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	diff --git a/src/validation.cpp b/src/validation.cpp
	index 1e57376e6b..6f751107e0 100644
	--- a/src/validation.cpp
	+++ b/src/validation.cpp
	@@ -1,7181 +1,7189 @@
	// Copyright (c) 2009-2010 Satoshi Nakamoto
	// Copyright (c) 2009-2018 The Bitcoin Core developers
	// Copyright (c) 2017-2020 The Bitcoin developers
	// Distributed under the MIT software license, see the accompanying
	// file COPYING or http://www.opensource.org/licenses/mit-license.php.

	#include <validation.h>

	#include <kernel/chainparams.h>
	#include <kernel/coinstats.h>
	#include <kernel/disconnected_transactions.h>
	#include <kernel/mempool_entry.h>
	#include <kernel/mempool_persist.h>

	#include <arith_uint256.h>
	#include <avalanche/avalanche.h>
	#include <avalanche/processor.h>
	#include <blockvalidity.h>
	#include <chainparams.h>
	#include <checkpoints.h>
	#include <checkqueue.h>
	#include <common/args.h>
	#include <config.h>
	#include <consensus/activation.h>
	#include <consensus/amount.h>
	#include <consensus/merkle.h>
	#include <consensus/tx_check.h>
	#include <consensus/tx_verify.h>
	#include <consensus/validation.h>
	#include <hash.h>
	#include <kernel/notifications_interface.h>
	#include <logging.h>
	#include <logging/timer.h>
	#include <minerfund.h>
	#include <node/blockstorage.h>
	#include <node/utxo_snapshot.h>
	#include <policy/block/minerfund.h>
	#include <policy/block/preconsensus.h>
	#include <policy/block/rtt.h>
	#include <policy/block/stakingrewards.h>
	#include <policy/policy.h>
	#include <policy/settings.h>
	#include <pow/pow.h>
	#include <primitives/block.h>
	#include <primitives/transaction.h>
	#include <random.h>
	#include <reverse_iterator.h>
	#include <script/script.h>
	#include <script/scriptcache.h>
	#include <script/sigcache.h>
	#include <shutdown.h>
	#include <tinyformat.h>
	#include <txdb.h>
	#include <txmempool.h>
	#include <undo.h>
	#include <util/check.h> // For NDEBUG compile time check
	#include <util/fs.h>
	#include <util/fs_helpers.h>
	#include <util/strencodings.h>
	#include <util/string.h>
	#include <util/time.h>
	#include <util/trace.h>
	#include <util/translation.h>
	#include <validationinterface.h>
	#include <warnings.h>

	#include <algorithm>
	#include <atomic>
	#include <cassert>
	#include <chrono>
	#include <deque>
	#include <numeric>
	#include <optional>
	#include <string>
	#include <thread>

	using kernel::CCoinsStats;
	using kernel::CoinStatsHashType;
	using kernel::ComputeUTXOStats;
	using kernel::LoadMempool;
	using kernel::Notifications;

	using fsbridge::FopenFn;
	using node::BLOCKFILE_CHUNK_SIZE;
	using node::BlockManager;
	using node::BlockMap;
	using node::fReindex;
	using node::SnapshotMetadata;
	using node::UNDOFILE_CHUNK_SIZE;

	#define MICRO 0.000001
	#define MILLI 0.001

	/** Time to wait between writing blocks/block index to disk. */
	static constexpr std::chrono::hours DATABASE_WRITE_INTERVAL{1};
	/** Time to wait between flushing chainstate to disk. */
	static constexpr std::chrono::hours DATABASE_FLUSH_INTERVAL{24};
	const std::vector<std::string> CHECKLEVEL_DOC{
	"level 0 reads the blocks from disk",
	"level 1 verifies block validity",
	"level 2 verifies undo data",
	"level 3 checks disconnection of tip blocks",
	"level 4 tries to reconnect the blocks",
	"each level includes the checks of the previous levels",
	};
	/**
	* The number of blocks to keep below the deepest prune lock.
	* There is nothing special about this number. It is higher than what we
	* expect to see in regular mainnet reorgs, but not so high that it would
	* noticeably interfere with the pruning mechanism.
	* */
	static constexpr int PRUNE_LOCK_BUFFER{10};

	static constexpr uint64_t HEADERS_TIME_VERSION{1};

	GlobalMutex g_best_block_mutex;
	std::condition_variable g_best_block_cv;
	const CBlockIndex *g_best_block;

	BlockValidationOptions::BlockValidationOptions(const Config &config)
	: excessiveBlockSize(config.GetMaxBlockSize()), checkPoW(true),
	checkMerkleRoot(true) {}

	const CBlockIndex *
	Chainstate::FindForkInGlobalIndex(const CBlockLocator &locator) const {
	AssertLockHeld(cs_main);

	// Find the latest block common to locator and chain - we expect that
	// locator.vHave is sorted descending by height.
	for (const BlockHash &hash : locator.vHave) {
	const CBlockIndex *pindex{m_blockman.LookupBlockIndex(hash)};
	if (pindex) {
	if (m_chain.Contains(pindex)) {
	return pindex;
	}
	if (pindex->GetAncestor(m_chain.Height()) == m_chain.Tip()) {
	return m_chain.Tip();
	}
	}
	}
	return m_chain.Genesis();
	}

	static uint32_t GetNextBlockScriptFlags(const CBlockIndex *pindex,
	const ChainstateManager &chainman);

	namespace {
	/**
	* A helper which calculates heights of inputs of a given transaction.
	*
	* @param[in] tip The current chain tip. If an input belongs to a mempool
	* transaction, we assume it will be confirmed in the next
	* block.
	* @param[in] coins Any CCoinsView that provides access to the relevant coins.
	* @param[in] tx The transaction being evaluated.
	*
	* @returns A vector of input heights or nullopt, in case of an error.
	*/
	std::optional<std::vector<int>> CalculatePrevHeights(const CBlockIndex &tip,
	const CCoinsView &coins,
	const CTransaction &tx) {
	std::vector<int> prev_heights;
	prev_heights.resize(tx.vin.size());
	for (size_t i = 0; i < tx.vin.size(); ++i) {
	const CTxIn &txin = tx.vin[i];
	Coin coin;
	if (!coins.GetCoin(txin.prevout, coin)) {
	LogPrintf("ERROR: %s: Missing input %d in transaction \'%s\'\n",
	__func__, i, tx.GetId().GetHex());
	return std::nullopt;
	}
	if (coin.GetHeight() == MEMPOOL_HEIGHT) {
	// Assume all mempool transaction confirm in the next block.
	prev_heights[i] = tip.nHeight + 1;
	} else {
	prev_heights[i] = coin.GetHeight();
	}
	}
	return prev_heights;
	}
	} // namespace

	std::optional<LockPoints> CalculateLockPointsAtTip(CBlockIndex *tip,
	const CCoinsView &coins_view,
	const CTransaction &tx) {
	assert(tip);

	auto prev_heights{CalculatePrevHeights(*tip, coins_view, tx)};
	if (!prev_heights.has_value()) {
	return std::nullopt;
	}

	CBlockIndex next_tip;
	next_tip.pprev = tip;
	// 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
	// active_chainstate.m_chain.Height()
	next_tip.nHeight = tip->nHeight + 1;
	const auto [min_height, min_time] = CalculateSequenceLocks(
	tx, STANDARD_LOCKTIME_VERIFY_FLAGS, prev_heights.value(), next_tip);

	return LockPoints{min_height, min_time};
	}

	bool CheckSequenceLocksAtTip(CBlockIndex *tip, const LockPoints &lock_points) {
	assert(tip != nullptr);

	CBlockIndex index;
	index.pprev = tip;
	// CheckSequenceLocksAtTip() uses active_chainstate.m_chain.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 active_chainstate.m_chain.Height()
	index.nHeight = tip->nHeight + 1;

	return EvaluateSequenceLocks(index, {lock_points.height, lock_points.time});
	}

	// Command-line argument "-replayprotectionactivationtime=<timestamp>" will
	// cause the node to switch to replay protected SigHash ForkID value when the
	// median timestamp of the previous 11 blocks is greater than or equal to
	// <timestamp>. Defaults to the pre-defined timestamp when not set.
	static bool IsReplayProtectionEnabled(const Consensus::Params &params,
	int64_t nMedianTimePast) {
	return nMedianTimePast >= gArgs.GetIntArg("-replayprotectionactivationtime",
	params.shibusawaActivationTime);
	}

	static bool IsReplayProtectionEnabled(const Consensus::Params &params,
	const CBlockIndex *pindexPrev) {
	if (pindexPrev == nullptr) {
	return false;
	}

	return IsReplayProtectionEnabled(params, pindexPrev->GetMedianTimePast());
	}

	/**
	* Checks to avoid mempool polluting consensus critical paths since cached
	* signature and script validity results will be reused if we validate this
	* transaction again during block validation.
	*/
	static bool CheckInputsFromMempoolAndCache(
	const CTransaction &tx, TxValidationState &state,
	const CCoinsViewCache &view, const CTxMemPool &pool, const uint32_t flags,
	PrecomputedTransactionData &txdata, int &nSigChecksOut,
	CCoinsViewCache &coins_tip) EXCLUSIVE_LOCKS_REQUIRED(cs_main, pool.cs) {
	AssertLockHeld(cs_main);
	AssertLockHeld(pool.cs);

	assert(!tx.IsCoinBase());
	for (const CTxIn &txin : tx.vin) {
	const Coin &coin = view.AccessCoin(txin.prevout);

	// This coin was checked in PreChecks and MemPoolAccept
	// has been holding cs_main since then.
	Assume(!coin.IsSpent());
	if (coin.IsSpent()) {
	return false;
	}

	// If the Coin is available, there are 2 possibilities:
	// it is available in our current ChainstateActive UTXO set,
	// or it's a UTXO provided by a transaction in our mempool.
	// Ensure the scriptPubKeys in Coins from CoinsView are correct.
	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 &coinFromUTXOSet = coins_tip.AccessCoin(txin.prevout);
	assert(!coinFromUTXOSet.IsSpent());
	assert(coinFromUTXOSet.GetTxOut() == coin.GetTxOut());
	}
	}

	// Call CheckInputScripts() to cache signature and script validity against
	// current tip consensus rules.
	return CheckInputScripts(tx, state, view, flags, /sigCacheStore=/true,
	/scriptCacheStore=/true, txdata, nSigChecksOut);
	}

	namespace {

	class MemPoolAccept {
	public:
	MemPoolAccept(CTxMemPool &mempool, Chainstate &active_chainstate)
	: m_pool(mempool), m_view(&m_dummy),
	m_viewmempool(&active_chainstate.CoinsTip(), m_pool),
	m_active_chainstate(active_chainstate) {}

	// We put the arguments we're handed into a struct, so we can pass them
	// around easier.
	struct ATMPArgs {
	const Config &m_config;
	const int64_t m_accept_time;
	const bool m_bypass_limits;
	/*
	* Return any outpoints which were not previously present in the coins
	* cache, but were added as a result of validating the tx for mempool
	* acceptance. This allows the caller to optionally remove the cache
	* additions if the associated transaction ends up being rejected by
	* the mempool.
	*/
	std::vector<COutPoint> &m_coins_to_uncache;
	const bool m_test_accept;
	const unsigned int m_heightOverride;
	/**
	* When true, the mempool will not be trimmed when any transactions are
	* submitted in Finalize(). Instead, limits should be enforced at the
	* end to ensure the package is not partially submitted.
	*/
	const bool m_package_submission;
	/**
	* When true, use package feerates instead of individual transaction
	* feerates for fee-based policies such as mempool min fee and min relay
	* fee.
	*/
	const bool m_package_feerates;

	/** Parameters for single transaction mempool validation. */
	static ATMPArgs SingleAccept(const Config &config, int64_t accept_time,
	bool bypass_limits,
	std::vector<COutPoint> &coins_to_uncache,
	bool test_accept,
	unsigned int heightOverride) {
	return ATMPArgs{
	config,
	accept_time,
	bypass_limits,
	coins_to_uncache,
	test_accept,
	heightOverride,
	/package_submission=/false,
	/package_feerates=/false,
	};
	}

	/**
	* Parameters for test package mempool validation through
	* testmempoolaccept.
	*/
	static ATMPArgs
	PackageTestAccept(const Config &config, int64_t accept_time,
	std::vector<COutPoint> &coins_to_uncache) {
	return ATMPArgs{
	config,
	accept_time,
	/bypass_limits=/false,
	coins_to_uncache,
	/test_accept=/true,
	/height_override=/0,
	// not submitting to mempool
	/package_submission=/false,
	/package_feerates=/false,
	};
	}

	/** Parameters for child-with-unconfirmed-parents package validation. */
	static ATMPArgs
	PackageChildWithParents(const Config &config, int64_t accept_time,
	std::vector<COutPoint> &coins_to_uncache) {
	return ATMPArgs{
	config,
	accept_time,
	/bypass_limits=/false,
	coins_to_uncache,
	/test_accept=/false,
	/height_override=/0,
	/package_submission=/true,
	/package_feerates=/true,
	};
	}

	/** Parameters for a single transaction within a package. */
	static ATMPArgs SingleInPackageAccept(const ATMPArgs &package_args) {
	return ATMPArgs{
	/config=/package_args.m_config,
	/accept_time=/package_args.m_accept_time,
	/bypass_limits=/false,
	/coins_to_uncache=/package_args.m_coins_to_uncache,
	/test_accept=/package_args.m_test_accept,
	/height_override=/package_args.m_heightOverride,
	// do not LimitMempoolSize in Finalize()
	/package_submission=/true,
	// only 1 transaction
	/package_feerates=/false,
	};
	}

	private:
	// Private ctor to avoid exposing details to clients and allowing the
	// possibility of mixing up the order of the arguments. Use static
	// functions above instead.
	ATMPArgs(const Config &config, int64_t accept_time, bool bypass_limits,
	std::vector<COutPoint> &coins_to_uncache, bool test_accept,
	unsigned int height_override, bool package_submission,
	bool package_feerates)
	: m_config{config}, m_accept_time{accept_time},
	m_bypass_limits{bypass_limits},
	m_coins_to_uncache{coins_to_uncache}, m_test_accept{test_accept},
	m_heightOverride{height_override},
	m_package_submission{package_submission},
	m_package_feerates(package_feerates) {}
	};

	// Single transaction acceptance
	MempoolAcceptResult AcceptSingleTransaction(const CTransactionRef &ptx,
	ATMPArgs &args)
	EXCLUSIVE_LOCKS_REQUIRED(cs_main);

	/**
	* Multiple transaction acceptance. Transactions may or may not be
	* interdependent, but must not conflict with each other, and the
	* transactions cannot already be in the mempool. Parents must come
	* before children if any dependencies exist.
	*/
	PackageMempoolAcceptResult
	AcceptMultipleTransactions(const std::vector<CTransactionRef> &txns,
	ATMPArgs &args)
	EXCLUSIVE_LOCKS_REQUIRED(cs_main);

	/**
	* Submission of a subpackage.
	* If subpackage size == 1, calls AcceptSingleTransaction() with adjusted
	* ATMPArgs to avoid package policy restrictions like no CPFP carve out
	* (PackageMempoolChecks), and creates a PackageMempoolAcceptResult wrapping
	* the result.
	*
	* If subpackage size > 1, calls AcceptMultipleTransactions() with the
	* provided ATMPArgs.
	*
	* Also cleans up all non-chainstate coins from m_view at the end.
	*/
	PackageMempoolAcceptResult
	AcceptSubPackage(const std::vector<CTransactionRef> &subpackage,
	ATMPArgs &args)
	EXCLUSIVE_LOCKS_REQUIRED(cs_main, m_pool.cs);

	/**
	* Package (more specific than just multiple transactions) acceptance.
	* Package must be a child with all of its unconfirmed parents, and
	* topologically sorted.
	*/
	PackageMempoolAcceptResult AcceptPackage(const Package &package,
	ATMPArgs &args)
	EXCLUSIVE_LOCKS_REQUIRED(cs_main);

	private:
	// All the intermediate state that gets passed between the various levels
	// of checking a given transaction.
	struct Workspace {
	Workspace(const CTransactionRef &ptx,
	const uint32_t next_block_script_verify_flags)
	: m_ptx(ptx),
	m_next_block_script_verify_flags(next_block_script_verify_flags) {
	}
	/**
	* Mempool entry constructed for this transaction.
	* Constructed in PreChecks() but not inserted into the mempool until
	* Finalize().
	*/
	std::unique_ptr<CTxMemPoolEntry> m_entry;

	/**
	* Virtual size of the transaction as used by the mempool, calculated
	* using serialized size of the transaction and sigchecks.
	*/
	int64_t m_vsize;
	/**
	* Fees paid by this transaction: total input amounts subtracted by
	* total output amounts.
	*/
	Amount m_base_fees;

	/**
	* Base fees + any fee delta set by the user with
	* prioritisetransaction.
	*/
	Amount m_modified_fees;

	/**
	* If we're doing package validation (i.e. m_package_feerates=true), the
	* "effective" package feerate of this transaction is the total fees
	* divided by the total size of transactions (which may include its
	* ancestors and/or descendants).
	*/
	CFeeRate m_package_feerate{Amount::zero()};

	const CTransactionRef &m_ptx;
	TxValidationState m_state;
	/**
	* A temporary cache containing serialized transaction data for
	* signature verification.
	* Reused across PreChecks and ConsensusScriptChecks.
	*/
	PrecomputedTransactionData m_precomputed_txdata;

	// ABC specific flags that are used in both PreChecks and
	// ConsensusScriptChecks
	const uint32_t m_next_block_script_verify_flags;
	int m_sig_checks_standard;
	};

	// Run the policy checks on a given transaction, excluding any script
	// checks. Looks up inputs, calculates feerate, considers replacement,
	// evaluates package limits, etc. As this function can be invoked for "free"
	// by a peer, only tests that are fast should be done here (to avoid CPU
	// DoS).
	bool PreChecks(ATMPArgs &args, Workspace &ws)
	EXCLUSIVE_LOCKS_REQUIRED(cs_main, m_pool.cs);

	// Re-run the script checks, using consensus flags, and try to cache the
	// result in the scriptcache. This should be done after
	// PolicyScriptChecks(). This requires that all inputs either be in our
	// utxo set or in the mempool.
	bool ConsensusScriptChecks(const ATMPArgs &args, Workspace &ws)
	EXCLUSIVE_LOCKS_REQUIRED(cs_main, m_pool.cs);

	// Try to add the transaction to the mempool, removing any conflicts first.
	// Returns true if the transaction is in the mempool after any size
	// limiting is performed, false otherwise.
	bool Finalize(const ATMPArgs &args, Workspace &ws)
	EXCLUSIVE_LOCKS_REQUIRED(cs_main, m_pool.cs);

