtxs and privkeys are reversed for
         // signrawtransactionwithkey
         new_request.params.push_back(request.params[2]);
         new_request.params.push_back(request.params[1]);
         new_request.params.push_back(request.params[3]);
         return signrawtransactionwithkey(config, new_request);
     }
 // Otherwise sign with the wallet which does not take a privkeys parameter
 #ifdef ENABLE_WALLET
     else {
         new_request.params.push_back(request.params[0]);
         new_request.params.push_back(request.params[1]);
         new_request.params.push_back(request.params[3]);
         return signrawtransactionwithwallet(config, new_request);
     }
 #endif
     // If we have made it this far, then wallet is disabled and no private keys
     // were given, so fail here.
     throw JSONRPCError(RPC_INVALID_PARAMETER, "No private keys available.");
 }
 
 static UniValue sendrawtransaction(const Config &config,
                                    const JSONRPCRequest &request) {
     if (request.fHelp || request.params.size() < 1 ||
         request.params.size() > 2) {
         throw std::runtime_error(
             "sendrawtransaction \"hexstring\" ( allowhighfees )\n"
             "\nSubmits raw transaction (serialized, hex-encoded) to local node "
             "and network.\n"
             "\nAlso see createrawtransaction and signrawtransaction calls.\n"
             "\nArguments:\n"
             "1. \"hexstring\"    (string, required) The hex string of the raw "
             "transaction)\n"
             "2. allowhighfees    (boolean, optional, default=false) Allow high "
             "fees\n"
             "\nResult:\n"
             "\"hex\"             (string) The transaction hash in hex\n"
             "\nExamples:\n"
             "\nCreate a transaction\n" +
             HelpExampleCli("createrawtransaction",
                            "\"[{\\\"txid\\\" : "
                            "\\\"mytxid\\\",\\\"vout\\\":0}]\" "
                            "\"{\\\"myaddress\\\":0.01}\"") +
             "Sign the transaction, and get back the hex\n" +
             HelpExampleCli("signrawtransaction", "\"myhex\"") +
             "\nSend the transaction (signed hex)\n" +
             HelpExampleCli("sendrawtransaction", "\"signedhex\"") +
             "\nAs a json rpc call\n" +
             HelpExampleRpc("sendrawtransaction", "\"signedhex\""));
     }
 
     LOCK(cs_main);
     RPCTypeCheck(request.params, {UniValue::VSTR, UniValue::VBOOL});
 
     // parse hex string from parameter
     CMutableTransaction mtx;
     if (!DecodeHexTx(mtx, request.params[0].get_str())) {
         throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "TX decode failed");
     }
 
     CTransactionRef tx(MakeTransactionRef(std::move(mtx)));
     const uint256 &txid = tx->GetId();
 
     bool fLimitFree = false;
     Amount nMaxRawTxFee = maxTxFee;
     if (request.params.size() > 1 && request.params[1].get_bool()) {
         nMaxRawTxFee = Amount::zero();
     }
 
     CCoinsViewCache &view = *pcoinsTip;
     bool fHaveChain = false;
     for (size_t o = 0; !fHaveChain && o < tx->vout.size(); o++) {
         const Coin &existingCoin = view.AccessCoin(COutPoint(txid, o));
         fHaveChain = !existingCoin.IsSpent();
     }
 
     bool fHaveMempool = g_mempool.exists(txid);
     if (!fHaveMempool && !fHaveChain) {
         // Push to local node and sync with wallets.
         CValidationState state;
         bool fMissingInputs;
         if (!AcceptToMemoryPool(config, g_mempool, state, std::move(tx),
                                 fLimitFree, &fMissingInputs, false,
                                 nMaxRawTxFee)) {
             if (state.IsInvalid()) {
                 throw JSONRPCError(RPC_TRANSACTION_REJECTED,
                                    strprintf("%i: %s", state.GetRejectCode(),
                                              state.GetRejectReason()));
             } else {
                 if (fMissingInputs) {
                     throw JSONRPCError(RPC_TRANSACTION_ERROR, "Missing inputs");
                 }
 
                 throw JSONRPCError(RPC_TRANSACTION_ERROR,
                                    state.GetRejectReason());
             }
         }
     } else if (fHaveChain) {
         throw JSONRPCError(RPC_TRANSACTION_ALREADY_IN_CHAIN,
                            "transaction already in block chain");
     }
 
     if (!g_connman) {
         throw JSONRPCError(
             RPC_CLIENT_P2P_DISABLED,
             "Error: Peer-to-peer functionality missing or disabled");
     }
 
     CInv inv(MSG_TX, txid);
     g_connman->ForEachNode([&inv](CNode *pnode) { pnode->PushInventory(inv); });
     return txid.GetHex();
 }
 
 UniValue testmempoolaccept(const Config &config,
                            const JSONRPCRequest &request) {
     if (request.fHelp || request.params.size() < 1 ||
         request.params.size() > 2) {
         throw std::runtime_error(
             // clang-format off
             "testmempoolaccept [\"rawtxs\"] ( allowhighfees )\n"
             "\nReturns if raw transaction (serialized, hex-encoded) would be accepted by mempool.\n"
             "\nThis checks if the transaction violates the consensus or policy rules.\n"
             "\nSee sendrawtransaction call.\n"
             "\nArguments:\n"
             "1. [\"rawtxs\"]       (array, required) An array of hex strings of raw transactions.\n"
             "                                        Length must be one for now.\n"
             "2. allowhighfees    (boolean, optional, default=false) Allow high fees\n"
             "\nResult:\n"
             "[                   (array) The result of the mempool acceptance test for each raw transaction in the input array.\n"
             "                            Length is exactly one for now.\n"
             " {\n"
             "  \"txid\"           (string) The transaction hash in hex\n"
             "  \"allowed\"        (boolean) If the mempool allows this tx to be inserted\n"
             "  \"reject-reason\"  (string) Rejection string (only present when 'allowed' is false)\n"
             " }\n"
             "]\n"
             "\nExamples:\n"
             "\nCreate a transaction\n"
             + HelpExampleCli("createrawtransaction", "\"[{\\\"txid\\\" : \\\"mytxid\\\",\\\"vout\\\":0}]\" \"{\\\"myaddress\\\":0.01}\"") +
             "Sign the transaction, and get back the hex\n"
             + HelpExampleCli("signrawtransaction", "\"myhex\"") +
             "\nTest acceptance of the transaction (signed hex)\n"
             + HelpExampleCli("testmempoolaccept", "\"signedhex\"") +
             "\nAs a json rpc call\n"
             + HelpExampleRpc("testmempoolaccept", "[\"signedhex\"]")
             // clang-format on
         );
     }
 
     RPCTypeCheck(request.params, {UniValue::VARR, UniValue::VBOOL});
     if (request.params[0].get_array().size() != 1) {
         throw JSONRPCError(
             RPC_INVALID_PARAMETER,
             "Array must contain exactly one raw transaction for now");
     }
 
     CMutableTransaction mtx;
     if (!DecodeHexTx(mtx, request.params[0].get_array()[0].get_str())) {
         throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "TX decode failed");
     }
     CTransactionRef tx(MakeTransactionRef(std::move(mtx)));
     const uint256 &txid = tx->GetId();
 
     bool fLimitFree = false;
     Amount max_raw_tx_fee = maxTxFee;
     if (!request.params[1].isNull() && request.params[1].get_bool()) {
         max_raw_tx_fee = Amount::zero();
     }
 
     UniValue result(UniValue::VARR);
     UniValue result_0(UniValue::VOBJ);
     result_0.pushKV("txid", txid.GetHex());
 
     CValidationState state;
     bool missing_inputs;
     bool test_accept_res;
     {
         LOCK(cs_main);
         test_accept_res = AcceptToMemoryPool(
             config, g_mempool, state, std::move(tx), fLimitFree,
             &missing_inputs, /* bypass_limits */ false, max_raw_tx_fee,
             /* test_accept */ true);
     }
     result_0.pushKV("allowed", test_accept_res);
     if (!test_accept_res) {
         if (state.IsInvalid()) {
             result_0.pushKV("reject-reason",
                             strprintf("%i: %s", state.GetRejectCode(),
                                       state.GetRejectReason()));
         } else if (missing_inputs) {
             result_0.pushKV("reject-reason", "missing-inputs");
         } else {
             result_0.pushKV("reject-reason", state.GetRejectReason());
         }
     }
 
     result.push_back(std::move(result_0));
     return result;
 }
 
 // clang-format off
 static const ContextFreeRPCCommand commands[] = {
     //  category            name                         actor (function)           argNames
     //  ------------------- ------------------------     ----------------------     ----------
     { "rawtransactions",    "getrawtransaction",         getrawtransaction,         {"txid","verbose","blockhash"} },
     { "rawtransactions",    "createrawtransaction",      createrawtransaction,      {"inputs","outputs","locktime"} },
     { "rawtransactions",    "decoderawtransaction",      decoderawtransaction,      {"hexstring"} },
     { "rawtransactions",    "decodescript",              decodescript,              {"hexstring"} },
     { "rawtransactions",    "sendrawtransaction",        sendrawtransaction,        {"hexstring","allowhighfees"} },
     { "rawtransactions",    "combinerawtransaction",     combinerawtransaction,     {"txs"} },
     { "rawtransactions",    "signrawtransaction",        signrawtransaction,        {"hexstring","prevtxs","privkeys","sighashtype"} }, /* uses wallet if enabled */
     { "rawtransactions",    "signrawtransactionwithkey", signrawtransactionwithkey, {"hexstring","privkeys","prevtxs","sighashtype"} },
     { "rawtransactions",    "testmempoolaccept",         testmempoolaccept,         {"rawtxs","allowhighfees"} },
 
     { "blockchain",         "gettxoutproof",             gettxoutproof,             {"txids", "blockhash"} },
     { "blockchain",         "verifytxoutproof",          verifytxoutproof,          {"proof"} },
 };
 // clang-format on
 
 void RegisterRawTransactionRPCCommands(CRPCTable &t) {
     for (unsigned int vcidx = 0; vcidx < ARRAYLEN(commands); vcidx++) {
         t.appendCommand(commands[vcidx].name, &commands[vcidx]);
     }
 }
diff --git a/src/test/CMakeLists.txt b/src/test/CMakeLists.txt
index cffbf230e8..6c771eed53 100644
--- a/src/test/CMakeLists.txt
+++ b/src/test/CMakeLists.txt
@@ -1,171 +1,172 @@
 # Copyright (c) 2018 The Bitcoin developers
 
 project(bitcoin-test)
 
 # Process json files.
 file(MAKE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/data")
 
 find_program(PYTHON python)
 function(gen_json_header NAME)
 	set(HEADERS "")
 	foreach(f ${ARGN})
 		set(h "${CMAKE_CURRENT_BINARY_DIR}/${f}.h")
 
 		# Get the proper name for the test variable.
 		get_filename_component(TEST_NAME ${f} NAME_WE)
 		add_custom_command(OUTPUT ${h}
 			COMMAND ${PYTHON}
 			ARGS
 				"${CMAKE_CURRENT_SOURCE_DIR}/data/generate_header.py"
 				"${TEST_NAME}"
 				"${CMAKE_CURRENT_SOURCE_DIR}/${f}" > ${h}
 			MAIN_DEPENDENCY ${f}
 			DEPENDS
 				"data/generate_header.py"
 			VERBATIM
 		)
 		list(APPEND HEADERS ${h})
 	endforeach(f)
 	set(${NAME} "${HEADERS}" PARENT_SCOPE)
 endfunction()
 
 gen_json_header(JSON_HEADERS
 	data/script_tests.json
 	data/base58_keys_valid.json
 	data/base58_encode_decode.json
 	data/base58_keys_invalid.json
 	data/blockfilters.json
 	data/tx_invalid.json
 	data/tx_valid.json
 	data/sighash.json
 )
 
 include(TestSuite)
 create_test_suite(bitcoin)
 add_dependencies(check check-bitcoin)
 
 add_test_to_suite(bitcoin test_bitcoin
 	activation_tests.cpp
 	addrman_tests.cpp
 	allocator_tests.cpp
 	amount_tests.cpp
 	arith_uint256_tests.cpp
 	avalanche_tests.cpp
 	base32_tests.cpp
 	base58_tests.cpp
 	base64_tests.cpp
 	bip32_tests.cpp
 	blockcheck_tests.cpp
 	blockencodings_tests.cpp
 	blockfilter_tests.cpp
 	blockindex_tests.cpp
 	blockstatus_tests.cpp
 	bloom_tests.cpp
 	bswap_tests.cpp
 	cashaddr_tests.cpp
 	cashaddrenc_tests.cpp
 	checkdatasig_tests.cpp
 	checkpoints_tests.cpp
 	checkqueue_tests.cpp
 	coins_tests.cpp
 	compress_tests.cpp
 	config_tests.cpp
 	core_io_tests.cpp
 	crypto_tests.cpp
 	cuckoocache_tests.cpp
 	dbwrapper_tests.cpp
 	DoS_tests.cpp
 	dstencode_tests.cpp
 	excessiveblock_tests.cpp
 	feerate_tests.cpp
 	finalization_tests.cpp
 	getarg_tests.cpp
 	hash_tests.cpp
 	inv_tests.cpp
 	jsonutil.cpp
 	key_tests.cpp
 	lcg_tests.cpp
 	limitedmap_tests.cpp
 	main_tests.cpp
 	mempool_tests.cpp
 	merkle_tests.cpp
 	miner_tests.cpp
 	monolith_opcodes_tests.cpp
 	multisig_tests.cpp
 	net_tests.cpp
 	netbase_tests.cpp
 	pmt_tests.cpp
 	policyestimator_tests.cpp
 	pow_tests.cpp
 	prevector_tests.cpp
 	radix_tests.cpp
 	raii_event_tests.cpp
 	random_tests.cpp
 	rcu_tests.cpp
 	reverselock_tests.cpp
 	rpc_tests.cpp
 	rpc_server_tests.cpp
 	rwcollection_tests.cpp
 	sanity_tests.cpp
 	scheduler_tests.cpp
 	schnorr_tests.cpp
 	script_commitment_tests.cpp
 	script_P2SH_tests.cpp
 	script_tests.cpp
 	scriptflags.cpp
 	scriptnum_tests.cpp
 	serialize_tests.cpp
 	sigcache_tests.cpp
 	sigencoding_tests.cpp
 	sighash_tests.cpp
 	sighashtype_tests.cpp
 	sigopcount_tests.cpp
 	sigutil.cpp
 	skiplist_tests.cpp
 	streams_tests.cpp
 	sync_tests.cpp
 	test_bitcoin.cpp
 	test_bitcoin_main.cpp
 	timedata_tests.cpp
 	transaction_tests.cpp
+	txindex_tests.cpp
 	txvalidationcache_tests.cpp
 	uint256_tests.cpp
 	undo_tests.cpp
 	univalue_tests.cpp
 	util_tests.cpp
 	validation_tests.cpp
 	work_comparator_tests.cpp
 
 	# RPC Tests
 	../rpc/test/server_tests.cpp
 
 	# Tests generated from JSON
 	${JSON_HEADERS}
 )
 
 find_package(Boost 1.58 REQUIRED unit_test_framework)
 
 target_link_libraries(test_bitcoin Boost::unit_test_framework rpcclient server)
 
 # We need to detect if the BOOST_TEST_DYN_LINK flag is required.
 set(CMAKE_REQUIRED_LIBRARIES Boost::unit_test_framework)
 check_cxx_source_compiles("
 	#define BOOST_TEST_DYN_LINK
 	#define BOOST_TEST_MAIN
 	#include <boost/test/unit_test.hpp>
 " BOOST_TEST_DYN_LINK)
 
 if(BOOST_TEST_DYN_LINK)
 	target_compile_definitions(test_bitcoin PRIVATE BOOST_TEST_DYN_LINK)
 endif(BOOST_TEST_DYN_LINK)
 
 if(BUILD_BITCOIN_WALLET)
 	target_sources(test_bitcoin
 		PRIVATE
 			../wallet/test/wallet_test_fixture.cpp
 			../wallet/test/accounting_tests.cpp
 			../wallet/test/wallet_tests.cpp
 			../wallet/test/walletdb_tests.cpp
 			../wallet/test/wallet_crypto_tests.cpp
 	)
 endif()
diff --git a/src/test/txindex_tests.cpp b/src/test/txindex_tests.cpp
new file mode 100644
index 0000000000..d2e6ca7dab
--- /dev/null
+++ b/src/test/txindex_tests.cpp
@@ -0,0 +1,76 @@
+// Copyright (c) 2017-2018 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 <index/txindex.h>
+#include <script/standard.h>
+#include <test/test_bitcoin.h>
+#include <util.h>
+#include <utiltime.h>
+#include <validation.h>
+
+#include <boost/test/unit_test.hpp>
+
+BOOST_AUTO_TEST_SUITE(txindex_tests)
+
+BOOST_FIXTURE_TEST_CASE(txindex_initial_sync, TestChain100Setup) {
+    TxIndex txindex(std::make_unique<TxIndexDB>(1 << 20, true));
+
+    CTransactionRef tx_disk;
+    uint256 block_hash;
+
+    // Transaction should not be found in the index before it is started.
+    for (const auto &txn : coinbaseTxns) {
+        BOOST_CHECK(!txindex.FindTx(txn.GetHash(), block_hash, tx_disk));
+    }
+
+    // BlockUntilSyncedToCurrentChain should return false before txindex is
+    // started.
+    BOOST_CHECK(!txindex.BlockUntilSyncedToCurrentChain());
+
+    txindex.Start();
+
+    // Allow tx index to catch up with the block index.
+    constexpr int64_t timeout_ms = 10 * 1000;
+    int64_t time_start = GetTimeMillis();
+    while (!txindex.BlockUntilSyncedToCurrentChain()) {
+        BOOST_REQUIRE(time_start + timeout_ms > GetTimeMillis());
+        MilliSleep(100);
+    }
+
+    // Check that txindex has all txs that were in the chain before it started.
+    for (const auto &txn : coinbaseTxns) {
+        if (!txindex.FindTx(txn.GetHash(), block_hash, tx_disk)) {
+            BOOST_ERROR("FindTx failed");
+        } else if (tx_disk->GetHash() != txn.GetHash()) {
+            BOOST_ERROR("Read incorrect tx");
+        }
+    }
+
+    // Check that new transactions in new blocks make it into the index.
+    for (int i = 0; i < 10; i++) {
+        CScript coinbase_script_pub_key =
+            GetScriptForDestination(coinbaseKey.GetPubKey().GetID());
+        std::vector<CMutableTransaction> no_txns;
+        const CBlock &block =
+            CreateAndProcessBlock(no_txns, coinbase_script_pub_key);
+        const CTransaction &txn = *block.vtx[0];
+
+        BOOST_CHECK(txindex.BlockUntilSyncedToCurrentChain());
+        if (!txindex.FindTx(txn.GetHash(), block_hash, tx_disk)) {
+            BOOST_ERROR("FindTx failed");
+        } else if (tx_disk->GetHash() != txn.GetHash()) {
+            BOOST_ERROR("Read incorrect tx");
+        }
+    }
+
+    // shutdown sequence (c.f. Shutdown() in init.cpp)
+    txindex.Stop();
+
+    threadGroup.interrupt_all();
+    threadGroup.join_all();
+
+    // Rest of shutdown sequence and destructors happen in ~TestingSetup()
+}
+
+BOOST_AUTO_TEST_SUITE_END()
diff --git a/src/txdb.h b/src/txdb.h
index f5cdf30cb6..e19912dadf 100644
--- a/src/txdb.h
+++ b/src/txdb.h
@@ -1,166 +1,166 @@
 // 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 <chain.h>
 #include <coins.h>
 #include <dbwrapper.h>
 #include <diskblockpos.h>
 #include <primitives/block.h>
 
 #include <map>
 #include <string>
 #include <utility>
 #include <vector>
 
 class CBlockIndex;
 class CCoinsViewDBCursor;
 class uint256;
 class Config;
 
 //! No need to periodic flush if at least this much space still available.
 static constexpr int MAX_BLOCK_COINSDB_USAGE = 10;
 //! -dbcache default (MiB)
 static const int64_t nDefaultDbCache = 450;
 //! -dbbatchsize default (bytes)
 static const int64_t nDefaultDbBatchSize = 16 << 20;
 //! max. -dbcache (MiB)
 static const int64_t nMaxDbCache = sizeof(void *) > 4 ? 16384 : 1024;
 //! min. -dbcache (MiB)
 static const int64_t nMinDbCache = 4;
 //! Max memory allocated to block tree DB specific cache, if no -txindex (MiB)
 static const int64_t nMaxBlockDBCache = 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 const int64_t nMaxBlockDBAndTxIndexCache = 1024;
+static const int64_t nMaxTxIndexCache = 1024;
 //! Max memory allocated to coin DB specific cache (MiB)
 static const int64_t nMaxCoinsDBCache = 8;
 
 struct CDiskTxPos : public CDiskBlockPos {
     unsigned int nTxOffset; // after header
 
     ADD_SERIALIZE_METHODS;
 
     template <typename Stream, typename Operation>
     inline void SerializationOp(Stream &s, Operation ser_action) {
         READWRITEAS(CDiskBlockPos, *this);
         READWRITE(VARINT(nTxOffset));
     }
 
     CDiskTxPos(const CDiskBlockPos &blockIn, unsigned int nTxOffsetIn)
         : CDiskBlockPos(blockIn.nFile, blockIn.nPos), nTxOffset(nTxOffsetIn) {}
 
     CDiskTxPos() { SetNull(); }
 
     void SetNull() {
         CDiskBlockPos::SetNull();
         nTxOffset = 0;
     }
 };
 
 /** CCoinsView backed by the coin database (chainstate/) */
 class CCoinsViewDB final : public CCoinsView {
 protected:
     CDBWrapper db;
 
 public:
     explicit CCoinsViewDB(size_t nCacheSize, bool fMemory = false,
                           bool fWipe = false);
 
     bool GetCoin(const COutPoint &outpoint, Coin &coin) const override;
     bool HaveCoin(const COutPoint &outpoint) const override;
     uint256 GetBestBlock() const override;
     std::vector<uint256> GetHeadBlocks() const override;
     bool BatchWrite(CCoinsMap &mapCoins, const uint256 &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 uint256 &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 ReadReindexing(bool &fReindexing);
     bool ReadTxIndex(const uint256 &txid, CDiskTxPos &pos);
     bool WriteTxIndex(const std::vector<std::pair<uint256, CDiskTxPos>> &vect);
     bool WriteFlag(const std::string &name, bool fValue);
     bool ReadFlag(const std::string &name, bool &fValue);
     bool LoadBlockIndexGuts(
         const Config &config,
         std::function<CBlockIndex *(const uint256 &)> insertBlockIndex);
 };
 
 /**
  * Access to the txindex database (indexes/txindex/)
  *
  * The database stores a block locator of the chain the database is synced to
  * so that the TxIndex can efficiently determine the point it last stopped at.
  * A locator is used instead of a simple hash of the chain tip because blocks
  * and block index entries may not be flushed to disk until after this database
  * is updated.
  */
 class TxIndexDB : public CDBWrapper {
 public:
     explicit TxIndexDB(size_t n_cache_size, bool f_memory = false,
                        bool f_wipe = false);
 
     /// Read the disk location of the transaction data with the given hash.
     /// Returns false if the transaction hash is not indexed.
     bool ReadTxPos(const uint256 &txid, CDiskTxPos &pos) const;
 
     /// Write a batch of transaction positions to the DB.
     bool WriteTxs(const std::vector<std::pair<uint256, CDiskTxPos>> &v_pos);
 
     /// Read block locator of the chain that the txindex is in sync with.
     bool ReadBestBlock(CBlockLocator &locator) const;
 
     /// Write block locator of the chain that the txindex is in sync with.
     bool WriteBestBlock(const CBlockLocator &locator);
 
     /// Migrate txindex data from the block tree DB, where it may be for older
     /// nodes that have not been upgraded yet to the new database.
     bool MigrateData(CBlockTreeDB &block_tree_db,
                      const CBlockLocator &best_locator);
 };
 
 #endif // BITCOIN_TXDB_H
diff --git a/src/validation.cpp b/src/validation.cpp
index ab84aeddc7..90f3d2468a 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -1,5708 +1,5651 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Copyright (c) 2017-2018 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 <blockindexworkcomparator.h>
 #include <blockvalidity.h>
 #include <chainparams.h>
 #include <checkpoints.h>
 #include <checkqueue.h>
 #include <config.h>
 #include <consensus/activation.h>
 #include <consensus/consensus.h>
 #include <consensus/merkle.h>
 #include <consensus/tx_verify.h>
 #include <consensus/validation.h>
 #include <fs.h>
 #include <hash.h>
+#include <index/txindex.h>
 #include <init.h>
 #include <policy/fees.h>
 #include <policy/policy.h>
 #include <pow.h>
 #include <primitives/block.h>
 #include <primitives/transaction.h>
 #include <random.h>
 #include <reverse_iterator.h>
 #include <script/script.h>
 #include <script/scriptcache.h>
 #include <script/sigcache.h>
 #include <script/standard.h>
 #include <timedata.h>
 #include <tinyformat.h>
 #include <txdb.h>
 #include <txmempool.h>
 #include <ui_interface.h>
 #include <undo.h>
 #include <util.h>
 #include <utilmoneystr.h>
 #include <utilstrencodings.h>
 #include <validationinterface.h>
 #include <warnings.h>
 
 #include <boost/algorithm/string/join.hpp>
 #include <boost/algorithm/string/replace.hpp>
 #include <boost/thread.hpp> // boost::this_thread::interruption_point() (mingw)
 
 #include <atomic>
 #include <future>
 #include <sstream>
 #include <thread>
 
 #if defined(NDEBUG)
 #error "Bitcoin cannot be compiled without assertions."
 #endif
 
 #define MICRO 0.000001
 #define MILLI 0.001
 class ConnectTrace;
 
 /**
  * CChainState stores and provides an API to update our local knowledge of the
  * current best chain and header tree.
  *
  * It generally provides access to the current block tree, as well as functions
  * to provide new data, which it will appropriately validate and incorporate in
  * its state as necessary.
  *
  * Eventually, the API here is targeted at being exposed externally as a
  * consumable libconsensus library, so any functions added must only call
  * other class member functions, pure functions in other parts of the consensus
  * library, callbacks via the validation interface, or read/write-to-disk
  * functions (eventually this will also be via callbacks).
  */
 class CChainState {
 private:
     /**
      * The set of all CBlockIndex entries with BLOCK_VALID_TRANSACTIONS (for
      * itself and all ancestors) and
      * as good as our current tip or better. Entries may be failed, though, and
      * pruning nodes may be
      * missing the data for the block.
      */
     std::set<CBlockIndex *, CBlockIndexWorkComparator> setBlockIndexCandidates;
 
 public:
     CChain chainActive;
     BlockMap mapBlockIndex;
     std::multimap<CBlockIndex *, CBlockIndex *> mapBlocksUnlinked;
     CBlockIndex *pindexBestInvalid = nullptr;
     CBlockIndex *pindexBestParked = nullptr;
 
     bool LoadBlockIndex(const Config &config, CBlockTreeDB &blocktree);
 
     bool ActivateBestChain(
         const Config &config, CValidationState &state,
         std::shared_ptr<const CBlock> pblock = std::shared_ptr<const CBlock>());
 
     bool AcceptBlockHeader(const Config &config, const CBlockHeader &block,
                            CValidationState &state, CBlockIndex **ppindex);
     bool AcceptBlock(const Config &config,
                      const std::shared_ptr<const CBlock> &pblock,
                      CValidationState &state, bool fRequested,
                      const CDiskBlockPos *dbp, bool *fNewBlock);
 
     // Block (dis)connection on a given view:
     DisconnectResult DisconnectBlock(const CBlock &block,
                                      const CBlockIndex *pindex,
                                      CCoinsViewCache &view);
     bool ConnectBlock(const Config &config, const CBlock &block,
                       CValidationState &state, CBlockIndex *pindex,
                       CCoinsViewCache &view, bool fJustCheck = false);
 
     // Block disconnection on our pcoinsTip:
     bool DisconnectTip(const Config &config, CValidationState &state,
                        DisconnectedBlockTransactions *disconnectpool);
 
     // Manual block validity manipulation:
     bool PreciousBlock(const Config &config, CValidationState &state,
                        CBlockIndex *pindex);
     bool UnwindBlock(const Config &config, CValidationState &state,
                      CBlockIndex *pindex, bool invalidate);
     bool ResetBlockFailureFlags(CBlockIndex *pindex);
     template <typename F>
     void UpdateFlagsForBlock(CBlockIndex *pindexBase, CBlockIndex *pindex, F f);
     template <typename F, typename C>
     void UpdateFlags(CBlockIndex *pindex, F f, C fchild);
     template <typename F> void UpdateFlags(CBlockIndex *pindex, F f);
     /** Remove parked status from a block and its descendants. */
     bool UnparkBlockImpl(CBlockIndex *pindex, bool fClearChildren);
 
     bool ReplayBlocks(const Config &config, CCoinsView *view);
     bool RewindBlockIndex(const Config &config);
     bool LoadGenesisBlock(const CChainParams &chainparams);
 
     void PruneBlockIndexCandidates();
 
     void UnloadBlockIndex();
 
 private:
     bool ActivateBestChainStep(const Config &config, CValidationState &state,
                                CBlockIndex *pindexMostWork,
                                const std::shared_ptr<const CBlock> &pblock,
                                bool &fInvalidFound, ConnectTrace &connectTrace);
     bool ConnectTip(const Config &config, CValidationState &state,
                     CBlockIndex *pindexNew,
                     const std::shared_ptr<const CBlock> &pblock,
                     ConnectTrace &connectTrace,
                     DisconnectedBlockTransactions &disconnectpool);
 
     CBlockIndex *AddToBlockIndex(const CBlockHeader &block);
     /** Create a new block index entry for a given block hash */
     CBlockIndex *InsertBlockIndex(const uint256 &hash);
     void CheckBlockIndex(const Consensus::Params &consensusParams);
 
     void InvalidBlockFound(CBlockIndex *pindex, const CValidationState &state);
     CBlockIndex *FindMostWorkChain();
     bool ReceivedBlockTransactions(const CBlock &block, CValidationState &state,
                                    CBlockIndex *pindexNew,
                                    const CDiskBlockPos &pos);
 
     bool RollforwardBlock(const CBlockIndex *pindex, CCoinsViewCache &inputs,
                           const Config &config);
 } g_chainstate;
 
 /**
  * Global state
  */
 CCriticalSection cs_main;
 
 BlockMap &mapBlockIndex = g_chainstate.mapBlockIndex;
 CChain &chainActive = g_chainstate.chainActive;
 CBlockIndex *pindexBestHeader = nullptr;
 Mutex g_best_block_mutex;
 std::condition_variable g_best_block_cv;
 uint256 g_best_block;
 int nScriptCheckThreads = 0;
 std::atomic_bool fImporting(false);
 std::atomic_bool fReindex(false);
-bool fTxIndex = false;
 bool fHavePruned = false;
 bool fPruneMode = false;
 bool fIsBareMultisigStd = DEFAULT_PERMIT_BAREMULTISIG;
 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;
 
 uint256 hashAssumeValid;
 arith_uint256 nMinimumChainWork;
 
 Amount maxTxFee = DEFAULT_TRANSACTION_MAXFEE;
 
 CTxMemPool g_mempool;
 std::atomic_bool g_is_mempool_loaded{false};
 
 /** Constant stuff for coinbase transactions we create: */
 CScript COINBASE_FLAGS;
 
 const std::string strMessageMagic = "Bitcoin Signed Message:\n";
 
 // Internal stuff
 namespace {
 CBlockIndex *&pindexBestInvalid = g_chainstate.pindexBestInvalid;
 CBlockIndex *&pindexBestParked = g_chainstate.pindexBestParked;
 
 /**
  * The best finalized block.
  * This block cannot be reorged in any way, shape or form.
  */
 CBlockIndex const *pindexFinalized;
 
 /**
  * All pairs A->B, where A (or one of its ancestors) misses transactions, but B
  * has transactions. Pruned nodes may have entries where B is missing data.
  */
 std::multimap<CBlockIndex *, CBlockIndex *> &mapBlocksUnlinked =
     g_chainstate.mapBlocksUnlinked;
 
 CCriticalSection 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;
 
 /**
  * Every received block is assigned a unique and increasing identifier, so we
  * know which one to give priority in case of a fork.
  * Blocks loaded from disk are assigned id 0, so start the counter at 1.
  */
 std::atomic<int32_t> nBlockSequenceId{1};
 /** Decreasing counter (used by subsequent preciousblock calls). */
 int32_t nBlockReverseSequenceId = -1;
 /** chainwork for the last block that preciousblock has been applied to. */
 arith_uint256 nLastPreciousChainwork = 0;
 
 /** Dirty block index entries. */
 std::set<const CBlockIndex *> setDirtyBlockIndex;
 
 /** Dirty block file entries. */
 std::set<int> setDirtyFileInfo;
 } // namespace
 
 CBlockIndex *FindForkInGlobalIndex(const CChain &chain,
                                    const CBlockLocator &locator) {
     AssertLockHeld(cs_main);
 
     // Find the first block the caller has in the main chain
     for (const uint256 &hash : locator.vHave) {
         CBlockIndex *pindex = LookupBlockIndex(hash);
         if (pindex) {
             if (chain.Contains(pindex)) {
                 return pindex;
             }
             if (pindex->GetAncestor(chain.Height()) == chain.Tip()) {
                 return chain.Tip();
             }
         }
     }
     return chain.Genesis();
 }
 
 std::unique_ptr<CCoinsViewDB> pcoinsdbview;
 std::unique_ptr<CCoinsViewCache> pcoinsTip;
 std::unique_ptr<CBlockTreeDB> pblocktree;
 
 enum class FlushStateMode { NONE, IF_NEEDED, PERIODIC, ALWAYS };
 
 // See definition for documentation
 static bool FlushStateToDisk(const CChainParams &chainParams,
                              CValidationState &state, FlushStateMode mode,
                              int nManualPruneHeight = 0);
 static void FindFilesToPruneManual(std::set<int> &setFilesToPrune,
                                    int nManualPruneHeight);
 static void FindFilesToPrune(std::set<int> &setFilesToPrune,
                              uint64_t nPruneAfterHeight);
 static FILE *OpenUndoFile(const CDiskBlockPos &pos, bool fReadOnly = false);
 static uint32_t GetBlockScriptFlags(const Config &config,
                                     const CBlockIndex *pChainTip);
 
 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 CTransaction &tx, int flags, LockPoints *lp,
                         bool useExistingLockPoints) {
     AssertLockHeld(cs_main);
     AssertLockHeld(g_mempool.cs);
 
     CBlockIndex *tip = chainActive.Tip();
     assert(tip != nullptr);
 
     CBlockIndex index;
     index.pprev = tip;
     // CheckSequenceLocks() uses chainActive.Height()+1 to evaluate height based
     // locks because when SequenceLocks() is called within ConnectBlock(), the
     // height of the block *being* evaluated is what is used. Thus if we want to
     // know if a transaction can be part of the *next* block, we need to use one
     // more than chainActive.Height()
     index.nHeight = tip->nHeight + 1;
 
     std::pair<int, int64_t> lockPair;
     if (useExistingLockPoints) {
         assert(lp);
         lockPair.first = lp->height;
         lockPair.second = lp->time;
     } else {
         // pcoinsTip contains the UTXO set for chainActive.Tip()
         CCoinsViewMemPool viewMemPool(pcoinsTip.get(), g_mempool);
         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 (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);
 }
 
 /** Convert CValidationState to a human-readable message for logging */
 std::string FormatStateMessage(const CValidationState &state) {
     return strprintf(
         "%s%s (code %i)", state.GetRejectReason(),
         state.GetDebugMessage().empty() ? "" : ", " + state.GetDebugMessage(),
         state.GetRejectCode());
 }
 
 static bool IsMagneticAnomalyEnabledForCurrentBlock(const Config &config) {
     AssertLockHeld(cs_main);
     return IsMagneticAnomalyEnabled(config, chainActive.Tip());
 }
 
 static bool IsGreatWallEnabledForCurrentBlock(const Config &config) {
     AssertLockHeld(cs_main);
     return IsGreatWallEnabled(config, chainActive.Tip());
 }
 
 // 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 Config &config,
                                       int64_t nMedianTimePast) {
     return nMedianTimePast >=
            gArgs.GetArg(
                "-replayprotectionactivationtime",
                config.GetChainParams().GetConsensus().gravitonActivationTime);
 }
 
 static bool IsReplayProtectionEnabled(const Config &config,
                                       const CBlockIndex *pindexPrev) {
     if (pindexPrev == nullptr) {
         return false;
     }
 
     return IsReplayProtectionEnabled(config, pindexPrev->GetMedianTimePast());
 }
 
 static bool IsReplayProtectionEnabledForCurrentBlock(const Config &config) {
     AssertLockHeld(cs_main);
     return IsReplayProtectionEnabled(config, chainActive.Tip());
 }
 
 // Used to avoid mempool polluting consensus critical paths if CCoinsViewMempool
 // were somehow broken and returning the wrong scriptPubKeys
 static bool CheckInputsFromMempoolAndCache(
     const CTransaction &tx, CValidationState &state,
     const CCoinsViewCache &view, const CTxMemPool &pool, const uint32_t flags,
     bool cacheSigStore, PrecomputedTransactionData &txdata) {
     AssertLockHeld(cs_main);
 
     // pool.cs should be locked already, but go ahead and re-take the lock here
     // to enforce that mempool doesn't change between when we check the view and
     // when we actually call through to CheckInputs
     LOCK(pool.cs);
 
     assert(!tx.IsCoinBase());
     for (const CTxIn &txin : tx.vin) {
         const Coin &coin = view.AccessCoin(txin.prevout);
 
         // At this point we haven't actually checked if the coins are all
         // available (or shouldn't assume we have, since CheckInputs does). So
         // we just return failure if the inputs are not available here, and then
         // only have to check equivalence for available inputs.
         if (coin.IsSpent()) {
             return false;
         }
 
         const CTransactionRef &txFrom = pool.get(txin.prevout.GetTxId());
         if (txFrom) {
             assert(txFrom->GetId() == txin.prevout.GetTxId());
             assert(txFrom->vout.size() > txin.prevout.GetN());
             assert(txFrom->vout[txin.prevout.GetN()] == coin.GetTxOut());
         } else {
             const Coin &coinFromDisk = pcoinsTip->AccessCoin(txin.prevout);
             assert(!coinFromDisk.IsSpent());
             assert(coinFromDisk.GetTxOut() == coin.GetTxOut());
         }
     }
 
     return CheckInputs(tx, state, view, true, flags, cacheSigStore, true,
                        txdata);
 }
 
 static bool AcceptToMemoryPoolWorker(
     const Config &config, CTxMemPool &pool, CValidationState &state,
     const CTransactionRef &ptx, bool fLimitFree, bool *pfMissingInputs,
     int64_t nAcceptTime, bool fOverrideMempoolLimit, const Amount nAbsurdFee,
     std::vector<COutPoint> &coins_to_uncache, bool test_accept) {
     AssertLockHeld(cs_main);
 
     const CTransaction &tx = *ptx;
     const TxId txid = tx.GetId();
 
     // mempool "read lock" (held through
     // GetMainSignals().TransactionAddedToMempool())
     LOCK(pool.cs);
     if (pfMissingInputs) {
         *pfMissingInputs = false;
     }
 
     // Coinbase is only valid in a block, not as a loose transaction.
     if (!CheckRegularTransaction(tx, state)) {
         // state filled in by CheckRegularTransaction.
         return false;
     }
 
     // Rather not work on nonstandard transactions (unless -testnet/-regtest)
     std::string reason;
     if (fRequireStandard && !IsStandardTx(tx, reason)) {
         return state.DoS(0, false, REJECT_NONSTANDARD, reason);
     }
 
     // Only accept nLockTime-using transactions that can be mined in the next
     // block; we don't want our mempool filled up with transactions that can't
     // be mined yet.
     CValidationState ctxState;
     if (!ContextualCheckTransactionForCurrentBlock(
             config, tx, ctxState, STANDARD_LOCKTIME_VERIFY_FLAGS)) {
         // We copy the state from a dummy to ensure we don't increase the
         // ban score of peer for transaction that could be valid in the future.
         return state.DoS(
             0, false, REJECT_NONSTANDARD, ctxState.GetRejectReason(),
             ctxState.CorruptionPossible(), ctxState.GetDebugMessage());
     }
 
     // Is it already in the memory pool?
     if (pool.exists(txid)) {
         return state.Invalid(false, REJECT_DUPLICATE, "txn-already-in-mempool");
     }
 
     // Check for conflicts with in-memory transactions
     for (const CTxIn &txin : tx.vin) {
         auto itConflicting = pool.mapNextTx.find(txin.prevout);
         if (itConflicting != pool.mapNextTx.end()) {
             // Disable replacement feature for good
             return state.Invalid(false, REJECT_DUPLICATE,
                                  "txn-mempool-conflict");
         }
     }
 
     {
         CCoinsView dummy;
         CCoinsViewCache view(&dummy);
 
         Amount nValueIn = Amount::zero();
         LockPoints lp;
         CCoinsViewMemPool viewMemPool(pcoinsTip.get(), pool);
         view.SetBackend(viewMemPool);
 
         // Do all inputs exist?
         for (const CTxIn txin : tx.vin) {
             if (!pcoinsTip->HaveCoinInCache(txin.prevout)) {
                 coins_to_uncache.push_back(txin.prevout);
             }
 
             if (!view.HaveCoin(txin.prevout)) {
                 // Are inputs missing because we already have the tx?
                 for (size_t out = 0; out < tx.vout.size(); out++) {
                     // Optimistically just do efficient check of cache for
                     // outputs.
                     if (pcoinsTip->HaveCoinInCache(COutPoint(txid, out))) {
                         return state.Invalid(false, REJECT_DUPLICATE,
                                              "txn-already-known");
                     }
                 }
 
                 // Otherwise assume this might be an orphan tx for which we just
                 // haven't seen parents yet.
                 if (pfMissingInputs) {
                     *pfMissingInputs = true;
                 }
 
                 // fMissingInputs and !state.IsInvalid() is used to detect this
                 // condition, don't set state.Invalid()
                 return false;
             }
         }
 
         // Are the actual inputs available?
         if (!view.HaveInputs(tx)) {
             return state.Invalid(false, REJECT_DUPLICATE,
                                  "bad-txns-inputs-spent");
         }
 
         // Bring the best block into scope.
         view.GetBestBlock();
 
         nValueIn = view.GetValueIn(tx);
 
         // 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(tx, STANDARD_LOCKTIME_VERIFY_FLAGS, &lp)) {
             return state.DoS(0, false, REJECT_NONSTANDARD, "non-BIP68-final");
         }
 
         // Check for non-standard pay-to-script-hash in inputs
         if (fRequireStandard && !AreInputsStandard(tx, view)) {
             return state.Invalid(false, REJECT_NONSTANDARD,
                                  "bad-txns-nonstandard-inputs");
         }
 
         int64_t nSigOpsCount =
             GetTransactionSigOpCount(tx, view, STANDARD_SCRIPT_VERIFY_FLAGS);
 
         Amount nValueOut = tx.GetValueOut();
         Amount nFees = nValueIn - nValueOut;
         // nModifiedFees includes any fee deltas from PrioritiseTransaction
         Amount nModifiedFees = nFees;
         double nPriorityDummy = 0;
         pool.ApplyDeltas(txid, nPriorityDummy, nModifiedFees);
 
         Amount inChainInputValue;
         double dPriority =
             view.GetPriority(tx, chainActive.Height(), inChainInputValue);
 
         // 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;
             }
         }
 
         CTxMemPoolEntry entry(ptx, nFees, nAcceptTime, dPriority,
                               chainActive.Height(), inChainInputValue,
                               fSpendsCoinbase, nSigOpsCount, lp);
         unsigned int nSize = entry.GetTxSize();
 
         // Check that the transaction doesn't have an excessive number of
         // sigops, making it impossible to mine. Since the coinbase transaction
         // itself can contain sigops MAX_STANDARD_TX_SIGOPS is less than
         // MAX_BLOCK_SIGOPS_PER_MB; we still consider this an invalid rather
         // than merely non-standard transaction.
         if (nSigOpsCount > MAX_STANDARD_TX_SIGOPS) {
             return state.DoS(0, false, REJECT_NONSTANDARD,
                              "bad-txns-too-many-sigops", false,
                              strprintf("%d", nSigOpsCount));
         }
 
         CFeeRate minRelayTxFee = config.GetMinFeePerKB();
         Amount mempoolRejectFee =
             pool.GetMinFee(
                     gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) *
                     1000000)
                 .GetFee(nSize);
         if (mempoolRejectFee > Amount::zero() &&
             nModifiedFees < mempoolRejectFee) {
             return state.DoS(0, false, REJECT_INSUFFICIENTFEE,
                              "mempool min fee not met", false,
                              strprintf("%d < %d", nFees, mempoolRejectFee));
         }
 
         if (gArgs.GetBoolArg("-relaypriority", DEFAULT_RELAYPRIORITY) &&
             nModifiedFees < minRelayTxFee.GetFee(nSize) &&
             !AllowFree(entry.GetPriority(chainActive.Height() + 1))) {
             // Require that free transactions have sufficient priority to be
             // mined in the next block.
             return state.DoS(0, false, REJECT_INSUFFICIENTFEE,
                              "insufficient priority");
         }
 
         // Continuously rate-limit free (really, very-low-fee) transactions.
         // This mitigates 'penny-flooding' -- sending thousands of free
         // transactions just to be annoying or make others' transactions take
         // longer to confirm.
         if (fLimitFree && nModifiedFees < minRelayTxFee.GetFee(nSize)) {
             static CCriticalSection csFreeLimiter;
             static double dFreeCount;
             static int64_t nLastTime;
             int64_t nNow = GetTime();
 
             LOCK(csFreeLimiter);
 
             // Use an exponentially decaying ~10-minute window:
             dFreeCount *= pow(1.0 - 1.0 / 600.0, double(nNow - nLastTime));
             nLastTime = nNow;
             // -limitfreerelay unit is thousand-bytes-per-minute
             // At default rate it would take over a month to fill 1GB
 
             // NOTE: Use the actual size here, and not the fee size since this
             // is counting real size for the rate limiter.
             if (dFreeCount + nSize >=
                 gArgs.GetArg("-limitfreerelay", DEFAULT_LIMITFREERELAY) * 10 *
                     1000) {
                 return state.DoS(0, false, REJECT_INSUFFICIENTFEE,
                                  "rate limited free transaction");
             }
 
             LogPrint(BCLog::MEMPOOL, "Rate limit dFreeCount: %g => %g\n",
                      dFreeCount, dFreeCount + nSize);
             dFreeCount += nSize;
         }
 
         if (nAbsurdFee != Amount::zero() && nFees > nAbsurdFee) {
             return state.Invalid(false, REJECT_HIGHFEE, "absurdly-high-fee",
                                  strprintf("%d > %d", nFees, nAbsurdFee));
         }
 
         // 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.DoS(0, false, REJECT_NONSTANDARD,
                              "too-long-mempool-chain", false, errString);
         }
 
         // Set extraFlags as a set of flags that needs to be activated.
         uint32_t extraFlags = SCRIPT_VERIFY_NONE;
         if (IsReplayProtectionEnabledForCurrentBlock(config)) {
             extraFlags |= SCRIPT_ENABLE_REPLAY_PROTECTION;
         }
 
         if (IsMagneticAnomalyEnabledForCurrentBlock(config)) {
             extraFlags |= SCRIPT_ENABLE_CHECKDATASIG;
         }
 
         if (IsGreatWallEnabledForCurrentBlock(config)) {
             if (!fRequireStandard) {
                 extraFlags |= SCRIPT_ALLOW_SEGWIT_RECOVERY;
             }
             extraFlags |= SCRIPT_ENABLE_SCHNORR;
         }
 
         // Make sure whatever we need to activate is actually activated.
         const uint32_t scriptVerifyFlags =
             STANDARD_SCRIPT_VERIFY_FLAGS | extraFlags;
 
         // Check against previous transactions. This is done last to help
         // prevent CPU exhaustion denial-of-service attacks.
         PrecomputedTransactionData txdata(tx);
         if (!CheckInputs(tx, state, view, true, scriptVerifyFlags, true, false,
                          txdata)) {
             // State filled in by CheckInputs.
             return false;
         }
 
         // Check again against the current block tip's script verification flags
         // to cache our script execution flags. This is, of course, useless if
         // the next block has different script flags from the previous one, but
         // because the cache tracks script flags for us it will auto-invalidate
         // and we'll just have a few blocks of extra misses on soft-fork
         // activation.
         //
         // 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.
         uint32_t currentBlockScriptVerifyFlags =
             GetBlockScriptFlags(config, chainActive.Tip());
 
         if (!CheckInputsFromMempoolAndCache(tx, state, view, pool,
                                             currentBlockScriptVerifyFlags, true,
                                             txdata)) {
             return error("%s: BUG! PLEASE REPORT THIS! CheckInputs failed "
                          "against latest-block but not STANDARD flags %s, %s",
                          __func__, txid.ToString(), FormatStateMessage(state));
         }
 
         if (test_accept) {
             // Tx was accepted, but not added
             return true;
         }
 
         // Store transaction in memory.
         pool.addUnchecked(txid, entry, setAncestors);
 
         // Trim mempool and check if tx was trimmed.
         if (!fOverrideMempoolLimit) {
             pool.LimitSize(
                 gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000,
                 gArgs.GetArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY) * 60 *
                     60);
             if (!pool.exists(txid)) {
                 return state.DoS(0, false, REJECT_INSUFFICIENTFEE,
                                  "mempool full");
             }
         }
     }
 
     GetMainSignals().TransactionAddedToMempool(ptx);
     return true;
 }
 
 /**
  * (try to) add transaction to memory pool with a specified acceptance time.
  */
 static bool
 AcceptToMemoryPoolWithTime(const Config &config, CTxMemPool &pool,
                            CValidationState &state, const CTransactionRef &tx,
                            bool fLimitFree, bool *pfMissingInputs,
                            int64_t nAcceptTime, bool fOverrideMempoolLimit,
                            const Amount nAbsurdFee, bool test_accept) {
     std::vector<COutPoint> coins_to_uncache;
     bool res = AcceptToMemoryPoolWorker(
         config, pool, state, tx, fLimitFree, pfMissingInputs, nAcceptTime,
         fOverrideMempoolLimit, nAbsurdFee, coins_to_uncache, test_accept);
     if (!res) {
         for (const COutPoint &outpoint : coins_to_uncache) {
             pcoinsTip->Uncache(outpoint);
         }
     }
 
     // After we've (potentially) uncached entries, ensure our coins cache is
     // still within its size limits
     CValidationState stateDummy;
     FlushStateToDisk(config.GetChainParams(), stateDummy,
                      FlushStateMode::PERIODIC);
     return res;
 }
 
 bool AcceptToMemoryPool(const Config &config, CTxMemPool &pool,
                         CValidationState &state, const CTransactionRef &tx,
                         bool fLimitFree, bool *pfMissingInputs,
                         bool fOverrideMempoolLimit, const Amount nAbsurdFee,
                         bool test_accept) {
     return AcceptToMemoryPoolWithTime(
         config, pool, state, tx, fLimitFree, pfMissingInputs, GetTime(),
         fOverrideMempoolLimit, 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 Config &config, const TxId &txid,
                     CTransactionRef &txOut, uint256 &hashBlock, bool fAllowSlow,
                     CBlockIndex *blockIndex) {
     CBlockIndex *pindexSlow = blockIndex;
 
     LOCK(cs_main);
 
     if (!blockIndex) {
         CTransactionRef ptx = g_mempool.get(txid);
         if (ptx) {
             txOut = ptx;
             return true;
         }
 
-        if (fTxIndex) {
-            CDiskTxPos postx;
-            if (pblocktree->ReadTxIndex(txid, postx)) {
-                CAutoFile file(OpenBlockFile(postx, true), SER_DISK,
-                               CLIENT_VERSION);
-                if (file.IsNull()) {
-                    return error("%s: OpenBlockFile failed", __func__);
-                }
-                CBlockHeader header;
-                try {
-                    file >> header;
-                    fseek(file.Get(), postx.nTxOffset, SEEK_CUR);
-                    file >> txOut;
-                } catch (const std::exception &e) {
-                    return error("%s: Deserialize or I/O error - %s", __func__,
-                                 e.what());
-                }
-                hashBlock = header.GetHash();
-                if (txOut->GetId() != txid) {
-                    return error("%s: txid mismatch", __func__);
-                }
-                return true;
-            }
-
-            // transaction not found in index, nothing more can be done
-            return false;
+        if (g_txindex) {
+            return g_txindex->FindTx(txid, hashBlock, txOut);
         }
 
         // use coin database to locate block that contains transaction, and scan
         // it
         if (fAllowSlow) {
             const Coin &coin = AccessByTxid(*pcoinsTip, txid);
             if (!coin.IsSpent()) {
                 pindexSlow = chainActive[coin.GetHeight()];
             }
         }
     }
 
     if (pindexSlow) {
         CBlock block;
         if (ReadBlockFromDisk(block, pindexSlow, config)) {
             for (const auto &tx : block.vtx) {
                 if (tx->GetId() == txid) {
                     txOut = tx;
                     hashBlock = pindexSlow->GetBlockHash();
                     return true;
                 }
             }
         }
     }
 
     return false;
 }
 
 //////////////////////////////////////////////////////////////////////////////
 //
 // CBlock and CBlockIndex
 //
 
 static bool WriteBlockToDisk(const CBlock &block, CDiskBlockPos &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(fileout, block);
     fileout << FLATDATA(messageStart) << nSize;
 
     // Write block
     long fileOutPos = ftell(fileout.Get());
     if (fileOutPos < 0) {
         return error("WriteBlockToDisk: ftell failed");
     }
 
     pos.nPos = (unsigned int)fileOutPos;
     fileout << block;
 
     return true;
 }
 
 bool ReadBlockFromDisk(CBlock &block, const CDiskBlockPos &pos,
                        const Config &config) {
     block.SetNull();
 
     // Open history file to read
     CAutoFile filein(OpenBlockFile(pos, true), SER_DISK, CLIENT_VERSION);
     if (filein.IsNull()) {
         return error("ReadBlockFromDisk: OpenBlockFile failed for %s",
                      pos.ToString());
     }
 
     // Read block
     try {
         filein >> block;
     } catch (const std::exception &e) {
         return error("%s: Deserialize or I/O error - %s at %s", __func__,
                      e.what(), pos.ToString());
     }
 
     // Check the header
     if (!CheckProofOfWork(block.GetHash(), block.nBits, config)) {
         return error("ReadBlockFromDisk: Errors in block header at %s",
                      pos.ToString());
     }
 
     return true;
 }
 
 bool ReadBlockFromDisk(CBlock &block, const CBlockIndex *pindex,
                        const Config &config) {
     CDiskBlockPos blockPos;
     {
         LOCK(cs_main);
         blockPos = pindex->GetBlockPos();
     }
 
     if (!ReadBlockFromDisk(block, blockPos, config)) {
         return false;
     }
 
     if (block.GetHash() != pindex->GetBlockHash()) {
         return error("ReadBlockFromDisk(CBlock&, CBlockIndex*): GetHash() "
                      "doesn't match index for %s at %s",
                      pindex->ToString(), pindex->GetBlockPos().ToString());
     }
 
     return true;
 }
 
 Amount GetBlockSubsidy(int nHeight, const Consensus::Params &consensusParams) {
     int halvings = nHeight / consensusParams.nSubsidyHalvingInterval;
     // Force block reward to zero when right shift is undefined.
     if (halvings >= 64) {
         return Amount::zero();
     }
 
     Amount nSubsidy = 50 * COIN;
     // Subsidy is cut in half every 210,000 blocks which will occur
     // approximately every 4 years.
     return ((nSubsidy / SATOSHI) >> halvings) * SATOSHI;
 }
 
 bool IsInitialBlockDownload() {
     // Once this function has returned false, it must remain false.
     static std::atomic<bool> latchToFalse{false};
     // Optimization: pre-test latch before taking the lock.
     if (latchToFalse.load(std::memory_order_relaxed)) {
         return false;
     }
 