	// Submit all transactions to the mempool and call ConsensusScriptChecks to
	// add to the script cache - should only be called after successful
	// validation of all transactions in the package.
	// Does not call LimitMempoolSize(), so mempool max_size_bytes may be
	// temporarily exceeded.
	bool SubmitPackage(const ATMPArgs &args, std::vector<Workspace> &workspaces,
	PackageValidationState &package_state,
	std::map<TxId, MempoolAcceptResult> &results)
	EXCLUSIVE_LOCKS_REQUIRED(cs_main, m_pool.cs);

	// Compare a package's feerate against minimum allowed.
	bool CheckFeeRate(size_t package_size, size_t package_vsize,
	Amount package_fee, TxValidationState &state)
	EXCLUSIVE_LOCKS_REQUIRED(::cs_main, m_pool.cs) {
	AssertLockHeld(::cs_main);
	AssertLockHeld(m_pool.cs);

	const Amount mempoolRejectFee =
	m_pool.GetMinFee().GetFee(package_vsize);

	if (mempoolRejectFee > Amount::zero() &&
	package_fee < mempoolRejectFee) {
	return state.Invalid(
	TxValidationResult::TX_PACKAGE_RECONSIDERABLE,
	"mempool min fee not met",
	strprintf("%d < %d", package_fee, mempoolRejectFee));
	}

	// Do not change this to use virtualsize without coordinating a network
	// policy upgrade.
	if (package_fee < m_pool.m_min_relay_feerate.GetFee(package_size)) {
	return state.Invalid(
	TxValidationResult::TX_PACKAGE_RECONSIDERABLE,
	"min relay fee not met",
	strprintf("%d < %d", package_fee,
	m_pool.m_min_relay_feerate.GetFee(package_size)));
	}

	return true;
	}

	private:
	CTxMemPool &m_pool;
	CCoinsViewCache m_view;
	CCoinsViewMemPool m_viewmempool;
	CCoinsView m_dummy;

	Chainstate &m_active_chainstate;
	};

	bool MemPoolAccept::PreChecks(ATMPArgs &args, Workspace &ws) {
	AssertLockHeld(cs_main);
	AssertLockHeld(m_pool.cs);
	const CTransactionRef &ptx = ws.m_ptx;
	const CTransaction &tx = *ws.m_ptx;
	const TxId &txid = ws.m_ptx->GetId();

	// Copy/alias what we need out of args
	const int64_t nAcceptTime = args.m_accept_time;
	const bool bypass_limits = args.m_bypass_limits;
	std::vector<COutPoint> &coins_to_uncache = args.m_coins_to_uncache;
	const unsigned int heightOverride = args.m_heightOverride;

	// Alias what we need out of ws
	TxValidationState &state = ws.m_state;
	// Coinbase is only valid in a block, not as a loose transaction.
	if (!CheckRegularTransaction(tx, state)) {
	// state filled in by CheckRegularTransaction.
	return false;
	}

	// Rather not work on nonstandard transactions (unless -testnet)
	std::string reason;
	if (m_pool.m_require_standard &&
	!IsStandardTx(tx, m_pool.m_max_datacarrier_bytes,
	m_pool.m_permit_bare_multisig,
	m_pool.m_dust_relay_feerate, reason)) {
	return state.Invalid(TxValidationResult::TX_NOT_STANDARD, reason);
	}

	// Only accept nLockTime-using transactions that can be mined in the next
	// block; we don't want our mempool filled up with transactions that can't
	// be mined yet.
	TxValidationState ctxState;
	if (!ContextualCheckTransactionForCurrentBlock(
	*Assert(m_active_chainstate.m_chain.Tip()),
	args.m_config.GetChainParams().GetConsensus(), tx, ctxState)) {
	// We copy the state from a dummy to ensure we don't increase the
	// ban score of peer for transaction that could be valid in the future.
	return state.Invalid(TxValidationResult::TX_PREMATURE_SPEND,
	ctxState.GetRejectReason(),
	ctxState.GetDebugMessage());
	}

	// Is it already in the memory pool?
	if (m_pool.exists(txid)) {
	return state.Invalid(TxValidationResult::TX_DUPLICATE,
	"txn-already-in-mempool");
	}

	// Check for conflicts with in-memory transactions
	for (const CTxIn &txin : tx.vin) {
	if (const auto ptxConflicting = m_pool.GetConflictTx(txin.prevout)) {
	if (m_pool.isAvalancheFinalized(ptxConflicting->GetId())) {
	return state.Invalid(TxValidationResult::TX_CONFLICT,
	"finalized-tx-conflict");
	}

	return state.Invalid(
	TxValidationResult::TX_AVALANCHE_RECONSIDERABLE,
	"txn-mempool-conflict");
	}
	}

	m_view.SetBackend(m_viewmempool);

	const CCoinsViewCache &coins_cache = m_active_chainstate.CoinsTip();
	// Do all inputs exist?
	for (const CTxIn &txin : tx.vin) {
	if (!coins_cache.HaveCoinInCache(txin.prevout)) {
	coins_to_uncache.push_back(txin.prevout);
	}

	// Note: this call may add txin.prevout to the coins cache
	// (coins_cache.cacheCoins) by way of FetchCoin(). It should be
	// removed later (via coins_to_uncache) if this tx turns out to be
	// invalid.
	if (!m_view.HaveCoin(txin.prevout)) {
	// Are inputs missing because we already have the tx?
	for (size_t out = 0; out < tx.vout.size(); out++) {
	// Optimistically just do efficient check of cache for
	// outputs.
	if (coins_cache.HaveCoinInCache(COutPoint(txid, out))) {
	return state.Invalid(TxValidationResult::TX_DUPLICATE,
	"txn-already-known");
	}
	}

	// Otherwise assume this might be an orphan tx for which we just
	// haven't seen parents yet.
	return state.Invalid(TxValidationResult::TX_MISSING_INPUTS,
	"bad-txns-inputs-missingorspent");
	}
	}

	// Are the actual inputs available?
	if (!m_view.HaveInputs(tx)) {
	return state.Invalid(TxValidationResult::TX_MEMPOOL_POLICY,
	"bad-txns-inputs-spent");
	}

	// Bring the best block into scope.
	m_view.GetBestBlock();

	// we have all inputs cached now, so switch back to dummy (to protect
	// against bugs where we pull more inputs from disk that miss being
	// added to coins_to_uncache)
	m_view.SetBackend(m_dummy);

	assert(m_active_chainstate.m_blockman.LookupBlockIndex(
	m_view.GetBestBlock()) == m_active_chainstate.m_chain.Tip());

	// 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.
	// Pass in m_view which has all of the relevant inputs cached. Note that,
	// since m_view's backend was removed, it no longer pulls coins from the
	// mempool.
	const std::optional<LockPoints> lock_points{CalculateLockPointsAtTip(
	m_active_chainstate.m_chain.Tip(), m_view, tx)};
	if (!lock_points.has_value() \|\|
	!CheckSequenceLocksAtTip(m_active_chainstate.m_chain.Tip(),
	*lock_points)) {
	return state.Invalid(TxValidationResult::TX_PREMATURE_SPEND,
	"non-BIP68-final");
	}

	// The mempool holds txs for the next block, so pass height+1 to
	// CheckTxInputs
	if (!Consensus::CheckTxInputs(tx, state, m_view,
	m_active_chainstate.m_chain.Height() + 1,
	ws.m_base_fees)) {
	// state filled in by CheckTxInputs
	return false;
	}

	// Check for non-standard pay-to-script-hash in inputs
	if (m_pool.m_require_standard &&
	!AreInputsStandard(tx, m_view, ws.m_next_block_script_verify_flags)) {
	return state.Invalid(TxValidationResult::TX_INPUTS_NOT_STANDARD,
	"bad-txns-nonstandard-inputs");
	}

	// ws.m_modified_fess includes any fee deltas from PrioritiseTransaction
	ws.m_modified_fees = ws.m_base_fees;
	m_pool.ApplyDelta(txid, ws.m_modified_fees);

	unsigned int nSize = tx.GetTotalSize();

	// Validate input scripts against standard script flags.
	const uint32_t scriptVerifyFlags =
	ws.m_next_block_script_verify_flags \| STANDARD_SCRIPT_VERIFY_FLAGS;
	ws.m_precomputed_txdata = PrecomputedTransactionData{tx};
	if (!CheckInputScripts(tx, state, m_view, scriptVerifyFlags, true, false,
	ws.m_precomputed_txdata, ws.m_sig_checks_standard)) {
	// State filled in by CheckInputScripts
	return false;
	}

	ws.m_entry = std::make_unique<CTxMemPoolEntry>(
	ptx, ws.m_base_fees, nAcceptTime,
	heightOverride ? heightOverride : m_active_chainstate.m_chain.Height(),
	ws.m_sig_checks_standard, lock_points.value());

	ws.m_vsize = ws.m_entry->GetTxVirtualSize();

	// No individual transactions are allowed below the min relay feerate except
	// from disconnected blocks. This requirement, unlike CheckFeeRate, cannot
	// be bypassed using m_package_feerates because, while a tx could be package
	// CPFP'd when entering the mempool, we do not have a DoS-resistant method
	// of ensuring the tx remains bumped. For example, the fee-bumping child
	// could disappear due to a replacement.
	if (!bypass_limits &&
	ws.m_modified_fees <
	m_pool.m_min_relay_feerate.GetFee(ws.m_ptx->GetTotalSize())) {
	// Even though this is a fee-related failure, this result is
	// TX_MEMPOOL_POLICY, not TX_PACKAGE_RECONSIDERABLE, because it cannot
	// be bypassed using package validation.
	return state.Invalid(
	TxValidationResult::TX_MEMPOOL_POLICY, "min relay fee not met",
	strprintf("%d < %d", ws.m_modified_fees,
	m_pool.m_min_relay_feerate.GetFee(nSize)));
	}
	// No individual transactions are allowed below the mempool min feerate
	// except from disconnected blocks and transactions in a package. Package
	// transactions will be checked using package feerate later.
	if (!bypass_limits && !args.m_package_feerates &&
	!CheckFeeRate(nSize, ws.m_vsize, ws.m_modified_fees, state)) {
	return false;
	}

	return true;
	}

	bool MemPoolAccept::ConsensusScriptChecks(const ATMPArgs &args, Workspace &ws) {
	AssertLockHeld(cs_main);
	AssertLockHeld(m_pool.cs);
	const CTransaction &tx = *ws.m_ptx;
	const TxId &txid = tx.GetId();
	TxValidationState &state = ws.m_state;

	// Check again against the next block's script verification flags
	// to cache our script execution flags.
	//
	// This is also useful in case of bugs in the standard flags that cause
	// transactions to pass as valid when they're actually invalid. For
	// instance the STRICTENC flag was incorrectly allowing certain CHECKSIG
	// NOT scripts to pass, even though they were invalid.
	//
	// There is a similar check in CreateNewBlock() to prevent creating
	// invalid blocks (using TestBlockValidity), however allowing such
	// transactions into the mempool can be exploited as a DoS attack.
	int nSigChecksConsensus;
	if (!CheckInputsFromMempoolAndCache(
	tx, state, m_view, m_pool, ws.m_next_block_script_verify_flags,
	ws.m_precomputed_txdata, nSigChecksConsensus,
	m_active_chainstate.CoinsTip())) {
	// This can occur under some circumstances, if the node receives an
	// unrequested tx which is invalid due to new consensus rules not
	// being activated yet (during IBD).
	LogPrintf("BUG! PLEASE REPORT THIS! CheckInputScripts failed against "
	"latest-block but not STANDARD flags %s, %s\n",
	txid.ToString(), state.ToString());
	return Assume(false);
	}

	if (ws.m_sig_checks_standard != nSigChecksConsensus) {
	// We can't accept this transaction as we've used the standard count
	// for the mempool/mining, but the consensus count will be enforced
	// in validation (we don't want to produce bad block templates).
	return error(
	"%s: BUG! PLEASE REPORT THIS! SigChecks count differed between "
	"standard and consensus flags in %s",
	__func__, txid.ToString());
	}
	return true;
	}

	// Get the coins spent by ptx from the coins_view. Assumes coins are present.
	static std::vector<Coin> getSpentCoins(const CTransactionRef &ptx,
	const CCoinsViewCache &coins_view) {
	std::vector<Coin> spent_coins;
	spent_coins.reserve(ptx->vin.size());
	for (const CTxIn &input : ptx->vin) {
	Coin coin;
	const bool coinFound = coins_view.GetCoin(input.prevout, coin);
	Assume(coinFound);
	spent_coins.push_back(std::move(coin));
	}
	return spent_coins;
	}

	bool MemPoolAccept::Finalize(const ATMPArgs &args, Workspace &ws) {
	AssertLockHeld(cs_main);
	AssertLockHeld(m_pool.cs);
	const TxId &txid = ws.m_ptx->GetId();
	TxValidationState &state = ws.m_state;
	const bool bypass_limits = args.m_bypass_limits;

	// Store transaction in memory
	CTxMemPoolEntry *pentry = ws.m_entry.release();
	auto entry = CTxMemPoolEntryRef::acquire(pentry);
	m_pool.addUnchecked(entry);

	GetMainSignals().TransactionAddedToMempool(
	ws.m_ptx,
	std::make_shared<const std::vector<Coin>>(
	getSpentCoins(ws.m_ptx, m_view)),
	m_pool.GetAndIncrementSequence());

	// Trim mempool and check if tx was trimmed.
	// If we are validating a package, don't trim here because we could evict a
	// previous transaction in the package. LimitMempoolSize() should be called
	// at the very end to make sure the mempool is still within limits and
	// package submission happens atomically.
	if (!args.m_package_submission && !bypass_limits) {
	m_pool.LimitSize(m_active_chainstate.CoinsTip());
	if (!m_pool.exists(txid)) {
	// The tx no longer meets our (new) mempool minimum feerate but
	// could be reconsidered in a package.
	return state.Invalid(TxValidationResult::TX_PACKAGE_RECONSIDERABLE,
	"mempool full");
	}
	}
	return true;
	}

	bool MemPoolAccept::SubmitPackage(
	const ATMPArgs &args, std::vector<Workspace> &workspaces,
	PackageValidationState &package_state,
	std::map<TxId, MempoolAcceptResult> &results) {
	AssertLockHeld(cs_main);
	AssertLockHeld(m_pool.cs);
	// Sanity check: none of the transactions should be in the mempool.
	assert(std::all_of(
	workspaces.cbegin(), workspaces.cend(),
	[this](const auto &ws) { return !m_pool.exists(ws.m_ptx->GetId()); }));

	bool all_submitted = true;
	// ConsensusScriptChecks adds to the script cache and is therefore
	// consensus-critical; CheckInputsFromMempoolAndCache asserts that
	// transactions only spend coins available from the mempool or UTXO set.
	// Submit each transaction to the mempool immediately after calling
	// ConsensusScriptChecks to make the outputs available for subsequent
	// transactions.
	for (Workspace &ws : workspaces) {
	if (!ConsensusScriptChecks(args, ws)) {
	results.emplace(ws.m_ptx->GetId(),
	MempoolAcceptResult::Failure(ws.m_state));
	// Since PreChecks() passed, this should never fail.
	all_submitted = false;
	package_state.Invalid(
	PackageValidationResult::PCKG_MEMPOOL_ERROR,
	strprintf("BUG! PolicyScriptChecks succeeded but "
	"ConsensusScriptChecks failed: %s",
	ws.m_ptx->GetId().ToString()));
	}

	// If we call LimitMempoolSize() for each individual Finalize(), the
	// mempool will not take the transaction's descendant feerate into
	// account because it hasn't seen them yet. Also, we risk evicting a
	// transaction that a subsequent package transaction depends on.
	// Instead, allow the mempool to temporarily bypass limits, the maximum
	// package size) while submitting transactions individually and then
	// trim at the very end.
	if (!Finalize(args, ws)) {
	results.emplace(ws.m_ptx->GetId(),
	MempoolAcceptResult::Failure(ws.m_state));
	// Since LimitMempoolSize() won't be called, this should never fail.
	all_submitted = false;
	package_state.Invalid(PackageValidationResult::PCKG_MEMPOOL_ERROR,
	strprintf("BUG! Adding to mempool failed: %s",
	ws.m_ptx->GetId().ToString()));
	}
	}

	// It may or may not be the case that all the transactions made it into the
	// mempool. Regardless, make sure we haven't exceeded max mempool size.
	m_pool.LimitSize(m_active_chainstate.CoinsTip());

	std::vector<TxId> all_package_txids;
	all_package_txids.reserve(workspaces.size());
	std::transform(workspaces.cbegin(), workspaces.cend(),
	std::back_inserter(all_package_txids),
	[](const auto &ws) { return ws.m_ptx->GetId(); });

	// Add successful results. The returned results may change later if
	// LimitMempoolSize() evicts them.
	for (Workspace &ws : workspaces) {
	const auto effective_feerate =
	args.m_package_feerates
	? ws.m_package_feerate
	: CFeeRate{ws.m_modified_fees,
	static_cast<uint32_t>(ws.m_vsize)};
	const auto effective_feerate_txids =
	args.m_package_feerates ? all_package_txids
	: std::vector<TxId>({ws.m_ptx->GetId()});
	results.emplace(ws.m_ptx->GetId(),
	MempoolAcceptResult::Success(ws.m_vsize, ws.m_base_fees,
	effective_feerate,
	effective_feerate_txids));
	}
	return all_submitted;
	}

	MempoolAcceptResult
	MemPoolAccept::AcceptSingleTransaction(const CTransactionRef &ptx,
	ATMPArgs &args) {
	AssertLockHeld(cs_main);
	// mempool "read lock" (held through
	// GetMainSignals().TransactionAddedToMempool())
	LOCK(m_pool.cs);

	const CBlockIndex *tip = m_active_chainstate.m_chain.Tip();

	Workspace ws(ptx,
	GetNextBlockScriptFlags(tip, m_active_chainstate.m_chainman));

	const std::vector<TxId> single_txid{ws.m_ptx->GetId()};

	// Perform the inexpensive checks first and avoid hashing and signature
	// verification unless those checks pass, to mitigate CPU exhaustion
	// denial-of-service attacks.
	if (!PreChecks(args, ws)) {
	if (ws.m_state.GetResult() ==
	TxValidationResult::TX_PACKAGE_RECONSIDERABLE) {
	// Failed for fee reasons. Provide the effective feerate and which
	// tx was included.
	return MempoolAcceptResult::FeeFailure(
	ws.m_state, CFeeRate(ws.m_modified_fees, ws.m_vsize),
	single_txid);
	}
	return MempoolAcceptResult::Failure(ws.m_state);
	}

	if (!ConsensusScriptChecks(args, ws)) {
	return MempoolAcceptResult::Failure(ws.m_state);
	}

	const TxId txid = ptx->GetId();