     LOCK(cs_main);
     if (latchToFalse.load(std::memory_order_relaxed)) {
         return false;
     }
     if (fImporting || fReindex) {
         return true;
     }
     if (chainActive.Tip() == nullptr) {
         return true;
     }
     if (chainActive.Tip()->nChainWork < nMinimumChainWork) {
         return true;
     }
     if (chainActive.Tip()->GetBlockTime() < (GetTime() - nMaxTipAge)) {
         return true;
     }
     LogPrintf("Leaving InitialBlockDownload (latching to false)\n");
     latchToFalse.store(true, std::memory_order_relaxed);
     return false;
 }
 
 CBlockIndex const *pindexBestForkTip = nullptr;
 CBlockIndex const *pindexBestForkBase = nullptr;
 
 static void AlertNotify(const std::string &strMessage) {
     uiInterface.NotifyAlertChanged();
     std::string strCmd = gArgs.GetArg("-alertnotify", "");
     if (strCmd.empty()) {
         return;
     }
 
     // Alert text should be plain ascii coming from a trusted source, but to be
     // safe we first strip anything not in safeChars, then add single quotes
     // around the whole string before passing it to the shell:
     std::string singleQuote("'");
     std::string safeStatus = SanitizeString(strMessage);
     safeStatus = singleQuote + safeStatus + singleQuote;
     boost::replace_all(strCmd, "%s", safeStatus);
 
     std::thread t(runCommand, strCmd);
     // thread runs free
     t.detach();
 }
 
 static void CheckForkWarningConditions() {
     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 (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(const CBlockIndex *pindexNewForkTip) {
     AssertLockHeld(cs_main);
     // If we are on a fork that is sufficiently large, set a warning flag.
     const CBlockIndex *pfork = chainActive.FindFork(pindexNewForkTip);
 
     // We define a condition where we should warn the user about as a fork of at
     // least 7 blocks with a tip within 72 blocks (+/- 12 hours if no one mines
     // it) of ours. We use 7 blocks rather arbitrarily as it represents just
     // under 10% of sustained network hash rate operating on the fork, or a
     // chain that is entirely longer than ours and invalid (note that this
     // should be detected by both). We define it this way because it allows us
     // to only store the highest fork tip (+ base) which meets the 7-block
     // condition and from this always have the most-likely-to-cause-warning fork
     if (pfork &&
         (!pindexBestForkTip ||
          pindexNewForkTip->nHeight > pindexBestForkTip->nHeight) &&
         pindexNewForkTip->nChainWork - pfork->nChainWork >
             (GetBlockProof(*pfork) * 7) &&
         chainActive.Height() - pindexNewForkTip->nHeight < 72) {
         pindexBestForkTip = pindexNewForkTip;
         pindexBestForkBase = pfork;
     }
 
     CheckForkWarningConditions();
 }
 
 static void InvalidChainFound(CBlockIndex *pindexNew) {
     if (!pindexBestInvalid ||
         pindexNew->nChainWork > pindexBestInvalid->nChainWork) {
         pindexBestInvalid = pindexNew;
     }
 
     // If the invalid chain found is supposed to be finalized, we need to move
     // back the finalization point.
     if (IsBlockFinalized(pindexNew)) {
         pindexFinalized = pindexNew->pprev;
     }
 
     LogPrintf("%s: invalid block=%s  height=%d  log2_work=%.8g  date=%s\n",
               __func__, pindexNew->GetBlockHash().ToString(),
               pindexNew->nHeight,
               log(pindexNew->nChainWork.getdouble()) / log(2.0),
               FormatISO8601DateTime(pindexNew->GetBlockTime()));
     CBlockIndex *tip = chainActive.Tip();
     assert(tip);
     LogPrintf("%s:  current best=%s  height=%d  log2_work=%.8g  date=%s\n",
               __func__, tip->GetBlockHash().ToString(), chainActive.Height(),
               log(tip->nChainWork.getdouble()) / log(2.0),
               FormatISO8601DateTime(tip->GetBlockTime()));
 }
 
 void CChainState::InvalidBlockFound(CBlockIndex *pindex,
                                     const CValidationState &state) {
     if (!state.CorruptionPossible()) {
         pindex->nStatus = pindex->nStatus.withFailed();
         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;
     return VerifyScript(scriptSig, scriptPubKey, nFlags,
                         CachingTransactionSignatureChecker(ptxTo, nIn, amount,
                                                            cacheStore, txdata),
                         &error);
 }
 
 int GetSpendHeight(const CCoinsViewCache &inputs) {
     LOCK(cs_main);
     CBlockIndex *pindexPrev = LookupBlockIndex(inputs.GetBestBlock());
     return pindexPrev->nHeight + 1;
 }
 
 bool CheckInputs(const CTransaction &tx, CValidationState &state,
                  const CCoinsViewCache &inputs, bool fScriptChecks,
                  const uint32_t flags, bool sigCacheStore,
                  bool scriptCacheStore,
                  const PrecomputedTransactionData &txdata,
                  std::vector<CScriptCheck> *pvChecks) {
     assert(!tx.IsCoinBase());
 
     // This call does all the inexpensive checks on all the inputs. Only if ALL
     // inputs pass do we perform expensive ECDSA signature checks. Helps prevent
     // CPU exhaustion attacks.
     if (!Consensus::CheckTxInputs(tx, state, inputs, GetSpendHeight(inputs))) {
         return false;
     }
 
     if (pvChecks) {
         pvChecks->reserve(tx.vin.size());
     }
 
     // Skip script verification when connecting blocks under the assumevalid
     // block. Assuming the assumevalid block is valid this is safe because
     // block merkle hashes are still computed and checked, of course, if an
     // assumed valid block is invalid due to false scriptSigs this optimization
     // would allow an invalid chain to be accepted.
     if (!fScriptChecks) {
         return true;
     }
 
     // First check if script executions have been cached with the same flags.
     // Note that this assumes that the inputs provided are correct (ie that the
     // transaction hash which is in tx's prevouts properly commits to the
     // scriptPubKey in the inputs view of that transaction).
     uint256 hashCacheEntry = GetScriptCacheKey(tx, flags);
     if (IsKeyInScriptCache(hashCacheEntry, !scriptCacheStore)) {
         return true;
     }
 
     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' witness hash. This provides a sanity
         // check that our caching is not introducing consensus failures through
         // additional data in, eg, the coins being spent being checked as a part
         // of CScriptCheck.
         const CScript &scriptPubKey = coin.GetTxOut().scriptPubKey;
         const Amount amount = coin.GetTxOut().nValue;
 
         // Verify signature
         CScriptCheck check(scriptPubKey, amount, tx, i, flags, sigCacheStore,
                            txdata);
         if (pvChecks) {
             pvChecks->push_back(std::move(check));
         } else if (!check()) {
             // Compute flags without the optional standardness flags.
             // This differs from MANDATORY_SCRIPT_VERIFY_FLAGS as it contains
             // additional upgrade flags (see AcceptToMemoryPoolWorker variable
             // extraFlags).
             // Even though it is not a mandatory flag,
             // SCRIPT_ALLOW_SEGWIT_RECOVERY is strictly more permissive than the
             // set of standard flags. It therefore needs to be added in order to
             // check if we need to penalize the peer that sent us the
             // transaction or not.
             uint32_t mandatoryFlags =
                 (flags & ~STANDARD_NOT_MANDATORY_VERIFY_FLAGS) |
                 SCRIPT_ALLOW_SEGWIT_RECOVERY;
             if (flags != mandatoryFlags) {
                 // Check whether the failure was caused by a non-mandatory
                 // script verification check. If so, don't trigger DoS
                 // protection to avoid splitting the network on the basis of
                 // relay policy disagreements.
                 CScriptCheck check2(scriptPubKey, amount, tx, i, mandatoryFlags,
                                     sigCacheStore, txdata);
                 if (check2()) {
                     return state.Invalid(
                         false, REJECT_NONSTANDARD,
                         strprintf("non-mandatory-script-verify-flag (%s)",
                                   ScriptErrorString(check.GetScriptError())));
                 }
             }
 
             // We also, regardless, need to check whether the transaction would
             // be valid on the other side of the upgrade, so as to avoid
             // splitting the network between upgraded and non-upgraded nodes.
             // Note that this will create strange error messages like
             // "upgrade-conditional-script-failure (Non-canonical DER ...)"
             // -- the tx was refused entry due to STRICTENC, a mandatory flag,
             // but after the upgrade the signature would have been interpreted
             // as valid Schnorr and thus STRICTENC would not happen.
             CScriptCheck check3(scriptPubKey, amount, tx, i,
                                 mandatoryFlags ^ SCRIPT_ENABLE_SCHNORR,
                                 sigCacheStore, txdata);
             if (check3()) {
                 return state.Invalid(
                     false, REJECT_INVALID,
                     strprintf("upgrade-conditional-script-failure (%s)",
                               ScriptErrorString(check.GetScriptError())));
             }
 
             // Failures of other flags indicate a transaction that is invalid in
             // new blocks, e.g. a invalid P2SH. We DoS ban such nodes as they
             // are not following the protocol. That said during an upgrade
             // careful thought should be taken as to the correct behavior - we
             // may want to continue peering with non-upgraded nodes even after
             // soft-fork super-majority signaling has occurred.
             return state.DoS(
                 100, false, REJECT_INVALID,
                 strprintf("mandatory-script-verify-flag-failed (%s)",
                           ScriptErrorString(check.GetScriptError())));
         }
     }
 
     if (scriptCacheStore && !pvChecks) {
         // We executed all of the provided scripts, and were told to cache the
         // result. Do so now.
         AddKeyInScriptCache(hashCacheEntry);
     }
 
     return true;
 }
 
 namespace {
 
 bool UndoWriteToDisk(const CBlockUndo &blockundo, CDiskBlockPos &pos,
                      const uint256 &hashBlock,
                      const CMessageHeader::MessageMagic &messageStart) {
     // Open history file to append
     CAutoFile fileout(OpenUndoFile(pos), SER_DISK, CLIENT_VERSION);
     if (fileout.IsNull()) {
         return error("%s: OpenUndoFile failed", __func__);
     }
 
     // Write index header
     unsigned int nSize = GetSerializeSize(fileout, blockundo);
     fileout << FLATDATA(messageStart) << nSize;
 
     // Write undo data
     long fileOutPos = ftell(fileout.Get());
     if (fileOutPos < 0) {
         return error("%s: ftell failed", __func__);
     }
     pos.nPos = (unsigned int)fileOutPos;
     fileout << blockundo;
 
     // calculate & write checksum
     CHashWriter hasher(SER_GETHASH, PROTOCOL_VERSION);
     hasher << hashBlock;
     hasher << blockundo;
     fileout << hasher.GetHash();
 
     return true;
 }
 
 static bool UndoReadFromDisk(CBlockUndo &blockundo, const CBlockIndex *pindex) {
     CDiskBlockPos 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 */
 bool AbortNode(const std::string &strMessage,
                const std::string &userMessage = "") {
     SetMiscWarning(strMessage);
     LogPrintf("*** %s\n", strMessage);
     uiInterface.ThreadSafeMessageBox(
         userMessage.empty() ? _("Error: A fatal internal error occurred, see "
                                 "debug.log for details")
                             : userMessage,
         "", CClientUIInterface::MSG_ERROR);
     StartShutdown();
     return false;
 }
 
 bool AbortNode(CValidationState &state, const std::string &strMessage,
                const std::string &userMessage = "") {
     AbortNode(strMessage, userMessage);
     return state.Error(strMessage);
 }
 
 } // namespace
 
 /** Restore the UTXO in a Coin at a given COutPoint. */
 DisconnectResult UndoCoinSpend(const Coin &undo, CCoinsViewCache &view,
                                const COutPoint &out) {
     bool fClean = true;
 
     if (view.HaveCoin(out)) {
         // Overwriting transaction output.
         fClean = false;
     }
 
     if (undo.GetHeight() == 0) {
         // Missing undo metadata (height and coinbase). Older versions included
         // this information only in undo records for the last spend of a
         // transactions' outputs. This implies that it must be present for some
         // other output of the same tx.
         const Coin &alternate = AccessByTxid(view, out.GetTxId());
         if (alternate.IsSpent()) {
             // Adding output for transaction without known metadata
             return DISCONNECT_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 ? DISCONNECT_OK : DISCONNECT_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 DISCONNECT_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 DISCONNECT_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 DISCONNECT_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 == DISCONNECT_FAILED) {
                 return DISCONNECT_FAILED;
             }
             fClean = fClean && res != DISCONNECT_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 ? DISCONNECT_OK : DISCONNECT_UNCLEAN;
 }
 
 static void FlushBlockFile(bool fFinalize = false) {
     LOCK(cs_LastBlockFile);
 
     CDiskBlockPos posOld(nLastBlockFile, 0);
 
     FILE *fileOld = OpenBlockFile(posOld);
     if (fileOld) {
         if (fFinalize) {
             TruncateFile(fileOld, vinfoBlockFile[nLastBlockFile].nSize);
         }
         FileCommit(fileOld);
         fclose(fileOld);
     }
 
     fileOld = OpenUndoFile(posOld);
     if (fileOld) {
         if (fFinalize) {
             TruncateFile(fileOld, vinfoBlockFile[nLastBlockFile].nUndoSize);
         }
         FileCommit(fileOld);
         fclose(fileOld);
     }
 }
 
 static bool FindUndoPos(CValidationState &state, int nFile, CDiskBlockPos &pos,
                         unsigned int nAddSize);
 
 static bool WriteUndoDataForBlock(const CBlockUndo &blockundo,
                                   CValidationState &state, CBlockIndex *pindex,
                                   const CChainParams &chainparams) {
     // Write undo information to disk
     if (pindex->GetUndoPos().IsNull()) {
         CDiskBlockPos _pos;
         if (!FindUndoPos(
                 state, pindex->nFile, _pos,
                 ::GetSerializeSize(blockundo, SER_DISK, 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 bool WriteTxIndexDataForBlock(const CBlock &block,
-                                     CValidationState &state,
-                                     CBlockIndex *pindex) {
-    CDiskTxPos pos(pindex->GetBlockPos(),
-                   GetSizeOfCompactSize(block.vtx.size()));
-    std::vector<std::pair<uint256, CDiskTxPos>> vPos;
-    vPos.reserve(block.vtx.size());
-    for (const CTransactionRef &tx : block.vtx) {
-        vPos.push_back(std::make_pair(tx->GetHash(), pos));
-        pos.nTxOffset += ::GetSerializeSize(*tx, SER_DISK, CLIENT_VERSION);
-    }
-
-    if (fTxIndex) {
-        if (!pblocktree->WriteTxIndex(vPos)) {
-            return AbortNode(state, "Failed to write transaction index");
-        }
-    }
-
-    return true;
-}
-
 static CCheckQueue<CScriptCheck> scriptcheckqueue(128);
 
 void ThreadScriptCheck() {
     RenameThread("bitcoin-scriptch");
     scriptcheckqueue.Thread();
 }
 
 int32_t ComputeBlockVersion(const CBlockIndex *pindexPrev,
                             const Consensus::Params &params) {
     int32_t nVersion = VERSIONBITS_TOP_BITS;
     return nVersion;
 }
 
 // Returns the script flags which should be checked for a given block
 static uint32_t GetBlockScriptFlags(const Config &config,
                                     const CBlockIndex *pChainTip) {
     AssertLockHeld(cs_main);
     const Consensus::Params &consensusParams =
         config.GetChainParams().GetConsensus();
 
     uint32_t flags = SCRIPT_VERIFY_NONE;
 
     // P2SH didn't become active until Apr 1 2012
     if (pChainTip->GetMedianTimePast() >= P2SH_ACTIVATION_TIME) {
         flags |= SCRIPT_VERIFY_P2SH;
     }
 
     // Start enforcing the DERSIG (BIP66) rule.
     if ((pChainTip->nHeight + 1) >= consensusParams.BIP66Height) {
         flags |= SCRIPT_VERIFY_DERSIG;
     }
 
     // Start enforcing CHECKLOCKTIMEVERIFY (BIP65) rule.
     if ((pChainTip->nHeight + 1) >= consensusParams.BIP65Height) {
         flags |= SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY;
     }
 
     // Start enforcing CSV (BIP68, BIP112 and BIP113) rule.
     if ((pChainTip->nHeight + 1) >= consensusParams.CSVHeight) {
         flags |= SCRIPT_VERIFY_CHECKSEQUENCEVERIFY;
     }
 
     // If the UAHF is enabled, we start accepting replay protected txns
     if (IsUAHFenabled(config, pChainTip)) {
         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(config, pChainTip)) {
         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(config, pChainTip)) {
         flags |= SCRIPT_ENABLE_CHECKDATASIG;
         flags |= SCRIPT_VERIFY_SIGPUSHONLY;
         flags |= SCRIPT_VERIFY_CLEANSTACK;
     }
 
     // If the Great Wall fork is enabled, we start accepting transactions
     // recovering coins sent to segwit addresses. We also start accepting
     // 65/64-byte Schnorr signatures in CHECKSIG and CHECKDATASIG respectively,
     // and their verify variants. We also stop accepting 65 byte signatures in
     // CHECKMULTISIG and its verify variant.
     if (IsGreatWallEnabled(config, pChainTip)) {
         flags |= SCRIPT_ALLOW_SEGWIT_RECOVERY;
         flags |= SCRIPT_ENABLE_SCHNORR;
     }
 
     // We make sure this node will have replay protection during the next hard
     // fork.
     if (IsReplayProtectionEnabled(config, pChainTip)) {
         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 Config &config, const CBlock &block,
                                CValidationState &state, CBlockIndex *pindex,
                                CCoinsViewCache &view, bool fJustCheck) {
     AssertLockHeld(cs_main);
     assert(pindex);
     assert(*pindex->phashBlock == block.GetHash());
     int64_t nTimeStart = GetTimeMicros();
 
     // Check it again in case a previous version let a bad block in
     BlockValidationOptions validationOptions =
         BlockValidationOptions(!fJustCheck, !fJustCheck);
     if (!CheckBlock(config, block, state, validationOptions)) {
         return error("%s: Consensus::CheckBlock: %s", __func__,
                      FormatStateMessage(state));
     }
 
     // Verify that the view's current state corresponds to the previous block
     uint256 hashPrevBlock =
         pindex->pprev == nullptr ? uint256() : pindex->pprev->GetBlockHash();
     assert(hashPrevBlock == view.GetBestBlock());
 
     // Special case for the genesis block, skipping connection of its
     // transactions (its coinbase is unspendable)
     const Consensus::Params &consensusParams =
         config.GetChainParams().GetConsensus();
     if (block.GetHash() == consensusParams.hashGenesisBlock) {
         if (!fJustCheck) {
             view.SetBestBlock(pindex->GetBlockHash());
         }
 
         return true;
     }
 
     nBlocksTotal++;
 
     bool fScriptChecks = true;
     if (!hashAssumeValid.IsNull()) {
         // We've been configured with the hash of a block which has been
         // externally verified to have a valid history. A suitable default value
         // is included with the software and updated from time to time. Because
         // validity relative to a piece of software is an objective fact these
         // defaults can be easily reviewed. This setting doesn't force the
         // selection of any particular chain but makes validating some faster by
         // effectively caching the result of part of the verification.
         BlockMap::const_iterator it = mapBlockIndex.find(hashAssumeValid);
         if (it != mapBlockIndex.end()) {
             if (it->second->GetAncestor(pindex->nHeight) == pindex &&
                 pindexBestHeader->GetAncestor(pindex->nHeight) == pindex &&
                 pindexBestHeader->nChainWork >= nMinimumChainWork) {
                 // This block is a member of the assumed verified chain and an
                 // ancestor of the best header. The equivalent time check
                 // discourages hash power from extorting the network via DOS
                 // attack into accepting an invalid block through telling users
                 // they must manually set assumevalid. Requiring a software
                 // change or burying the invalid block, regardless of the
                 // setting, makes it hard to hide the implication of the demand.
                 // This also avoids having release candidates that are hardly
                 // doing any signature verification at all in testing without
                 // having to artificially set the default assumed verified block
                 // further back. The test against nMinimumChainWork prevents the
                 // skipping when denied access to any chain at least as good as
                 // the expected chain.
                 fScriptChecks =
                     (GetBlockProofEquivalentTime(
                          *pindexBestHeader, *pindex, *pindexBestHeader,
                          consensusParams) <= 60 * 60 * 24 * 7 * 2);
             }
         }
     }
 
     int64_t nTime1 = GetTimeMicros();
     nTimeCheck += nTime1 - nTimeStart;
     LogPrint(BCLog::BENCH, "    - Sanity checks: %.2fms [%.2fs (%.2fms/blk)]\n",
              MILLI * (nTime1 - nTimeStart), nTimeCheck * MICRO,
              nTimeCheck * MILLI / nBlocksTotal);
 
     // Do not allow blocks that contain transactions which 'overwrite' older
     // transactions, unless those are already completely spent. If such
     // overwrites are allowed, coinbases and transactions depending upon those
     // can be duplicated to remove the ability to spend the first instance --
     // even after being sent to another address. See BIP30 and
     // http://r6.ca/blog/20120206T005236Z.html for more information. This logic
     // is not necessary for memory pool transactions, as AcceptToMemoryPool
     // already refuses previously-known transaction ids entirely. This rule was
     // originally applied to all blocks with a timestamp after March 15, 2012,
     // 0:00 UTC. Now that the whole chain is irreversibly beyond that time it is
     // applied to all blocks except the two in the chain that violate it. This
     // prevents exploiting the issue against nodes during their initial block
     // download.
     bool fEnforceBIP30 = !((pindex->nHeight == 91842 &&
                             pindex->GetBlockHash() ==
                                 uint256S("0x00000000000a4d0a398161ffc163c503763"
                                          "b1f4360639393e0e4c8e300e0caec")) ||
                            (pindex->nHeight == 91880 &&
                             pindex->GetBlockHash() ==
                                 uint256S("0x00000000000743f190a18c5577a3c2d2a1f"
                                          "610ae9601ac046a38084ccb7cd721")));
 
     // Once BIP34 activated it was not possible to create new duplicate
     // coinbases and thus other than starting with the 2 existing duplicate
     // coinbase pairs, not possible to create overwriting txs. But by the time
     // BIP34 activated, in each of the existing pairs the duplicate coinbase had
     // overwritten the first before the first had been spent. Since those
     // coinbases are sufficiently buried its no longer possible to create
     // further duplicate transactions descending from the known pairs either. If
     // we're on the known chain at height greater than where BIP34 activated, we
     // can save the db accesses needed for the BIP30 check.
     assert(pindex->pprev);
     CBlockIndex *pindexBIP34height =
         pindex->pprev->GetAncestor(consensusParams.BIP34Height);
     // Only continue to enforce if we're below BIP34 activation height or the
     // block hash at that height doesn't correspond.
     fEnforceBIP30 =
         fEnforceBIP30 &&
         (!pindexBIP34height ||
          !(pindexBIP34height->GetBlockHash() == consensusParams.BIP34Hash));
 
     if (fEnforceBIP30) {
         for (const auto &tx : block.vtx) {
             for (size_t o = 0; o < tx->vout.size(); o++) {
                 if (view.HaveCoin(COutPoint(tx->GetId(), o))) {
                     return state.DoS(
                         100,
                         error("ConnectBlock(): tried to overwrite transaction"),
                         REJECT_INVALID, "bad-txns-BIP30");
                 }
             }
         }
     }
 
     // Start enforcing BIP68 (sequence locks).
     int nLockTimeFlags = 0;
     if (pindex->nHeight >= consensusParams.CSVHeight) {
         nLockTimeFlags |= LOCKTIME_VERIFY_SEQUENCE;
     }
 
     const uint32_t flags = GetBlockScriptFlags(config, 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);
 
     CBlockUndo blockundo;
 
     CCheckQueueControl<CScriptCheck> control(fScriptChecks ? &scriptcheckqueue
                                                            : nullptr);
 
     std::vector<int> prevheights;
     Amount nFees = Amount::zero();
     int nInputs = 0;
 
     // Sigops counting. We need to do it again because of P2SH.
     uint64_t nSigOpsCount = 0;
     const uint64_t currentBlockSize =
         ::GetSerializeSize(block, SER_NETWORK, PROTOCOL_VERSION);
     const uint64_t nMaxSigOpsCount = GetMaxBlockSigOpsCount(currentBlockSize);
 
     blockundo.vtxundo.reserve(block.vtx.size() - 1);
 
     for (const auto &ptx : block.vtx) {
         const CTransaction &tx = *ptx;
 
         nInputs += tx.vin.size();
 
         if (tx.IsCoinBase()) {
             // We've already checked for sigops count before P2SH in CheckBlock.
             nSigOpsCount += GetSigOpCountWithoutP2SH(tx, flags);
         }
 
         // We do not need to throw when a transaction is duplicated. If they are
         // in the same block, CheckBlock will catch it, and if they are in a
         // different block, it'll register as a double spend or BIP30 violation.
         // In both cases, we get a more meaningful feedback out of it.
         AddCoins(view, tx, pindex->nHeight, true);
     }
 
     for (const auto &ptx : block.vtx) {
         const CTransaction &tx = *ptx;
         if (tx.IsCoinBase()) {
             continue;
         }
 
         if (!view.HaveInputs(tx)) {
             return state.DoS(100, error("ConnectBlock(): inputs missing/spent"),
                              REJECT_INVALID, "bad-txns-inputs-missingorspent");
         }
 
         // Check that transaction is BIP68 final BIP68 lock checks (as
         // opposed to nLockTime checks) must be in ConnectBlock because they
         // require the UTXO set.
         prevheights.resize(tx.vin.size());
         for (size_t j = 0; j < tx.vin.size(); j++) {
             prevheights[j] = view.AccessCoin(tx.vin[j].prevout).GetHeight();
         }
 
         if (!SequenceLocks(tx, nLockTimeFlags, &prevheights, *pindex)) {
             return state.DoS(
                 100,
                 error("%s: contains a non-BIP68-final transaction", __func__),
                 REJECT_INVALID, "bad-txns-nonfinal");
         }
 
         // GetTransactionSigOpCount counts 2 types of sigops:
         // * legacy (always)
         // * p2sh (when P2SH enabled in flags and excludes coinbase)
         auto txSigOpsCount = GetTransactionSigOpCount(tx, view, flags);
         if (txSigOpsCount > MAX_TX_SIGOPS_COUNT) {
             return state.DoS(100, false, REJECT_INVALID, "bad-txn-sigops");
         }
 
         nSigOpsCount += txSigOpsCount;
         if (nSigOpsCount > nMaxSigOpsCount) {
             return state.DoS(100, error("ConnectBlock(): too many sigops"),
                              REJECT_INVALID, "bad-blk-sigops");
         }
 
         Amount fee = view.GetValueIn(tx) - tx.GetValueOut();
         nFees += fee;
 
         // Don't cache results if we're actually connecting blocks (still
         // consult the cache, though).
         bool fCacheResults = fJustCheck;
 
         std::vector<CScriptCheck> vChecks;
         if (!CheckInputs(tx, state, view, fScriptChecks, flags, fCacheResults,
                          fCacheResults, PrecomputedTransactionData(tx),
                          &vChecks)) {
             return error("ConnectBlock(): CheckInputs on %s failed with %s",
                          tx.GetId().ToString(), FormatStateMessage(state));
         }
 
         control.Add(vChecks);
 
         blockundo.vtxundo.push_back(CTxUndo());
         SpendCoins(view, tx, blockundo.vtxundo.back(), pindex->nHeight);
     }
 
     int64_t nTime3 = GetTimeMicros();
     nTimeConnect += nTime3 - nTime2;
     LogPrint(BCLog::BENCH,
              "      - Connect %u transactions: %.2fms (%.3fms/tx, %.3fms/txin) "
              "[%.2fs (%.2fms/blk)]\n",
              (unsigned)block.vtx.size(), MILLI * (nTime3 - nTime2),
              MILLI * (nTime3 - nTime2) / block.vtx.size(),
              nInputs <= 1 ? 0 : MILLI * (nTime3 - nTime2) / (nInputs - 1),
              nTimeConnect * MICRO, nTimeConnect * MILLI / nBlocksTotal);
 
     Amount blockReward =
         nFees + GetBlockSubsidy(pindex->nHeight, consensusParams);
     if (block.vtx[0]->GetValueOut() > blockReward) {
         return state.DoS(100,
                          error("ConnectBlock(): coinbase pays too much "
                                "(actual=%d vs limit=%d)",
                                block.vtx[0]->GetValueOut(), blockReward),
                          REJECT_INVALID, "bad-cb-amount");
     }
 
     if (!control.Wait()) {
         return state.DoS(100, false, REJECT_INVALID, "blk-bad-inputs", false,
                          "parallel script check failed");
     }
 
     int64_t nTime4 = GetTimeMicros();
     nTimeVerify += nTime4 - nTime2;
     LogPrint(
         BCLog::BENCH,
         "    - Verify %u txins: %.2fms (%.3fms/txin) [%.2fs (%.2fms/blk)]\n",
         nInputs - 1, MILLI * (nTime4 - nTime2),
         nInputs <= 1 ? 0 : MILLI * (nTime4 - nTime2) / (nInputs - 1),
         nTimeVerify * MICRO, nTimeVerify * MILLI / nBlocksTotal);
 
     if (fJustCheck) {
         return true;
     }
 
     if (!WriteUndoDataForBlock(blockundo, state, pindex,
                                config.GetChainParams())) {
         return false;
     }
 
     if (!pindex->IsValid(BlockValidity::SCRIPTS)) {
         pindex->RaiseValidity(BlockValidity::SCRIPTS);
         setDirtyBlockIndex.insert(pindex);
     }
 
-    if (!WriteTxIndexDataForBlock(block, state, pindex)) {
-        return false;
-    }
-
     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;
 }
 
 /**
  * Update the on-disk chain state.
  * The caches and indexes are flushed depending on the mode we're called with if
  * they're too large, if it's been a while since the last write, or always and
  * in all cases if we're in prune mode and are deleting files.
  */
 static bool FlushStateToDisk(const CChainParams &chainparams,
                              CValidationState &state, FlushStateMode mode,
                              int nManualPruneHeight) {
     int64_t nMempoolUsage = g_mempool.DynamicMemoryUsage();
     LOCK(cs_main);
     static int64_t nLastWrite = 0;
     static int64_t nLastFlush = 0;
     std::set<int> setFilesToPrune;
     bool full_flush_completed = false;
     try {
         {
             bool fFlushForPrune = false;
             bool fDoFullFlush = false;
             LOCK(cs_LastBlockFile);
             if (fPruneMode && (fCheckForPruning || nManualPruneHeight > 0) &&
                 !fReindex) {
                 if (nManualPruneHeight > 0) {
                     FindFilesToPruneManual(setFilesToPrune, nManualPruneHeight);
                 } else {
                     FindFilesToPrune(setFilesToPrune,
                                      chainparams.PruneAfterHeight());
                     fCheckForPruning = false;
                 }
                 if (!setFilesToPrune.empty()) {
                     fFlushForPrune = true;
                     if (!fHavePruned) {
                         pblocktree->WriteFlag("prunedblockfiles", true);
                         fHavePruned = true;
                     }
                 }
             }
             int64_t nNow = GetTimeMicros();
             // Avoid writing/flushing immediately after startup.
             if (nLastWrite == 0) {
                 nLastWrite = nNow;
             }
             if (nLastFlush == 0) {
                 nLastFlush = nNow;
             }
             int64_t nMempoolSizeMax =
                 gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000;
             int64_t cacheSize = pcoinsTip->DynamicMemoryUsage();
             int64_t nTotalSpace =
                 nCoinCacheUsage +
                 std::max<int64_t>(nMempoolSizeMax - nMempoolUsage, 0);
             // The cache is large and we're within 10% and 10 MiB of the limit,
             // but we have time now (not in the middle of a block processing).
             bool fCacheLarge =
                 mode == FlushStateMode::PERIODIC &&
                 cacheSize > std::max((9 * nTotalSpace) / 10,
                                      nTotalSpace -
                                          MAX_BLOCK_COINSDB_USAGE * 1024 * 1024);
             // The cache is over the limit, we have to write now.
             bool fCacheCritical =
                 mode == FlushStateMode::IF_NEEDED && cacheSize > nTotalSpace;
             // It's been a while since we wrote the block index to disk. Do this
             // frequently, so we don't need to redownload after a crash.
             bool fPeriodicWrite =
                 mode == FlushStateMode::PERIODIC &&
                 nNow > nLastWrite + (int64_t)DATABASE_WRITE_INTERVAL * 1000000;
             // It's been very long since we flushed the cache. Do this
             // infrequently, to optimize cache usage.
             bool fPeriodicFlush =
                 mode == FlushStateMode::PERIODIC &&
                 nNow > nLastFlush + (int64_t)DATABASE_FLUSH_INTERVAL * 1000000;
             // Combine all conditions that result in a full cache flush.
             fDoFullFlush = (mode == FlushStateMode::ALWAYS) || fCacheLarge ||
                            fCacheCritical || fPeriodicFlush || fFlushForPrune;
             // Write blocks and block index to disk.
             if (fDoFullFlush || fPeriodicWrite) {
                 // Depend on nMinDiskSpace to ensure we can write block index
                 if (!CheckDiskSpace(0, true)) {
                     return state.Error("out of disk space");
                 }
 
                 // First make sure all block and undo data is flushed to disk.
                 FlushBlockFile();
                 // Then update all block file information (which may refer to
                 // block and undo files).
                 {
                     std::vector<std::pair<int, const CBlockFileInfo *>> vFiles;
                     vFiles.reserve(setDirtyFileInfo.size());
                     for (int i : setDirtyFileInfo) {
                         vFiles.push_back(std::make_pair(i, &vinfoBlockFile[i]));
                     }
 
                     setDirtyFileInfo.clear();
 
                     std::vector<const CBlockIndex *> vBlocks;
                     vBlocks.reserve(setDirtyBlockIndex.size());
                     for (const CBlockIndex *cbi : setDirtyBlockIndex) {
                         vBlocks.push_back(cbi);
                     }
 
                     setDirtyBlockIndex.clear();
 
                     if (!pblocktree->WriteBatchSync(vFiles, nLastBlockFile,
                                                     vBlocks)) {
                         return AbortNode(
                             state, "Failed to write to block index database");
                     }
                 }
 
                 // Finally remove any pruned files
                 if (fFlushForPrune) {
                     UnlinkPrunedFiles(setFilesToPrune);
                 }
                 nLastWrite = nNow;
             }
             // Flush best chain related state. This can only be done if the
             // blocks / block index write was also done.
             if (fDoFullFlush && !pcoinsTip->GetBestBlock().IsNull()) {
                 // Typical Coin structures on disk are around 48 bytes in size.
                 // Pushing a new one to the database can cause it to be written
                 // twice (once in the log, and once in the tables). This is
                 // already an overestimation, as most will delete an existing
                 // entry or overwrite one. Still, use a conservative safety
                 // factor of 2.
                 if (!CheckDiskSpace(48 * 2 * 2 * pcoinsTip->GetCacheSize())) {
                     return state.Error("out of disk space");
                 }
 
                 // Flush the chainstate (which may refer to block index
                 // entries).
                 if (!pcoinsTip->Flush()) {
                     return AbortNode(state, "Failed to write to coin database");
                 }
                 nLastFlush = nNow;
                 full_flush_completed = true;
             }
         }
 
         if (full_flush_completed) {
             // Update best block in wallet (so we can detect restored wallets).
             GetMainSignals().ChainStateFlushed(chainActive.GetLocator());
         }
     } catch (const std::runtime_error &e) {
         return AbortNode(state, std::string("System error while flushing: ") +
                                     e.what());
     }
     return true;
 }
 
 void FlushStateToDisk() {
     CValidationState state;
     const CChainParams &chainparams = Params();
     FlushStateToDisk(chainparams, state, FlushStateMode::ALWAYS);
 }
 
 void PruneAndFlush() {
     CValidationState state;
     fCheckForPruning = true;
     const CChainParams &chainparams = Params();
     FlushStateToDisk(chainparams, state, FlushStateMode::NONE);
 }
 
 /**
  * Update chainActive and related internal data structures when adding a new
  * block to the chain tip.
  */
 static void UpdateTip(const Config &config, CBlockIndex *pindexNew) {
     const Consensus::Params &consensusParams =
         config.GetChainParams().GetConsensus();
 
     chainActive.SetTip(pindexNew);
 
     // New best block
     g_mempool.AddTransactionsUpdated(1);
 
     {
         LOCK(g_best_block_mutex);
         g_best_block = pindexNew->GetBlockHash();
         g_best_block_cv.notify_all();
     }
 
     static bool fWarned = false;
     std::vector<std::string> warningMessages;
     if (!IsInitialBlockDownload()) {
         int nUpgraded = 0;
         const CBlockIndex *pindex = chainActive.Tip();
 
         // Check the version of the last 100 blocks to see if we need to
         // upgrade:
         for (int i = 0; i < 100 && pindex != nullptr; i++) {
             int32_t nExpectedVersion =
                 ComputeBlockVersion(pindex->pprev, consensusParams);
             if (pindex->nVersion > VERSIONBITS_LAST_OLD_BLOCK_VERSION &&
                 (pindex->nVersion & ~nExpectedVersion) != 0) {
                 ++nUpgraded;
             }
             pindex = pindex->pprev;
         }
         if (nUpgraded > 0) {
             warningMessages.push_back(strprintf(
                 "%d of last 100 blocks have unexpected version", nUpgraded));
         }
         if (nUpgraded > 100 / 2) {
             std::string strWarning =
                 _("Warning: Unknown block versions being mined! It's possible "
                   "unknown rules are in effect");
             // notify GetWarnings(), called by Qt and the JSON-RPC code to warn
             // the user:
             SetMiscWarning(strWarning);
             if (!fWarned) {
                 AlertNotify(strWarning);
                 fWarned = true;
             }
         }
     }
     LogPrintf("%s: new best=%s height=%d version=0x%08x log2_work=%.8g tx=%lu "
               "date='%s' progress=%f cache=%.1fMiB(%utxo)",
               __func__, chainActive.Tip()->GetBlockHash().ToString(),
               chainActive.Height(), chainActive.Tip()->nVersion,
               log(chainActive.Tip()->nChainWork.getdouble()) / log(2.0),
               (unsigned long)chainActive.Tip()->nChainTx,
               FormatISO8601DateTime(chainActive.Tip()->GetBlockTime()),
               GuessVerificationProgress(config.GetChainParams().TxData(),
                                         chainActive.Tip()),
               pcoinsTip->DynamicMemoryUsage() * (1.0 / (1 << 20)),
               pcoinsTip->GetCacheSize());
     if (!warningMessages.empty()) {
         LogPrintf(" warning='%s'",
                   boost::algorithm::join(warningMessages, ", "));
     }
     LogPrintf("\n");
 }
 
 /**
  * Disconnect chainActive'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 Config &config, CValidationState &state,
                                 DisconnectedBlockTransactions *disconnectpool) {
     CBlockIndex *pindexDelete = chainActive.Tip();
     assert(pindexDelete);
 
     // Read block from disk.
     std::shared_ptr<CBlock> pblock = std::make_shared<CBlock>();
     CBlock &block = *pblock;
     if (!ReadBlockFromDisk(block, pindexDelete, config)) {
         return AbortNode(state, "Failed to read block");
     }
 
     // Apply the block atomically to the chain state.
     int64_t nStart = GetTimeMicros();
     {
         CCoinsViewCache view(pcoinsTip.get());
         assert(view.GetBestBlock() == pindexDelete->GetBlockHash());
         if (DisconnectBlock(block, pindexDelete, view) != DISCONNECT_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(config.GetChainParams(), 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 &&
         GetBlockScriptFlags(config, pindexDelete) !=
             GetBlockScriptFlags(config, pindexDelete->pprev)) {
         LogPrint(BCLog::MEMPOOL,
                  "Disconnecting mempool due to rewind of upgrade block\n");
         if (disconnectpool) {
             disconnectpool->importMempool(g_mempool);
         }
         g_mempool.clear();
     }
 
     if (disconnectpool) {
         disconnectpool->addForBlock(block.vtx);
     }
 
     // If the tip is finalized, then undo it.
     if (pindexFinalized == pindexDelete) {
         pindexFinalized = pindexDelete->pprev;
     }
 
     // Update chainActive and related variables.
     UpdateTip(config, pindexDelete->pprev);
     // Let wallets know transactions went from 1-confirmed to
     // 0-confirmed or conflicted:
     GetMainSignals().BlockDisconnected(pblock);
     return true;
 }
 
 static int64_t nTimeReadFromDisk = 0;
 static int64_t nTimeConnectTotal = 0;
 static int64_t nTimeFlush = 0;
 static int64_t nTimeChainState = 0;
 static int64_t nTimePostConnect = 0;
 
 struct PerBlockConnectTrace {
     CBlockIndex *pindex = nullptr;
     std::shared_ptr<const CBlock> pblock;
     std::shared_ptr<std::vector<CTransactionRef>> conflictedTxs;
     PerBlockConnectTrace()
         : conflictedTxs(std::make_shared<std::vector<CTransactionRef>>()) {}
 };
 
 /**
  * Used to track blocks whose transactions were applied to the UTXO state as a
  * part of a single ActivateBestChainStep call.
  *
  * This class also tracks transactions that are removed from the mempool as
  * conflicts (per block) and can be used to pass all those transactions through
  * SyncTransaction.
  *
  * This class assumes (and asserts) that the conflicted transactions for a given
  * block are added via mempool callbacks prior to the BlockConnected()
  * associated with those transactions. If any transactions are marked
  * conflicted, it is assumed that an associated block will always be added.
  *
  * This class is single-use, once you call GetBlocksConnected() you have to
  * throw it away and make a new one.
  */
 class ConnectTrace {
 private:
     std::vector<PerBlockConnectTrace> blocksConnected;
     CTxMemPool &pool;
 
 public:
     explicit ConnectTrace(CTxMemPool &_pool) : blocksConnected(1), pool(_pool) {
         pool.NotifyEntryRemoved.connect(
             boost::bind(&ConnectTrace::NotifyEntryRemoved, this, _1, _2));
     }
 
     ~ConnectTrace() {
         pool.NotifyEntryRemoved.disconnect(
             boost::bind(&ConnectTrace::NotifyEntryRemoved, this, _1, _2));
     }
 
     void BlockConnected(CBlockIndex *pindex,
                         std::shared_ptr<const CBlock> pblock) {
         assert(!blocksConnected.back().pindex);
         assert(pindex);
         assert(pblock);
         blocksConnected.back().pindex = pindex;
         blocksConnected.back().pblock = std::move(pblock);
         blocksConnected.emplace_back();
     }
 
     std::vector<PerBlockConnectTrace> &GetBlocksConnected() {
         // We always keep one extra block at the end of our list because blocks
         // are added after all the conflicted transactions have been filled in.
         // Thus, the last entry should always be an empty one waiting for the
         // transactions from the next block. We pop the last entry here to make
         // sure the list we return is sane.
         assert(!blocksConnected.back().pindex);
         assert(blocksConnected.back().conflictedTxs->empty());
         blocksConnected.pop_back();
         return blocksConnected;
     }
 
     void NotifyEntryRemoved(CTransactionRef txRemoved,
                             MemPoolRemovalReason reason) {
         assert(!blocksConnected.back().pindex);
         if (reason == MemPoolRemovalReason::CONFLICT) {
             blocksConnected.back().conflictedTxs->emplace_back(
                 std::move(txRemoved));
         }
     }
 };
 
 static bool FinalizeBlockInternal(const Config &config, CValidationState &state,
                                   const CBlockIndex *pindex) {
     AssertLockHeld(cs_main);
     if (pindex->nStatus.isInvalid()) {
         // We try to finalize an invalid block.
         return state.DoS(100,
                          error("%s: Trying to finalize invalid block %s",
                                __func__, pindex->GetBlockHash().ToString()),
                          REJECT_INVALID, "finalize-invalid-block");
     }
 
     // Check that the request is consistent with current finalization.
     if (pindexFinalized && !AreOnTheSameFork(pindex, pindexFinalized)) {
         return state.DoS(
             20,
             error("%s: Trying to finalize block %s which conflicts "
                   "with already finalized block",
                   __func__, pindex->GetBlockHash().ToString()),
             REJECT_AGAINST_FINALIZED, "bad-fork-prior-finalized");
     }
 
     if (IsBlockFinalized(pindex)) {
         // The block is already finalized.
         return true;
     }
 
     // We have a new block to finalize.
     pindexFinalized = pindex;
     return true;
 }
 
 static const CBlockIndex *FindBlockToFinalize(const Config &config,
                                               CBlockIndex *pindexNew) {
     AssertLockHeld(cs_main);
 
     const int32_t maxreorgdepth =
         gArgs.GetArg("-maxreorgdepth", DEFAULT_MAX_REORG_DEPTH);
 
     const int64_t finalizationdelay =
         gArgs.GetArg("-finalizationdelay", DEFAULT_MIN_FINALIZATION_DELAY);
 
     // Find our candidate.
     // If maxreorgdepth is < 0 pindex will be null and auto finalization
     // disabled
     const CBlockIndex *pindex =
         pindexNew->GetAncestor(pindexNew->nHeight - maxreorgdepth);
 
     int64_t now = GetTime();
 
     // If the finalization delay is not expired since the startup time,
     // finalization should be avoided. Header receive time is not saved to disk
     // and so cannot be anterior to startup time.
     if (now < (GetStartupTime() + finalizationdelay)) {
         return nullptr;
     }
 
     // While our candidate is not eligible (finalization delay not expired), try
     // the previous one.
     while (pindex && (pindex != pindexFinalized)) {
         // Check that the block to finalize is known for a long enough time.
         // This test will ensure that an attacker could not cause a block to
         // finalize by forking the chain with a depth > maxreorgdepth.
         // If the block is loaded from disk, header receive time is 0 and the
         // block will be finalized. This is safe because the delay since the
         // node startup is already expired.
         auto headerReceivedTime = pindex->GetHeaderReceivedTime();
 
         // If finalization delay is <= 0, finalization always occurs immediately
         if (now >= (headerReceivedTime + finalizationdelay)) {
             return pindex;
         }
 
         pindex = pindex->pprev;
     }
 
     return nullptr;
 }
 
 /**
  * Connect a new block to chainActive. pblock is either nullptr or a pointer to
  * a CBlock corresponding to pindexNew, to bypass loading it again from disk.
  *
  * The block is always added to connectTrace (either after loading from disk or
  * by copying pblock) - if that is not intended, care must be taken to remove
  * the last entry in blocksConnected in case of failure.
  */
 bool CChainState::ConnectTip(const Config &config, CValidationState &state,
                              CBlockIndex *pindexNew,
                              const std::shared_ptr<const CBlock> &pblock,
                              ConnectTrace &connectTrace,
                              DisconnectedBlockTransactions &disconnectpool) {
     AssertLockHeld(cs_main);
 
     assert(pindexNew->pprev == chainActive.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, config)) {
             return AbortNode(state, "Failed to read block");
         }
         pthisBlock = pblockNew;
     } else {
         pthisBlock = pblock;
     }
 
     const CBlock &blockConnecting = *pthisBlock;
 
     // Apply the block atomically to the chain state.
     int64_t nTime2 = GetTimeMicros();
     nTimeReadFromDisk += nTime2 - nTime1;
     int64_t nTime3;
     LogPrint(BCLog::BENCH, "  - Load block from disk: %.2fms [%.2fs]\n",
              (nTime2 - nTime1) * MILLI, nTimeReadFromDisk * MICRO);
     {
         CCoinsViewCache view(pcoinsTip.get());
         bool rv = ConnectBlock(config, blockConnecting, state, pindexNew, view);
         GetMainSignals().BlockChecked(blockConnecting, state);
         if (!rv) {
             if (state.IsInvalid()) {
                 InvalidBlockFound(pindexNew, state);
             }
 
             return error("ConnectTip(): ConnectBlock %s failed (%s)",
                          pindexNew->GetBlockHash().ToString(),
                          FormatStateMessage(state));
         }
 
         // Update the finalized block.
         const CBlockIndex *pindexToFinalize =
             FindBlockToFinalize(config, pindexNew);
         if (pindexToFinalize &&
             !FinalizeBlockInternal(config, state, pindexToFinalize)) {
             state.SetCorruptionPossible();
             return error("ConnectTip(): FinalizeBlock %s failed (%s)",
                          pindexNew->GetBlockHash().ToString(),
                          FormatStateMessage(state));
         }
 
         nTime3 = GetTimeMicros();
         nTimeConnectTotal += nTime3 - nTime2;
         LogPrint(BCLog::BENCH,
                  "  - Connect total: %.2fms [%.2fs (%.2fms/blk)]\n",
                  (nTime3 - nTime2) * MILLI, nTimeConnectTotal * MICRO,
                  nTimeConnectTotal * MILLI / nBlocksTotal);
         bool flushed = view.Flush();
         assert(flushed);
     }
 
     int64_t nTime4 = GetTimeMicros();
     nTimeFlush += nTime4 - nTime3;
     LogPrint(BCLog::BENCH, "  - Flush: %.2fms [%.2fs (%.2fms/blk)]\n",
              (nTime4 - nTime3) * MILLI, nTimeFlush * MICRO,
              nTimeFlush * MILLI / nBlocksTotal);
 
     // Write the chain state to disk, if necessary.
     if (!FlushStateToDisk(config.GetChainParams(), state,
                           FlushStateMode::IF_NEEDED)) {
         return false;
     }
 
     int64_t nTime5 = GetTimeMicros();
     nTimeChainState += nTime5 - nTime4;
     LogPrint(BCLog::BENCH,
              "  - Writing chainstate: %.2fms [%.2fs (%.2fms/blk)]\n",
              (nTime5 - nTime4) * MILLI, nTimeChainState * MICRO,
              nTimeChainState * MILLI / nBlocksTotal);
 
     // Remove conflicting transactions from the mempool.;
     g_mempool.removeForBlock(blockConnecting.vtx, pindexNew->nHeight);
     disconnectpool.removeForBlock(blockConnecting.vtx);
 
     // If this block is activating a fork, we move all mempool transactions
     // in front of disconnectpool for reprocessing in a future
     // updateMempoolForReorg call
     if (pindexNew->pprev != nullptr &&
         GetBlockScriptFlags(config, pindexNew) !=
             GetBlockScriptFlags(config, pindexNew->pprev)) {
         LogPrint(BCLog::MEMPOOL,
                  "Disconnecting mempool due to acceptance of upgrade block\n");
         disconnectpool.importMempool(g_mempool);
     }
 
     // Update chainActive & related variables.
     UpdateTip(config, pindexNew);
 
     int64_t nTime6 = GetTimeMicros();
     nTimePostConnect += nTime6 - nTime5;
     nTimeTotal += nTime6 - nTime1;
     LogPrint(BCLog::BENCH,
              "  - Connect postprocess: %.2fms [%.2fs (%.2fms/blk)]\n",
              (nTime6 - nTime5) * MILLI, nTimePostConnect * MICRO,
              nTimePostConnect * MILLI / nBlocksTotal);
     LogPrint(BCLog::BENCH, "- Connect block: %.2fms [%.2fs (%.2fms/blk)]\n",
              (nTime6 - nTime1) * MILLI, nTimeTotal * MICRO,
              nTimeTotal * MILLI / nBlocksTotal);
 
     connectTrace.BlockConnected(pindexNew, std::move(pthisBlock));
     return true;
 }
 
 /**
  * Return the tip of the chain with the most work in it, that isn't known to be
  * invalid (it's however far from certain to be valid).
  */
 CBlockIndex *CChainState::FindMostWorkChain() {
     AssertLockHeld(cs_main);
     do {
         CBlockIndex *pindexNew = nullptr;
 
         // Find the best candidate header.
         {
             std::set<CBlockIndex *, CBlockIndexWorkComparator>::reverse_iterator
                 it = setBlockIndexCandidates.rbegin();
             if (it == setBlockIndexCandidates.rend()) {
                 return nullptr;
             }
             pindexNew = *it;
         }
 
         // If this block will cause a finalized block to be reorged, then we
         // mark it as invalid.
         if (pindexFinalized && !AreOnTheSameFork(pindexNew, pindexFinalized)) {
             LogPrintf("Mark block %s invalid because it forks prior to the "
                       "finalization point %d.\n",
                       pindexNew->GetBlockHash().ToString(),
                       pindexFinalized->nHeight);
             pindexNew->nStatus = pindexNew->nStatus.withFailed();
             InvalidChainFound(pindexNew);
         }
 
         const CBlockIndex *pindexFork = chainActive.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->nChainTx || 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("-parkdeepreorg", true)) {
                 const CBlockIndex *pindexTip = chainActive.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 accidentaly.
                     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 block %s as its chain has accumulated "
                               "enough PoW.\n",
                               pindexTest->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 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;
             }
 
             CBlockIndex *pindexFailed = pindexNew;
             // Remove the entire chain from the set.
             while (pindexTest != pindexFailed) {
                 if (fInvalidChain || fParkedChain) {
                     pindexFailed->nStatus =
                         pindexFailed->nStatus.withFailedParent(fInvalidChain)
                             .withParkedParent(fParkedChain);
                 } else if (fMissingData) {
                     // If we're missing data, then add back to
                     // mapBlocksUnlinked, so that if the block arrives in the
                     // future we can try adding to setBlockIndexCandidates
                     // again.
                     mapBlocksUnlinked.insert(
                         std::make_pair(pindexFailed->pprev, pindexFailed));
                 }
                 setBlockIndexCandidates.erase(pindexFailed);
                 pindexFailed = pindexFailed->pprev;
             }
 
             if (fInvalidChain || fParkedChain) {
                 // We discovered a new chain tip that is either parked or
                 // invalid, we may want to warn.
                 CheckForkWarningConditionsOnNewFork(pindexNew);
             }
         }
 
         // 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, chainActive.Tip())) {
         setBlockIndexCandidates.erase(it++);
     }
 
     // Either the current tip or a successor of it we're working towards is left
     // in setBlockIndexCandidates.
     assert(!setBlockIndexCandidates.empty());
 }
 
 /**
  * Try to make some progress towards making pindexMostWork the active block.
  * pblock is either nullptr or a pointer to a CBlock corresponding to
  * pindexMostWork.
  */
 bool CChainState::ActivateBestChainStep(
     const Config &config, CValidationState &state, CBlockIndex *pindexMostWork,
     const std::shared_ptr<const CBlock> &pblock, bool &fInvalidFound,
     ConnectTrace &connectTrace) {
     AssertLockHeld(cs_main);
     const CBlockIndex *pindexOldTip = chainActive.Tip();
     const CBlockIndex *pindexFork = chainActive.FindFork(pindexMostWork);
 
     // Disconnect active blocks which are no longer in the best chain.
     bool fBlocksDisconnected = false;
     DisconnectedBlockTransactions disconnectpool;
     while (chainActive.Tip() && chainActive.Tip() != pindexFork) {
         if (!DisconnectTip(config, state, &disconnectpool)) {
             // This is likely a fatal error, but keep the mempool consistent,
             // just in case. Only remove from the mempool in this case.
             disconnectpool.updateMempoolForReorg(config, false);
             return false;
         }
 
         fBlocksDisconnected = true;
     }
 
     // Build list of new blocks to connect.
     std::vector<CBlockIndex *> vpindexToConnect;
     bool fContinue = true;
     int nHeight = pindexFork ? pindexFork->nHeight : -1;
     while (fContinue && nHeight != pindexMostWork->nHeight) {
         // Don't iterate the entire list of potential improvements toward the
         // best tip, as we likely only need a few blocks along the way.
         int nTargetHeight = std::min(nHeight + 32, pindexMostWork->nHeight);
         vpindexToConnect.clear();
         vpindexToConnect.reserve(nTargetHeight - nHeight);
         CBlockIndex *pindexIter = pindexMostWork->GetAncestor(nTargetHeight);
         while (pindexIter && pindexIter->nHeight != nHeight) {
             vpindexToConnect.push_back(pindexIter);
             pindexIter = pindexIter->pprev;
         }
 
         nHeight = nTargetHeight;
 