	// Mempool sanity check -- in our new mempool no tx can be added if its
	// outputs are already spent in the mempool (that is, no children before
	// parents allowed; the mempool must be consistent at all times).
	//
	// This means that on reorg, the disconnectpool must always import
	// the existing mempool tx's, clear the mempool, and then re-add
	// remaining tx's in topological order via this function. Our new mempool
	// has fast adds, so this is ok.
	if (auto it = m_pool.mapNextTx.lower_bound(COutPoint{txid, 0});
	it != m_pool.mapNextTx.end() && it->first->GetTxId() == txid) {
	LogPrintf("%s: BUG! PLEASE REPORT THIS! Attempt to add txid %s, but "
	"its outputs are already spent in the "
	"mempool\n",
	__func__, txid.ToString());
	ws.m_state.Invalid(TxValidationResult::TX_CHILD_BEFORE_PARENT,
	"txn-child-before-parent");
	return MempoolAcceptResult::Failure(ws.m_state);
	}

	const CFeeRate effective_feerate{ws.m_modified_fees,
	static_cast<uint32_t>(ws.m_vsize)};
	// Tx was accepted, but not added
	if (args.m_test_accept) {
	return MempoolAcceptResult::Success(ws.m_vsize, ws.m_base_fees,
	effective_feerate, single_txid);
	}

	if (!Finalize(args, ws)) {
	// The only possible failure reason is fee-related (mempool full).
	// Failed for fee reasons. Provide the effective feerate and which txns
	// were included.
	Assume(ws.m_state.GetResult() ==
	TxValidationResult::TX_PACKAGE_RECONSIDERABLE);
	return MempoolAcceptResult::FeeFailure(
	ws.m_state, CFeeRate(ws.m_modified_fees, ws.m_vsize), single_txid);
	}

	return MempoolAcceptResult::Success(ws.m_vsize, ws.m_base_fees,
	effective_feerate, single_txid);
	}

	PackageMempoolAcceptResult MemPoolAccept::AcceptMultipleTransactions(
	const std::vector<CTransactionRef> &txns, ATMPArgs &args) {
	AssertLockHeld(cs_main);

	// These context-free package limits can be done before taking the mempool
	// lock.
	PackageValidationState package_state;
	if (!CheckPackage(txns, package_state)) {
	return PackageMempoolAcceptResult(package_state, {});
	}

	std::vector<Workspace> workspaces{};
	workspaces.reserve(txns.size());
	std::transform(
	txns.cbegin(), txns.cend(), std::back_inserter(workspaces),
	[this](const auto &tx) {
	return Workspace(
	tx, GetNextBlockScriptFlags(m_active_chainstate.m_chain.Tip(),
	m_active_chainstate.m_chainman));
	});
	std::map<TxId, MempoolAcceptResult> results;

	LOCK(m_pool.cs);

	// Do all PreChecks first and fail fast to avoid running expensive script
	// checks when unnecessary.
	std::vector<TxId> valid_txids;
	for (Workspace &ws : workspaces) {
	if (!PreChecks(args, ws)) {
	package_state.Invalid(PackageValidationResult::PCKG_TX,
	"transaction failed");
	// Exit early to avoid doing pointless work. Update the failed tx
	// result; the rest are unfinished.
	results.emplace(ws.m_ptx->GetId(),
	MempoolAcceptResult::Failure(ws.m_state));
	return PackageMempoolAcceptResult(package_state,
	std::move(results));
	}
	// Make the coins created by this transaction available for subsequent
	// transactions in the package to spend.
	m_viewmempool.PackageAddTransaction(ws.m_ptx);
	valid_txids.push_back(ws.m_ptx->GetId());
	}

	// Transactions must meet two minimum feerates: the mempool minimum fee and
	// min relay fee. For transactions consisting of exactly one child and its
	// parents, it suffices to use the package feerate
	// (total modified fees / total size or vsize) to check this requirement.
	// Note that this is an aggregate feerate; this function has not checked
	// that there are transactions too low feerate to pay for themselves, or
	// that the child transactions are higher feerate than their parents. Using
	// aggregate feerate may allow "parents pay for child" behavior and permit
	// a child that is below mempool minimum feerate. To avoid these behaviors,
	// callers of AcceptMultipleTransactions need to restrict txns topology
	// (e.g. to ancestor sets) and check the feerates of individuals and
	// subsets.
	const auto m_total_size = std::accumulate(
	workspaces.cbegin(), workspaces.cend(), int64_t{0},
	[](int64_t sum, auto &ws) { return sum + ws.m_ptx->GetTotalSize(); });
	const auto m_total_vsize =
	std::accumulate(workspaces.cbegin(), workspaces.cend(), int64_t{0},
	[](int64_t sum, auto &ws) { return sum + ws.m_vsize; });
	const auto m_total_modified_fees = std::accumulate(
	workspaces.cbegin(), workspaces.cend(), Amount::zero(),
	[](Amount sum, auto &ws) { return sum + ws.m_modified_fees; });
	const CFeeRate package_feerate(m_total_modified_fees, m_total_vsize);
	std::vector<TxId> all_package_txids;
	all_package_txids.reserve(workspaces.size());
	std::transform(workspaces.cbegin(), workspaces.cend(),
	std::back_inserter(all_package_txids),
	[](const auto &ws) { return ws.m_ptx->GetId(); });
	TxValidationState placeholder_state;
	if (args.m_package_feerates &&
	!CheckFeeRate(m_total_size, m_total_vsize, m_total_modified_fees,
	placeholder_state)) {
	package_state.Invalid(PackageValidationResult::PCKG_TX,
	"transaction failed");
	return PackageMempoolAcceptResult(
	package_state, {{workspaces.back().m_ptx->GetId(),
	MempoolAcceptResult::FeeFailure(
	placeholder_state,
	CFeeRate(m_total_modified_fees, m_total_vsize),
	all_package_txids)}});
	}

	for (Workspace &ws : workspaces) {
	ws.m_package_feerate = package_feerate;
	const TxId &ws_txid = ws.m_ptx->GetId();
	if (args.m_test_accept &&
	std::find(valid_txids.begin(), valid_txids.end(), ws_txid) !=
	valid_txids.end()) {
	const auto effective_feerate =
	args.m_package_feerates
	? ws.m_package_feerate
	: CFeeRate{ws.m_modified_fees,
	static_cast<uint32_t>(ws.m_vsize)};
	const auto effective_feerate_txids =
	args.m_package_feerates ? all_package_txids
	: std::vector<TxId>{ws.m_ptx->GetId()};
	// When test_accept=true, transactions that pass PreChecks
	// are valid because there are no further mempool checks (passing
	// PreChecks implies passing ConsensusScriptChecks).
	results.emplace(ws_txid,
	MempoolAcceptResult::Success(
	ws.m_vsize, ws.m_base_fees, effective_feerate,
	effective_feerate_txids));
	}
	}

	if (args.m_test_accept) {
	return PackageMempoolAcceptResult(package_state, std::move(results));
	}

	if (!SubmitPackage(args, workspaces, package_state, results)) {
	// PackageValidationState filled in by SubmitPackage().
	return PackageMempoolAcceptResult(package_state, std::move(results));
	}

	return PackageMempoolAcceptResult(package_state, std::move(results));
	}

	PackageMempoolAcceptResult
	MemPoolAccept::AcceptSubPackage(const std::vector<CTransactionRef> &subpackage,
	ATMPArgs &args) {
	AssertLockHeld(::cs_main);
	AssertLockHeld(m_pool.cs);

	auto result = [&]() EXCLUSIVE_LOCKS_REQUIRED(::cs_main, m_pool.cs) {
	if (subpackage.size() > 1) {
	return AcceptMultipleTransactions(subpackage, args);
	}
	const auto &tx = subpackage.front();
	ATMPArgs single_args = ATMPArgs::SingleInPackageAccept(args);
	const auto single_res = AcceptSingleTransaction(tx, single_args);
	PackageValidationState package_state_wrapped;
	if (single_res.m_result_type !=
	MempoolAcceptResult::ResultType::VALID) {
	package_state_wrapped.Invalid(PackageValidationResult::PCKG_TX,
	"transaction failed");
	}
	return PackageMempoolAcceptResult(package_state_wrapped,
	{{tx->GetId(), single_res}});
	}();

	// Clean up m_view and m_viewmempool so that other subpackage evaluations
	// don't have access to coins they shouldn't. Keep some coins in order to
	// minimize re-fetching coins from the UTXO set.
	//
	// There are 3 kinds of coins in m_view:
	// (1) Temporary coins from the transactions in subpackage, constructed by
	// m_viewmempool.
	// (2) Mempool coins from transactions in the mempool, constructed by
	// m_viewmempool.
	// (3) Confirmed coins fetched from our current UTXO set.
	//
	// (1) Temporary coins need to be removed, regardless of whether the
	// transaction was submitted. If the transaction was submitted to the
	// mempool, m_viewmempool will be able to fetch them from there. If it
	// wasn't submitted to mempool, it is incorrect to keep them - future calls
	// may try to spend those coins that don't actually exist.
	// (2) Mempool coins also need to be removed. If the mempool contents have
	// changed as a result of submitting or replacing transactions, coins
	// previously fetched from mempool may now be spent or nonexistent. Those
	// coins need to be deleted from m_view.
	// (3) Confirmed coins don't need to be removed. The chainstate has not
	// changed (we are holding cs_main and no blocks have been processed) so the
	// confirmed tx cannot disappear like a mempool tx can. The coin may now be
	// spent after we submitted a tx to mempool, but we have already checked
	// that the package does not have 2 transactions spending the same coin.
	// Keeping them in m_view is an optimization to not re-fetch confirmed coins
	// if we later look up inputs for this transaction again.
	for (const auto &outpoint : m_viewmempool.GetNonBaseCoins()) {
	// In addition to resetting m_viewmempool, we also need to manually
	// delete these coins from m_view because it caches copies of the coins
	// it fetched from m_viewmempool previously.
	m_view.Uncache(outpoint);
	}
	// This deletes the temporary and mempool coins.
	m_viewmempool.Reset();
	return result;
	}

	PackageMempoolAcceptResult MemPoolAccept::AcceptPackage(const Package &package,
	ATMPArgs &args) {
	AssertLockHeld(cs_main);
	// Used if returning a PackageMempoolAcceptResult directly from this
	// function.
	PackageValidationState package_state_quit_early;

	// Check that the package is well-formed. If it isn't, we won't try to
	// validate any of the transactions and thus won't return any
	// MempoolAcceptResults, just a package-wide error.

	// Context-free package checks.
	if (!CheckPackage(package, package_state_quit_early)) {
	return PackageMempoolAcceptResult(package_state_quit_early, {});
	}

	// All transactions in the package must be a parent of the last transaction.
	// This is just an opportunity for us to fail fast on a context-free check
	// without taking the mempool lock.
	if (!IsChildWithParents(package)) {
	package_state_quit_early.Invalid(PackageValidationResult::PCKG_POLICY,
	"package-not-child-with-parents");
	return PackageMempoolAcceptResult(package_state_quit_early, {});
	}

	// IsChildWithParents() guarantees the package is > 1 transactions.
	assert(package.size() > 1);
	// The package must be 1 child with all of its unconfirmed parents. The
	// package is expected to be sorted, so the last transaction is the child.
	const auto &child = package.back();
	std::unordered_set<TxId, SaltedTxIdHasher> unconfirmed_parent_txids;
	std::transform(
	package.cbegin(), package.cend() - 1,
	std::inserter(unconfirmed_parent_txids, unconfirmed_parent_txids.end()),
	[](const auto &tx) { return tx->GetId(); });

	// All child inputs must refer to a preceding package transaction or a
	// confirmed UTXO. The only way to verify this is to look up the child's
	// inputs in our current coins view (not including mempool), and enforce
	// that all parents not present in the package be available at chain tip.
	// Since this check can bring new coins into the coins cache, keep track of
	// these coins and uncache them if we don't end up submitting this package
	// to the mempool.
	const CCoinsViewCache &coins_tip_cache = m_active_chainstate.CoinsTip();
	for (const auto &input : child->vin) {
	if (!coins_tip_cache.HaveCoinInCache(input.prevout)) {
	args.m_coins_to_uncache.push_back(input.prevout);
	}
	}
	// Using the MemPoolAccept m_view cache allows us to look up these same
	// coins faster later. This should be connecting directly to CoinsTip, not
	// to m_viewmempool, because we specifically require inputs to be confirmed
	// if they aren't in the package.
	m_view.SetBackend(m_active_chainstate.CoinsTip());
	const auto package_or_confirmed = [this, &unconfirmed_parent_txids](
	const auto &input) {
	return unconfirmed_parent_txids.count(input.prevout.GetTxId()) > 0 \|\|
	m_view.HaveCoin(input.prevout);
	};
	if (!std::all_of(child->vin.cbegin(), child->vin.cend(),
	package_or_confirmed)) {
	package_state_quit_early.Invalid(
	PackageValidationResult::PCKG_POLICY,
	"package-not-child-with-unconfirmed-parents");
	return PackageMempoolAcceptResult(package_state_quit_early, {});
	}
	// Protect against bugs where we pull more inputs from disk that miss being
	// added to coins_to_uncache. The backend will be connected again when
	// needed in PreChecks.
	m_view.SetBackend(m_dummy);

	LOCK(m_pool.cs);
	// Stores results from which we will create the returned
	// PackageMempoolAcceptResult. A result may be changed if a mempool
	// transaction is evicted later due to LimitMempoolSize().
	std::map<TxId, MempoolAcceptResult> results_final;
	// Results from individual validation which will be returned if no other
	// result is available for this transaction. "Nonfinal" because if a
	// transaction fails by itself but succeeds later (i.e. when evaluated with
	// a fee-bumping child), the result in this map may be discarded.
	std::map<TxId, MempoolAcceptResult> individual_results_nonfinal;
	bool quit_early{false};
	std::vector<CTransactionRef> txns_package_eval;
	for (const auto &tx : package) {
	const auto &txid = tx->GetId();
	// An already confirmed tx is treated as one not in mempool, because all
	// we know is that the inputs aren't available.
	if (m_pool.exists(txid)) {
	// Exact transaction already exists in the mempool.
	// Node operators are free to set their mempool policies however
	// they please, nodes may receive transactions in different orders,
	// and malicious counterparties may try to take advantage of policy
	// differences to pin or delay propagation of transactions. As such,
	// it's possible for some package transaction(s) to already be in
	// the mempool, and we don't want to reject the entire package in
	// that case (as that could be a censorship vector). De-duplicate
	// the transactions that are already in the mempool, and only call
	// AcceptMultipleTransactions() with the new transactions. This
	// ensures we don't double-count transaction counts and sizes when
	// checking ancestor/descendant limits, or double-count transaction
	// fees for fee-related policy.
	auto iter = m_pool.GetIter(txid);
	assert(iter != std::nullopt);
	results_final.emplace(txid, MempoolAcceptResult::MempoolTx(
	(*iter.value())->GetTxSize(),
	(*iter.value())->GetFee()));
	} else {
	// Transaction does not already exist in the mempool.
	// Try submitting the transaction on its own.
	const auto single_package_res = AcceptSubPackage({tx}, args);
	const auto &single_res = single_package_res.m_tx_results.at(txid);
	if (single_res.m_result_type ==
	MempoolAcceptResult::ResultType::VALID) {
	// The transaction succeeded on its own and is now in the
	// mempool. Don't include it in package validation, because its
	// fees should only be "used" once.
	assert(m_pool.exists(txid));
	results_final.emplace(txid, single_res);
	} else if (single_res.m_state.GetResult() !=
	TxValidationResult::TX_PACKAGE_RECONSIDERABLE &&
	single_res.m_state.GetResult() !=
	TxValidationResult::TX_MISSING_INPUTS) {
	// Package validation policy only differs from individual policy
	// in its evaluation of feerate. For example, if a transaction
	// fails here due to violation of a consensus rule, the result
	// will not change when it is submitted as part of a package. To
	// minimize the amount of repeated work, unless the transaction
	// fails due to feerate or missing inputs (its parent is a
	// previous transaction in the package that failed due to
	// feerate), don't run package validation. Note that this
	// decision might not make sense if different types of packages
	// are allowed in the future. Continue individually validating
	// the rest of the transactions, because some of them may still
	// be valid.
	quit_early = true;
	package_state_quit_early.Invalid(
	PackageValidationResult::PCKG_TX, "transaction failed");
	individual_results_nonfinal.emplace(txid, single_res);
	} else {
	individual_results_nonfinal.emplace(txid, single_res);
	txns_package_eval.push_back(tx);
	}
	}
	}

	auto multi_submission_result =
	quit_early \|\| txns_package_eval.empty()
	? PackageMempoolAcceptResult(package_state_quit_early, {})
	: AcceptSubPackage(txns_package_eval, args);
	PackageValidationState &package_state_final =
	multi_submission_result.m_state;

	// Make sure we haven't exceeded max mempool size.
	// Package transactions that were submitted to mempool or already in mempool
	// may be evicted.
	m_pool.LimitSize(m_active_chainstate.CoinsTip());

	for (const auto &tx : package) {
	const auto &txid = tx->GetId();
	if (multi_submission_result.m_tx_results.count(txid) > 0) {
	// We shouldn't have re-submitted if the tx result was already in
	// results_final.
	Assume(results_final.count(txid) == 0);
	// If it was submitted, check to see if the tx is still in the
	// mempool. It could have been evicted due to LimitMempoolSize()
	// above.
	const auto &txresult =
	multi_submission_result.m_tx_results.at(txid);
	if (txresult.m_result_type ==
	MempoolAcceptResult::ResultType::VALID &&
	!m_pool.exists(txid)) {
	package_state_final.Invalid(PackageValidationResult::PCKG_TX,
	"transaction failed");
	TxValidationState mempool_full_state;
	mempool_full_state.Invalid(
	TxValidationResult::TX_MEMPOOL_POLICY, "mempool full");
	results_final.emplace(
	txid, MempoolAcceptResult::Failure(mempool_full_state));
	} else {
	results_final.emplace(txid, txresult);
	}
	} else if (const auto final_it{results_final.find(txid)};
	final_it != results_final.end()) {
	// Already-in-mempool transaction. Check to see if it's still there,
	// as it could have been evicted when LimitMempoolSize() was called.
	Assume(final_it->second.m_result_type !=
	MempoolAcceptResult::ResultType::INVALID);
	Assume(individual_results_nonfinal.count(txid) == 0);
	if (!m_pool.exists(tx->GetId())) {
	package_state_final.Invalid(PackageValidationResult::PCKG_TX,
	"transaction failed");
	TxValidationState mempool_full_state;
	mempool_full_state.Invalid(
	TxValidationResult::TX_MEMPOOL_POLICY, "mempool full");
	// Replace the previous result.
	results_final.erase(txid);
	results_final.emplace(
	txid, MempoolAcceptResult::Failure(mempool_full_state));
	}
	} else if (const auto non_final_it{
	individual_results_nonfinal.find(txid)};
	non_final_it != individual_results_nonfinal.end()) {
	Assume(non_final_it->second.m_result_type ==
	MempoolAcceptResult::ResultType::INVALID);
	// Interesting result from previous processing.
	results_final.emplace(txid, non_final_it->second);
	}
	}
	Assume(results_final.size() == package.size());
	return PackageMempoolAcceptResult(package_state_final,
	std::move(results_final));
	}
	} // namespace