         // Connect new blocks.
         for (CBlockIndex *pindexConnect : reverse_iterate(vpindexToConnect)) {
             if (!ConnectTip(config, state, pindexConnect,
                             pindexConnect == pindexMostWork
                                 ? pblock
                                 : std::shared_ptr<const CBlock>(),
                             connectTrace, disconnectpool)) {
                 if (state.IsInvalid()) {
                     // The block violates a consensus rule.
                     if (!state.CorruptionPossible()) {
                         InvalidChainFound(vpindexToConnect.back());
                     }
 
                     state = CValidationState();
                     fInvalidFound = true;
                     fContinue = false;
                     break;
                 }
 
                 // A system error occurred (disk space, database error, ...).
                 // Make the mempool consistent with the current tip, just in
                 // case any observers try to use it before shutdown.
                 disconnectpool.updateMempoolForReorg(config, false);
                 return false;
             } else {
                 PruneBlockIndexCandidates();
                 if (!pindexOldTip ||
                     chainActive.Tip()->nChainWork > pindexOldTip->nChainWork) {
                     // We're in a better position than we were. Return
                     // temporarily to release the lock.
                     fContinue = false;
                     break;
                 }
             }
         }
     }
 
     if (fBlocksDisconnected || !disconnectpool.isEmpty()) {
         // If any blocks were disconnected, we need to update the mempool even
         // if disconnectpool is empty. The disconnectpool may also be non-empty
         // if the mempool was imported due to new validation rules being in
         // effect.
         LogPrint(BCLog::MEMPOOL, "Updating mempool due to reorganization or "
                                  "rules upgrade/downgrade\n");
         disconnectpool.updateMempoolForReorg(config, true);
     }
 
     g_mempool.check(pcoinsTip.get());
 
     // Callbacks/notifications for a new best chain.
     if (fInvalidFound) {
         CheckForkWarningConditionsOnNewFork(pindexMostWork);
     } else {
         CheckForkWarningConditions();
     }
 
     return true;
 }
 
 static void NotifyHeaderTip() {
     bool fNotify = false;
     bool fInitialBlockDownload = false;
     static CBlockIndex *pindexHeaderOld = nullptr;
     CBlockIndex *pindexHeader = nullptr;
     {
         LOCK(cs_main);
         pindexHeader = pindexBestHeader;
 
         if (pindexHeader != pindexHeaderOld) {
             fNotify = true;
             fInitialBlockDownload = IsInitialBlockDownload();
             pindexHeaderOld = pindexHeader;
         }
     }
 
     // Send block tip changed notifications without cs_main
     if (fNotify) {
         uiInterface.NotifyHeaderTip(fInitialBlockDownload, pindexHeader);
     }
 }
 
 bool CChainState::ActivateBestChain(const Config &config,
                                     CValidationState &state,
                                     std::shared_ptr<const CBlock> pblock) {
     // Note that while we're often called here from ProcessNewBlock, this is
     // far from a guarantee. Things in the P2P/RPC will often end up calling
     // us in the middle of ProcessNewBlock - do not assume pblock is set
     // sanely for performance or correctness!
     AssertLockNotHeld(cs_main);
 
     CBlockIndex *pindexMostWork = nullptr;
     CBlockIndex *pindexNewTip = nullptr;
     int nStopAtHeight = gArgs.GetArg("-stopatheight", DEFAULT_STOPATHEIGHT);
     do {
         boost::this_thread::interruption_point();
 
         if (GetMainSignals().CallbacksPending() > 10) {
             // Block until the validation queue drains. This should largely
             // never happen in normal operation, however may happen during
             // reindex, causing memory blowup if we run too far ahead.
             SyncWithValidationInterfaceQueue();
         }
 
         const CBlockIndex *pindexFork;
         bool fInitialDownload;
         {
             LOCK(cs_main);
 
             // Destructed before cs_main is unlocked.
             ConnectTrace connectTrace(g_mempool);
 
             CBlockIndex *pindexOldTip = chainActive.Tip();
             if (pindexMostWork == nullptr) {
                 pindexMostWork = FindMostWorkChain();
             }
 
             // Whether we have anything to do at all.
             if (pindexMostWork == nullptr ||
                 pindexMostWork == chainActive.Tip()) {
                 return true;
             }
 
             bool fInvalidFound = false;
             std::shared_ptr<const CBlock> nullBlockPtr;
             if (!ActivateBestChainStep(
                     config, state, pindexMostWork,
                     pblock &&
                             pblock->GetHash() == pindexMostWork->GetBlockHash()
                         ? pblock
                         : nullBlockPtr,
                     fInvalidFound, connectTrace)) {
                 return false;
             }
 
             if (fInvalidFound) {
                 // Wipe cache, we may need another branch now.
                 pindexMostWork = nullptr;
             }
 
             pindexNewTip = chainActive.Tip();
             pindexFork = chainActive.FindFork(pindexOldTip);
             fInitialDownload = IsInitialBlockDownload();
 
             for (const PerBlockConnectTrace &trace :
                  connectTrace.GetBlocksConnected()) {
                 assert(trace.pblock && trace.pindex);
                 GetMainSignals().BlockConnected(trace.pblock, trace.pindex,
                                                 *trace.conflictedTxs);
             }
         }
 
         // When we reach this point, we switched to a new tip (stored in
         // pindexNewTip).
 
         // Notifications/callbacks that can run without cs_main
 
         // Notify external listeners about the new tip.
         GetMainSignals().UpdatedBlockTip(pindexNewTip, pindexFork,
                                          fInitialDownload);
 
         // Always notify the UI if a new block tip was connected
         if (pindexFork != pindexNewTip) {
             uiInterface.NotifyBlockTip(fInitialDownload, 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);
 
     const CChainParams &params = config.GetChainParams();
     CheckBlockIndex(params.GetConsensus());
 
     // Write changes periodically to disk, after relay.
     if (!FlushStateToDisk(params, state, FlushStateMode::PERIODIC)) {
         return false;
     }
 
     return true;
 }
 
 bool ActivateBestChain(const Config &config, CValidationState &state,
                        std::shared_ptr<const CBlock> pblock) {
     return g_chainstate.ActivateBestChain(config, state, std::move(pblock));
 }
 
 bool CChainState::PreciousBlock(const Config &config, CValidationState &state,
                                 CBlockIndex *pindex) {
     {
         LOCK(cs_main);
         if (pindex->nChainWork < chainActive.Tip()->nChainWork) {
             // Nothing to do, this block is not at the tip.
             return true;
         }
 
         if (chainActive.Tip()->nChainWork > nLastPreciousChainwork) {
             // The chain has been extended since the last call, reset the
             // counter.
             nBlockReverseSequenceId = -1;
         }
 
         nLastPreciousChainwork = chainActive.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 apropriate.
         if (pindex->IsValid(BlockValidity::TRANSACTIONS) && pindex->nChainTx) {
             setBlockIndexCandidates.insert(pindex);
             PruneBlockIndexCandidates();
         }
     }
 
     return ActivateBestChain(config, state);
 }
 
 bool PreciousBlock(const Config &config, CValidationState &state,
                    CBlockIndex *pindex) {
     return g_chainstate.PreciousBlock(config, state, pindex);
 }
 
 bool CChainState::UnwindBlock(const Config &config, CValidationState &state,
                               CBlockIndex *pindex, bool invalidate) {
     AssertLockHeld(cs_main);
 
     // Mark the block as either invalid or parked.
     pindex->nStatus = invalidate ? pindex->nStatus.withFailed()
                                  : pindex->nStatus.withParked();
     setDirtyBlockIndex.insert(pindex);
 
     DisconnectedBlockTransactions disconnectpool;
     while (chainActive.Contains(pindex)) {
         CBlockIndex *pindexWalk = chainActive.Tip();
         if (pindexWalk != pindex) {
             pindexWalk->nStatus = invalidate
                                       ? pindexWalk->nStatus.withFailedParent()
                                       : pindexWalk->nStatus.withParkedParent();
             setDirtyBlockIndex.insert(pindexWalk);
         }
 
         // ActivateBestChain considers blocks already in chainActive
         // unconditionally valid already, so force disconnect away from it.
         if (!DisconnectTip(config, state, &disconnectpool)) {
             // It's probably hopeless to try to make the mempool consistent
             // here if DisconnectTip failed, but we can try.
             disconnectpool.updateMempoolForReorg(config, false);
             return false;
         }
     }
 
     // DisconnectTip will add transactions to disconnectpool; try to add these
     // back to the mempool.
     disconnectpool.updateMempoolForReorg(config, true);
 
     // The resulting new best tip may not be in setBlockIndexCandidates anymore,
     // so add it again.
     for (const std::pair<const uint256, CBlockIndex *> &it : mapBlockIndex) {
         CBlockIndex *i = it.second;
         if (i->IsValid(BlockValidity::TRANSACTIONS) && i->nChainTx &&
             !setBlockIndexCandidates.value_comp()(i, chainActive.Tip())) {
             setBlockIndexCandidates.insert(i);
         }
     }
 
     if (invalidate) {
         InvalidChainFound(pindex);
     }
     uiInterface.NotifyBlockTip(IsInitialBlockDownload(), pindex->pprev);
     return true;
 }
 
 bool FinalizeBlockAndInvalidate(const Config &config, CValidationState &state,
                                 CBlockIndex *pindex) {
     AssertLockHeld(cs_main);
     if (!FinalizeBlockInternal(config, state, pindex)) {
         // state is set by FinalizeBlockInternal.
         return false;
     }
 
     // We have a valid candidate, make sure it is not parked.
     if (pindex->nStatus.isOnParkedChain()) {
         UnparkBlock(pindex);
     }
 
     // If the finalized block is not on the active chain, we need to rewind.
     if (!AreOnTheSameFork(pindex, chainActive.Tip())) {
         const CBlockIndex *pindexFork = chainActive.FindFork(pindex);
         CBlockIndex *pindexToInvalidate =
             chainActive.Tip()->GetAncestor(pindexFork->nHeight + 1);
         return InvalidateBlock(config, state, pindexToInvalidate);
     }
 
     return true;
 }
 
 bool InvalidateBlock(const Config &config, CValidationState &state,
                      CBlockIndex *pindex) {
     return g_chainstate.UnwindBlock(config, state, pindex, true);
 }
 
 bool ParkBlock(const Config &config, CValidationState &state,
                CBlockIndex *pindex) {
     return g_chainstate.UnwindBlock(config, state, pindex, false);
 }
 
 template <typename F>
 void CChainState::UpdateFlagsForBlock(CBlockIndex *pindexBase,
                                       CBlockIndex *pindex, F f) {
     BlockStatus newStatus = f(pindex->nStatus);
     if (pindex->nStatus != newStatus &&
         pindex->GetAncestor(pindexBase->nHeight) == pindexBase) {
         pindex->nStatus = newStatus;
         setDirtyBlockIndex.insert(pindex);
 
         if (pindex->IsValid(BlockValidity::TRANSACTIONS) && pindex->nChainTx &&
             setBlockIndexCandidates.value_comp()(chainActive.Tip(), pindex)) {
             setBlockIndexCandidates.insert(pindex);
         }
     }
 }
 
 template <typename F, typename C>
 void CChainState::UpdateFlags(CBlockIndex *pindex, F f, C fchild) {
     AssertLockHeld(cs_main);
 
     // Update the current block.
     UpdateFlagsForBlock(pindex, pindex, f);
 
     // Update the flags from this block and all its descendants.
     BlockMap::iterator it = mapBlockIndex.begin();
     while (it != mapBlockIndex.end()) {
         UpdateFlagsForBlock(pindex, it->second, fchild);
         it++;
     }
 
     // Update the flags from all ancestors too.
     while (pindex != nullptr) {
         BlockStatus newStatus = f(pindex->nStatus);
         if (pindex->nStatus != newStatus) {
             pindex->nStatus = newStatus;
             setDirtyBlockIndex.insert(pindex);
         }
         pindex = pindex->pprev;
     }
 }
 
 template <typename F> void CChainState::UpdateFlags(CBlockIndex *pindex, F f) {
     // Handy shorthand.
     UpdateFlags(pindex, f, f);
 }
 
 bool CChainState::ResetBlockFailureFlags(CBlockIndex *pindex) {
     AssertLockHeld(cs_main);
 
     if (pindexBestInvalid &&
         (pindexBestInvalid->GetAncestor(pindex->nHeight) == pindex ||
          pindex->GetAncestor(pindexBestInvalid->nHeight) ==
              pindexBestInvalid)) {
         // Reset the invalid block marker if it is about to be cleared.
         pindexBestInvalid = nullptr;
     }
 
     // In case we are reconsidering something before the finalization point,
     // move the finalization point to the last common ancestor.
     if (pindexFinalized) {
         pindexFinalized = LastCommonAncestor(pindex, pindexFinalized);
     }
 
     UpdateFlags(pindex, [](const BlockStatus status) {
         return status.withClearedFailureFlags();
     });
 
     return true;
 }
 
 bool ResetBlockFailureFlags(CBlockIndex *pindex) {
     return g_chainstate.ResetBlockFailureFlags(pindex);
 }
 
 bool CChainState::UnparkBlockImpl(CBlockIndex *pindex, bool fClearChildren) {
     AssertLockHeld(cs_main);
 
     if (pindexBestParked &&
         (pindexBestParked->GetAncestor(pindex->nHeight) == pindex ||
          pindex->GetAncestor(pindexBestParked->nHeight) == pindexBestParked)) {
         // Reset the parked block marker if it is about to be cleared.
         pindexBestParked = nullptr;
     }
 
     UpdateFlags(pindex,
                 [](const BlockStatus status) {
                     return status.withClearedParkedFlags();
                 },
                 [fClearChildren](const BlockStatus status) {
                     return fClearChildren ? status.withClearedParkedFlags()
                                           : status.withParkedParent(false);
                 });
 
     return true;
 }
 
 bool UnparkBlockAndChildren(CBlockIndex *pindex) {
     return g_chainstate.UnparkBlockImpl(pindex, true);
 }
 
 bool UnparkBlock(CBlockIndex *pindex) {
     return g_chainstate.UnparkBlockImpl(pindex, false);
 }
 
 const CBlockIndex *GetFinalizedBlock() {
     AssertLockHeld(cs_main);
     return pindexFinalized;
 }
 
 bool IsBlockFinalized(const CBlockIndex *pindex) {
     AssertLockHeld(cs_main);
     return pindexFinalized &&
            pindexFinalized->GetAncestor(pindex->nHeight) == pindex;
 }
 
 CBlockIndex *CChainState::AddToBlockIndex(const CBlockHeader &block) {
     AssertLockHeld(cs_main);
 
     // Check for duplicate
     uint256 hash = block.GetHash();
     BlockMap::iterator it = mapBlockIndex.find(hash);
     if (it != mapBlockIndex.end()) {
         return it->second;
     }
 
     // Construct new block index object
     CBlockIndex *pindexNew = new CBlockIndex(block);
     // We assign the sequence id to blocks only when the full data is available,
     // to avoid miners withholding blocks but broadcasting headers, to get a
     // competitive advantage.
     pindexNew->nSequenceId = 0;
     BlockMap::iterator mi =
         mapBlockIndex.insert(std::make_pair(hash, pindexNew)).first;
     pindexNew->phashBlock = &((*mi).first);
     BlockMap::iterator miPrev = mapBlockIndex.find(block.hashPrevBlock);
     if (miPrev != mapBlockIndex.end()) {
         pindexNew->pprev = (*miPrev).second;
         pindexNew->nHeight = pindexNew->pprev->nHeight + 1;
         pindexNew->BuildSkip();
     }
     pindexNew->nTimeReceived = GetTime();
     pindexNew->nTimeMax =
         (pindexNew->pprev
              ? std::max(pindexNew->pprev->nTimeMax, pindexNew->nTime)
              : pindexNew->nTime);
     pindexNew->nChainWork =
         (pindexNew->pprev ? pindexNew->pprev->nChainWork : 0) +
         GetBlockProof(*pindexNew);
     pindexNew->RaiseValidity(BlockValidity::TREE);
     if (pindexBestHeader == nullptr ||
         pindexBestHeader->nChainWork < pindexNew->nChainWork) {
         pindexBestHeader = pindexNew;
     }
 
     setDirtyBlockIndex.insert(pindexNew);
     return pindexNew;
 }
 
 /**
  * Mark a block as having its data received and checked (up to
  * BLOCK_VALID_TRANSACTIONS).
  */
 bool CChainState::ReceivedBlockTransactions(const CBlock &block,
                                             CValidationState &state,
                                             CBlockIndex *pindexNew,
                                             const CDiskBlockPos &pos) {
     pindexNew->nTx = block.vtx.size();
     pindexNew->nChainTx = 0;
     pindexNew->nFile = pos.nFile;
     pindexNew->nDataPos = pos.nPos;
     pindexNew->nUndoPos = 0;
     pindexNew->nStatus = pindexNew->nStatus.withData();
     pindexNew->RaiseValidity(BlockValidity::TRANSACTIONS);
     setDirtyBlockIndex.insert(pindexNew);
 
     if (pindexNew->pprev == nullptr || pindexNew->pprev->nChainTx) {
         // If pindexNew is the genesis block or all parents are
         // BLOCK_VALID_TRANSACTIONS.
         std::deque<CBlockIndex *> queue;
         queue.push_back(pindexNew);
 
         // Recursively process any descendant blocks that now may be eligible to
         // be connected.
         while (!queue.empty()) {
             CBlockIndex *pindex = queue.front();
             queue.pop_front();
             pindex->nChainTx =
                 (pindex->pprev ? pindex->pprev->nChainTx : 0) + pindex->nTx;
             if (pindex->nSequenceId == 0) {
                 // We assign a sequence is when transaction are recieved 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 (chainActive.Tip() == nullptr ||
                 !setBlockIndexCandidates.value_comp()(pindex,
                                                       chainActive.Tip())) {
                 setBlockIndexCandidates.insert(pindex);
             }
 
             std::pair<std::multimap<CBlockIndex *, CBlockIndex *>::iterator,
                       std::multimap<CBlockIndex *, CBlockIndex *>::iterator>
                 range = mapBlocksUnlinked.equal_range(pindex);
             while (range.first != range.second) {
                 std::multimap<CBlockIndex *, CBlockIndex *>::iterator it =
                     range.first;
                 queue.push_back(it->second);
                 range.first++;
                 mapBlocksUnlinked.erase(it);
             }
         }
     } else if (pindexNew->pprev &&
                pindexNew->pprev->IsValid(BlockValidity::TREE)) {
         mapBlocksUnlinked.insert(std::make_pair(pindexNew->pprev, pindexNew));
     }
 
     return true;
 }
 
 static bool FindBlockPos(CDiskBlockPos &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) {
         unsigned int nOldChunks =
             (pos.nPos + BLOCKFILE_CHUNK_SIZE - 1) / BLOCKFILE_CHUNK_SIZE;
         unsigned int nNewChunks =
             (vinfoBlockFile[nFile].nSize + BLOCKFILE_CHUNK_SIZE - 1) /
             BLOCKFILE_CHUNK_SIZE;
         if (nNewChunks > nOldChunks) {
             if (fPruneMode) {
                 fCheckForPruning = true;
             }
 
             if (CheckDiskSpace(nNewChunks * BLOCKFILE_CHUNK_SIZE - pos.nPos,
                                true)) {
                 FILE *file = OpenBlockFile(pos);
                 if (file) {
                     LogPrintf(
                         "Pre-allocating up to position 0x%x in blk%05u.dat\n",
                         nNewChunks * BLOCKFILE_CHUNK_SIZE, pos.nFile);
                     AllocateFileRange(file, pos.nPos,
                                       nNewChunks * BLOCKFILE_CHUNK_SIZE -
                                           pos.nPos);
                     fclose(file);
                 }
             } else {
                 return error("out of disk space");
             }
         }
     }
 
     setDirtyFileInfo.insert(nFile);
     return true;
 }
 
 static bool FindUndoPos(CValidationState &state, int nFile, CDiskBlockPos &pos,
                         unsigned int nAddSize) {
     pos.nFile = nFile;
 
     LOCK(cs_LastBlockFile);
 
     unsigned int nNewSize;
     pos.nPos = vinfoBlockFile[nFile].nUndoSize;
     nNewSize = vinfoBlockFile[nFile].nUndoSize += nAddSize;
     setDirtyFileInfo.insert(nFile);
 
     unsigned int nOldChunks =
         (pos.nPos + UNDOFILE_CHUNK_SIZE - 1) / UNDOFILE_CHUNK_SIZE;
     unsigned int nNewChunks =
         (nNewSize + UNDOFILE_CHUNK_SIZE - 1) / UNDOFILE_CHUNK_SIZE;
     if (nNewChunks > nOldChunks) {
         if (fPruneMode) {
             fCheckForPruning = true;
         }
 
         if (CheckDiskSpace(nNewChunks * UNDOFILE_CHUNK_SIZE - pos.nPos, true)) {
             FILE *file = OpenUndoFile(pos);
             if (file) {
                 LogPrintf("Pre-allocating up to position 0x%x in rev%05u.dat\n",
                           nNewChunks * UNDOFILE_CHUNK_SIZE, pos.nFile);
                 AllocateFileRange(file, pos.nPos,
                                   nNewChunks * UNDOFILE_CHUNK_SIZE - pos.nPos);
                 fclose(file);
             }
         } else {
             return state.Error("out of disk space");
         }
     }
 
     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-dependant calls, see ContextualCheckBlockHeader.
  */
 static bool CheckBlockHeader(
     const Config &config, const CBlockHeader &block, CValidationState &state,
     BlockValidationOptions validationOptions = BlockValidationOptions()) {
     // Check proof of work matches claimed amount
     if (validationOptions.shouldValidatePoW() &&
         !CheckProofOfWork(block.GetHash(), block.nBits, config)) {
         return state.DoS(50, false, REJECT_INVALID, "high-hash", false,
                          "proof of work failed");
     }
 
     return true;
 }
 
 bool CheckBlock(const Config &config, const CBlock &block,
                 CValidationState &state,
                 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(config, block, state, validationOptions)) {
         return false;
     }
 
     // Check the merkle root.
     if (validationOptions.shouldValidateMerkleRoot()) {
         bool mutated;
         uint256 hashMerkleRoot2 = BlockMerkleRoot(block, &mutated);
         if (block.hashMerkleRoot != hashMerkleRoot2) {
             return state.DoS(100, false, REJECT_INVALID, "bad-txnmrklroot",
                              true, "hashMerkleRoot mismatch");
         }
 
         // Check for merkle tree malleability (CVE-2012-2459): repeating
         // sequences of transactions in a block without affecting the merkle
         // root of a block, while still invalidating it.
         if (mutated) {
             return state.DoS(100, false, REJECT_INVALID, "bad-txns-duplicate",
                              true, "duplicate transaction");
         }
     }
 
     // All potential-corruption validation must be done before we do any
     // transaction validation, as otherwise we may mark the header as invalid
     // because we receive the wrong transactions for it.
 
     // First transaction must be coinbase.
     if (block.vtx.empty()) {
         return state.DoS(100, false, REJECT_INVALID, "bad-cb-missing", false,
                          "first tx is not coinbase");
     }
 
     // Size limits.
     auto nMaxBlockSize = config.GetMaxBlockSize();
 
     // Bail early if there is no way this block is of reasonable size.
     if ((block.vtx.size() * MIN_TRANSACTION_SIZE) > nMaxBlockSize) {
         return state.DoS(100, false, REJECT_INVALID, "bad-blk-length", false,
                          "size limits failed");
     }
 
     auto currentBlockSize =
         ::GetSerializeSize(block, SER_NETWORK, PROTOCOL_VERSION);
     if (currentBlockSize > nMaxBlockSize) {
         return state.DoS(100, false, REJECT_INVALID, "bad-blk-length", false,
                          "size limits failed");
     }
 
     // And a valid coinbase.
     if (!CheckCoinbase(*block.vtx[0], state)) {
         return state.Invalid(false, state.GetRejectCode(),
                              state.GetRejectReason(),
                              strprintf("Coinbase check failed (txid %s) %s",
                                        block.vtx[0]->GetId().ToString(),
                                        state.GetDebugMessage()));
     }
 
     // Keep track of the sigops count.
     uint64_t nSigOps = 0;
     auto nMaxSigOpsCount = GetMaxBlockSigOpsCount(currentBlockSize);
 
     // Check transactions
     auto txCount = block.vtx.size();
     auto *tx = block.vtx[0].get();
 
     size_t i = 0;
     while (true) {
         // Count the sigops for the current transaction. If the total sigops
         // count is too high, the the block is invalid.
         nSigOps += GetSigOpCountWithoutP2SH(*tx, STANDARD_SCRIPT_VERIFY_FLAGS);
         if (nSigOps > nMaxSigOpsCount) {
             return state.DoS(100, false, REJECT_INVALID, "bad-blk-sigops",
                              false, "out-of-bounds SigOpCount");
         }
 
         // Go to the next transaction.
         i++;
 
         // We reached the end of the block, success.
         if (i >= txCount) {
             break;
         }
 
         // Check that the transaction is valid. Because this check differs for
         // the coinbase, the loop is arranged such as this only runs after at
         // least one increment.
         tx = block.vtx[i].get();
         if (!CheckRegularTransaction(*tx, state)) {
             return state.Invalid(
                 false, state.GetRejectCode(), state.GetRejectReason(),
                 strprintf("Transaction check failed (txid %s) %s",
                           tx->GetId().ToString(), state.GetDebugMessage()));
         }
     }
 
     if (validationOptions.shouldValidatePoW() &&
         validationOptions.shouldValidateMerkleRoot()) {
         block.fChecked = true;
     }
 
     return true;
 }
 
 /**
  * Context-dependent validity checks.
  * By "context", we mean only the previous block headers, but not the UTXO
  * set; UTXO-related validity checks are done in ConnectBlock().
  */
 static bool ContextualCheckBlockHeader(const Config &config,
                                        const CBlockHeader &block,
                                        CValidationState &state,
                                        const CBlockIndex *pindexPrev,
                                        int64_t nAdjustedTime) {
     assert(pindexPrev != nullptr);
     const int nHeight = pindexPrev->nHeight + 1;
 
     // Check proof of work
     const Consensus::Params &consensusParams =
         config.GetChainParams().GetConsensus();
     if (block.nBits != GetNextWorkRequired(pindexPrev, &block, config)) {
         LogPrintf("bad bits after height: %d\n", pindexPrev->nHeight);
         return state.DoS(100, false, REJECT_INVALID, "bad-diffbits", false,
                          "incorrect proof of work");
     }
 
     // Check against checkpoints
     if (fCheckpointsEnabled) {
         const CCheckpointData &checkpoints =
             config.GetChainParams().Checkpoints();
 
         // Check that the block chain matches the known block chain up to a
         // checkpoint.
         if (!Checkpoints::CheckBlock(checkpoints, nHeight, block.GetHash())) {
             return state.DoS(100,
                              error("%s: rejected by checkpoint lock-in at %d",
                                    __func__, nHeight),
                              REJECT_CHECKPOINT, "checkpoint mismatch");
         }
 
         // Don't accept any forks from the main chain prior to last checkpoint.
         // GetLastCheckpoint finds the last checkpoint in MapCheckpoints that's
         // in our MapBlockIndex.
         CBlockIndex *pcheckpoint = Checkpoints::GetLastCheckpoint(checkpoints);
         if (pcheckpoint && nHeight < pcheckpoint->nHeight) {
             return state.DoS(
                 100,
                 error("%s: forked chain older than last checkpoint (height %d)",
                       __func__, nHeight),
                 REJECT_CHECKPOINT, "bad-fork-prior-to-checkpoint");
         }
     }
 
     // Check timestamp against prev
     if (block.GetBlockTime() <= pindexPrev->GetMedianTimePast()) {
         return state.Invalid(false, REJECT_INVALID, "time-too-old",
                              "block's timestamp is too early");
     }
 
     // Check timestamp
     if (block.GetBlockTime() > nAdjustedTime + MAX_FUTURE_BLOCK_TIME) {
         return state.Invalid(false, REJECT_INVALID, "time-too-new",
                              "block timestamp too far in the future");
     }
 