	MempoolAcceptResult AcceptToMemoryPool(Chainstate &active_chainstate,
	const CTransactionRef &tx,
	int64_t accept_time, bool bypass_limits,
	bool test_accept,
	unsigned int heightOverride) {
	AssertLockHeld(::cs_main);
	assert(active_chainstate.GetMempool() != nullptr);
	CTxMemPool &pool{*active_chainstate.GetMempool()};

	std::vector<COutPoint> coins_to_uncache;
	auto args = MemPoolAccept::ATMPArgs::SingleAccept(
	active_chainstate.m_chainman.GetConfig(), accept_time, bypass_limits,
	coins_to_uncache, test_accept, heightOverride);
	const MempoolAcceptResult result = MemPoolAccept(pool, active_chainstate)
	.AcceptSingleTransaction(tx, args);
	if (result.m_result_type != MempoolAcceptResult::ResultType::VALID) {
	// Remove coins that were not present in the coins cache before calling
	// ATMPW; this is to prevent memory DoS in case we receive a large
	// number of invalid transactions that attempt to overrun the in-memory
	// coins cache
	// (`CCoinsViewCache::cacheCoins`).

	for (const COutPoint &outpoint : coins_to_uncache) {
	active_chainstate.CoinsTip().Uncache(outpoint);
	}
	}

	// After we've (potentially) uncached entries, ensure our coins cache is
	// still within its size limits
	BlockValidationState stateDummy;
	active_chainstate.FlushStateToDisk(stateDummy, FlushStateMode::PERIODIC);
	return result;
	}

	PackageMempoolAcceptResult ProcessNewPackage(Chainstate &active_chainstate,
	CTxMemPool &pool,
	const Package &package,
	bool test_accept) {
	AssertLockHeld(cs_main);
	assert(!package.empty());
	assert(std::all_of(package.cbegin(), package.cend(),
	[](const auto &tx) { return tx != nullptr; }));

	const Config &config = active_chainstate.m_chainman.GetConfig();

	std::vector<COutPoint> coins_to_uncache;
	const auto result = [&]() EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
	AssertLockHeld(cs_main);
	if (test_accept) {
	auto args = MemPoolAccept::ATMPArgs::PackageTestAccept(
	config, GetTime(), coins_to_uncache);
	return MemPoolAccept(pool, active_chainstate)
	.AcceptMultipleTransactions(package, args);
	} else {
	auto args = MemPoolAccept::ATMPArgs::PackageChildWithParents(
	config, GetTime(), coins_to_uncache);
	return MemPoolAccept(pool, active_chainstate)
	.AcceptPackage(package, args);
	}
	}();

	// Uncache coins pertaining to transactions that were not submitted to the
	// mempool.
	if (test_accept \|\| result.m_state.IsInvalid()) {
	for (const COutPoint &hashTx : coins_to_uncache) {
	active_chainstate.CoinsTip().Uncache(hashTx);
	}
	}
	// Ensure the coins cache is still within limits.
	BlockValidationState state_dummy;
	active_chainstate.FlushStateToDisk(state_dummy, FlushStateMode::PERIODIC);
	return result;
	}

	Amount GetBlockSubsidy(int nHeight, const Consensus::Params &consensusParams) {
	int halvings = nHeight / consensusParams.nSubsidyHalvingInterval;
	// Force block reward to zero when right shift is undefined.
	if (halvings >= 64) {
	return Amount::zero();
	}

	Amount nSubsidy = 50 * COIN;
	// Subsidy is cut in half every 210,000 blocks which will occur
	// approximately every 4 years.
	return ((nSubsidy / SATOSHI) >> halvings) * SATOSHI;
	}

	CoinsViews::CoinsViews(DBParams db_params, CoinsViewOptions options)
	: m_dbview{std::move(db_params), std::move(options)},
	m_catcherview(&m_dbview) {}

	void CoinsViews::InitCache() {
	AssertLockHeld(::cs_main);
	m_cacheview = std::make_unique<CCoinsViewCache>(&m_catcherview);
	}

	Chainstate::Chainstate(CTxMemPool *mempool, BlockManager &blockman,
	ChainstateManager &chainman,
	std::optional<BlockHash> from_snapshot_blockhash)
	: m_mempool(mempool), m_blockman(blockman), m_chainman(chainman),
	m_from_snapshot_blockhash(from_snapshot_blockhash) {}

	const CBlockIndex *Chainstate::SnapshotBase() {
	if (!m_from_snapshot_blockhash) {
	return nullptr;
	}
	if (!m_cached_snapshot_base) {
	m_cached_snapshot_base = Assert(
	m_chainman.m_blockman.LookupBlockIndex(*m_from_snapshot_blockhash));
	}
	return m_cached_snapshot_base;
	}

	void Chainstate::InitCoinsDB(size_t cache_size_bytes, bool in_memory,
	bool should_wipe, std::string leveldb_name) {
	if (m_from_snapshot_blockhash) {
	leveldb_name += node::SNAPSHOT_CHAINSTATE_SUFFIX;
	}

	m_coins_views = std::make_unique<CoinsViews>(
	DBParams{.path = m_chainman.m_options.datadir / leveldb_name,
	.cache_bytes = cache_size_bytes,
	.memory_only = in_memory,
	.wipe_data = should_wipe,
	.obfuscate = true,
	.options = m_chainman.m_options.coins_db},
	m_chainman.m_options.coins_view);
	}

	void Chainstate::InitCoinsCache(size_t cache_size_bytes) {
	AssertLockHeld(::cs_main);
	assert(m_coins_views != nullptr);
	m_coinstip_cache_size_bytes = cache_size_bytes;
	m_coins_views->InitCache();
	}

	// Note that though this is marked const, we may end up modifying
	// `m_cached_finished_ibd`, which is a performance-related implementation
	// detail. This function must be marked `const` so that `CValidationInterface`
	// clients (which are given a `const Chainstate*`) can call it.
	//
	bool ChainstateManager::IsInitialBlockDownload() const {
	// Optimization: pre-test latch before taking the lock.
	if (m_cached_finished_ibd.load(std::memory_order_relaxed)) {
	return false;
	}

	LOCK(cs_main);
	if (m_cached_finished_ibd.load(std::memory_order_relaxed)) {
	return false;
	}
	if (m_blockman.LoadingBlocks()) {
	return true;
	}
	CChain &chain{ActiveChain()};
	if (chain.Tip() == nullptr) {
	return true;
	}
	if (chain.Tip()->nChainWork < MinimumChainWork()) {
	return true;
	}
	if (chain.Tip()->Time() < Now<NodeSeconds>() - m_options.max_tip_age) {
	return true;
	}
	LogPrintf("Leaving InitialBlockDownload (latching to false)\n");
	m_cached_finished_ibd.store(true, std::memory_order_relaxed);
	return false;
	}

	void Chainstate::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 (m_chainman.IsInitialBlockDownload()) {
	return;
	}

	// If our best fork is no longer within 72 blocks (+/- 12 hours if no one
	// mines it) of our head, or if it is back on the active chain, drop it
	if (m_best_fork_tip && (m_chain.Height() - m_best_fork_tip->nHeight >= 72 \|\|
	m_chain.Contains(m_best_fork_tip))) {
	m_best_fork_tip = nullptr;
	}

	if (m_best_fork_tip \|\|
	(m_chainman.m_best_invalid &&
	m_chainman.m_best_invalid->nChainWork >
	m_chain.Tip()->nChainWork + (GetBlockProof(m_chain.Tip()) 6))) {
	if (!GetfLargeWorkForkFound() && m_best_fork_base) {
	std::string warning =
	std::string("'Warning: Large-work fork detected, forking after "
	"block ") +
	m_best_fork_base->phashBlock->ToString() + std::string("'");
	m_chainman.GetNotifications().warning(warning);
	}

	if (m_best_fork_tip && m_best_fork_base) {
	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__, m_best_fork_base->nHeight,
	m_best_fork_base->phashBlock->ToString(),
	m_best_fork_tip->nHeight,
	m_best_fork_tip->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);
	}
	}

	void Chainstate::CheckForkWarningConditionsOnNewFork(
	CBlockIndex *pindexNewForkTip) {
	AssertLockHeld(cs_main);

	// If we are on a fork that is sufficiently large, set a warning flag.
	const CBlockIndex *pfork = m_chain.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 &&
	(!m_best_fork_tip \|\|
	pindexNewForkTip->nHeight > m_best_fork_tip->nHeight) &&
	pindexNewForkTip->nChainWork - pfork->nChainWork >
	(GetBlockProof(pfork) 7) &&
	m_chain.Height() - pindexNewForkTip->nHeight < 72) {
	m_best_fork_tip = pindexNewForkTip;
	m_best_fork_base = pfork;
	}

	CheckForkWarningConditions();
	}

	// Called both upon regular invalid block discovery and InvalidateBlock
	void Chainstate::InvalidChainFound(CBlockIndex *pindexNew) {
	AssertLockHeld(cs_main);
	if (!m_chainman.m_best_invalid \|\|
	pindexNew->nChainWork > m_chainman.m_best_invalid->nChainWork) {
	m_chainman.m_best_invalid = pindexNew;
	}
	if (m_chainman.m_best_header != nullptr &&
	m_chainman.m_best_header->GetAncestor(pindexNew->nHeight) ==
	pindexNew) {
	m_chainman.m_best_header = m_chain.Tip();
	}

	// If the invalid chain found is supposed to be finalized, we need to move
	// back the finalization point.
	if (IsBlockAvalancheFinalized(pindexNew)) {
	LOCK(cs_avalancheFinalizedBlockIndex);
	m_avalancheFinalizedBlockIndex = pindexNew->pprev;
	}

	LogPrintf("%s: invalid block=%s height=%d log2_work=%f date=%s\n",
	__func__, pindexNew->GetBlockHash().ToString(),
	pindexNew->nHeight,
	log(pindexNew->nChainWork.getdouble()) / log(2.0),
	FormatISO8601DateTime(pindexNew->GetBlockTime()));
	CBlockIndex *tip = m_chain.Tip();
	assert(tip);
	LogPrintf("%s: current best=%s height=%d log2_work=%f date=%s\n",
	__func__, tip->GetBlockHash().ToString(), m_chain.Height(),
	log(tip->nChainWork.getdouble()) / log(2.0),
	FormatISO8601DateTime(tip->GetBlockTime()));
	}

	// Same as InvalidChainFound, above, except not called directly from
	// InvalidateBlock, which does its own setBlockIndexCandidates management.
	void Chainstate::InvalidBlockFound(CBlockIndex *pindex,
	const BlockValidationState &state) {
	AssertLockHeld(cs_main);
	if (state.GetResult() != BlockValidationResult::BLOCK_MUTATED) {
	pindex->nStatus = pindex->nStatus.withFailed();
	m_chainman.m_failed_blocks.insert(pindex);
	m_blockman.m_dirty_blockindex.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);
	}

	bool CScriptCheck::operator()() {
	const CScript &scriptSig = ptxTo->vin[nIn].scriptSig;
	if (!VerifyScript(scriptSig, m_tx_out.scriptPubKey, nFlags,
	CachingTransactionSignatureChecker(
	ptxTo, nIn, m_tx_out.nValue, cacheStore, txdata),
	metrics, &error)) {
	return false;
	}
	if ((pTxLimitSigChecks &&
	!pTxLimitSigChecks->consume_and_check(metrics.nSigChecks)) \|\|
	(pBlockLimitSigChecks &&
	!pBlockLimitSigChecks->consume_and_check(metrics.nSigChecks))) {
	// we can't assign a meaningful script error (since the script
	// succeeded), but remove the ScriptError::OK which could be
	// misinterpreted.
	error = ScriptError::SIGCHECKS_LIMIT_EXCEEDED;
	return false;
	}
	return true;
	}

	bool CheckInputScripts(const CTransaction &tx, TxValidationState &state,
	const CCoinsViewCache &inputs, const uint32_t flags,
	bool sigCacheStore, bool scriptCacheStore,
	const PrecomputedTransactionData &txdata,
	int &nSigChecksOut, TxSigCheckLimiter &txLimitSigChecks,
	CheckInputsLimiter *pBlockLimitSigChecks,
	std::vector<CScriptCheck> *pvChecks) {
	AssertLockHeld(cs_main);
	assert(!tx.IsCoinBase());

	if (pvChecks) {
	pvChecks->reserve(tx.vin.size());
	}

	// First check if script executions have been cached with the same flags.
	// Note that this assumes that the inputs provided are correct (ie that the
	// transaction hash which is in tx's prevouts properly commits to the
	// scriptPubKey in the inputs view of that transaction).
	ScriptCacheKey hashCacheEntry(tx, flags);
	if (IsKeyInScriptCache(hashCacheEntry, !scriptCacheStore, nSigChecksOut)) {
	if (!txLimitSigChecks.consume_and_check(nSigChecksOut) \|\|
	(pBlockLimitSigChecks &&
	!pBlockLimitSigChecks->consume_and_check(nSigChecksOut))) {
	return state.Invalid(TxValidationResult::TX_CONSENSUS,
	"too-many-sigchecks");
	}
	return true;
	}

	int nSigChecksTotal = 0;

	for (size_t i = 0; i < tx.vin.size(); i++) {
	const COutPoint &prevout = tx.vin[i].prevout;
	const Coin &coin = inputs.AccessCoin(prevout);
	assert(!coin.IsSpent());

	// We very carefully only pass in things to CScriptCheck which are
	// clearly committed to by tx's hash. This provides a sanity
	// check that our caching is not introducing consensus failures through
	// additional data in, eg, the coins being spent being checked as a part
	// of CScriptCheck.

	// Verify signature
	CScriptCheck check(coin.GetTxOut(), tx, i, flags, sigCacheStore, txdata,
	&txLimitSigChecks, pBlockLimitSigChecks);

	// If pvChecks is not null, defer the check execution to the caller.
	if (pvChecks) {
	pvChecks->push_back(std::move(check));
	continue;
	}

	if (!check()) {
	ScriptError scriptError = check.GetScriptError();
	// Compute flags without the optional standardness flags.
	// This differs from MANDATORY_SCRIPT_VERIFY_FLAGS as it contains
	// additional upgrade flags (see AcceptToMemoryPoolWorker variable
	// extraFlags).
	uint32_t mandatoryFlags =
	flags & ~STANDARD_NOT_MANDATORY_VERIFY_FLAGS;
	if (flags != mandatoryFlags) {
	// Check whether the failure was caused by a non-mandatory
	// script verification check. If so, ensure we return
	// NOT_STANDARD instead of CONSENSUS to avoid downstream users
	// splitting the network between upgraded and non-upgraded nodes
	// by banning CONSENSUS-failing data providers.
	CScriptCheck check2(coin.GetTxOut(), tx, i, mandatoryFlags,
	sigCacheStore, txdata);
	if (check2()) {
	return state.Invalid(
	TxValidationResult::TX_NOT_STANDARD,
	strprintf("non-mandatory-script-verify-flag (%s)",
	ScriptErrorString(scriptError)));
	}
	// update the error message to reflect the mandatory violation.
	scriptError = check2.GetScriptError();
	}

	// MANDATORY flag failures correspond to
	// TxValidationResult::TX_CONSENSUS. Because CONSENSUS failures are
	// the most serious case of validation failures, we may need to
	// consider using RECENT_CONSENSUS_CHANGE for any script failure
	// that could be due to non-upgraded nodes which we may want to
	// support, to avoid splitting the network (but this depends on the
	// details of how net_processing handles such errors).
	return state.Invalid(
	TxValidationResult::TX_CONSENSUS,
	strprintf("mandatory-script-verify-flag-failed (%s)",
	ScriptErrorString(scriptError)));
	}

	nSigChecksTotal += check.GetScriptExecutionMetrics().nSigChecks;
	}

	nSigChecksOut = nSigChecksTotal;

	if (scriptCacheStore && !pvChecks) {
	// We executed all of the provided scripts, and were told to cache the
	// result. Do so now.
	AddKeyInScriptCache(hashCacheEntry, nSigChecksTotal);
	}

	return true;
	}

	bool AbortNode(BlockValidationState &state, const std::string &strMessage,
	const bilingual_str &userMessage) {
	AbortNode(strMessage, userMessage);
	return state.Error(strMessage);
	}

	/** Restore the UTXO in a Coin at a given COutPoint. */
	DisconnectResult UndoCoinSpend(Coin &&undo, CCoinsViewCache &view,
	const COutPoint &out) {
	bool fClean = true;

	if (view.HaveCoin(out)) {
	// Overwriting transaction output.
	fClean = false;
	}

	if (undo.GetHeight() == 0) {
	// Missing undo metadata (height and coinbase). Older versions included
	// this information only in undo records for the last spend of a
	// transactions' outputs. This implies that it must be present for some
	// other output of the same tx.
	const Coin &alternate = AccessByTxid(view, out.GetTxId());
	if (alternate.IsSpent()) {
	// Adding output for transaction without known metadata
	return DisconnectResult::FAILED;
	}

	// This is somewhat ugly, but hopefully utility is limited. This is only
	// useful when working from legacy on disck data. In any case, putting
	// the correct information in there doesn't hurt.
	const_cast<Coin &>(undo) = Coin(undo.GetTxOut(), alternate.GetHeight(),
	alternate.IsCoinBase());
	}

	// If the coin already exists as an unspent coin in the cache, then the
	// possible_overwrite parameter to AddCoin must be set to true. We have
	// already checked whether an unspent coin exists above using HaveCoin, so
	// we don't need to guess. When fClean is false, an unspent coin already
	// existed and it is an overwrite.
	view.AddCoin(out, std::move(undo), !fClean);

	return fClean ? DisconnectResult::OK : DisconnectResult::UNCLEAN;
	}

	/**
	* Undo the effects of this block (with given index) on the UTXO set represented
	* by coins. When FAILED is returned, view is left in an indeterminate state.
	*/
	DisconnectResult Chainstate::DisconnectBlock(const CBlock &block,
	const CBlockIndex *pindex,
	CCoinsViewCache &view) {
	AssertLockHeld(::cs_main);
	CBlockUndo blockUndo;
	if (!m_blockman.UndoReadFromDisk(blockUndo, *pindex)) {
	error("DisconnectBlock(): failure reading undo data");
	return DisconnectResult::FAILED;
	}

	return ApplyBlockUndo(std::move(blockUndo), block, pindex, view);
	}

	DisconnectResult ApplyBlockUndo(CBlockUndo &&blockUndo, const CBlock &block,
	const CBlockIndex *pindex,
	CCoinsViewCache &view) {
	bool fClean = true;

	if (blockUndo.vtxundo.size() + 1 != block.vtx.size()) {
	error("DisconnectBlock(): block and undo data inconsistent");
	return DisconnectResult::FAILED;
	}

	// First, restore inputs.
	for (size_t i = 1; i < block.vtx.size(); i++) {
	const CTransaction &tx = *(block.vtx[i]);
	CTxUndo &txundo = blockUndo.vtxundo[i - 1];
	if (txundo.vprevout.size() != tx.vin.size()) {
	error("DisconnectBlock(): transaction and undo data inconsistent");
	return DisconnectResult::FAILED;
	}

	for (size_t j = 0; j < tx.vin.size(); j++) {
	const COutPoint &out = tx.vin[j].prevout;
	DisconnectResult res =
	UndoCoinSpend(std::move(txundo.vprevout[j]), view, out);
	if (res == DisconnectResult::FAILED) {
	return DisconnectResult::FAILED;
	}
	fClean = fClean && res != DisconnectResult::UNCLEAN;
	}
	// At this point, all of txundo.vprevout should have been moved out.
	}

	// Second, revert created outputs.
	for (const auto &ptx : block.vtx) {
	const CTransaction &tx = *ptx;
	const TxId &txid = tx.GetId();
	const bool is_coinbase = tx.IsCoinBase();

	// Check that all outputs are available and match the outputs in the
	// block itself exactly.
	for (size_t o = 0; o < tx.vout.size(); o++) {
	if (tx.vout[o].scriptPubKey.IsUnspendable()) {
	continue;
	}

	COutPoint out(txid, o);
	Coin coin;
	bool is_spent = view.SpendCoin(out, &coin);
	if (!is_spent \|\| tx.vout[o] != coin.GetTxOut() \|\|
	uint32_t(pindex->nHeight) != coin.GetHeight() \|\|
	is_coinbase != coin.IsCoinBase()) {
	// transaction output mismatch
	fClean = false;
	}
	}
	}

	// Move best block pointer to previous block.
	view.SetBestBlock(block.hashPrevBlock);

	return fClean ? DisconnectResult::OK : DisconnectResult::UNCLEAN;
	}

	static CCheckQueue<CScriptCheck> scriptcheckqueue(128);

	void StartScriptCheckWorkerThreads(int threads_num) {
	scriptcheckqueue.StartWorkerThreads(threads_num);
	}

	void StopScriptCheckWorkerThreads() {
	scriptcheckqueue.StopWorkerThreads();
	}

	// Returns the script flags which should be checked for the block after
	// the given block.
	static uint32_t GetNextBlockScriptFlags(const CBlockIndex *pindex,
	const ChainstateManager &chainman) {
	const Consensus::Params &consensusparams = chainman.GetConsensus();

	uint32_t flags = SCRIPT_VERIFY_NONE;

	// Enforce P2SH (BIP16)
	if (DeploymentActiveAfter(pindex, chainman, Consensus::DEPLOYMENT_P2SH)) {
	flags \|= SCRIPT_VERIFY_P2SH;
	}

	// Enforce the DERSIG (BIP66) rule.
	if (DeploymentActiveAfter(pindex, chainman, Consensus::DEPLOYMENT_DERSIG)) {
	flags \|= SCRIPT_VERIFY_DERSIG;
	}

	// Start enforcing CHECKLOCKTIMEVERIFY (BIP65) rule.
	if (DeploymentActiveAfter(pindex, chainman, Consensus::DEPLOYMENT_CLTV)) {
	flags \|= SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY;
	}

	// Start enforcing CSV (BIP68, BIP112 and BIP113) rule.
	if (DeploymentActiveAfter(pindex, chainman, Consensus::DEPLOYMENT_CSV)) {
	flags \|= SCRIPT_VERIFY_CHECKSEQUENCEVERIFY;
	}

	// If the UAHF is enabled, we start accepting replay protected txns
	if (IsUAHFenabled(consensusparams, pindex)) {
	flags \|= SCRIPT_VERIFY_STRICTENC;
	flags \|= SCRIPT_ENABLE_SIGHASH_FORKID;
	}

	// If the DAA HF is enabled, we start rejecting transaction that use a high
	// s in their signature. We also make sure that signature that are supposed
	// to fail (for instance in multisig or other forms of smart contracts) are
	// null.
	if (IsDAAEnabled(consensusparams, pindex)) {
	flags \|= SCRIPT_VERIFY_LOW_S;
	flags \|= SCRIPT_VERIFY_NULLFAIL;
	}

	// When the magnetic anomaly fork is enabled, we start accepting
	// transactions using the OP_CHECKDATASIG opcode and it's verify
	// alternative. We also start enforcing push only signatures and
	// clean stack.
	if (IsMagneticAnomalyEnabled(consensusparams, pindex)) {
	flags \|= SCRIPT_VERIFY_SIGPUSHONLY;
	flags \|= SCRIPT_VERIFY_CLEANSTACK;
	}

	if (IsGravitonEnabled(consensusparams, pindex)) {
	flags \|= SCRIPT_ENABLE_SCHNORR_MULTISIG;
	flags \|= SCRIPT_VERIFY_MINIMALDATA;
	}

	if (IsPhononEnabled(consensusparams, pindex)) {
	flags \|= SCRIPT_ENFORCE_SIGCHECKS;
	}

	// We make sure this node will have replay protection during the next hard
	// fork.
	if (IsReplayProtectionEnabled(consensusparams, pindex)) {
	flags \|= SCRIPT_ENABLE_REPLAY_PROTECTION;
	}

	return flags;
	}

	static int64_t nTimeCheck = 0;
	static int64_t nTimeForks = 0;
	static int64_t nTimeVerify = 0;
	static int64_t nTimeConnect = 0;
	static int64_t nTimeIndex = 0;
	static int64_t 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 Chainstate::ConnectBlock(const CBlock &block, BlockValidationState &state,
	CBlockIndex *pindex, CCoinsViewCache &view,
	BlockValidationOptions options, Amount *blockFees,
	bool fJustCheck) {
	AssertLockHeld(cs_main);
	assert(pindex);

	const BlockHash block_hash{block.GetHash()};
	assert(*pindex->phashBlock == block_hash);

	int64_t nTimeStart = GetTimeMicros();

	const CChainParams &params{m_chainman.GetParams()};
	const Consensus::Params &consensusParams = params.GetConsensus();

	// Check it again in case a previous version let a bad block in
	// NOTE: We don't currently (re-)invoke ContextualCheckBlock() or
	// ContextualCheckBlockHeader() here. This means that if we add a new
	// consensus rule that is enforced in one of those two functions, then we
	// may have let in a block that violates the rule prior to updating the
	// software, and we would NOT be enforcing the rule here. Fully solving
	// upgrade from one software version to the next after a consensus rule
	// change is potentially tricky and issue-specific.
	// Also, currently the rule against blocks more than 2 hours in the future
	// is enforced in ContextualCheckBlockHeader(); we wouldn't want to
	// re-enforce that rule here (at least until we make it impossible for
	// m_adjusted_time_callback() to go backward).
	if (!CheckBlock(block, state, consensusParams,
	options.withCheckPoW(!fJustCheck)
	.withCheckMerkleRoot(!fJustCheck))) {
	if (state.GetResult() == BlockValidationResult::BLOCK_MUTATED) {
	// We don't write down blocks to disk if they may have been
	// corrupted, so this should be impossible unless we're having
	// hardware problems.
	return AbortNode(state, "Corrupt block found indicating potential "
	"hardware failure; shutting down");
	}
	return error("%s: Consensus::CheckBlock: %s", __func__,
	state.ToString());
	}

	// Verify that the view's current state corresponds to the previous block
	BlockHash hashPrevBlock =
	pindex->pprev == nullptr ? BlockHash() : pindex->pprev->GetBlockHash();
	assert(hashPrevBlock == view.GetBestBlock());

	nBlocksTotal++;

	// Special case for the genesis block, skipping connection of its
	// transactions (its coinbase is unspendable)
	if (block_hash == consensusParams.hashGenesisBlock) {
	if (!fJustCheck) {
	view.SetBestBlock(pindex->GetBlockHash());
	}

	return true;
	}

	bool fScriptChecks = true;
	if (!m_chainman.AssumedValidBlock().IsNull()) {
	// We've been configured with the hash of a block which has been
	// externally verified to have a valid history. A suitable default value
	// is included with the software and updated from time to time. Because
	// validity relative to a piece of software is an objective fact these
	// defaults can be easily reviewed. This setting doesn't force the
	// selection of any particular chain but makes validating some faster by
	// effectively caching the result of part of the verification.
	BlockMap::const_iterator it{
	m_blockman.m_block_index.find(m_chainman.AssumedValidBlock())};
	if (it != m_blockman.m_block_index.end()) {
	if (it->second.GetAncestor(pindex->nHeight) == pindex &&
	m_chainman.m_best_header->GetAncestor(pindex->nHeight) ==
	pindex &&
	m_chainman.m_best_header->nChainWork >=
	m_chainman.MinimumChainWork()) {
	// This block is a member of the assumed verified chain and an
	// ancestor of the best header.
	// Script verification is skipped when connecting blocks under
	// the assumevalid block. Assuming the assumevalid block is
	// valid this is safe because block merkle hashes are still
	// computed and checked, Of course, if an assumed valid block is
	// invalid due to false scriptSigs this optimization would allow
	// an invalid chain to be accepted.
	// The equivalent time check discourages hash power from
	// extorting the network via DOS attack into accepting an
	// invalid block through telling users they must manually set
	// assumevalid. Requiring a software change or burying the
	// invalid block, regardless of the setting, makes it hard to
	// hide the implication of the demand. This also avoids having
	// release candidates that are hardly doing any signature
	// verification at all in testing without having to artificially
	// set the default assumed verified block further back. The test
	// against the minimum chain work prevents the skipping when
	// denied access to any chain at least as good as the expected
	// chain.
	fScriptChecks = (GetBlockProofEquivalentTime(
	m_chainman.m_best_header, pindex,
	*m_chainman.m_best_header,
	consensusParams) <= 60 * 60 * 24 * 7 * 2);
	}
	}
	}

	int64_t nTime1 = GetTimeMicros();
	nTimeCheck += nTime1 - nTimeStart;
	LogPrint(BCLog::BENCH, " - Sanity checks: %.2fms [%.2fs (%.2fms/blk)]\n",
	MILLI * (nTime1 - nTimeStart), nTimeCheck * MICRO,
	nTimeCheck * MILLI / nBlocksTotal);

	// Do not allow blocks that contain transactions which 'overwrite' older
	// transactions, unless those are already completely spent. If such
	// overwrites are allowed, coinbases and transactions depending upon those
	// can be duplicated to remove the ability to spend the first instance --
	// even after being sent to another address.
	// See BIP30, CVE-2012-1909, and http://r6.ca/blog/20120206T005236Z.html
	// for more information. This rule was originally applied to all blocks
	// with a timestamp after March 15, 2012, 0:00 UTC. Now that the whole
	// chain is irreversibly beyond that time it is applied to all blocks
	// except the two in the chain that violate it. This prevents exploiting
	// the issue against nodes during their initial block download.
	bool fEnforceBIP30 = !((pindex->nHeight == 91842 &&
	pindex->GetBlockHash() ==
	uint256S("0x00000000000a4d0a398161ffc163c503763"
	"b1f4360639393e0e4c8e300e0caec")) \|\|
	(pindex->nHeight == 91880 &&
	pindex->GetBlockHash() ==
	uint256S("0x00000000000743f190a18c5577a3c2d2a1f"
	"610ae9601ac046a38084ccb7cd721")));

	// Once BIP34 activated it was not possible to create new duplicate
	// coinbases and thus other than starting with the 2 existing duplicate
	// coinbase pairs, not possible to create overwriting txs. But by the time
	// BIP34 activated, in each of the existing pairs the duplicate coinbase had
	// overwritten the first before the first had been spent. Since those
	// coinbases are sufficiently buried it's no longer possible to create
	// further duplicate transactions descending from the known pairs either. If
	// we're on the known chain at height greater than where BIP34 activated, we
	// can save the db accesses needed for the BIP30 check.

	// BIP34 requires that a block at height X (block X) has its coinbase
	// scriptSig start with a CScriptNum of X (indicated height X). The above
	// logic of no longer requiring BIP30 once BIP34 activates is flawed in the
	// case that there is a block X before the BIP34 height of 227,931 which has
	// an indicated height Y where Y is greater than X. The coinbase for block
	// X would also be a valid coinbase for block Y, which could be a BIP30
	// violation. An exhaustive search of all mainnet coinbases before the
	// BIP34 height which have an indicated height greater than the block height
	// reveals many occurrences. The 3 lowest indicated heights found are
	// 209,921, 490,897, and 1,983,702 and thus coinbases for blocks at these 3
	// heights would be the first opportunity for BIP30 to be violated.

	// The search reveals a great many blocks which have an indicated height
	// greater than 1,983,702, so we simply remove the optimization to skip
	// BIP30 checking for blocks at height 1,983,702 or higher. Before we reach
	// that block in another 25 years or so, we should take advantage of a
	// future consensus change to do a new and improved version of BIP34 that
	// will actually prevent ever creating any duplicate coinbases in the
	// future.
	static constexpr int BIP34_IMPLIES_BIP30_LIMIT = 1983702;

	// There is no potential to create a duplicate coinbase at block 209,921
	// because this is still before the BIP34 height and so explicit BIP30
	// checking is still active.

	// The final case is block 176,684 which has an indicated height of
	// 490,897. Unfortunately, this issue was not discovered until about 2 weeks
	// before block 490,897 so there was not much opportunity to address this
	// case other than to carefully analyze it and determine it would not be a
	// problem. Block 490,897 was, in fact, mined with a different coinbase than
	// block 176,684, but it is important to note that even if it hadn't been or
	// is remined on an alternate fork with a duplicate coinbase, we would still
	// not run into a BIP30 violation. This is because the coinbase for 176,684
	// is spent in block 185,956 in transaction
	// d4f7fbbf92f4a3014a230b2dc70b8058d02eb36ac06b4a0736d9d60eaa9e8781. This
	// spending transaction can't be duplicated because it also spends coinbase
	// 0328dd85c331237f18e781d692c92de57649529bd5edf1d01036daea32ffde29. This
	// coinbase has an indicated height of over 4.2 billion, and wouldn't be
	// duplicatable until that height, and it's currently impossible to create a
	// chain that long. Nevertheless we may wish to consider a future soft fork
	// which retroactively prevents block 490,897 from creating a duplicate
	// coinbase. The two historical BIP30 violations often provide a confusing
	// edge case when manipulating the UTXO and it would be simpler not to have
	// another edge case to deal with.

	// testnet3 has no blocks before the BIP34 height with indicated heights
	// post BIP34 before approximately height 486,000,000 and presumably will
	// be reset before it reaches block 1,983,702 and starts doing unnecessary
	// BIP30 checking again.
	assert(pindex->pprev);
	CBlockIndex *pindexBIP34height =
	pindex->pprev->GetAncestor(consensusParams.BIP34Height);
	// Only continue to enforce if we're below BIP34 activation height or the
	// block hash at that height doesn't correspond.
	fEnforceBIP30 =
	fEnforceBIP30 &&
	(!pindexBIP34height \|\|
	!(pindexBIP34height->GetBlockHash() == consensusParams.BIP34Hash));

	// TODO: Remove BIP30 checking from block height 1,983,702 on, once we have
	// a consensus change that ensures coinbases at those heights can not
	// duplicate earlier coinbases.
	if (fEnforceBIP30 \|\| pindex->nHeight >= BIP34_IMPLIES_BIP30_LIMIT) {
	for (const auto &tx : block.vtx) {
	for (size_t o = 0; o < tx->vout.size(); o++) {
	if (view.HaveCoin(COutPoint(tx->GetId(), o))) {
	LogPrintf("ERROR: ConnectBlock(): tried to overwrite "
	"transaction\n");
	return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
	"bad-txns-BIP30");
	}
	}
	}
	}

	// Enforce BIP68 (sequence locks).
	int nLockTimeFlags = 0;
	if (DeploymentActiveAt(*pindex, consensusParams,
	Consensus::DEPLOYMENT_CSV)) {
	nLockTimeFlags \|= LOCKTIME_VERIFY_SEQUENCE;
	}

	const uint32_t flags = GetNextBlockScriptFlags(pindex->pprev, m_chainman);

	int64_t nTime2 = GetTimeMicros();
	nTimeForks += nTime2 - nTime1;
	LogPrint(BCLog::BENCH, " - Fork checks: %.2fms [%.2fs (%.2fms/blk)]\n",
	MILLI * (nTime2 - nTime1), nTimeForks * MICRO,
	nTimeForks * MILLI / nBlocksTotal);

	std::vector<int> prevheights;
	Amount nFees = Amount::zero();
	int nInputs = 0;

	// Limit the total executed signature operations in the block, a consensus
	// rule. Tracking during the CPU-consuming part (validation of uncached
	// inputs) is per-input atomic and validation in each thread stops very
	// quickly after the limit is exceeded, so an adversary cannot cause us to
	// exceed the limit by much at all.
	CheckInputsLimiter nSigChecksBlockLimiter(
	GetMaxBlockSigChecksCount(options.getExcessiveBlockSize()));

	std::vector<TxSigCheckLimiter> nSigChecksTxLimiters;
	nSigChecksTxLimiters.resize(block.vtx.size() - 1);

	CBlockUndo blockundo;
	blockundo.vtxundo.resize(block.vtx.size() - 1);

	CCheckQueueControl<CScriptCheck> control(fScriptChecks ? &scriptcheckqueue
	: nullptr);

	// Add all outputs
	try {
	for (const auto &ptx : block.vtx) {
	AddCoins(view, *ptx, pindex->nHeight);
	}
	} catch (const std::logic_error &e) {
	// This error will be thrown from AddCoin if we try to connect a block
	// containing duplicate transactions. Such a thing should normally be
	// caught early nowadays (due to ContextualCheckBlock's CTOR
	// enforcement) however some edge cases can escape that:
	// - ContextualCheckBlock does not get re-run after saving the block to
	// disk, and older versions may have saved a weird block.
	// - its checks are not applied to pre-CTOR chains, which we might visit
	// with checkpointing off.
	LogPrintf("ERROR: ConnectBlock(): tried to overwrite transaction\n");
	return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
	"tx-duplicate");
	}

	size_t txIndex = 0;
	// nSigChecksRet may be accurate (found in cache) or 0 (checks were
	// deferred into vChecks).
	int nSigChecksRet;
	for (const auto &ptx : block.vtx) {
	const CTransaction &tx = *ptx;
	const bool isCoinBase = tx.IsCoinBase();
	nInputs += tx.vin.size();