     // Reject outdated version blocks when 95% (75% on testnet) of the network
     // has upgraded:
     // check for version 2, 3 and 4 upgrades
     if ((block.nVersion < 2 && nHeight >= consensusParams.BIP34Height) ||
         (block.nVersion < 3 && nHeight >= consensusParams.BIP66Height) ||
         (block.nVersion < 4 && nHeight >= consensusParams.BIP65Height)) {
         return state.Invalid(
             false, REJECT_OBSOLETE,
             strprintf("bad-version(0x%08x)", block.nVersion),
             strprintf("rejected nVersion=0x%08x block", block.nVersion));
     }
 
     return true;
 }
 
 bool ContextualCheckTransactionForCurrentBlock(const Config &config,
                                                const CTransaction &tx,
                                                CValidationState &state,
                                                int flags) {
     AssertLockHeld(cs_main);
 
     // By convention a negative value for flags indicates that the current
     // network-enforced consensus rules should be used. In a future soft-fork
     // scenario that would mean checking which rules would be enforced for the
     // next block and setting the appropriate flags. At the present time no
     // soft-forks are scheduled, so no flags are set.
     flags = std::max(flags, 0);
 
     // ContextualCheckTransactionForCurrentBlock() uses chainActive.Height()+1
     // to evaluate nLockTime because when IsFinalTx() is called within
     // CBlock::AcceptBlock(), the height of the block *being* evaluated is what
     // is used. Thus if we want to know if a transaction can be part of the
     // *next* block, we need to call ContextualCheckTransaction() with one more
     // than chainActive.Height().
     const int nBlockHeight = chainActive.Height() + 1;
 
     // BIP113 will require that time-locked transactions have nLockTime set to
     // less than the median time of the previous block they're contained in.
     // When the next block is created its previous block will be the current
     // chain tip, so we use that to calculate the median time passed to
     // ContextualCheckTransaction() if LOCKTIME_MEDIAN_TIME_PAST is set.
     const int64_t nMedianTimePast =
         chainActive.Tip() == nullptr ? 0
                                      : chainActive.Tip()->GetMedianTimePast();
     const int64_t nLockTimeCutoff = (flags & LOCKTIME_MEDIAN_TIME_PAST)
                                         ? nMedianTimePast
                                         : GetAdjustedTime();
 
     return ContextualCheckTransaction(config, tx, state, nBlockHeight,
                                       nLockTimeCutoff, nMedianTimePast);
 }
 
 static bool ContextualCheckBlock(const Config &config, const CBlock &block,
                                  CValidationState &state,
                                  const CBlockIndex *pindexPrev) {
     const int nHeight = pindexPrev == nullptr ? 0 : pindexPrev->nHeight + 1;
     const Consensus::Params &consensusParams =
         config.GetChainParams().GetConsensus();
 
     // Start enforcing BIP113 (Median Time Past).
     int nLockTimeFlags = 0;
     if (nHeight >= consensusParams.CSVHeight) {
         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(config, pindexPrev);
 
     // Check that all transactions are finalized
     const CTransaction *prevTx = nullptr;
     for (const auto &ptx : block.vtx) {
         const CTransaction &tx = *ptx;
         if (fIsMagneticAnomalyEnabled) {
             if (prevTx && (tx.GetId() <= prevTx->GetId())) {
                 if (tx.GetId() == prevTx->GetId()) {
                     return state.DoS(100, false, REJECT_INVALID, "tx-duplicate",
                                      false,
                                      strprintf("Duplicated transaction %s",
                                                tx.GetId().ToString()));
                 }
 
                 return state.DoS(
                     100, false, REJECT_INVALID, "tx-ordering", false,
                     strprintf("Transaction order is invalid (%s < %s)",
                               tx.GetId().ToString(),
                               prevTx->GetId().ToString()));
             }
 
             if (prevTx || !tx.IsCoinBase()) {
                 prevTx = &tx;
             }
         }
 
         if (!ContextualCheckTransaction(config, tx, state, nHeight,
                                         nLockTimeCutoff, nMedianTimePast)) {
             // state set by ContextualCheckTransaction.
             return false;
         }
     }
 
     // Enforce rule that the coinbase starts with serialized block height
     if (nHeight >= consensusParams.BIP34Height) {
         CScript expect = CScript() << nHeight;
         if (block.vtx[0]->vin[0].scriptSig.size() < expect.size() ||
             !std::equal(expect.begin(), expect.end(),
                         block.vtx[0]->vin[0].scriptSig.begin())) {
             return state.DoS(100, false, REJECT_INVALID, "bad-cb-height", false,
                              "block height mismatch in coinbase");
         }
     }
 
     return true;
 }
 
 /**
  * If the provided block header is valid, add it to the block index.
  *
  * Returns true if the block is succesfully added to the block index.
  */
 bool CChainState::AcceptBlockHeader(const Config &config,
                                     const CBlockHeader &block,
                                     CValidationState &state,
                                     CBlockIndex **ppindex) {
     AssertLockHeld(cs_main);
     const CChainParams &chainparams = config.GetChainParams();
 
     // Check for duplicate
     uint256 hash = block.GetHash();
     BlockMap::iterator miSelf = mapBlockIndex.find(hash);
     CBlockIndex *pindex = nullptr;
     if (hash != chainparams.GetConsensus().hashGenesisBlock) {
         if (miSelf != mapBlockIndex.end()) {
             // Block header is already known.
             pindex = miSelf->second;
             if (ppindex) {
                 *ppindex = pindex;
             }
 
             if (pindex->nStatus.isInvalid()) {
                 return state.Invalid(error("%s: block %s is marked invalid",
                                            __func__, hash.ToString()),
                                      0, "duplicate");
             }
 
             return true;
         }
 
         if (!CheckBlockHeader(config, block, state)) {
             return error("%s: Consensus::CheckBlockHeader: %s, %s", __func__,
                          hash.ToString(), FormatStateMessage(state));
         }
 
         // Get prev block index
         BlockMap::iterator mi = mapBlockIndex.find(block.hashPrevBlock);
         if (mi == mapBlockIndex.end()) {
             return state.DoS(10, error("%s: prev block not found", __func__), 0,
                              "prev-blk-not-found");
         }
 
         CBlockIndex *pindexPrev = (*mi).second;
         assert(pindexPrev);
         if (pindexPrev->nStatus.isInvalid()) {
             return state.DoS(100, error("%s: prev block invalid", __func__),
                              REJECT_INVALID, "bad-prevblk");
         }
 
         if (!ContextualCheckBlockHeader(config, block, state, pindexPrev,
                                         GetAdjustedTime())) {
             return error("%s: Consensus::ContextualCheckBlockHeader: %s, %s",
                          __func__, hash.ToString(), FormatStateMessage(state));
         }
     }
 
     if (pindex == nullptr) {
         pindex = AddToBlockIndex(block);
     }
 
     if (ppindex) {
         *ppindex = pindex;
     }
 
     CheckBlockIndex(chainparams.GetConsensus());
     return true;
 }
 
 // Exposed wrapper for AcceptBlockHeader
 bool ProcessNewBlockHeaders(const Config &config,
                             const std::vector<CBlockHeader> &headers,
                             CValidationState &state,
                             const CBlockIndex **ppindex,
                             CBlockHeader *first_invalid) {
     if (first_invalid != nullptr) {
         first_invalid->SetNull();
     }
 
     {
         LOCK(cs_main);
         for (const CBlockHeader &header : headers) {
             // Use a temp pindex instead of ppindex to avoid a const_cast
             CBlockIndex *pindex = nullptr;
             if (!g_chainstate.AcceptBlockHeader(config, header, state,
                                                 &pindex)) {
                 if (first_invalid) {
                     *first_invalid = header;
                 }
                 return false;
             }
 
             if (ppindex) {
                 *ppindex = pindex;
             }
         }
     }
 
     NotifyHeaderTip();
     return true;
 }
 
 /**
  * Store block on disk. If dbp is non-nullptr, the file is known to already
  * reside on disk.
  */
 static CDiskBlockPos SaveBlockToDisk(const CBlock &block, int nHeight,
                                      const CChainParams &chainparams,
                                      const CDiskBlockPos *dbp) {
     unsigned int nBlockSize =
         ::GetSerializeSize(block, SER_DISK, CLIENT_VERSION);
     CDiskBlockPos blockPos;
     if (dbp != nullptr) {
         blockPos = *dbp;
     }
     if (!FindBlockPos(blockPos, nBlockSize + 8, nHeight, block.GetBlockTime(),
                       dbp != nullptr)) {
         error("%s: FindBlockPos failed", __func__);
         return CDiskBlockPos();
     }
     if (dbp == nullptr) {
         if (!WriteBlockToDisk(block, blockPos, chainparams.DiskMagic())) {
             AbortNode("Failed to write block");
             return CDiskBlockPos();
         }
     }
     return blockPos;
 }
 
 /**
  * Store a block on disk.
  *
  * @param[in]     config     The global config.
  * @param[in-out] pblock     The block we want to accept.
  * @param[in]     fRequested A boolean to indicate if this block was requested
  *                           from our peers.
  * @param[in]     dbp        If non-null, the disk position of the block.
  * @param[in-out] fNewBlock  True if block was first received via this call.
  * @return True if the block is accepted as a valid block and written to disk.
  */
 bool CChainState::AcceptBlock(const Config &config,
                               const std::shared_ptr<const CBlock> &pblock,
                               CValidationState &state, bool fRequested,
                               const CDiskBlockPos *dbp, bool *fNewBlock) {
     AssertLockHeld(cs_main);
 
     const CBlock &block = *pblock;
     if (fNewBlock) {
         *fNewBlock = false;
     }
 
     CBlockIndex *pindex = nullptr;
     if (!AcceptBlockHeader(config, block, state, &pindex)) {
         return false;
     }
 
     // Try to process all requested blocks that we don't have, but only
     // process an unrequested block if it's new and has enough work to
     // advance our tip, and isn't too many blocks ahead.
     bool fAlreadyHave = pindex->nStatus.hasData();
 
     // TODO: deal better with return value and error conditions for duplicate
     // and unrequested blocks.
     if (fAlreadyHave) {
         return true;
     }
 
     // Compare block header timestamps and received times of the block and the
     // chaintip.  If they have the same chain height, use these diffs as a
     // tie-breaker, attempting to pick the more honestly-mined block.
     int64_t newBlockTimeDiff = std::llabs(pindex->GetReceivedTimeDiff());
     int64_t chainTipTimeDiff =
         chainActive.Tip() ? std::llabs(chainActive.Tip()->GetReceivedTimeDiff())
                           : 0;
 
     bool isSameHeight = chainActive.Tip() &&
                         (pindex->nChainWork == chainActive.Tip()->nChainWork);
     if (isSameHeight) {
         LogPrintf("Chain tip timestamp-to-received-time difference: hash=%s, "
                   "diff=%d\n",
                   chainActive.Tip()->GetBlockHash().ToString(),
                   chainTipTimeDiff);
         LogPrintf("New block timestamp-to-received-time difference: hash=%s, "
                   "diff=%d\n",
                   pindex->GetBlockHash().ToString(), newBlockTimeDiff);
     }
 
     bool fHasMoreOrSameWork =
         (chainActive.Tip() ? pindex->nChainWork >= chainActive.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(chainActive.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;
         }
     }
 
     if (fNewBlock) {
         *fNewBlock = true;
     }
 
     if (!CheckBlock(config, block, state) ||
         !ContextualCheckBlock(config, block, state, pindex->pprev)) {
         if (state.IsInvalid() && !state.CorruptionPossible()) {
             pindex->nStatus = pindex->nStatus.withFailed();
             setDirtyBlockIndex.insert(pindex);
         }
 
         return error("%s: %s (block %s)", __func__, FormatStateMessage(state),
                      block.GetHash().ToString());
     }
 
     // If this is a deep reorg (a regorg of more than one block), preemptively
     // mark the chain as parked. If it has enough work, it'll unpark
     // automatically. 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 = chainActive.FindFork(pindex);
         if (pindexFork && pindexFork->nHeight + 1 < pindex->nHeight) {
             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() && chainActive.Tip() == pindex->pprev) {
         GetMainSignals().NewPoWValidBlock(pindex, pblock);
     }
 
     const CChainParams &chainparams = config.GetChainParams();
 
     // Write block to history file
     try {
         CDiskBlockPos 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;
         }
         if (!ReceivedBlockTransactions(block, state, pindex, blockPos)) {
             return error("AcceptBlock(): ReceivedBlockTransactions failed");
         }
     } catch (const std::runtime_error &e) {
         return AbortNode(state, std::string("System error: ") + e.what());
     }
 
     if (fCheckForPruning) {
         // we just allocated more disk space for block files.
         FlushStateToDisk(config.GetChainParams(), state, FlushStateMode::NONE);
     }
 
     CheckBlockIndex(chainparams.GetConsensus());
 
     return true;
 }
 
 bool ProcessNewBlock(const Config &config,
                      const std::shared_ptr<const CBlock> pblock,
                      bool fForceProcessing, bool *fNewBlock) {
     AssertLockNotHeld(cs_main);
 
     {
         if (fNewBlock) {
             *fNewBlock = false;
         }
 
         CValidationState state;
         // Ensure that CheckBlock() passes before calling AcceptBlock, as
         // belt-and-suspenders.
         bool ret = CheckBlock(config, *pblock, state);
 
         LOCK(cs_main);
 
         if (ret) {
             // Store to disk
             ret = g_chainstate.AcceptBlock(
                 config, pblock, state, fForceProcessing, nullptr, fNewBlock);
         }
 
         if (!ret) {
             GetMainSignals().BlockChecked(*pblock, state);
             return error("%s: AcceptBlock FAILED", __func__);
         }
     }
 
     NotifyHeaderTip();
 
     // Only used to report errors, not invalidity - ignore it
     CValidationState state;
     if (!g_chainstate.ActivateBestChain(config, state, pblock)) {
         return error("%s: ActivateBestChain failed", __func__);
     }
 
     return true;
 }
 
 bool TestBlockValidity(const Config &config, CValidationState &state,
                        const CBlock &block, CBlockIndex *pindexPrev,
                        BlockValidationOptions validationOptions) {
     AssertLockHeld(cs_main);
     assert(pindexPrev && pindexPrev == chainActive.Tip());
     CCoinsViewCache viewNew(pcoinsTip.get());
     uint256 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(config, block, state, pindexPrev,
                                     GetAdjustedTime())) {
         return error("%s: Consensus::ContextualCheckBlockHeader: %s", __func__,
                      FormatStateMessage(state));
     }
 
     if (!CheckBlock(config, block, state, validationOptions)) {
         return error("%s: Consensus::CheckBlock: %s", __func__,
                      FormatStateMessage(state));
     }
 
     if (!ContextualCheckBlock(config, block, state, pindexPrev)) {
         return error("%s: Consensus::ContextualCheckBlock: %s", __func__,
                      FormatStateMessage(state));
     }
 
     if (!g_chainstate.ConnectBlock(config, block, state, &indexDummy, viewNew,
                                    true)) {
         return false;
     }
 
     assert(state.IsValid());
     return true;
 }
 
 /**
  * BLOCK PRUNING CODE
  */
 
 /**
  * Calculate the amount of disk space the block & undo files currently use.
  */
 uint64_t CalculateCurrentUsage() {
     LOCK(cs_LastBlockFile);
 
     uint64_t retval = 0;
     for (const CBlockFileInfo &file : vinfoBlockFile) {
         retval += file.nSize + file.nUndoSize;
     }
 
     return retval;
 }
 
 /**
  * Prune a block file (modify associated database entries)
  */
 void PruneOneBlockFile(const int fileNumber) {
     LOCK(cs_LastBlockFile);
 
     for (const auto &entry : mapBlockIndex) {
         CBlockIndex *pindex = entry.second;
         if (pindex->nFile == fileNumber) {
             pindex->nStatus = pindex->nStatus.withData(false).withUndo(false);
             pindex->nFile = 0;
             pindex->nDataPos = 0;
             pindex->nUndoPos = 0;
             setDirtyBlockIndex.insert(pindex);
 
             // Prune from mapBlocksUnlinked -- any block we prune would have
             // to be downloaded again in order to consider its chain, at which
             // point it would be considered as a candidate for
             // mapBlocksUnlinked or setBlockIndexCandidates.
             std::pair<std::multimap<CBlockIndex *, CBlockIndex *>::iterator,
                       std::multimap<CBlockIndex *, CBlockIndex *>::iterator>
                 range = mapBlocksUnlinked.equal_range(pindex->pprev);
             while (range.first != range.second) {
                 std::multimap<CBlockIndex *, CBlockIndex *>::iterator _it =
                     range.first;
                 range.first++;
                 if (_it->second == pindex) {
                     mapBlocksUnlinked.erase(_it);
                 }
             }
         }
     }
 
     vinfoBlockFile[fileNumber].SetNull();
     setDirtyFileInfo.insert(fileNumber);
 }
 
 void UnlinkPrunedFiles(const std::set<int> &setFilesToPrune) {
     for (const int i : setFilesToPrune) {
         CDiskBlockPos pos(i, 0);
         fs::remove(GetBlockPosFilename(pos, "blk"));
         fs::remove(GetBlockPosFilename(pos, "rev"));
         LogPrintf("Prune: %s deleted blk/rev (%05u)\n", __func__, i);
     }
 }
 
 /**
  * Calculate the block/rev files to delete based on height specified by user
  * with RPC command pruneblockchain
  */
 static void FindFilesToPruneManual(std::set<int> &setFilesToPrune,
                                    int nManualPruneHeight) {
     assert(fPruneMode && nManualPruneHeight > 0);
 
     LOCK2(cs_main, cs_LastBlockFile);
     if (chainActive.Tip() == nullptr) {
         return;
     }
 
     // last block to prune is the lesser of (user-specified height,
     // MIN_BLOCKS_TO_KEEP from the tip)
     unsigned int nLastBlockWeCanPrune =
         std::min((unsigned)nManualPruneHeight,
                  chainActive.Tip()->nHeight - MIN_BLOCKS_TO_KEEP);
     int count = 0;
     for (int fileNumber = 0; fileNumber < nLastBlockFile; fileNumber++) {
         if (vinfoBlockFile[fileNumber].nSize == 0 ||
             vinfoBlockFile[fileNumber].nHeightLast > nLastBlockWeCanPrune) {
             continue;
         }
         PruneOneBlockFile(fileNumber);
         setFilesToPrune.insert(fileNumber);
         count++;
     }
     LogPrintf("Prune (Manual): prune_height=%d removed %d blk/rev pairs\n",
               nLastBlockWeCanPrune, count);
 }
 
 /* This function is called from the RPC code for pruneblockchain */
 void PruneBlockFilesManual(int nManualPruneHeight) {
     CValidationState state;
     const CChainParams &chainparams = Params();
     FlushStateToDisk(chainparams, state, FlushStateMode::NONE,
                      nManualPruneHeight);
 }
 
 /**
  * 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) {
         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);
 }
 
 bool CheckDiskSpace(uint64_t nAdditionalBytes, bool blocks_dir) {
     uint64_t nFreeBytesAvailable =
         fs::space(blocks_dir ? GetBlocksDir() : GetDataDir()).available;
 
     // Check for nMinDiskSpace bytes (currently 50MB)
     if (nFreeBytesAvailable < nMinDiskSpace + nAdditionalBytes) {
         return AbortNode("Disk space is low!", _("Error: Disk space is low!"));
     }
 
     return true;
 }
 
 static FILE *OpenDiskFile(const CDiskBlockPos &pos, const char *prefix,
                           bool fReadOnly) {
     if (pos.IsNull()) {
         return nullptr;
     }
 
     fs::path path = GetBlockPosFilename(pos, prefix);
     fs::create_directories(path.parent_path());
     FILE *file = fsbridge::fopen(path, "rb+");
     if (!file && !fReadOnly) {
         file = fsbridge::fopen(path, "wb+");
     }
 
     if (!file) {
         LogPrintf("Unable to open file %s\n", path.string());
         return nullptr;
     }
 
     if (pos.nPos) {
         if (fseek(file, pos.nPos, SEEK_SET)) {
             LogPrintf("Unable to seek to position %u of %s\n", pos.nPos,
                       path.string());
             fclose(file);
             return nullptr;
         }
     }
 
     return file;
 }
 
 FILE *OpenBlockFile(const CDiskBlockPos &pos, bool fReadOnly) {
     return OpenDiskFile(pos, "blk", fReadOnly);
 }
 
 /** Open an undo file (rev?????.dat) */
 static FILE *OpenUndoFile(const CDiskBlockPos &pos, bool fReadOnly) {
     return OpenDiskFile(pos, "rev", fReadOnly);
 }
 
 fs::path GetBlockPosFilename(const CDiskBlockPos &pos, const char *prefix) {
     return GetBlocksDir() / strprintf("%s%05u.dat", prefix, pos.nFile);
 }
 
 CBlockIndex *CChainState::InsertBlockIndex(const uint256 &hash) {
     AssertLockHeld(cs_main);
 
     if (hash.IsNull()) {
         return nullptr;
     }
 
     // Return existing
     BlockMap::iterator mi = mapBlockIndex.find(hash);
     if (mi != mapBlockIndex.end()) {
         return (*mi).second;
     }
 
     // Create new
     CBlockIndex *pindexNew = new CBlockIndex();
     mi = mapBlockIndex.insert(std::make_pair(hash, pindexNew)).first;
     pindexNew->phashBlock = &((*mi).first);
 
     return pindexNew;
 }
 
 bool CChainState::LoadBlockIndex(const Config &config,
                                  CBlockTreeDB &blocktree) {
     if (!blocktree.LoadBlockIndexGuts(config, [this](const uint256 &hash) {
             return this->InsertBlockIndex(hash);
         })) {
         return false;
     }
 
     boost::this_thread::interruption_point();
 
     // Calculate nChainWork
     std::vector<std::pair<int, CBlockIndex *>> vSortedByHeight;
     vSortedByHeight.reserve(mapBlockIndex.size());
     for (const std::pair<uint256, CBlockIndex *> &item : mapBlockIndex) {
         CBlockIndex *pindex = item.second;
         vSortedByHeight.push_back(std::make_pair(pindex->nHeight, pindex));
     }
 
     sort(vSortedByHeight.begin(), vSortedByHeight.end());
     for (const std::pair<int, CBlockIndex *> &item : vSortedByHeight) {
         CBlockIndex *pindex = item.second;
         pindex->nChainWork = (pindex->pprev ? pindex->pprev->nChainWork : 0) +
                              GetBlockProof(*pindex);
         pindex->nTimeMax =
             (pindex->pprev ? std::max(pindex->pprev->nTimeMax, pindex->nTime)
                            : pindex->nTime);
         // We can link the chain of blocks for which we've received transactions
         // at some point. Pruned nodes may have deleted the block.
         if (pindex->nTx > 0) {
             if (pindex->pprev) {
                 if (pindex->pprev->nChainTx) {
                     pindex->nChainTx = pindex->pprev->nChainTx + pindex->nTx;
                 } else {
                     pindex->nChainTx = 0;
                     mapBlocksUnlinked.insert(
                         std::make_pair(pindex->pprev, pindex));
                 }
             } else {
                 pindex->nChainTx = pindex->nTx;
             }
         }
 
         if (pindex->IsValid(BlockValidity::TRANSACTIONS) &&
             (pindex->nChainTx || pindex->pprev == nullptr)) {
             setBlockIndexCandidates.insert(pindex);
         }
 
         if (pindex->nStatus.isInvalid() &&
             (!pindexBestInvalid ||
              pindex->nChainWork > pindexBestInvalid->nChainWork)) {
             pindexBestInvalid = pindex;
         }
 
         if (pindex->nStatus.isOnParkedChain() &&
             (!pindexBestParked ||
              pindex->nChainWork > pindexBestParked->nChainWork)) {
             pindexBestParked = pindex;
         }
 
         if (pindex->pprev) {
             pindex->BuildSkip();
         }
 
         if (pindex->IsValid(BlockValidity::TREE) &&
             (pindexBestHeader == nullptr ||
              CBlockIndexWorkComparator()(pindexBestHeader, pindex))) {
             pindexBestHeader = pindex;
         }
     }
 
     return true;
 }
 
 bool static LoadBlockIndexDB(const Config &config) {
     if (!g_chainstate.LoadBlockIndex(config, *pblocktree)) {
         return false;
     }
 
     // Load block file info
     pblocktree->ReadLastBlockFile(nLastBlockFile);
     vinfoBlockFile.resize(nLastBlockFile + 1);
     LogPrintf("%s: last block file = %i\n", __func__, nLastBlockFile);
     for (int nFile = 0; nFile <= nLastBlockFile; nFile++) {
         pblocktree->ReadBlockFileInfo(nFile, vinfoBlockFile[nFile]);
     }
 
     LogPrintf("%s: last block file info: %s\n", __func__,
               vinfoBlockFile[nLastBlockFile].ToString());
 
     for (int nFile = nLastBlockFile + 1; true; nFile++) {
         CBlockFileInfo info;
         if (pblocktree->ReadBlockFileInfo(nFile, info)) {
             vinfoBlockFile.push_back(info);
         } else {
             break;
         }
     }
 
     // Check presence of blk files
     LogPrintf("Checking all blk files are present...\n");
     std::set<int> setBlkDataFiles;
     for (const std::pair<uint256, CBlockIndex *> &item : mapBlockIndex) {
         CBlockIndex *pindex = item.second;
         if (pindex->nStatus.hasData()) {
             setBlkDataFiles.insert(pindex->nFile);
         }
     }
 
     for (const int i : setBlkDataFiles) {
         CDiskBlockPos pos(i, 0);
         if (CAutoFile(OpenBlockFile(pos, true), SER_DISK, CLIENT_VERSION)
                 .IsNull()) {
             return false;
         }
     }
 
     // Check whether we have ever pruned block & undo files
     pblocktree->ReadFlag("prunedblockfiles", fHavePruned);
     if (fHavePruned) {
         LogPrintf(
             "LoadBlockIndexDB(): Block files have previously been pruned\n");
     }
 
     // Check whether we need to continue reindexing
     bool fReindexing = false;
     pblocktree->ReadReindexing(fReindexing);
     if (fReindexing) {
         fReindex = true;
     }
 
-    // Check whether we have a transaction index
-    pblocktree->ReadFlag("txindex", fTxIndex);
-    LogPrintf("%s: transaction index %s\n", __func__,
-              fTxIndex ? "enabled" : "disabled");
-
     return true;
 }
 
 bool LoadChainTip(const Config &config) {
     AssertLockHeld(cs_main);
 
     if (chainActive.Tip() &&
         chainActive.Tip()->GetBlockHash() == pcoinsTip->GetBestBlock()) {
         return true;
     }
 
     if (pcoinsTip->GetBestBlock().IsNull() && mapBlockIndex.size() == 1) {
         // In case we just added the genesis block, connect it now, so
         // that we always have a chainActive.Tip() when we return.
         LogPrintf("%s: Connecting genesis block...\n", __func__);
         CValidationState state;
         if (!ActivateBestChain(config, state)) {
             return false;
         }
     }
 
     // Load pointer to end of best chain
     CBlockIndex *pindex = LookupBlockIndex(pcoinsTip->GetBestBlock());
     if (!pindex) {
         return false;
     }
     chainActive.SetTip(pindex);
 
     g_chainstate.PruneBlockIndexCandidates();
 
     LogPrintf(
         "Loaded best chain: hashBestChain=%s height=%d date=%s progress=%f\n",
         chainActive.Tip()->GetBlockHash().ToString(), chainActive.Height(),
         FormatISO8601DateTime(chainActive.Tip()->GetBlockTime()),
         GuessVerificationProgress(config.GetChainParams().TxData(),
                                   chainActive.Tip()));
     return true;
 }
 
 CVerifyDB::CVerifyDB() {
     uiInterface.ShowProgress(_("Verifying blocks..."), 0, false);
 }
 
 CVerifyDB::~CVerifyDB() {
     uiInterface.ShowProgress("", 100, false);
 }
 
 bool CVerifyDB::VerifyDB(const Config &config, CCoinsView *coinsview,
                          int nCheckLevel, int nCheckDepth) {
     LOCK(cs_main);
     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 *pindexState = chainActive.Tip();
     CBlockIndex *pindexFailure = nullptr;
     int nGoodTransactions = 0;
     CValidationState state;
     int reportDone = 0;
     LogPrintf("[0%%]...");
     for (CBlockIndex *pindex = chainActive.Tip(); pindex && pindex->pprev;
          pindex = pindex->pprev) {
         boost::this_thread::interruption_point();
         int percentageDone = std::max(
             1, std::min(
                    99,
                    (int)(((double)(chainActive.Height() - pindex->nHeight)) /
                          (double)nCheckDepth * (nCheckLevel >= 4 ? 50 : 100))));
 
         if (reportDone < percentageDone / 10) {
             // report every 10% step
             LogPrintf("[%d%%]...", percentageDone);
             reportDone = percentageDone / 10;
         }
 
         uiInterface.ShowProgress(_("Verifying blocks..."), 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, config)) {
             return error(
                 "VerifyDB(): *** ReadBlockFromDisk failed at %d, hash=%s",
                 pindex->nHeight, pindex->GetBlockHash().ToString());
         }
 