	{
	Amount txfee = Amount::zero();
	TxValidationState tx_state;
	if (!isCoinBase &&
	!Consensus::CheckTxInputs(tx, tx_state, view, pindex->nHeight,
	txfee)) {
	// Any transaction validation failure in ConnectBlock is a block
	// consensus failure.
	state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
	tx_state.GetRejectReason(),
	tx_state.GetDebugMessage());

	return error("%s: Consensus::CheckTxInputs: %s, %s", __func__,
	tx.GetId().ToString(), state.ToString());
	}
	nFees += txfee;
	}

	if (!MoneyRange(nFees)) {
	LogPrintf("ERROR: %s: accumulated fee in the block out of range.\n",
	__func__);
	return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
	"bad-txns-accumulated-fee-outofrange");
	}

	// The following checks do not apply to the coinbase.
	if (isCoinBase) {
	continue;
	}

	// Check that transaction is BIP68 final BIP68 lock checks (as
	// opposed to nLockTime checks) must be in ConnectBlock because they
	// require the UTXO set.
	prevheights.resize(tx.vin.size());
	for (size_t j = 0; j < tx.vin.size(); j++) {
	prevheights[j] = view.AccessCoin(tx.vin[j].prevout).GetHeight();
	}

	if (!SequenceLocks(tx, nLockTimeFlags, prevheights, *pindex)) {
	LogPrintf("ERROR: %s: contains a non-BIP68-final transaction\n",
	__func__);
	return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
	"bad-txns-nonfinal");
	}

	// Don't cache results if we're actually connecting blocks (still
	// consult the cache, though).
	bool fCacheResults = fJustCheck;

	const bool fEnforceSigCheck = flags & SCRIPT_ENFORCE_SIGCHECKS;
	if (!fEnforceSigCheck) {
	// Historically, there has been transactions with a very high
	// sigcheck count, so we need to disable this check for such
	// transactions.
	nSigChecksTxLimiters[txIndex] = TxSigCheckLimiter::getDisabled();
	}

	std::vector<CScriptCheck> vChecks;
	TxValidationState tx_state;
	if (fScriptChecks &&
	!CheckInputScripts(tx, tx_state, view, flags, fCacheResults,
	fCacheResults, PrecomputedTransactionData(tx),
	nSigChecksRet, nSigChecksTxLimiters[txIndex],
	&nSigChecksBlockLimiter, &vChecks)) {
	// Any transaction validation failure in ConnectBlock is a block
	// consensus failure
	state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
	tx_state.GetRejectReason(),
	tx_state.GetDebugMessage());
	return error(
	"ConnectBlock(): CheckInputScripts on %s failed with %s",
	tx.GetId().ToString(), state.ToString());
	}

	control.Add(std::move(vChecks));

	// Note: this must execute in the same iteration as CheckTxInputs (not
	// in a separate loop) in order to detect double spends. However,
	// this does not prevent double-spending by duplicated transaction
	// inputs in the same transaction (cf. CVE-2018-17144) -- that check is
	// done in CheckBlock (CheckRegularTransaction).
	SpendCoins(view, tx, blockundo.vtxundo.at(txIndex), pindex->nHeight);
	txIndex++;
	}

	int64_t nTime3 = GetTimeMicros();
	nTimeConnect += nTime3 - nTime2;
	LogPrint(BCLog::BENCH,
	" - Connect %u transactions: %.2fms (%.3fms/tx, %.3fms/txin) "
	"[%.2fs (%.2fms/blk)]\n",
	(unsigned)block.vtx.size(), MILLI * (nTime3 - nTime2),
	MILLI * (nTime3 - nTime2) / block.vtx.size(),
	nInputs <= 1 ? 0 : MILLI * (nTime3 - nTime2) / (nInputs - 1),
	nTimeConnect * MICRO, nTimeConnect * MILLI / nBlocksTotal);

	const Amount blockReward =
	nFees + GetBlockSubsidy(pindex->nHeight, consensusParams);
	if (block.vtx[0]->GetValueOut() > blockReward) {
	LogPrintf("ERROR: ConnectBlock(): coinbase pays too much (actual=%d vs "
	"limit=%d)\n",
	block.vtx[0]->GetValueOut(), blockReward);
	return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
	"bad-cb-amount");
	}

	if (blockFees) {
	*blockFees = nFees;
	}

	if (!control.Wait()) {
	return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
	"blk-bad-inputs", "parallel script check failed");
	}

	int64_t nTime4 = GetTimeMicros();
	nTimeVerify += nTime4 - nTime2;
	LogPrint(
	BCLog::BENCH,
	" - Verify %u txins: %.2fms (%.3fms/txin) [%.2fs (%.2fms/blk)]\n",
	nInputs - 1, MILLI * (nTime4 - nTime2),
	nInputs <= 1 ? 0 : MILLI * (nTime4 - nTime2) / (nInputs - 1),
	nTimeVerify * MICRO, nTimeVerify * MILLI / nBlocksTotal);

	if (fJustCheck) {
	return true;
	}

	if (!m_blockman.WriteUndoDataForBlock(blockundo, state, *pindex)) {
	return false;
	}

	if (!pindex->IsValid(BlockValidity::SCRIPTS)) {
	pindex->RaiseValidity(BlockValidity::SCRIPTS);
	m_blockman.m_dirty_blockindex.insert(pindex);
	}

	// 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);

	TRACE6(validation, block_connected, block_hash.data(), pindex->nHeight,
	block.vtx.size(), nInputs, nSigChecksRet,
	// in microseconds (µs)
	nTime5 - nTimeStart);

	return true;
	}

	CoinsCacheSizeState Chainstate::GetCoinsCacheSizeState() {
	AssertLockHeld(::cs_main);
	return this->GetCoinsCacheSizeState(m_coinstip_cache_size_bytes,
	m_mempool ? m_mempool->m_max_size_bytes
	: 0);
	}

	CoinsCacheSizeState
	Chainstate::GetCoinsCacheSizeState(size_t max_coins_cache_size_bytes,
	size_t max_mempool_size_bytes) {
	AssertLockHeld(::cs_main);
	int64_t nMempoolUsage = m_mempool ? m_mempool->DynamicMemoryUsage() : 0;
	int64_t cacheSize = CoinsTip().DynamicMemoryUsage();
	int64_t nTotalSpace =
	max_coins_cache_size_bytes +
	std::max<int64_t>(int64_t(max_mempool_size_bytes) - nMempoolUsage, 0);

	//! No need to periodic flush if at least this much space still available.
	static constexpr int64_t MAX_BLOCK_COINSDB_USAGE_BYTES =
	10 * 1024 * 1024; // 10MB
	int64_t large_threshold = std::max(
	(9 * nTotalSpace) / 10, nTotalSpace - MAX_BLOCK_COINSDB_USAGE_BYTES);

	if (cacheSize > nTotalSpace) {
	LogPrintf("Cache size (%s) exceeds total space (%s)\n", cacheSize,
	nTotalSpace);
	return CoinsCacheSizeState::CRITICAL;
	} else if (cacheSize > large_threshold) {
	return CoinsCacheSizeState::LARGE;
	}
	return CoinsCacheSizeState::OK;
	}

	bool Chainstate::FlushStateToDisk(BlockValidationState &state,
	FlushStateMode mode, int nManualPruneHeight) {
	LOCK(cs_main);
	assert(this->CanFlushToDisk());
	std::set<int> setFilesToPrune;
	bool full_flush_completed = false;

	const size_t coins_count = CoinsTip().GetCacheSize();
	const size_t coins_mem_usage = CoinsTip().DynamicMemoryUsage();

	try {
	{
	bool fFlushForPrune = false;
	bool fDoFullFlush = false;

	CoinsCacheSizeState cache_state = GetCoinsCacheSizeState();
	LOCK(m_blockman.cs_LastBlockFile);
	if (m_blockman.IsPruneMode() &&
	(m_blockman.m_check_for_pruning \|\| nManualPruneHeight > 0) &&
	!fReindex) {
	// Make sure we don't prune any of the prune locks bestblocks.
	// Pruning is height-based.
	int last_prune{m_chain.Height()};
	// prune lock that actually was the limiting factor, only used
	// for logging
	std::optional<std::string> limiting_lock;

	for (const auto &prune_lock : m_blockman.m_prune_locks) {
	if (prune_lock.second.height_first ==
	std::numeric_limits<int>::max()) {
	continue;
	}
	// Remove the buffer and one additional block here to get
	// actual height that is outside of the buffer
	const int lock_height{prune_lock.second.height_first -
	PRUNE_LOCK_BUFFER - 1};
	last_prune = std::max(1, std::min(last_prune, lock_height));
	if (last_prune == lock_height) {
	limiting_lock = prune_lock.first;
	}
	}

	if (limiting_lock) {
	LogPrint(BCLog::PRUNE, "%s limited pruning to height %d\n",
	limiting_lock.value(), last_prune);
	}

	if (nManualPruneHeight > 0) {
	LOG_TIME_MILLIS_WITH_CATEGORY(
	"find files to prune (manual)", BCLog::BENCH);
	m_blockman.FindFilesToPruneManual(
	setFilesToPrune,
	std::min(last_prune, nManualPruneHeight),
	m_chain.Height());
	} else {
	LOG_TIME_MILLIS_WITH_CATEGORY("find files to prune",
	BCLog::BENCH);
	m_blockman.FindFilesToPrune(
	setFilesToPrune,
	m_chainman.GetParams().PruneAfterHeight(),
	m_chain.Height(), last_prune,
	m_chainman.IsInitialBlockDownload());
	m_blockman.m_check_for_pruning = false;
	}
	if (!setFilesToPrune.empty()) {
	fFlushForPrune = true;
	if (!m_blockman.m_have_pruned) {
	m_blockman.m_block_tree_db->WriteFlag(
	"prunedblockfiles", true);
	m_blockman.m_have_pruned = true;
	}
	}
	}
	const auto nNow = GetTime<std::chrono::microseconds>();
	// Avoid writing/flushing immediately after startup.
	if (m_last_write.count() == 0) {
	m_last_write = nNow;
	}
	if (m_last_flush.count() == 0) {
	m_last_flush = nNow;
	}
	// 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 &&
	cache_state >= CoinsCacheSizeState::LARGE;
	// The cache is over the limit, we have to write now.
	bool fCacheCritical = mode == FlushStateMode::IF_NEEDED &&
	cache_state >= CoinsCacheSizeState::CRITICAL;
	// 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 > m_last_write + DATABASE_WRITE_INTERVAL;
	// It's been very long since we flushed the cache. Do this
	// infrequently, to optimize cache usage.
	bool fPeriodicFlush = mode == FlushStateMode::PERIODIC &&
	nNow > m_last_flush + DATABASE_FLUSH_INTERVAL;
	// 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) {
	// Ensure we can write block index
	if (!CheckDiskSpace(gArgs.GetBlocksDirPath())) {
	return AbortNode(state, "Disk space is too low!",
	_("Disk space is too low!"));
	}

	{
	LOG_TIME_MILLIS_WITH_CATEGORY(
	"write block and undo data to disk", BCLog::BENCH);

	// First make sure all block and undo data is flushed to
	// disk.
	// TODO: Handle return error, or add detailed comment why
	// it is safe to not return an error upon failure.
	if (!m_blockman.FlushBlockFile()) {
	LogPrintLevel(BCLog::VALIDATION, BCLog::Level::Warning,
	"%s: Failed to flush block file.\n",
	__func__);
	}
	}
	// Then update all block file information (which may refer to
	// block and undo files).
	{
	LOG_TIME_MILLIS_WITH_CATEGORY("write block index to disk",
	BCLog::BENCH);

	if (!m_blockman.WriteBlockIndexDB()) {
	return AbortNode(
	state, "Failed to write to block index database");
	}
	}

	// Finally remove any pruned files
	if (fFlushForPrune) {
	LOG_TIME_MILLIS_WITH_CATEGORY("unlink pruned files",
	BCLog::BENCH);

	m_blockman.UnlinkPrunedFiles(setFilesToPrune);
	}
	m_last_write = nNow;
	}
	// Flush best chain related state. This can only be done if the
	// blocks / block index write was also done.
	if (fDoFullFlush && !CoinsTip().GetBestBlock().IsNull()) {
	LOG_TIME_MILLIS_WITH_CATEGORY(
	strprintf("write coins cache to disk (%d coins, %.2fkB)",
	coins_count, coins_mem_usage / 1000),
	BCLog::BENCH);

	// 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(gArgs.GetDataDirNet(),
	48 * 2 * 2 * CoinsTip().GetCacheSize())) {
	return AbortNode(state, "Disk space is too low!",
	_("Disk space is too low!"));
	}

	// Flush the chainstate (which may refer to block index
	// entries).
	if (!CoinsTip().Flush()) {
	return AbortNode(state, "Failed to write to coin database");
	}
	m_last_flush = nNow;
	full_flush_completed = true;
	}

	TRACE5(utxocache, flush,
	// in microseconds (µs)
	GetTimeMicros() - nNow.count(), uint32_t(mode), coins_count,
	uint64_t(coins_mem_usage), fFlushForPrune);
	}

	if (full_flush_completed) {
	// Update best block in wallet (so we can detect restored wallets).
	GetMainSignals().ChainStateFlushed(m_chain.GetLocator());
	}
	} catch (const std::runtime_error &e) {
	return AbortNode(state, std::string("System error while flushing: ") +
	e.what());
	}
	return true;
	}

	void Chainstate::ForceFlushStateToDisk() {
	BlockValidationState state;
	if (!this->FlushStateToDisk(state, FlushStateMode::ALWAYS)) {
	LogPrintf("%s: failed to flush state (%s)\n", __func__,
	state.ToString());
	}
	}

	void Chainstate::PruneAndFlush() {
	BlockValidationState state;
	m_blockman.m_check_for_pruning = true;
	if (!this->FlushStateToDisk(state, FlushStateMode::NONE)) {
	LogPrintf("%s: failed to flush state (%s)\n", __func__,
	state.ToString());
	}
	}

	static void UpdateTipLog(const CCoinsViewCache &coins_tip,
	const CBlockIndex *tip, const CChainParams &params,
	const std::string &func_name,
	const std::string &prefix)
	EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
	AssertLockHeld(::cs_main);
	LogPrintf("%s%s: new best=%s height=%d version=0x%08x log2_work=%f tx=%ld "
	"date='%s' progress=%f cache=%.1fMiB(%utxo)\n",
	prefix, func_name, tip->GetBlockHash().ToString(), tip->nHeight,
	tip->nVersion, log(tip->nChainWork.getdouble()) / log(2.0),
	tip->GetChainTxCount(),
	FormatISO8601DateTime(tip->GetBlockTime()),
	GuessVerificationProgress(params.TxData(), tip),
	coins_tip.DynamicMemoryUsage() * (1.0 / (1 << 20)),
	coins_tip.GetCacheSize());
	}

	void Chainstate::UpdateTip(const CBlockIndex *pindexNew) {
	AssertLockHeld(::cs_main);
	const auto &coins_tip = CoinsTip();

	const CChainParams &params{m_chainman.GetParams()};

	// The remainder of the function isn't relevant if we are not acting on
	// the active chainstate, so return if need be.
	if (this != &m_chainman.ActiveChainstate()) {
	// Only log every so often so that we don't bury log messages at the
	// tip.
	constexpr int BACKGROUND_LOG_INTERVAL = 2000;
	if (pindexNew->nHeight % BACKGROUND_LOG_INTERVAL == 0) {
	UpdateTipLog(coins_tip, pindexNew, params, __func__,
	"[background validation] ");
	}
	return;
	}

	// New best block
	if (m_mempool) {
	m_mempool->AddTransactionsUpdated(1);
	}

	{
	LOCK(g_best_block_mutex);
	g_best_block = pindexNew;
	g_best_block_cv.notify_all();
	}

	UpdateTipLog(coins_tip, pindexNew, params, __func__, "");
	}

	/**
	* Disconnect m_chain's tip.
	* After calling, the mempool will be in an inconsistent state, with
	* transactions from disconnected blocks being added to disconnectpool. You
	* should make the mempool consistent again by calling updateMempoolForReorg.
	* with cs_main held.
	*
	* If disconnectpool is nullptr, then no disconnected transactions are added to
	* disconnectpool (note that the caller is responsible for mempool consistency
	* in any case).
	*/
	bool Chainstate::DisconnectTip(BlockValidationState &state,
	DisconnectedBlockTransactions *disconnectpool) {
	AssertLockHeld(cs_main);
	if (m_mempool) {
	AssertLockHeld(m_mempool->cs);
	}

	CBlockIndex *pindexDelete = m_chain.Tip();

	assert(pindexDelete);
	assert(pindexDelete->pprev);

	// Read block from disk.
	std::shared_ptr<CBlock> pblock = std::make_shared<CBlock>();
	CBlock &block = *pblock;
	if (!m_blockman.ReadBlockFromDisk(block, *pindexDelete)) {
	return error("DisconnectTip(): Failed to read block");
	}

	// Apply the block atomically to the chain state.
	int64_t nStart = GetTimeMicros();
	{
	CCoinsViewCache view(&CoinsTip());
	assert(view.GetBestBlock() == pindexDelete->GetBlockHash());
	if (DisconnectBlock(block, pindexDelete, view) !=
	DisconnectResult::OK) {
	return error("DisconnectTip(): DisconnectBlock %s failed",
	pindexDelete->GetBlockHash().ToString());
	}

	bool flushed = view.Flush();
	assert(flushed);
	}

	LogPrint(BCLog::BENCH, "- Disconnect block: %.2fms\n",
	(GetTimeMicros() - nStart) * MILLI);

	{
	// Prune locks that began at or after the tip should be moved backward
	// so they get a chance to reorg
	const int max_height_first{pindexDelete->nHeight - 1};
	for (auto &prune_lock : m_blockman.m_prune_locks) {
	if (prune_lock.second.height_first <= max_height_first) {
	continue;
	}

	prune_lock.second.height_first = max_height_first;
	LogPrint(BCLog::PRUNE, "%s prune lock moved back to %d\n",
	prune_lock.first, max_height_first);
	}
	}

	// Write the chain state to disk, if necessary.
	if (!FlushStateToDisk(state, FlushStateMode::IF_NEEDED)) {
	return false;
	}

	if (m_mempool) {
	// If this block is deactivating a fork, we move all mempool
	// transactions in front of disconnectpool for reprocessing in a future
	// updateMempoolForReorg call
	if (pindexDelete->pprev != nullptr &&
	GetNextBlockScriptFlags(pindexDelete, m_chainman) !=
	GetNextBlockScriptFlags(pindexDelete->pprev, m_chainman)) {
	LogPrint(BCLog::MEMPOOL,
	"Disconnecting mempool due to rewind of upgrade block\n");
	if (disconnectpool) {
	disconnectpool->importMempool(*m_mempool);
	}
	m_mempool->clear();
	}

	if (disconnectpool) {
	disconnectpool->addForBlock(block.vtx, *m_mempool);
	}
	}

	m_chain.SetTip(*pindexDelete->pprev);

	UpdateTip(pindexDelete->pprev);
	// Let wallets know transactions went from 1-confirmed to
	// 0-confirmed or conflicted:
	GetMainSignals().BlockDisconnected(pblock, pindexDelete);
	return true;
	}

	static int64_t nTimeReadFromDisk = 0;
	static int64_t nTimeConnectTotal = 0;
	static int64_t nTimeFlush = 0;
	static int64_t nTimeChainState = 0;
	static int64_t nTimePostConnect = 0;

	/**
	* Connect a new block to m_chain. pblock is either nullptr or a pointer to
	* a CBlock corresponding to pindexNew, to bypass loading it again from disk.
	*/
	bool Chainstate::ConnectTip(BlockValidationState &state,
	BlockPolicyValidationState &blockPolicyState,
	CBlockIndex *pindexNew,
	const std::shared_ptr<const CBlock> &pblock,
	DisconnectedBlockTransactions &disconnectpool,
	const avalanche::Processor *const avalanche) {
	AssertLockHeld(cs_main);
	if (m_mempool) {
	AssertLockHeld(m_mempool->cs);
	}

	const Consensus::Params &consensusParams = m_chainman.GetConsensus();

	assert(pindexNew->pprev == m_chain.Tip());
	// Read block from disk.
	int64_t nTime1 = GetTimeMicros();
	std::shared_ptr<const CBlock> pthisBlock;
	if (!pblock) {
	std::shared_ptr<CBlock> pblockNew = std::make_shared<CBlock>();
	if (!m_blockman.ReadBlockFromDisk(pblockNew, pindexNew)) {
	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);
	{
	Amount blockFees{Amount::zero()};
	CCoinsViewCache view(&CoinsTip());
	bool rv = ConnectBlock(blockConnecting, state, pindexNew, view,
	BlockValidationOptions(m_chainman.GetConfig()),
	&blockFees);
	GetMainSignals().BlockChecked(blockConnecting, state);
	if (!rv) {
	if (state.IsInvalid()) {
	InvalidBlockFound(pindexNew, state);
	}

	return error("%s: ConnectBlock %s failed, %s", __func__,
	pindexNew->GetBlockHash().ToString(),
	state.ToString());
	}

	/**
	* The block is valid by consensus rules so now we check if the block
	* passes all block policy checks. If not, then park the block and bail.
	*
	* We check block parking policies before flushing changes to the UTXO
	* set. This allows us to avoid rewinding everything immediately after.
	*
	* Only check block parking policies the first time the block is
	* connected. Avalanche voting can override the parking decision made by
	* these policies.
	*/
	const BlockHash blockhash = pindexNew->GetBlockHash();
	if (!m_chainman.IsInitialBlockDownload() &&
	!m_filterParkingPoliciesApplied.contains(blockhash)) {
	m_filterParkingPoliciesApplied.insert(blockhash);

	const Amount blockReward =
	blockFees +
	GetBlockSubsidy(pindexNew->nHeight, consensusParams);

	std::vector<std::unique_ptr<ParkingPolicy>> parkingPolicies;
	parkingPolicies.emplace_back(std::make_unique<MinerFundPolicy>(
	consensusParams, *pindexNew, blockConnecting, blockReward));

	if (avalanche) {
	// Only enable the RTT policy if the node already finalized a
	// block. This is because it's very possible that new blocks
	// will be parked after a node restart (but after IBD) if the
	// node is behind by a few blocks. We want to make sure that the
	// node will be able to switch back to the right tip in this
	// case.
	if (avalanche->hasFinalizedTip()) {
	// Special case for testnet, don't reject blocks mined with
	// the min difficulty
	if (!consensusParams.fPowAllowMinDifficultyBlocks \|\|
	(blockConnecting.GetBlockTime() <=
	pindexNew->pprev->GetBlockTime() +
	2 * consensusParams.nPowTargetSpacing)) {
	parkingPolicies.emplace_back(
	std::make_unique<RTTPolicy>(consensusParams,
	*pindexNew));
	}
	}

	parkingPolicies.emplace_back(
	std::make_unique<StakingRewardsPolicy>(
	avalanche, consensusParams, pindexNew,
	blockConnecting, blockReward));

	if (m_mempool) {
	parkingPolicies.emplace_back(
	std::make_unique<PreConsensusPolicy>(
	*pindexNew, blockConnecting, m_mempool));
	}
	}

	// If any block policy is violated, bail on the first one found
	if (std::find_if_not(parkingPolicies.begin(), parkingPolicies.end(),
	[&](const auto &policy) {
	bool ret = (*policy)(blockPolicyState);
	if (!ret) {
	LogPrintf(
	"Park block because it "
	"violated a block policy: %s\n",
	blockPolicyState.ToString());
	}
	return ret;
	}) != parkingPolicies.end()) {
	pindexNew->nStatus = pindexNew->nStatus.withParked();
	m_blockman.m_dirty_blockindex.insert(pindexNew);
	return false;
	}
	}

	nTime3 = GetTimeMicros();
	nTimeConnectTotal += nTime3 - nTime2;
	assert(nBlocksTotal > 0);
	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(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;
	if (m_mempool) {
	disconnectpool.removeForBlock(blockConnecting.vtx, *m_mempool);

	// If this block is activating a fork, we move all mempool transactions
	// in front of disconnectpool for reprocessing in a future
	// updateMempoolForReorg call
	if (pindexNew->pprev != nullptr &&
	GetNextBlockScriptFlags(pindexNew, m_chainman) !=
	GetNextBlockScriptFlags(pindexNew->pprev, m_chainman)) {
	LogPrint(
	BCLog::MEMPOOL,
	"Disconnecting mempool due to acceptance of upgrade block\n");
	disconnectpool.importMempool(*m_mempool);
	}
	}

	// Update m_chain & related variables.
	m_chain.SetTip(*pindexNew);
	UpdateTip(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);

	// If we are the background validation chainstate, check to see if we are
	// done validating the snapshot (i.e. our tip has reached the snapshot's
	// base block).
	if (this != &m_chainman.ActiveChainstate()) {
	// This call may set `m_disabled`, which is referenced immediately
	// afterwards in ActivateBestChain, so that we stop connecting blocks
	// past the snapshot base.
	m_chainman.MaybeCompleteSnapshotValidation();
	}

	GetMainSignals().BlockConnected(pthisBlock, pindexNew);
	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 *Chainstate::FindMostWorkChain(
	std::vector<const CBlockIndex *> &blocksToReconcile, bool fAutoUnpark) {
	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 an avalanche finalized block to be reorged,
	// then we park it.
	{
	LOCK(cs_avalancheFinalizedBlockIndex);
	if (m_avalancheFinalizedBlockIndex &&
	!AreOnTheSameFork(pindexNew, m_avalancheFinalizedBlockIndex)) {
	LogPrintf("Park block %s because it forks prior to the "
	"avalanche finalized chaintip.\n",
	pindexNew->GetBlockHash().ToString());
	pindexNew->nStatus = pindexNew->nStatus.withParked();
	m_blockman.m_dirty_blockindex.insert(pindexNew);
	}
	}

	const CBlockIndex *pindexFork = m_chain.FindFork(pindexNew);

	// Check whether all blocks on the path between the currently active
	// chain and the candidate are valid. Just going until the active chain
	// is an optimization, as we know all blocks in it are valid already.
	CBlockIndex *pindexTest = pindexNew;
	bool hasValidAncestor = true;
	while (hasValidAncestor && pindexTest && pindexTest != pindexFork) {
	assert(pindexTest->HaveNumChainTxs() \|\| pindexTest->nHeight == 0);

	// If this is a parked chain, but it has enough PoW, clear the park
	// state.
	bool fParkedChain = pindexTest->nStatus.isOnParkedChain();
	if (fAutoUnpark && fParkedChain) {
	const CBlockIndex *pindexTip = m_chain.Tip();

	// During initialization, pindexTip and/or pindexFork may be
	// null. In this case, we just ignore the fact that the chain is
	// parked.
	if (!pindexTip \|\| !pindexFork) {
	UnparkBlock(pindexTest);
	continue;
	}

	// A parked chain can be unparked if it has twice as much PoW
	// accumulated as the main chain has since the fork block.
	CBlockIndex const *pindexExtraPow = pindexTip;
	arith_uint256 requiredWork = pindexTip->nChainWork;
	switch (pindexTip->nHeight - pindexFork->nHeight) {
	// Limit the penality for depth 1, 2 and 3 to half a block
	// worth of work to ensure we don't fork accidentally.
	case 3:
	case 2:
	pindexExtraPow = pindexExtraPow->pprev;
	// FALLTHROUGH
	case 1: {
	const arith_uint256 deltaWork =
	pindexExtraPow->nChainWork - pindexFork->nChainWork;
	requiredWork += (deltaWork >> 1);
	break;
	}
	default:
	requiredWork +=
	pindexExtraPow->nChainWork - pindexFork->nChainWork;
	break;
	}

	if (pindexNew->nChainWork > requiredWork) {
	// We have enough, clear the parked state.
	LogPrintf("Unpark chain up to block %s as it has "
	"accumulated enough PoW.\n",
	pindexNew->GetBlockHash().ToString());
	fParkedChain = false;
	UnparkBlock(pindexTest);
	}
	}

	// Pruned nodes may have entries in setBlockIndexCandidates for
	// which block files have been deleted. Remove those as candidates
	// for the most work chain if we come across them; we can't switch
	// to a chain unless we have all the non-active-chain parent blocks.
	bool fInvalidChain = pindexTest->nStatus.isInvalid();
	bool fMissingData = !pindexTest->nStatus.hasData();
	if (!(fInvalidChain \|\| fParkedChain \|\| fMissingData)) {
	// The current block is acceptable, move to the parent, up to
	// the fork point.
	pindexTest = pindexTest->pprev;
	continue;
	}

	// Candidate chain is not usable (either invalid or parked or
	// missing data)
	hasValidAncestor = false;
	setBlockIndexCandidates.erase(pindexTest);

	if (fInvalidChain && (m_chainman.m_best_invalid == nullptr \|\|
	pindexNew->nChainWork >
	m_chainman.m_best_invalid->nChainWork)) {
	m_chainman.m_best_invalid = pindexNew;
	}

	if (fParkedChain && (m_chainman.m_best_parked == nullptr \|\|
	pindexNew->nChainWork >
	m_chainman.m_best_parked->nChainWork)) {
	m_chainman.m_best_parked = pindexNew;
	}

	LogPrintf("Considered switching to better tip %s but that chain "
	"contains a%s%s%s block.\n",
	pindexNew->GetBlockHash().ToString(),
	fInvalidChain ? "n invalid" : "",
	fParkedChain ? " parked" : "",
	fMissingData ? " missing-data" : "");

	CBlockIndex *pindexFailed = pindexNew;
	// Remove the entire chain from the set.
	while (pindexTest != pindexFailed) {
	if (fInvalidChain \|\| fParkedChain) {
	pindexFailed->nStatus =
	pindexFailed->nStatus.withFailedParent(fInvalidChain)
	.withParkedParent(fParkedChain);
	} else if (fMissingData) {
	// If we're missing data, then add back to
	// m_blocks_unlinked, so that if the block arrives in the
	// future we can try adding to setBlockIndexCandidates
	// again.
	m_blockman.m_blocks_unlinked.insert(
	std::make_pair(pindexFailed->pprev, pindexFailed));
	}
	setBlockIndexCandidates.erase(pindexFailed);
	pindexFailed = pindexFailed->pprev;
	}

	if (fInvalidChain \|\| fParkedChain) {
	// We discovered a new chain tip that is either parked or
	// invalid, we may want to warn.
	CheckForkWarningConditionsOnNewFork(pindexNew);
	}
	}

	blocksToReconcile.push_back(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 Chainstate::PruneBlockIndexCandidates() {
	// Note that we can't delete the current block itself, as we may need to
	// return to it later in case a reorganization to a better block fails.
	auto it = setBlockIndexCandidates.begin();
	while (it != setBlockIndexCandidates.end() &&
	setBlockIndexCandidates.value_comp()(*it, m_chain.Tip())) {
	setBlockIndexCandidates.erase(it++);
	}

	// Either the current tip or a successor of it we're working towards is left
	// in setBlockIndexCandidates.
	assert(!setBlockIndexCandidates.empty());
	}

	/**
	* Try to make some progress towards making pindexMostWork the active block.
	* pblock is either nullptr or a pointer to a CBlock corresponding to
	* pindexMostWork.
	*
	* @returns true unless a system error occurred
	*/
	bool Chainstate::ActivateBestChainStep(
	BlockValidationState &state, CBlockIndex *pindexMostWork,
	const std::shared_ptr<const CBlock> &pblock, bool &fInvalidFound,
	const avalanche::Processor *const avalanche) {
	AssertLockHeld(cs_main);
	if (m_mempool) {
	AssertLockHeld(m_mempool->cs);
	}

	const CBlockIndex *pindexOldTip = m_chain.Tip();
	const CBlockIndex *pindexFork = m_chain.FindFork(pindexMostWork);

	// Disconnect active blocks which are no longer in the best chain.
	bool fBlocksDisconnected = false;
	DisconnectedBlockTransactions disconnectpool;
	while (m_chain.Tip() && m_chain.Tip() != pindexFork) {
	if (!fBlocksDisconnected) {
	// Import and clear mempool; we must do this to preserve
	// topological ordering in the mempool index. This is ok since
	// inserts into the mempool are very fast now in our new
	// implementation.
	disconnectpool.importMempool(*m_mempool);
	}

	if (!DisconnectTip(state, &disconnectpool)) {
	// This is likely a fatal error, but keep the mempool consistent,
	// just in case. Only remove from the mempool in this case.
	if (m_mempool) {
	disconnectpool.updateMempoolForReorg(this, false, m_mempool);
	}

	// If we're unable to disconnect a block during normal operation,
	// then that is a failure of our local system -- we should abort
	// rather than stay on a less work chain.
	AbortNode(state,
	"Failed to disconnect block; see debug.log for details");
	return false;
	}

	fBlocksDisconnected = true;
	}

	// Build list of new blocks to connect.
	std::vector<CBlockIndex *> vpindexToConnect;
	bool fContinue = true;
	int nHeight = pindexFork ? pindexFork->nHeight : -1;
	while (fContinue && nHeight != pindexMostWork->nHeight) {
	// Don't iterate the entire list of potential improvements toward the
	// best tip, as we likely only need a few blocks along the way.
	int nTargetHeight = std::min(nHeight + 32, pindexMostWork->nHeight);
	vpindexToConnect.clear();
	vpindexToConnect.reserve(nTargetHeight - nHeight);
	CBlockIndex *pindexIter = pindexMostWork->GetAncestor(nTargetHeight);
	while (pindexIter && pindexIter->nHeight != nHeight) {
	vpindexToConnect.push_back(pindexIter);
	pindexIter = pindexIter->pprev;
	}

	nHeight = nTargetHeight;

	// Connect new blocks.
	for (CBlockIndex *pindexConnect : reverse_iterate(vpindexToConnect)) {
	BlockPolicyValidationState blockPolicyState;
	if (!ConnectTip(state, blockPolicyState, pindexConnect,
	pindexConnect == pindexMostWork
	? pblock
	: std::shared_ptr<const CBlock>(),
	disconnectpool, avalanche)) {
	if (state.IsInvalid()) {
	// The block violates a consensus rule.
	if (state.GetResult() !=
	BlockValidationResult::BLOCK_MUTATED) {
	InvalidChainFound(vpindexToConnect.back());
	}
	state = BlockValidationState();
	fInvalidFound = true;
	fContinue = false;
	break;
	}

	if (blockPolicyState.IsInvalid()) {
	// The block violates a policy rule.
	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.
	if (m_mempool) {
	disconnectpool.updateMempoolForReorg(*this, false,
	*m_mempool);
	}
	return false;
	} else {
	PruneBlockIndexCandidates();
	if (!pindexOldTip \|\|
	m_chain.Tip()->nChainWork > pindexOldTip->nChainWork) {
	// We're in a better position than we were. Return
	// temporarily to release the lock.
	fContinue = false;
	break;
	}
	}
	}
	}

	if (m_mempool) {
	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(this, true, m_mempool);
	}

	m_mempool->check(this->CoinsTip(), this->m_chain.Height() + 1);
	}

	// Callbacks/notifications for a new best chain.
	if (fInvalidFound) {
	CheckForkWarningConditionsOnNewFork(pindexMostWork);
	} else {
	CheckForkWarningConditions();
	}

	return true;
	}

	static SynchronizationState GetSynchronizationState(bool init) {
	if (!init) {
	return SynchronizationState::POST_INIT;
	}
	if (::fReindex) {
	return SynchronizationState::INIT_REINDEX;
	}
	return SynchronizationState::INIT_DOWNLOAD;
	}

	static bool NotifyHeaderTip(ChainstateManager &chainman)
	LOCKS_EXCLUDED(cs_main) {
	bool fNotify = false;
	bool fInitialBlockDownload = false;
	static CBlockIndex *pindexHeaderOld = nullptr;
	CBlockIndex *pindexHeader = nullptr;
	{
	LOCK(cs_main);
	pindexHeader = chainman.m_best_header;

	if (pindexHeader != pindexHeaderOld) {
	fNotify = true;
	fInitialBlockDownload = chainman.IsInitialBlockDownload();
	pindexHeaderOld = pindexHeader;
	}
	}

	// Send block tip changed notifications without cs_main
	if (fNotify) {
	chainman.GetNotifications().headerTip(
	GetSynchronizationState(fInitialBlockDownload),
	pindexHeader->nHeight, pindexHeader->nTime, false);
	}
	return fNotify;
	}

	static void LimitValidationInterfaceQueue() LOCKS_EXCLUDED(cs_main) {
	AssertLockNotHeld(cs_main);

	if (GetMainSignals().CallbacksPending() > 10) {
	SyncWithValidationInterfaceQueue();
	}
	}

	bool Chainstate::ActivateBestChain(BlockValidationState &state,
	std::shared_ptr<const CBlock> pblock,
	avalanche::Processor *const avalanche) {
	AssertLockNotHeld(m_chainstate_mutex);

	// 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);