         // check level 1: verify block validity
         if (nCheckLevel >= 1 && !CheckBlock(config, block, state)) {
             return error("%s: *** found bad block at %d, hash=%s (%s)\n",
                          __func__, pindex->nHeight,
                          pindex->GetBlockHash().ToString(),
                          FormatStateMessage(state));
         }
 
         // check level 2: verify undo validity
         if (nCheckLevel >= 2 && pindex) {
             CBlockUndo undo;
             if (!pindex->GetUndoPos().IsNull()) {
                 if (!UndoReadFromDisk(undo, pindex)) {
                     return error(
                         "VerifyDB(): *** found bad undo data at %d, hash=%s\n",
                         pindex->nHeight, pindex->GetBlockHash().ToString());
                 }
             }
         }
 
         // check level 3: check for inconsistencies during memory-only
         // disconnect of tip blocks
         if (nCheckLevel >= 3 && pindex == pindexState &&
             (coins.DynamicMemoryUsage() + pcoinsTip->DynamicMemoryUsage()) <=
                 nCoinCacheUsage) {
             assert(coins.GetBestBlock() == pindex->GetBlockHash());
             DisconnectResult res =
                 g_chainstate.DisconnectBlock(block, pindex, coins);
             if (res == DISCONNECT_FAILED) {
                 return error("VerifyDB(): *** irrecoverable inconsistency in "
                              "block data at %d, hash=%s",
                              pindex->nHeight,
                              pindex->GetBlockHash().ToString());
             }
 
             pindexState = pindex->pprev;
             if (res == DISCONNECT_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);
     }
 
     // check level 4: try reconnecting blocks
     if (nCheckLevel >= 4) {
         CBlockIndex *pindex = pindexState;
         while (pindex != chainActive.Tip()) {
             boost::this_thread::interruption_point();
             uiInterface.ShowProgress(
                 _("Verifying blocks..."),
                 std::max(
                     1, std::min(99, 100 - (int)(((double)(chainActive.Height() -
                                                           pindex->nHeight)) /
                                                 (double)nCheckDepth * 50))),
                 false);
             pindex = chainActive.Next(pindex);
             CBlock block;
             if (!ReadBlockFromDisk(block, pindex, config)) {
                 return error(
                     "VerifyDB(): *** ReadBlockFromDisk failed at %d, hash=%s",
                     pindex->nHeight, pindex->GetBlockHash().ToString());
             }
             if (!g_chainstate.ConnectBlock(config, block, state, pindex,
                                            coins)) {
                 return error(
                     "VerifyDB(): *** found unconnectable block at %d, hash=%s",
                     pindex->nHeight, pindex->GetBlockHash().ToString());
             }
         }
     }
 
     LogPrintf("[DONE].\n");
     LogPrintf("No coin database inconsistencies in last %i blocks (%i "
               "transactions)\n",
               chainActive.Height() - pindexState->nHeight, 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 Config &config) {
     // TODO: merge with ConnectBlock
     CBlock block;
     if (!ReadBlockFromDisk(block, pindex, config)) {
         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 Config &config, CCoinsView *view) {
     LOCK(cs_main);
 
     CCoinsViewCache cache(view);
 
     std::vector<uint256> hashHeads = view->GetHeadBlocks();
     if (hashHeads.empty()) {
         // We're already in a consistent state.
         return true;
     }
 
     if (hashHeads.size() != 2) {
         return error("ReplayBlocks(): unknown inconsistent state");
     }
 
     uiInterface.ShowProgress(_("Replaying blocks..."), 0, false);
     LogPrintf("Replaying blocks\n");
 
     // Old tip during the interrupted flush.
     const CBlockIndex *pindexOld = nullptr;
     // New tip during the interrupted flush.
     const CBlockIndex *pindexNew;
     // Latest block common to both the old and the new tip.
     const CBlockIndex *pindexFork = nullptr;
 
     if (mapBlockIndex.count(hashHeads[0]) == 0) {
         return error(
             "ReplayBlocks(): reorganization to unknown block requested");
     }
 
     pindexNew = mapBlockIndex[hashHeads[0]];
 
     if (!hashHeads[1].IsNull()) {
         // The old tip is allowed to be 0, indicating it's the first flush.
         if (mapBlockIndex.count(hashHeads[1]) == 0) {
             return error(
                 "ReplayBlocks(): reorganization from unknown block requested");
         }
 
         pindexOld = mapBlockIndex[hashHeads[1]];
         pindexFork = LastCommonAncestor(pindexOld, pindexNew);
         assert(pindexFork != nullptr);
     }
 
     // Rollback along the old branch.
     while (pindexOld != pindexFork) {
         if (pindexOld->nHeight > 0) {
             // Never disconnect the genesis block.
             CBlock block;
             if (!ReadBlockFromDisk(block, pindexOld, config)) {
                 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 == DISCONNECT_FAILED) {
                 return error(
                     "RollbackBlock(): DisconnectBlock failed at %d, hash=%s",
                     pindexOld->nHeight, pindexOld->GetBlockHash().ToString());
             }
 
             // If DISCONNECT_UNCLEAN is returned, it means a non-existing UTXO
             // was deleted, or an existing UTXO was overwritten. It corresponds
             // to cases where the block-to-be-disconnect never had all its
             // operations applied to the UTXO set. However, as both writing a
             // UTXO and deleting a UTXO are idempotent operations, the result is
             // still a version of the UTXO set with the effects of that block
             // undone.
         }
         pindexOld = pindexOld->pprev;
     }
 
     // Roll forward from the forking point to the new tip.
     int nForkHeight = pindexFork ? pindexFork->nHeight : 0;
     for (int nHeight = nForkHeight + 1; nHeight <= pindexNew->nHeight;
          ++nHeight) {
         const CBlockIndex *pindex = pindexNew->GetAncestor(nHeight);
         LogPrintf("Rolling forward %s (%i)\n",
                   pindex->GetBlockHash().ToString(), nHeight);
         if (!RollforwardBlock(pindex, cache, config)) {
             return false;
         }
     }
 
     cache.SetBestBlock(pindexNew->GetBlockHash());
     cache.Flush();
     uiInterface.ShowProgress("", 100, false);
     return true;
 }
 
 bool ReplayBlocks(const Config &config, CCoinsView *view) {
     return g_chainstate.ReplayBlocks(config, view);
 }
 
 bool CChainState::RewindBlockIndex(const Config &config) {
     LOCK(cs_main);
 
     const CChainParams &params = config.GetChainParams();
     int nHeight = chainActive.Height() + 1;
 
     // nHeight is now the height of the first insufficiently-validated block, or
     // tipheight + 1
     CValidationState state;
     CBlockIndex *pindex = chainActive.Tip();
     while (chainActive.Height() >= nHeight) {
         if (fPruneMode && !chainActive.Tip()->nStatus.hasData()) {
             // If pruning, don't try rewinding past the HAVE_DATA point; since
             // older blocks can't be served anyway, there's no need to walk
             // further, and trying to DisconnectTip() will fail (and require a
             // needless reindex/redownload of the blockchain).
             break;
         }
 
         if (!DisconnectTip(config, state, nullptr)) {
             return error(
                 "RewindBlockIndex: unable to disconnect block at height %i",
                 pindex->nHeight);
         }
 
         // Occasionally flush state to disk.
         if (!FlushStateToDisk(params, state, FlushStateMode::PERIODIC)) {
             return false;
         }
     }
 
     // Reduce validity flag and have-data flags.
     // We do this after actual disconnecting, otherwise we'll end up writing the
     // lack of data to disk before writing the chainstate, resulting in a
     // failure to continue if interrupted.
     for (const auto &entry : mapBlockIndex) {
         CBlockIndex *pindexIter = entry.second;
         if (pindexIter->IsValid(BlockValidity::TRANSACTIONS) &&
             pindexIter->nChainTx) {
             setBlockIndexCandidates.insert(pindexIter);
         }
     }
 
     if (chainActive.Tip() != nullptr) {
         // We can't prune block index candidates based on our tip if we have
         // no tip due to chainActive being empty!
         PruneBlockIndexCandidates();
 
         CheckBlockIndex(params.GetConsensus());
     }
 
     return true;
 }
 
 bool RewindBlockIndex(const Config &config) {
     if (!g_chainstate.RewindBlockIndex(config)) {
         return false;
     }
 
     if (chainActive.Tip() != nullptr) {
         // FlushStateToDisk can possibly read chainActive. Be conservative
         // and skip it here, we're about to -reindex-chainstate anyway, so
         // it'll get called a bunch real soon.
         CValidationState state;
         if (!FlushStateToDisk(config.GetChainParams(), state,
                               FlushStateMode::ALWAYS)) {
             return 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() {
     setBlockIndexCandidates.clear();
 }
 
 // May NOT be used after any connections are up as much
 // of the peer-processing logic assumes a consistent
 // block index state
 void UnloadBlockIndex() {
     LOCK(cs_main);
     chainActive.SetTip(nullptr);
     pindexFinalized = nullptr;
     pindexBestInvalid = nullptr;
     pindexBestParked = nullptr;
     pindexBestHeader = nullptr;
     g_mempool.clear();
     mapBlocksUnlinked.clear();
     vinfoBlockFile.clear();
     nLastBlockFile = 0;
     nBlockSequenceId = 1;
     setDirtyBlockIndex.clear();
     setDirtyFileInfo.clear();
 
     for (BlockMap::value_type &entry : mapBlockIndex) {
         delete entry.second;
     }
 
     mapBlockIndex.clear();
     fHavePruned = false;
 
     g_chainstate.UnloadBlockIndex();
 }
 
 bool LoadBlockIndex(const Config &config) {
     // Load block index from databases
     bool needs_init = fReindex;
     if (!fReindex) {
         bool ret = LoadBlockIndexDB(config);
         if (!ret) {
             return false;
         }
 
         needs_init = mapBlockIndex.empty();
     }
 
     if (needs_init) {
         // Everything here is for *new* reindex/DBs. Thus, though
         // LoadBlockIndexDB may have set fReindex if we shut down
         // mid-reindex previously, we don't check fReindex and
         // instead only check it prior to LoadBlockIndexDB to set
         // needs_init.
 
         LogPrintf("Initializing databases...\n");
-        // Use the provided setting for -txindex in the new database
-        fTxIndex = gArgs.GetBoolArg("-txindex", DEFAULT_TXINDEX);
-        pblocktree->WriteFlag("txindex", fTxIndex);
     }
     return true;
 }
 
 bool CChainState::LoadGenesisBlock(const CChainParams &chainparams) {
     LOCK(cs_main);
 
     // Check whether we're already initialized by checking for genesis in
     // mapBlockIndex. Note that we can't use chainActive here, since it is
     // set based on the coins db, not the block index db, which is the only
     // thing loaded at this point.
     if (mapBlockIndex.count(chainparams.GenesisBlock().GetHash())) {
         return true;
     }
 
     try {
         CBlock &block = const_cast<CBlock &>(chainparams.GenesisBlock());
         CDiskBlockPos blockPos =
             SaveBlockToDisk(block, 0, chainparams, nullptr);
         if (blockPos.IsNull()) {
             return error("%s: writing genesis block to disk failed", __func__);
         }
         CBlockIndex *pindex = AddToBlockIndex(block);
         CValidationState state;
         if (!ReceivedBlockTransactions(block, state, pindex, blockPos)) {
             return error("%s: genesis block not accepted", __func__);
         }
     } 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 g_chainstate.LoadGenesisBlock(chainparams);
 }
 
 bool LoadExternalBlockFile(const Config &config, FILE *fileIn,
                            CDiskBlockPos *dbp) {
     // Map of disk positions for blocks with unknown parent (only used for
     // reindex)
     static std::multimap<uint256, CDiskBlockPos> 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 >> FLATDATA(buf);
                 if (memcmp(buf, std::begin(chainparams.DiskMagic()),
                            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();
 
                 uint256 hash = block.GetHash();
                 {
                     LOCK(cs_main);
                     // detect out of order blocks, and store them for later
                     if (hash != chainparams.GetConsensus().hashGenesisBlock &&
                         !LookupBlockIndex(block.hashPrevBlock)) {
                         LogPrint(
                             BCLog::REINDEX,
                             "%s: Out of order block %s, parent %s not known\n",
                             __func__, hash.ToString(),
                             block.hashPrevBlock.ToString());
                         if (dbp) {
                             mapBlocksUnknownParent.insert(
                                 std::make_pair(block.hashPrevBlock, *dbp));
                         }
                         continue;
                     }
 
                     // process in case the block isn't known yet
                     CBlockIndex *pindex = LookupBlockIndex(hash);
                     if (!pindex || !pindex->nStatus.hasData()) {
                         CValidationState state;
                         if (g_chainstate.AcceptBlock(config, pblock, state,
                                                      true, dbp, nullptr)) {
                             nLoaded++;
                         }
                         if (state.IsError()) {
                             break;
                         }
                     } else if (hash != chainparams.GetConsensus()
                                            .hashGenesisBlock &&
                                pindex->nHeight % 1000 == 0) {
                         LogPrint(
                             BCLog::REINDEX,
                             "Block Import: already had block %s at height %d\n",
                             hash.ToString(), pindex->nHeight);
                     }
                 }
 
                 // Activate the genesis block so normal node progress can
                 // continue
                 if (hash == chainparams.GetConsensus().hashGenesisBlock) {
                     CValidationState state;
                     if (!ActivateBestChain(config, state)) {
                         break;
                     }
                 }
 
                 NotifyHeaderTip();
 
                 // Recursively process earlier encountered successors of this
                 // block
                 std::deque<uint256> queue;
                 queue.push_back(hash);
                 while (!queue.empty()) {
                     uint256 head = queue.front();
                     queue.pop_front();
                     std::pair<std::multimap<uint256, CDiskBlockPos>::iterator,
                               std::multimap<uint256, CDiskBlockPos>::iterator>
                         range = mapBlocksUnknownParent.equal_range(head);
                     while (range.first != range.second) {
                         std::multimap<uint256, CDiskBlockPos>::iterator it =
                             range.first;
                         std::shared_ptr<CBlock> pblockrecursive =
                             std::make_shared<CBlock>();
                         if (ReadBlockFromDisk(*pblockrecursive, it->second,
                                               config)) {
                             LogPrint(
                                 BCLog::REINDEX,
                                 "%s: Processing out of order child %s of %s\n",
                                 __func__, pblockrecursive->GetHash().ToString(),
                                 head.ToString());
                             LOCK(cs_main);
                             CValidationState dummy;
                             if (g_chainstate.AcceptBlock(
                                     config, pblockrecursive, dummy, true,
                                     &it->second, nullptr)) {
                                 nLoaded++;
                                 queue.push_back(pblockrecursive->GetHash());
                             }
                         }
                         range.first++;
                         mapBlocksUnknownParent.erase(it);
                         NotifyHeaderTip();
                     }
                 }
             } catch (const std::exception &e) {
                 LogPrintf("%s: Deserialize or I/O error - %s\n", __func__,
                           e.what());
             }
         }
     } catch (const std::runtime_error &e) {
         AbortNode(std::string("System error: ") + e.what());
     }
 
     if (nLoaded > 0) {
         LogPrintf("Loaded %i blocks from external file in %dms\n", nLoaded,
                   GetTimeMillis() - nStart);
     }
 
     return nLoaded > 0;
 }
 
 void CChainState::CheckBlockIndex(const Consensus::Params &consensusParams) {
     if (!fCheckBlockIndex) {
         return;
     }
 
     LOCK(cs_main);
 
     // During a reindex, we read the genesis block and call CheckBlockIndex
     // before ActivateBestChain, so we have the genesis block in mapBlockIndex
     // but no active chain. (A few of the tests when iterating the block tree
     // require that chainActive has been initialized.)
     if (chainActive.Height() < 0) {
         assert(mapBlockIndex.size() <= 1);
         return;
     }
 
     // Build forward-pointing map of the entire block tree.
     std::multimap<CBlockIndex *, CBlockIndex *> forward;
     for (auto &entry : mapBlockIndex) {
         forward.emplace(entry.second->pprev, entry.second);
     }
 
     assert(forward.size() == mapBlockIndex.size());
 
     std::pair<std::multimap<CBlockIndex *, CBlockIndex *>::iterator,
               std::multimap<CBlockIndex *, CBlockIndex *>::iterator>
         rangeGenesis = forward.equal_range(nullptr);
     CBlockIndex *pindex = rangeGenesis.first->second;
     rangeGenesis.first++;
     // There is only one index entry with parent nullptr.
     assert(rangeGenesis.first == rangeGenesis.second);
 
     // Iterate over the entire block tree, using depth-first search.
     // Along the way, remember whether there are blocks on the path from genesis
     // block being explored which are the first to have certain properties.
     size_t nNodes = 0;
     int nHeight = 0;
     // Oldest ancestor of pindex which is invalid.
     CBlockIndex *pindexFirstInvalid = nullptr;
     // Oldest ancestor of pindex which is parked.
     CBlockIndex *pindexFirstParked = nullptr;
     // Oldest ancestor of pindex which does not have data available.
     CBlockIndex *pindexFirstMissing = nullptr;
     // Oldest ancestor of pindex for which nTx == 0.
     CBlockIndex *pindexFirstNeverProcessed = nullptr;
     // Oldest ancestor of pindex which does not have BLOCK_VALID_TREE
     // (regardless of being valid or not).
     CBlockIndex *pindexFirstNotTreeValid = nullptr;
     // Oldest ancestor of pindex which does not have BLOCK_VALID_TRANSACTIONS
     // (regardless of being valid or not).
     CBlockIndex *pindexFirstNotTransactionsValid = nullptr;
     // Oldest ancestor of pindex which does not have BLOCK_VALID_CHAIN
     // (regardless of being valid or not).
     CBlockIndex *pindexFirstNotChainValid = nullptr;
     // Oldest ancestor of pindex which does not have BLOCK_VALID_SCRIPTS
     // (regardless of being valid or not).
     CBlockIndex *pindexFirstNotScriptsValid = nullptr;
     while (pindex != nullptr) {
         nNodes++;
         if (pindexFirstInvalid == nullptr && pindex->nStatus.hasFailed()) {
             pindexFirstInvalid = pindex;
         }
         if (pindexFirstParked == nullptr && pindex->nStatus.isParked()) {
             pindexFirstParked = pindex;
         }
         if (pindexFirstMissing == nullptr && !pindex->nStatus.hasData()) {
             pindexFirstMissing = pindex;
         }
         if (pindexFirstNeverProcessed == nullptr && pindex->nTx == 0) {
             pindexFirstNeverProcessed = pindex;
         }
         if (pindex->pprev != nullptr && pindexFirstNotTreeValid == nullptr &&
             pindex->nStatus.getValidity() < BlockValidity::TREE) {
             pindexFirstNotTreeValid = pindex;
         }
         if (pindex->pprev != nullptr &&
             pindexFirstNotTransactionsValid == nullptr &&
             pindex->nStatus.getValidity() < BlockValidity::TRANSACTIONS) {
             pindexFirstNotTransactionsValid = pindex;
         }
         if (pindex->pprev != nullptr && pindexFirstNotChainValid == nullptr &&
             pindex->nStatus.getValidity() < BlockValidity::CHAIN) {
             pindexFirstNotChainValid = pindex;
         }
         if (pindex->pprev != nullptr && pindexFirstNotScriptsValid == nullptr &&
             pindex->nStatus.getValidity() < BlockValidity::SCRIPTS) {
             pindexFirstNotScriptsValid = pindex;
         }
 
         // Begin: actual consistency checks.
         if (pindex->pprev == nullptr) {
             // Genesis block checks.
             // Genesis block's hash must match.
             assert(pindex->GetBlockHash() == consensusParams.hashGenesisBlock);
             // The current active chain's genesis block must be this block.
             assert(pindex == chainActive.Genesis());
         }
         if (pindex->nChainTx == 0) {
             // 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 nChainTx
         // being set.
         // nChainTx != 0 is used to signal that all parent blocks have been
         // processed (but may have been pruned).
         assert((pindexFirstNeverProcessed != nullptr) ==
                (pindex->nChainTx == 0));
         assert((pindexFirstNotTransactionsValid != nullptr) ==
                (pindex->nChainTx == 0));
         // nHeight must be consistent.
         assert(pindex->nHeight == nHeight);
         // For every block except the genesis block, the chainwork must be
         // larger than the parent's.
         assert(pindex->pprev == nullptr ||
                pindex->nChainWork >= pindex->pprev->nChainWork);
         // The pskip pointer must point back for all but the first 2 blocks.
         assert(nHeight < 2 ||
                (pindex->pskip && (pindex->pskip->nHeight < nHeight)));
         // All mapBlockIndex entries must at least be TREE valid
         assert(pindexFirstNotTreeValid == nullptr);
         if (pindex->nStatus.getValidity() >= BlockValidity::TREE) {
             // TREE valid implies all parents are TREE valid
             assert(pindexFirstNotTreeValid == nullptr);
         }
         if (pindex->nStatus.getValidity() >= BlockValidity::CHAIN) {
             // CHAIN valid implies all parents are CHAIN valid
             assert(pindexFirstNotChainValid == nullptr);
         }
         if (pindex->nStatus.getValidity() >= BlockValidity::SCRIPTS) {
             // SCRIPTS valid implies all parents are SCRIPTS valid
             assert(pindexFirstNotScriptsValid == nullptr);
         }
         if (pindexFirstInvalid == nullptr) {
             // Checks for not-invalid blocks.
             // The failed mask cannot be set for blocks without invalid parents.
             assert(!pindex->nStatus.isInvalid());
         }
         if (pindexFirstParked == nullptr) {
             // Checks for not-invalid blocks.
             // The failed mask cannot be set for blocks without invalid parents.
             assert(!pindex->nStatus.isOnParkedChain());
         }
         if (!CBlockIndexWorkComparator()(pindex, chainActive.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));
                 }
                 // chainActive.Tip() must also be there even if some data has
                 // been pruned.
                 if (pindex == chainActive.Tip()) {
                     assert(setBlockIndexCandidates.count(pindex));
                 }
                 // If some parent is missing, then it could be that this block
                 // was in setBlockIndexCandidates but had to be removed because
                 // of the missing data. In this case it must be in
                 // mapBlocksUnlinked -- see test below.
             }
         } else {
             // If this block sorts worse than the current tip or some ancestor's
             // block has never been seen, it cannot be in
             // setBlockIndexCandidates.
             assert(setBlockIndexCandidates.count(pindex) == 0);
         }
         // Check whether this block is in mapBlocksUnlinked.
         std::pair<std::multimap<CBlockIndex *, CBlockIndex *>::iterator,
                   std::multimap<CBlockIndex *, CBlockIndex *>::iterator>
             rangeUnlinked = mapBlocksUnlinked.equal_range(pindex->pprev);
         bool foundInUnlinked = false;
         while (rangeUnlinked.first != rangeUnlinked.second) {
             assert(rangeUnlinked.first->first == pindex->pprev);
             if (rangeUnlinked.first->second == pindex) {
                 foundInUnlinked = true;
                 break;
             }
             rangeUnlinked.first++;
         }
         if (pindex->pprev && pindex->nStatus.hasData() &&
             pindexFirstNeverProcessed != nullptr &&
             pindexFirstInvalid == nullptr) {
             // If this block has block data available, some parent was never
             // received, and has no invalid parents, it must be in
             // mapBlocksUnlinked.
             assert(foundInUnlinked);
         }
         if (!pindex->nStatus.hasData()) {
             // Can't be in mapBlocksUnlinked if we don't HAVE_DATA
             assert(!foundInUnlinked);
         }
         if (pindexFirstMissing == nullptr) {
             // We aren't missing data for any parent -- cannot be in
             // mapBlocksUnlinked.
             assert(!foundInUnlinked);
         }
         if (pindex->pprev && pindex->nStatus.hasData() &&
             pindexFirstNeverProcessed == nullptr &&
             pindexFirstMissing != nullptr) {
             // We HAVE_DATA for this block, have received data for all parents
             // at some point, but we're currently missing data for some parent.
             // We must have pruned.
             assert(fHavePruned);
             // This block may have entered mapBlocksUnlinked if:
             //  - it has a descendant that at some point had more work than the
             //    tip, and
             //  - we tried switching to that descendant but were missing
             //    data for some intermediate block between chainActive and the
             //    tip.
             // So if this block is itself better than chainActive.Tip() and it
             // wasn't in
             // setBlockIndexCandidates, then it must be in mapBlocksUnlinked.
             if (!CBlockIndexWorkComparator()(pindex, chainActive.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 const uint64_t MEMPOOL_DUMP_VERSION = 1;
 
 bool LoadMempool(const Config &config) {
     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 skipped = 0;
     int64_t failed = 0;
     int64_t nNow = GetTime();
 
     try {
         uint64_t version;
         file >> version;
         if (version != MEMPOOL_DUMP_VERSION) {
             return false;
         }
 
         uint64_t num;
         file >> num;
         double prioritydummy = 0;
         while (num--) {
             CTransactionRef tx;
             int64_t nTime;
             int64_t nFeeDelta;
             file >> tx;
             file >> nTime;
             file >> nFeeDelta;
 
             Amount amountdelta = nFeeDelta * SATOSHI;
             if (amountdelta != Amount::zero()) {
                 g_mempool.PrioritiseTransaction(tx->GetId(), prioritydummy,
                                                 amountdelta);
             }
             CValidationState state;
             if (nTime + nExpiryTimeout > nNow) {
                 LOCK(cs_main);
                 AcceptToMemoryPoolWithTime(
                     config, g_mempool, state, tx, true /* fLimitFree */,
                     nullptr /* pfMissingInputs */, nTime,
                     false /* fOverrideMempoolLimit */,
                     Amount::zero() /* nAbsurdFee */, false /* test_accept */);
                 if (state.IsValid()) {
                     ++count;
                 } else {
                     ++failed;
                 }
             } else {
                 ++skipped;
             }
 
             if (ShutdownRequested()) {
                 return false;
             }
         }
         std::map<uint256, Amount> mapDeltas;
         file >> mapDeltas;
 
         for (const auto &i : mapDeltas) {
             g_mempool.PrioritiseTransaction(i.first, prioritydummy, 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 successes, %i "
               "failed, %i expired\n",
               count, failed, skipped);
     return true;
 }
 
 bool DumpMempool(void) {
     int64_t start = GetTimeMicros();
 
     std::map<uint256, Amount> mapDeltas;
     std::vector<TxMempoolInfo> vinfo;
 
     static Mutex dump_mutex;
     LOCK(dump_mutex);
 
     {
         LOCK(g_mempool.cs);
         for (const auto &i : g_mempool.mapDeltas) {
             mapDeltas[i.first] = i.second.second;
         }
 
         vinfo = g_mempool.infoAll();
     }
 
     int64_t mid = GetTimeMicros();
 
     try {
         FILE *filestr = fsbridge::fopen(GetDataDir() / "mempool.dat.new", "wb");
         if (!filestr) {
             return false;
         }
 
         CAutoFile file(filestr, SER_DISK, CLIENT_VERSION);
 
         uint64_t version = MEMPOOL_DUMP_VERSION;
         file << version;
 
         file << uint64_t(vinfo.size());
         for (const auto &i : vinfo) {
             file << *(i.tx);
             file << int64_t(i.nTime);
             file << i.nFeeDelta;
             mapDeltas.erase(i.tx->GetId());
         }
 
         file << mapDeltas;
         FileCommit(file.Get());
         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;
 }
 
 //! Guess how far we are in the verification process at the given block index
 double GuessVerificationProgress(const ChainTxData &data,
                                  const CBlockIndex *pindex) {
     if (pindex == nullptr) {
         return 0.0;
     }
 
     int64_t nNow = time(nullptr);
 
     double fTxTotal;
     if (pindex->nChainTx <= data.nTxCount) {
         fTxTotal = data.nTxCount + (nNow - data.nTime) * data.dTxRate;
     } else {
         fTxTotal =
             pindex->nChainTx + (nNow - pindex->GetBlockTime()) * data.dTxRate;
     }
 
     return pindex->nChainTx / fTxTotal;
 }
 
 class CMainCleanup {
 public:
     CMainCleanup() {}
     ~CMainCleanup() {
         // block headers
         for (const std::pair<const uint256, CBlockIndex *> &it :
              mapBlockIndex) {
             delete it.second;
         }
         mapBlockIndex.clear();
     }
 } instance_of_cmaincleanup;
diff --git a/src/validation.h b/src/validation.h
index 753b26514f..d4d2d3f815 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -1,725 +1,724 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Copyright (c) 2017 The Bitcoin developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_VALIDATION_H
 #define BITCOIN_VALIDATION_H
 
 #if defined(HAVE_CONFIG_H)
 #include <config/bitcoin-config.h>
 #endif
 
 #include <amount.h>
 #include <blockfileinfo.h>
 #include <coins.h>
 #include <consensus/consensus.h>
 #include <consensus/params.h>
 #include <diskblockpos.h>
 #include <fs.h>
 #include <protocol.h> // For CMessageHeader::MessageMagic
 #include <script/script_error.h>
 #include <sync.h>
 #include <versionbits.h>
 
 #include <algorithm>
 #include <atomic>
 #include <cstdint>
 #include <exception>
 #include <map>
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
 
 class arith_uint256;
 
 class CBlockIndex;
 class CBlockTreeDB;
 class CBloomFilter;
 class CChainParams;
 class CChain;
 class CCoinsViewDB;
 class CConnman;
 class CInv;
 class Config;
 class CScriptCheck;
 class CTxMemPool;
 class CTxUndo;
 class CValidationInterface;
 class CValidationState;
 
 struct CDiskBlockPos;
 struct ChainTxData;
 struct PrecomputedTransactionData;
 struct LockPoints;
 
 #define MIN_TRANSACTION_SIZE                                                   \
     (::GetSerializeSize(CTransaction(), SER_NETWORK, PROTOCOL_VERSION))
 
 /** Default for DEFAULT_WHITELISTRELAY. */
 static const bool DEFAULT_WHITELISTRELAY = true;
 /** Default for DEFAULT_WHITELISTFORCERELAY. */
 static const bool DEFAULT_WHITELISTFORCERELAY = true;
 /** Default for -minrelaytxfee, minimum relay fee for transactions */
 static const Amount DEFAULT_MIN_RELAY_TX_FEE_PER_KB(1000 * SATOSHI);
 /** Default for -excessutxocharge for transactions transactions */
 static const Amount DEFAULT_UTXO_FEE = Amount::zero();
 //! -maxtxfee default
 static const Amount DEFAULT_TRANSACTION_MAXFEE(COIN / 10);
 //! Discourage users to set fees higher than this amount (in satoshis) per kB
 static const Amount HIGH_TX_FEE_PER_KB(COIN / 100);
 /**
  * -maxtxfee will warn if called with a higher fee than this amount (in satoshis
  */
 static const Amount HIGH_MAX_TX_FEE(100 * HIGH_TX_FEE_PER_KB);
 /** Default for -limitancestorcount, max number of in-mempool ancestors */
 static const unsigned int DEFAULT_ANCESTOR_LIMIT = 25;
 /** Default for -limitancestorsize, maximum kilobytes of tx + all in-mempool
  * ancestors */
 static const unsigned int DEFAULT_ANCESTOR_SIZE_LIMIT = 101;
 /** Default for -limitdescendantcount, max number of in-mempool descendants */
 static const unsigned int DEFAULT_DESCENDANT_LIMIT = 25;
 /** Default for -limitdescendantsize, maximum kilobytes of in-mempool
  * descendants */
 static const unsigned int DEFAULT_DESCENDANT_SIZE_LIMIT = 101;
 /** Default for -mempoolexpiry, expiration time for mempool transactions in
  * hours */
 static const unsigned int DEFAULT_MEMPOOL_EXPIRY = 336;
 /** The maximum size of a blk?????.dat file (since 0.8) */
 static const unsigned int MAX_BLOCKFILE_SIZE = 0x8000000; // 128 MiB
 /** The pre-allocation chunk size for blk?????.dat files (since 0.8) */
 static const unsigned int BLOCKFILE_CHUNK_SIZE = 0x1000000; // 16 MiB
 /** The pre-allocation chunk size for rev?????.dat files (since 0.8) */
 static const unsigned int UNDOFILE_CHUNK_SIZE = 0x100000; // 1 MiB
 
 /** Maximum number of script-checking threads allowed */
 static const int MAX_SCRIPTCHECK_THREADS = 16;
 /** -par default (number of script-checking threads, 0 = auto) */
 static const int DEFAULT_SCRIPTCHECK_THREADS = 0;
 /**
  * Number of blocks that can be requested at any given time from a single peer.
  */
 static const int MAX_BLOCKS_IN_TRANSIT_PER_PEER = 16;
 /**
  * Timeout in seconds during which a peer must stall block download progress
  * before being disconnected.
  */
 static const unsigned int BLOCK_STALLING_TIMEOUT = 2;
 /**
  * Number of headers sent in one getheaders result. We rely on the assumption
  * that if a peer sends less than this number, we reached its tip. Changing this
  * value is a protocol upgrade.
  */
 static const unsigned int MAX_HEADERS_RESULTS = 2000;
 /**
  * Maximum depth of blocks we're willing to serve as compact blocks to peers
  * when requested. For older blocks, a regular BLOCK response will be sent.
  */
 static const int MAX_CMPCTBLOCK_DEPTH = 5;
 /**
  * Maximum depth of blocks we're willing to respond to GETBLOCKTXN requests for.
  */
 static const int MAX_BLOCKTXN_DEPTH = 10;
 /**
  * Size of the "block download window": how far ahead of our current height do
  * we fetch ? Larger windows tolerate larger download speed differences between
  * peer, but increase the potential degree of disordering of blocks on disk
  * (which make reindexing and in the future perhaps pruning harder). We'll
  * probably want to make this a per-peer adaptive value at some point.
  */
 static const unsigned int BLOCK_DOWNLOAD_WINDOW = 1024;
 /** Time to wait (in seconds) between writing blocks/block index to disk. */
 static const unsigned int DATABASE_WRITE_INTERVAL = 60 * 60;
 /** Time to wait (in seconds) between flushing chainstate to disk. */
 static const unsigned int DATABASE_FLUSH_INTERVAL = 24 * 60 * 60;
 /** Maximum length of reject messages. */
 static const unsigned int MAX_REJECT_MESSAGE_LENGTH = 111;
 /** Average delay between local address broadcasts in seconds. */
 static const unsigned int AVG_LOCAL_ADDRESS_BROADCAST_INTERVAL = 24 * 24 * 60;
 /** Average delay between peer address broadcasts in seconds. */
 static const unsigned int AVG_ADDRESS_BROADCAST_INTERVAL = 30;
 /**
  * Average delay between trickled inventory transmissions in seconds.
  * Blocks and whitelisted receivers bypass this, outbound peers get half this
  * delay.
  */
 static const unsigned int INVENTORY_BROADCAST_INTERVAL = 5;
 /**
  * Maximum number of inventory items to send per transmission.
  * Limits the impact of low-fee transaction floods.
  */
 static const unsigned int INVENTORY_BROADCAST_MAX_PER_MB =
     7 * INVENTORY_BROADCAST_INTERVAL;
 /** Average delay between feefilter broadcasts in seconds. */
 static const unsigned int AVG_FEEFILTER_BROADCAST_INTERVAL = 10 * 60;
 /** Maximum feefilter broadcast delay after significant change. */
 static const unsigned int MAX_FEEFILTER_CHANGE_DELAY = 5 * 60;
 /** Block download timeout base, expressed in millionths of the block interval
  * (i.e. 10 min) */
 static const int64_t BLOCK_DOWNLOAD_TIMEOUT_BASE = 1000000;
 /**
  * Additional block download timeout per parallel downloading peer (i.e. 5 min)
  */
 static const int64_t BLOCK_DOWNLOAD_TIMEOUT_PER_PEER = 500000;
 
 static const unsigned int DEFAULT_LIMITFREERELAY = 0;
 static const bool DEFAULT_RELAYPRIORITY = true;
 static const int64_t DEFAULT_MAX_TIP_AGE = 24 * 60 * 60;
 /**
  * Maximum age of our tip in seconds for us to be considered current for fee
  * estimation.
  */
 static const int64_t MAX_FEE_ESTIMATION_TIP_AGE = 3 * 60 * 60;
 
 /** Default for -permitbaremultisig */
 static const bool DEFAULT_PERMIT_BAREMULTISIG = true;
 static const bool DEFAULT_CHECKPOINTS_ENABLED = true;
 static const bool DEFAULT_TXINDEX = false;
 static const unsigned int DEFAULT_BANSCORE_THRESHOLD = 100;
 
 /** Default for -persistmempool */
 static const bool DEFAULT_PERSIST_MEMPOOL = true;
 /** Default for using fee filter */
 static const bool DEFAULT_FEEFILTER = true;
 
 /**
  * Maximum number of headers to announce when relaying blocks with headers
  * message.
  */
 static const unsigned int MAX_BLOCKS_TO_ANNOUNCE = 8;
 
 /** Maximum number of unconnecting headers announcements before DoS score */
 static const int MAX_UNCONNECTING_HEADERS = 10;
 
 static const bool DEFAULT_PEERBLOOMFILTERS = true;
 
 /** Default for -stopatheight */
 static const int DEFAULT_STOPATHEIGHT = 0;
 /** Default for -maxreorgdepth */
 static const int DEFAULT_MAX_REORG_DEPTH = 10;
 /**
  * Default for -finalizationdelay
  * This is the minimum time between a block header reception and the block
  * finalization.
  * This value should be >> block propagation and validation time
  */
 static const int64_t DEFAULT_MIN_FINALIZATION_DELAY = 2 * 60 * 60;
 
 extern CScript COINBASE_FLAGS;
 extern CCriticalSection cs_main;
 extern CTxMemPool g_mempool;
 extern std::atomic_bool g_is_mempool_loaded;
 extern uint64_t nLastBlockTx;
 extern uint64_t nLastBlockSize;
 extern const std::string strMessageMagic;
 extern Mutex g_best_block_mutex;
 extern std::condition_variable g_best_block_cv;
 extern uint256 g_best_block;
 extern std::atomic_bool fImporting;
 extern std::atomic_bool fReindex;
 extern int nScriptCheckThreads;
-extern bool fTxIndex;
 extern bool fIsBareMultisigStd;
 extern bool fRequireStandard;
 extern bool fCheckBlockIndex;
 extern bool fCheckpointsEnabled;
 extern size_t nCoinCacheUsage;
 
 /**
  * Absolute maximum transaction fee (in satoshis) used by wallet and mempool
  * (rejects high fee in sendrawtransaction)
  */
 extern Amount maxTxFee;
 /**
  * If the tip is older than this (in seconds), the node is considered to be in
  * initial block download.
  */
 extern int64_t nMaxTipAge;
 
 /**
  * Block hash whose ancestors we will assume to have valid scripts without
  * checking them.
  */
 extern uint256 hashAssumeValid;
 
 /**
  * Minimum work we will assume exists on some valid chain.
  */
 extern arith_uint256 nMinimumChainWork;
 
 /**
  * Best header we've seen so far (used for getheaders queries' starting points).
  */
 extern CBlockIndex *pindexBestHeader;
 
 /** Minimum disk space required - used in CheckDiskSpace() */
 static const uint64_t nMinDiskSpace = 52428800;
 
 /** Pruning-related variables and constants */
 /** True if any block files have ever been pruned. */
 extern bool fHavePruned;
 /** True if we're running in -prune mode. */
 extern bool fPruneMode;
 /** Number of MiB of block files that we're trying to stay below. */
 extern uint64_t nPruneTarget;
 /** Block files containing a block-height within MIN_BLOCKS_TO_KEEP of
  * chainActive.Tip() will not be pruned. */
 static const unsigned int MIN_BLOCKS_TO_KEEP = 288;
 /** Minimum blocks required to signal NODE_NETWORK_LIMITED */
 static const unsigned int NODE_NETWORK_LIMITED_MIN_BLOCKS = 288;
 
 static const signed int DEFAULT_CHECKBLOCKS = 6;
 static const unsigned int DEFAULT_CHECKLEVEL = 3;
 
 /**
  * Require that user allocate at least 550MB for block & undo files (blk???.dat
  * and rev???.dat)
  * At 1MB per block, 288 blocks = 288MB.
  * Add 15% for Undo data = 331MB
  * Add 20% for Orphan block rate = 397MB
  * We want the low water mark after pruning to be at least 397 MB and since we
  * prune in full block file chunks, we need the high water mark which triggers
  * the prune to be one 128MB block file + added 15% undo data = 147MB greater
  * for a total of 545MB. Setting the target to > than 550MB will make it likely
  * we can respect the target.
  */
 static const uint64_t MIN_DISK_SPACE_FOR_BLOCK_FILES = 550 * 1024 * 1024;
 
 class BlockValidationOptions {
 private:
     bool checkPoW : 1;
     bool checkMerkleRoot : 1;
 
 public:
     // Do full validation by default
     BlockValidationOptions() : checkPoW(true), checkMerkleRoot(true) {}
     BlockValidationOptions(bool checkPoWIn, bool checkMerkleRootIn)
         : checkPoW(checkPoWIn), checkMerkleRoot(checkMerkleRootIn) {}
 
     bool shouldValidatePoW() const { return checkPoW; }
     bool shouldValidateMerkleRoot() const { return checkMerkleRoot; }
 };
 
 /**
  * Process an incoming block. This only returns after the best known valid
  * block is made active. Note that it does not, however, guarantee that the
  * specific block passed to it has been checked for validity!
  *
  * If you want to *possibly* get feedback on whether pblock is valid, you must
  * install a CValidationInterface (see validationinterface.h) - this will have
  * its BlockChecked method called whenever *any* block completes validation.
  *
  * Note that we guarantee that either the proof-of-work is valid on pblock, or
  * (and possibly also) BlockChecked will have been called.
  *
  * Call without cs_main held.
  *
  * @param[in]   config  The global config.
  * @param[in]   pblock  The block we want to process.
  * @param[in]   fForceProcessing Process this block even if unrequested; used
  * for non-network block sources and whitelisted peers.
  * @param[out]  fNewBlock A boolean which is set to indicate if the block was
  *                        first received via this call.
  * @return True if the block is accepted as a valid block.
  */
 bool ProcessNewBlock(const Config &config,
                      const std::shared_ptr<const CBlock> pblock,
                      bool fForceProcessing, bool *fNewBlock);
 
 /**
  * Process incoming block headers.
  *
  * Call without cs_main held.
  *
  * @param[in]  config        The config.
  * @param[in]  block         The block headers themselves.
  * @param[out] state         This may be set to an Error state if any error
  *                           occurred processing them.
  * @param[out] ppindex       If set, the pointer will be set to point to the
  *                           last new block index object for the given headers.
  * @param[out] first_invalid First header that fails validation, if one exists.
  * @return True if block headers were accepted as valid.
  */
 bool ProcessNewBlockHeaders(const Config &config,
                             const std::vector<CBlockHeader> &block,
                             CValidationState &state,
                             const CBlockIndex **ppindex = nullptr,
                             CBlockHeader *first_invalid = nullptr);
 
 /**
  * Check whether enough disk space is available for an incoming block.
  */
 bool CheckDiskSpace(uint64_t nAdditionalBytes = 0, bool blocks_dir = false);
 
 /**
  * Open a block file (blk?????.dat).
  */
 FILE *OpenBlockFile(const CDiskBlockPos &pos, bool fReadOnly = false);
 
 /**
  * Translation to a filesystem path.
  */
 fs::path GetBlockPosFilename(const CDiskBlockPos &pos, const char *prefix);
 
 /**
  * Import blocks from an external file.
  */
 bool LoadExternalBlockFile(const Config &config, FILE *fileIn,
                            CDiskBlockPos *dbp = nullptr);
 
 /**
  * Ensures we have a genesis block in the block tree, possibly writing one to
  * disk.
  */
 bool LoadGenesisBlock(const CChainParams &chainparams);
 
 /**
  * Load the block tree and coins database from disk, initializing state if we're
  * running with -reindex.
  */
 bool LoadBlockIndex(const Config &config);
 
 /**
  * Update the chain tip based on database information.
  */
 bool LoadChainTip(const Config &config);
 
 /**
  * Unload database information.
  */
 void UnloadBlockIndex();
 
 /**
  * Run an instance of the script checking thread.
  */
 void ThreadScriptCheck();
 
 /**
  * Check whether we are doing an initial block download (synchronizing from disk
  * or network)
  */
 bool IsInitialBlockDownload();
 
 /**
  * Retrieve a transaction (from memory pool, or from disk, if possible).
  */
 bool GetTransaction(const Config &config, const TxId &txid, CTransactionRef &tx,
                     uint256 &hashBlock, bool fAllowSlow = false,
                     CBlockIndex *blockIndex = nullptr);
 
 /**
  * Find the best known block, and make it the active tip of the block chain.
  * If it fails, the tip is not updated.
  *
  * pblock is either nullptr or a pointer to a block that is already loaded
  * in memory (to avoid loading it from disk again).
  *
  * Returns true if a new chain tip was set.
  */
 bool ActivateBestChain(
     const Config &config, CValidationState &state,
     std::shared_ptr<const CBlock> pblock = std::shared_ptr<const CBlock>());
 Amount GetBlockSubsidy(int nHeight, const Consensus::Params &consensusParams);
 
 /**
  * Guess verification progress (as a fraction between 0.0=genesis and
  * 1.0=current tip).
  */
 double GuessVerificationProgress(const ChainTxData &data,
                                  const CBlockIndex *pindex);
 
 /**
  * Calculate the amount of disk space the block & undo files currently use.
  */
 uint64_t CalculateCurrentUsage();
 
 /**
  * Mark one block file as pruned.
  */
 void PruneOneBlockFile(const int fileNumber);
 
 /**
  * Actually unlink the specified files
  */
 void UnlinkPrunedFiles(const std::set<int> &setFilesToPrune);
 
 /** Flush all state, indexes and buffers to disk. */
 void FlushStateToDisk();
 /** Prune block files and flush state to disk. */
 void PruneAndFlush();
 /** Prune block files up to a given height */
 void PruneBlockFilesManual(int nManualPruneHeight);
 
 /**
  * (try to) add transaction to memory pool
  */
 bool AcceptToMemoryPool(const Config &config, CTxMemPool &pool,
                         CValidationState &state, const CTransactionRef &tx,
                         bool fLimitFree, bool *pfMissingInputs,
                         bool fOverrideMempoolLimit = false,
                         const Amount nAbsurdFee = Amount::zero(),
                         bool test_accept = false);
 
 /** Convert CValidationState to a human-readable message for logging */
 std::string FormatStateMessage(const CValidationState &state);
 
 /**
  * Check whether all inputs of this transaction are valid (no double spends,
  * scripts & sigs, amounts). This does not modify the UTXO set.
  *
  * If pvChecks is not nullptr, script checks are pushed onto it instead of being
  * performed inline. Any script checks which are not necessary (eg due to script
  * execution cache hits) are, obviously, not pushed onto pvChecks/run.
  *
  * Setting sigCacheStore/scriptCacheStore to false will remove elements from the
  * corresponding cache which are matched. This is useful for checking blocks
  * where we will likely never need the cache entry again.
  */
 bool CheckInputs(const CTransaction &tx, CValidationState &state,
                  const CCoinsViewCache &view, bool fScriptChecks,
                  const uint32_t flags, bool sigCacheStore,
                  bool scriptCacheStore,
                  const PrecomputedTransactionData &txdata,
                  std::vector<CScriptCheck> *pvChecks = nullptr);
 
 /**
  * Mark all the coins corresponding to a given transaction inputs as spent.
  */
 void SpendCoins(CCoinsViewCache &view, const CTransaction &tx, CTxUndo &txundo,
                 int nHeight);
 
 /**
  * Apply the effects of this transaction on the UTXO set represented by view.
  */
 void UpdateCoins(CCoinsViewCache &view, const CTransaction &tx, int nHeight);
 void UpdateCoins(CCoinsViewCache &view, const CTransaction &tx, CTxUndo &txundo,
                  int nHeight);
 
 /**
  * Test whether the LockPoints height and time are still valid on the current
  * chain.
  */
 bool TestLockPointValidity(const LockPoints *lp);
 
 /**
  * Check if transaction will be BIP 68 final in the next block to be created.
  *
  * Simulates calling SequenceLocks() with data from the tip of the current
  * active chain. Optionally stores in LockPoints the resulting height and time
  * calculated and the hash of the block needed for calculation or skips the
  * calculation and uses the LockPoints passed in for evaluation. The LockPoints
  * should not be considered valid if CheckSequenceLocks returns false.
  *
  * See consensus/consensus.h for flag definitions.
  */
 bool CheckSequenceLocks(const CTransaction &tx, int flags,
                         LockPoints *lp = nullptr,
                         bool useExistingLockPoints = false);
 
 /**
  * Closure representing one script verification.
  * Note that this stores references to the spending transaction.
  */
 class CScriptCheck {
 private:
     CScript scriptPubKey;
     Amount amount;
     const CTransaction *ptxTo;
     unsigned int nIn;
     uint32_t nFlags;
     bool cacheStore;
     ScriptError error;
     PrecomputedTransactionData txdata;
 
 public:
     CScriptCheck()
         : amount(), ptxTo(nullptr), nIn(0), nFlags(0), cacheStore(false),
           error(SCRIPT_ERR_UNKNOWN_ERROR), txdata() {}
 
     CScriptCheck(const CScript &scriptPubKeyIn, const Amount amountIn,
                  const CTransaction &txToIn, unsigned int nInIn,
                  uint32_t nFlagsIn, bool cacheIn,
                  const PrecomputedTransactionData &txdataIn)
         : scriptPubKey(scriptPubKeyIn), amount(amountIn), ptxTo(&txToIn),
           nIn(nInIn), nFlags(nFlagsIn), cacheStore(cacheIn),
           error(SCRIPT_ERR_UNKNOWN_ERROR), txdata(txdataIn) {}
 
     bool operator()();
 
     void swap(CScriptCheck &check) {
         scriptPubKey.swap(check.scriptPubKey);
         std::swap(ptxTo, check.ptxTo);
         std::swap(amount, check.amount);
         std::swap(nIn, check.nIn);
         std::swap(nFlags, check.nFlags);
         std::swap(cacheStore, check.cacheStore);
         std::swap(error, check.error);
         std::swap(txdata, check.txdata);
     }
 
     ScriptError GetScriptError() const { return error; }
 };
 
 /** Functions for disk access for blocks */
 bool ReadBlockFromDisk(CBlock &block, const CDiskBlockPos &pos,
                        const Config &config);
 bool ReadBlockFromDisk(CBlock &block, const CBlockIndex *pindex,
                        const Config &config);
 
 /** Functions for validating blocks and updating the block tree */
 
 /**
  * Context-independent validity checks.
  *
  * Returns true if the provided block is valid (has valid header,
  * transactions are valid, block is a valid size, etc.)
  */
 bool CheckBlock(
     const Config &Config, const CBlock &block, CValidationState &state,
     BlockValidationOptions validationOptions = BlockValidationOptions());
 
 /**
  * This is a variant of ContextualCheckTransaction which computes the contextual
  * check for a transaction based on the chain tip.
  *
  * See consensus/consensus.h for flag definitions.
  */
 bool ContextualCheckTransactionForCurrentBlock(const Config &config,
                                                const CTransaction &tx,
                                                CValidationState &state,
                                                int flags = -1);
 
 /**
  * Check a block is completely valid from start to finish (only works on top of
  * our current best block, with cs_main held)
  */
 bool TestBlockValidity(
     const Config &config, CValidationState &state, const CBlock &block,
     CBlockIndex *pindexPrev,
     BlockValidationOptions validationOptions = BlockValidationOptions());
 
 /**
  * When there are blocks in the active chain with missing data, rewind the
  * chainstate and remove them from the block index.
  */
 bool RewindBlockIndex(const Config &config);
 
 /**
  * RAII wrapper for VerifyDB: Verify consistency of the block and coin
  * databases.
  */
 class CVerifyDB {
 public:
     CVerifyDB();
     ~CVerifyDB();
     bool VerifyDB(const Config &config, CCoinsView *coinsview, int nCheckLevel,
                   int nCheckDepth);
 };
 
 /** Replay blocks that aren't fully applied to the database. */
 bool ReplayBlocks(const Config &config, CCoinsView *view);
 
 /** Find the last common block between the parameter chain and a locator. */
 CBlockIndex *FindForkInGlobalIndex(const CChain &chain,
                                    const CBlockLocator &locator);
 
 /**
  * Treats a block as if it were received before others with the same work,
  * making it the active chain tip if applicable. Successive calls to
  * PreciousBlock() will override the effects of earlier calls. The effects of
  * calls to PreciousBlock() are not retained across restarts.
  *
  * Returns true if the provided block index successfully became the chain tip.
  */
 bool PreciousBlock(const Config &config, CValidationState &state,
                    CBlockIndex *pindex);
 
 /**
  * Mark a block as finalized.
  * A finalized block can not be reorged in any way.
  */
 bool FinalizeBlockAndInvalidate(const Config &config, CValidationState &state,
                                 CBlockIndex *pindex);
 
 /** Mark a block as invalid. */
 bool InvalidateBlock(const Config &config, CValidationState &state,
                      CBlockIndex *pindex);
 
 /** Park a block. */
 bool ParkBlock(const Config &config, CValidationState &state,
                CBlockIndex *pindex);
 
 /** Remove invalidity status from a block and its descendants. */
 bool ResetBlockFailureFlags(CBlockIndex *pindex);
 
 /** Remove parked status from a block and its descendants. */
 bool UnparkBlockAndChildren(CBlockIndex *pindex);
 
 /** Remove parked status from a block. */
 bool UnparkBlock(CBlockIndex *pindex);
 
 /**
  * Retrieve the topmost finalized block.
  */
 const CBlockIndex *GetFinalizedBlock();
 
 /**
  * Checks if a block is finalized.
  */
 bool IsBlockFinalized(const CBlockIndex *pindex);
 
 /** The currently-connected chain of blocks (protected by cs_main). */
 extern CChain &chainActive;
 
 /**
  * Global variable that points to the coins database (protected by cs_main)
  */
 extern std::unique_ptr<CCoinsViewDB> pcoinsdbview;
 
 /**
  * Global variable that points to the active CCoinsView (protected by cs_main)
  */
 extern std::unique_ptr<CCoinsViewCache> pcoinsTip;
 
 /**
  * Global variable that points to the active block tree (protected by cs_main)
  */
 extern std::unique_ptr<CBlockTreeDB> pblocktree;
 
 /**
  * Return the spend height, which is one more than the inputs.GetBestBlock().
  * While checking, GetBestBlock() refers to the parent block. (protected by
  * cs_main)
  * This is also true for mempool checks.
  */
 int GetSpendHeight(const CCoinsViewCache &inputs);
 
 /**
  * Determine what nVersion a new block should use.
  */
 int32_t ComputeBlockVersion(const CBlockIndex *pindexPrev,
                             const Consensus::Params &params);
 
 /**
  * Reject codes greater or equal to this can be returned by AcceptToMemPool or
  * AcceptBlock for blocks/transactions, to signal internal conditions. They
  * cannot and should not be sent over the P2P network.
  */
 static const unsigned int REJECT_INTERNAL = 0x100;
 /** Too high fee. Can not be triggered by P2P transactions */
 static const unsigned int REJECT_HIGHFEE = 0x100;
 /** Block conflicts with a transaction already known */
 static const unsigned int REJECT_AGAINST_FINALIZED = 0x103;
 
 /** Get block file info entry for one block file */
 CBlockFileInfo *GetBlockFileInfo(size_t n);
 
 /** Dump the mempool to disk. */
 bool DumpMempool();
 
 /** Load the mempool from disk. */
 bool LoadMempool(const Config &config);
 
 #endif // BITCOIN_VALIDATION_H