	// ABC maintains a fair degree of expensive-to-calculate internal state
	// because this function periodically releases cs_main so that it does not
	// lock up other threads for too long during large connects - and to allow
	// for e.g. the callback queue to drain we use m_chainstate_mutex to enforce
	// mutual exclusion so that only one caller may execute this function at a
	// time
	LOCK(m_chainstate_mutex);

	// Belt-and-suspenders check that we aren't attempting to advance the
	// background chainstate past the snapshot base block.
	if (WITH_LOCK(::cs_main, return m_disabled)) {
	LogPrintf("m_disabled is set - this chainstate should not be in "
	"operation. Please report this as a bug. %s\n",
	PACKAGE_BUGREPORT);
	return false;
	}

	CBlockIndex *pindexMostWork = nullptr;
	CBlockIndex *pindexNewTip = nullptr;
	int nStopAtHeight = gArgs.GetIntArg("-stopatheight", DEFAULT_STOPATHEIGHT);
	do {
	// Block until the validation queue drains. This should largely
	// never happen in normal operation, however may happen during
	// reindex, causing memory blowup if we run too far ahead.
	// Note that if a validationinterface callback ends up calling
	// ActivateBestChain this may lead to a deadlock! We should
	// probably have a DEBUG_LOCKORDER test for this in the future.
	LimitValidationInterfaceQueue();

	std::vector<const CBlockIndex *> blocksToReconcile;
	bool blocks_connected = false;

	const bool fAutoUnpark =
	gArgs.GetBoolArg("-automaticunparking", !avalanche);

	{
	LOCK(cs_main);
	// Lock transaction pool for at least as long as it takes for
	// updateMempoolForReorg to be executed if needed
	LOCK(MempoolMutex());
	CBlockIndex *starting_tip = m_chain.Tip();
	do {
	// We absolutely may not unlock cs_main until we've made forward
	// progress (with the exception of shutdown due to hardware
	// issues, low disk space, etc).

	if (pindexMostWork == nullptr) {
	pindexMostWork =
	FindMostWorkChain(blocksToReconcile, fAutoUnpark);
	}

	// Whether we have anything to do at all.
	if (pindexMostWork == nullptr \|\|
	pindexMostWork == m_chain.Tip()) {
	break;
	}

	bool fInvalidFound = false;
	std::shared_ptr<const CBlock> nullBlockPtr;
	if (!ActivateBestChainStep(
	state, pindexMostWork,
	pblock && pblock->GetHash() ==
	pindexMostWork->GetBlockHash()
	? pblock
	: nullBlockPtr,
	fInvalidFound, avalanche)) {
	// A system error occurred
	return false;
	}
	blocks_connected = true;

	if (fInvalidFound \|\|
	(pindexMostWork && pindexMostWork->nStatus.isParked())) {
	// Wipe cache, we may need another branch now.
	pindexMostWork = nullptr;
	}

	pindexNewTip = m_chain.Tip();

	// This will have been toggled in
	// ActivateBestChainStep -> ConnectTip ->
	// MaybeCompleteSnapshotValidation, if at all, so we should
	// catch it here.
	//
	// Break this do-while to ensure we don't advance past the base
	// snapshot.
	if (m_disabled) {
	break;
	}
	} while (!m_chain.Tip() \|\|
	(starting_tip && CBlockIndexWorkComparator()(
	m_chain.Tip(), starting_tip)));

	// Check the index once we're done with the above loop, since
	// we're going to release cs_main soon. If the index is in a bad
	// state now, then it's better to know immediately rather than
	// randomly have it cause a problem in a race.
	m_chainman.CheckBlockIndex();

	if (blocks_connected) {
	const CBlockIndex *pindexFork = m_chain.FindFork(starting_tip);
	bool fInitialDownload = m_chainman.IsInitialBlockDownload();

	// Notify external listeners about the new tip.
	// Enqueue while holding cs_main to ensure that UpdatedBlockTip
	// is called in the order in which blocks are connected
	if (pindexFork != pindexNewTip) {
	// Notify ValidationInterface subscribers
	GetMainSignals().UpdatedBlockTip(pindexNewTip, pindexFork,
	fInitialDownload);

	// Always notify the UI if a new block tip was connected
	m_chainman.GetNotifications().blockTip(
	GetSynchronizationState(fInitialDownload),
	*pindexNewTip);
	}
	}
	}
	// When we reach this point, we switched to a new tip (stored in
	// pindexNewTip).
	if (avalanche) {
	const CBlockIndex *pfinalized =
	WITH_LOCK(cs_avalancheFinalizedBlockIndex,
	return m_avalancheFinalizedBlockIndex);
	for (const CBlockIndex *pindex : blocksToReconcile) {
	avalanche->addToReconcile(pindex);

	// Compute staking rewards for all blocks with more chainwork to
	// just after the finalized block. We could stop at the fork
	// point, but this is more robust.
	if (blocks_connected) {
	const CBlockIndex *pindexTest = pindex;
	while (pindexTest && pindexTest != pfinalized) {
	if (pindexTest->nHeight < pindex->nHeight - 3) {
	// Only compute up to some max depth
	break;
	}
	avalanche->computeStakingReward(pindexTest);
	pindexTest = pindexTest->pprev;
	}
	}
	}
	}

	if (!blocks_connected) {
	return true;
	}

	if (nStopAtHeight && pindexNewTip &&
	pindexNewTip->nHeight >= nStopAtHeight) {
	StartShutdown();
	}

	if (WITH_LOCK(::cs_main, return m_disabled)) {
	// Background chainstate has reached the snapshot base block, so
	// exit.
	break;
	}

	// We check shutdown only after giving ActivateBestChainStep a chance to
	// run once so that we never shutdown before connecting the genesis
	// block during LoadChainTip(). Previously this caused an assert()
	// failure during shutdown in such cases as the UTXO DB flushing checks
	// that the best block hash is non-null.
	if (ShutdownRequested()) {
	break;
	}
	} while (pindexNewTip != pindexMostWork);

	// Write changes periodically to disk, after relay.
	if (!FlushStateToDisk(state, FlushStateMode::PERIODIC)) {
	return false;
	}

	return true;
	}

	bool Chainstate::PreciousBlock(BlockValidationState &state, CBlockIndex *pindex,
	avalanche::Processor *const avalanche) {
	AssertLockNotHeld(m_chainstate_mutex);
	AssertLockNotHeld(::cs_main);
	{
	LOCK(cs_main);
	if (pindex->nChainWork < m_chain.Tip()->nChainWork) {
	// Nothing to do, this block is not at the tip.
	return true;
	}

	if (m_chain.Tip()->nChainWork > m_chainman.nLastPreciousChainwork) {
	// The chain has been extended since the last call, reset the
	// counter.
	m_chainman.nBlockReverseSequenceId = -1;
	}

	m_chainman.nLastPreciousChainwork = m_chain.Tip()->nChainWork;
	setBlockIndexCandidates.erase(pindex);
	pindex->nSequenceId = m_chainman.nBlockReverseSequenceId;
	if (m_chainman.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...
	m_chainman.nBlockReverseSequenceId--;
	}

	// In case this was parked, unpark it.
	UnparkBlock(pindex);

	// Make sure it is added to the candidate list if appropriate.
	if (pindex->IsValid(BlockValidity::TRANSACTIONS) &&
	pindex->HaveNumChainTxs()) {
	setBlockIndexCandidates.insert(pindex);
	PruneBlockIndexCandidates();
	}
	}

	return ActivateBestChain(state, /pblock=/nullptr, avalanche);
	}

	namespace {
	// Leverage RAII to run a functor at scope end
	template <typename Func> struct Defer {
	Func func;
	Defer(Func &&f) : func(std::move(f)) {}
	~Defer() { func(); }
	};
	} // namespace

	bool Chainstate::UnwindBlock(BlockValidationState &state, CBlockIndex *pindex,
	bool invalidate) {
	// Genesis block can't be invalidated or parked
	assert(pindex);
	if (pindex->nHeight == 0) {
	return false;
	}

	CBlockIndex *to_mark_failed_or_parked = pindex;
	bool pindex_was_in_chain = false;
	int disconnected = 0;

	// We do not allow ActivateBestChain() to run while UnwindBlock() is
	// running, as that could cause the tip to change while we disconnect
	// blocks. (Note for backport of Core PR16849: we acquire
	// LOCK(m_chainstate_mutex) in the Park, Invalidate and FinalizeBlock
	// functions due to differences in our code)
	AssertLockHeld(m_chainstate_mutex);

	// We'll be acquiring and releasing cs_main below, to allow the validation
	// callbacks to run. However, we should keep the block index in a
	// consistent state as we disconnect blocks -- in particular we need to
	// add equal-work blocks to setBlockIndexCandidates as we disconnect.
	// To avoid walking the block index repeatedly in search of candidates,
	// build a map once so that we can look up candidate blocks by chain
	// work as we go.
	std::multimap<const arith_uint256, CBlockIndex *> candidate_blocks_by_work;

	{
	LOCK(cs_main);
	for (auto &entry : m_blockman.m_block_index) {
	CBlockIndex *candidate = &entry.second;
	// We don't need to put anything in our active chain into the
	// multimap, because those candidates will be found and considered
	// as we disconnect.
	// Instead, consider only non-active-chain blocks that have at
	// least as much work as where we expect the new tip to end up.
	if (!m_chain.Contains(candidate) &&
	!CBlockIndexWorkComparator()(candidate, pindex->pprev) &&
	candidate->IsValid(BlockValidity::TRANSACTIONS) &&
	candidate->HaveNumChainTxs()) {
	candidate_blocks_by_work.insert(
	std::make_pair(candidate->nChainWork, candidate));
	}
	}
	}

	{
	LOCK(cs_main);
	// Lock for as long as disconnectpool is in scope to make sure
	// UpdateMempoolForReorg is called after DisconnectTip without unlocking
	// in between
	LOCK(MempoolMutex());

	constexpr int maxDisconnectPoolBlocks = 10;
	bool ret = false;
	DisconnectedBlockTransactions disconnectpool;
	// After 10 blocks this becomes nullptr, so that DisconnectTip will
	// stop giving us unwound block txs if we are doing a deep unwind.
	DisconnectedBlockTransactions *optDisconnectPool = &disconnectpool;

	// Disable thread safety analysis because we can't require m_mempool->cs
	// as m_mempool can be null. We keep the runtime analysis though.
	Defer deferred([&]() NO_THREAD_SAFETY_ANALYSIS {
	AssertLockHeld(cs_main);
	if (m_mempool && !disconnectpool.isEmpty()) {
	AssertLockHeld(m_mempool->cs);
	// DisconnectTip will add transactions to disconnectpool.
	// When all unwinding is done and we are on a new tip, we must
	// add all transactions back to the mempool against the new tip.
	disconnectpool.updateMempoolForReorg(*this,
	/* fAddToMempool = */ ret,
	*m_mempool);
	}
	});

	// Disconnect (descendants of) pindex, and mark them invalid.
	while (true) {
	if (ShutdownRequested()) {
	break;
	}

	// Make sure the queue of validation callbacks doesn't grow
	// unboundedly.
	// FIXME this commented code is a regression and could cause OOM if
	// a very old block is invalidated via the invalidateblock RPC.
	// This can be uncommented if the main signals are moved away from
	// cs_main or this code is refactored so that cs_main can be
	// released at this point.
	//
	// LimitValidationInterfaceQueue();

	if (!m_chain.Contains(pindex)) {
	break;
	}

	if (m_mempool && disconnected == 0) {
	// On first iteration, we grab all the mempool txs to preserve
	// topological ordering. This has the side-effect of temporarily
	// clearing the mempool, but we will re-add later in
	// updateMempoolForReorg() (above). This technique guarantees
	// mempool consistency as well as ensures that our topological
	// entry_id index is always correct.
	disconnectpool.importMempool(*m_mempool);
	}

	pindex_was_in_chain = true;
	CBlockIndex *invalid_walk_tip = m_chain.Tip();

	// ActivateBestChain considers blocks already in m_chain
	// unconditionally valid already, so force disconnect away from it.

	ret = DisconnectTip(state, optDisconnectPool);
	++disconnected;

	if (optDisconnectPool && disconnected > maxDisconnectPoolBlocks) {
	// Stop using the disconnect pool after 10 blocks. After 10
	// blocks we no longer add block tx's to the disconnectpool.
	// However, when this scope ends we will reconcile what's
	// in the pool with the new tip (in the deferred d'tor above).
	optDisconnectPool = nullptr;
	}

	if (!ret) {
	return false;
	}

	assert(invalid_walk_tip->pprev == m_chain.Tip());

	// We immediately mark the disconnected blocks as invalid.
	// This prevents a case where pruned nodes may fail to
	// invalidateblock and be left unable to start as they have no tip
	// candidates (as there are no blocks that meet the "have data and
	// are not invalid per nStatus" criteria for inclusion in
	// setBlockIndexCandidates).

	invalid_walk_tip->nStatus =
	invalidate ? invalid_walk_tip->nStatus.withFailed()
	: invalid_walk_tip->nStatus.withParked();

	m_blockman.m_dirty_blockindex.insert(invalid_walk_tip);
	setBlockIndexCandidates.insert(invalid_walk_tip->pprev);

	if (invalid_walk_tip == to_mark_failed_or_parked->pprev &&
	(invalidate ? to_mark_failed_or_parked->nStatus.hasFailed()
	: to_mark_failed_or_parked->nStatus.isParked())) {
	// We only want to mark the last disconnected block as
	// Failed (or Parked); its children need to be FailedParent (or
	// ParkedParent) instead.
	to_mark_failed_or_parked->nStatus =
	(invalidate
	? to_mark_failed_or_parked->nStatus.withFailed(false)
	.withFailedParent()
	: to_mark_failed_or_parked->nStatus.withParked(false)
	.withParkedParent());

	m_blockman.m_dirty_blockindex.insert(to_mark_failed_or_parked);
	}

	// Add any equal or more work headers to setBlockIndexCandidates
	auto candidate_it = candidate_blocks_by_work.lower_bound(
	invalid_walk_tip->pprev->nChainWork);
	while (candidate_it != candidate_blocks_by_work.end()) {
	if (!CBlockIndexWorkComparator()(candidate_it->second,
	invalid_walk_tip->pprev)) {
	setBlockIndexCandidates.insert(candidate_it->second);
	candidate_it = candidate_blocks_by_work.erase(candidate_it);
	} else {
	++candidate_it;
	}
	}

	// Track the last disconnected block, so we can correct its
	// FailedParent (or ParkedParent) status in future iterations, or,
	// if it's the last one, call InvalidChainFound on it.
	to_mark_failed_or_parked = invalid_walk_tip;
	}
	}

	m_chainman.CheckBlockIndex();

	{
	LOCK(cs_main);
	if (m_chain.Contains(to_mark_failed_or_parked)) {
	// If the to-be-marked invalid block is in the active chain,
	// something is interfering and we can't proceed.
	return false;
	}

	// Mark pindex (or the last disconnected block) as invalid (or parked),
	// even when it never was in the main chain.
	to_mark_failed_or_parked->nStatus =
	invalidate ? to_mark_failed_or_parked->nStatus.withFailed()
	: to_mark_failed_or_parked->nStatus.withParked();
	m_blockman.m_dirty_blockindex.insert(to_mark_failed_or_parked);
	if (invalidate) {
	m_chainman.m_failed_blocks.insert(to_mark_failed_or_parked);
	}

	// If any new blocks somehow arrived while we were disconnecting
	// (above), then the pre-calculation of what should go into
	// setBlockIndexCandidates may have missed entries. This would
	// technically be an inconsistency in the block index, but if we clean
	// it up here, this should be an essentially unobservable error.
	// Loop back over all block index entries and add any missing entries
	// to setBlockIndexCandidates.
	for (auto &[_, block_index] : m_blockman.m_block_index) {
	if (block_index.IsValid(BlockValidity::TRANSACTIONS) &&
	block_index.HaveNumChainTxs() &&
	!setBlockIndexCandidates.value_comp()(&block_index,
	m_chain.Tip())) {
	setBlockIndexCandidates.insert(&block_index);
	}
	}

	if (invalidate) {
	InvalidChainFound(to_mark_failed_or_parked);
	}
	}

	// Only notify about a new block tip if the active chain was modified.
	if (pindex_was_in_chain) {
	m_chainman.GetNotifications().blockTip(
	GetSynchronizationState(m_chainman.IsInitialBlockDownload()),
	*to_mark_failed_or_parked->pprev);
	}
	return true;
	}

	bool Chainstate::InvalidateBlock(BlockValidationState &state,
	CBlockIndex *pindex) {
	AssertLockNotHeld(m_chainstate_mutex);
	AssertLockNotHeld(::cs_main);
	// See 'Note for backport of Core PR16849' in Chainstate::UnwindBlock
	LOCK(m_chainstate_mutex);

	return UnwindBlock(state, pindex, true);
	}

	bool Chainstate::ParkBlock(BlockValidationState &state, CBlockIndex *pindex) {
	AssertLockNotHeld(m_chainstate_mutex);
	AssertLockNotHeld(::cs_main);
	// See 'Note for backport of Core PR16849' in Chainstate::UnwindBlock
	LOCK(m_chainstate_mutex);

	return UnwindBlock(state, pindex, false);
	}

	template <typename F>
	bool Chainstate::UpdateFlagsForBlock(CBlockIndex *pindexBase,
	CBlockIndex *pindex, F f) {
	BlockStatus newStatus = f(pindex->nStatus);
	if (pindex->nStatus != newStatus &&
	(!pindexBase \|\|
	pindex->GetAncestor(pindexBase->nHeight) == pindexBase)) {
	pindex->nStatus = newStatus;
	m_blockman.m_dirty_blockindex.insert(pindex);
	if (newStatus.isValid()) {
	m_chainman.m_failed_blocks.erase(pindex);
	}

	if (pindex->IsValid(BlockValidity::TRANSACTIONS) &&
	pindex->HaveNumChainTxs() &&
	setBlockIndexCandidates.value_comp()(m_chain.Tip(), pindex)) {
	setBlockIndexCandidates.insert(pindex);
	}
	return true;
	}
	return false;
	}

	template <typename F, typename C, typename AC>
	void Chainstate::UpdateFlags(CBlockIndex pindex, CBlockIndex &pindexReset,
	F f, C fChild, AC fAncestorWasChanged) {
	AssertLockHeld(cs_main);

	// Update the current block and ancestors; while we're doing this, identify
	// which was the deepest ancestor we changed.
	CBlockIndex *pindexDeepestChanged = pindex;
	for (auto pindexAncestor = pindex; pindexAncestor != nullptr;
	pindexAncestor = pindexAncestor->pprev) {
	if (UpdateFlagsForBlock(nullptr, pindexAncestor, f)) {
	pindexDeepestChanged = pindexAncestor;
	}
	}

	if (pindexReset &&
	pindexReset->GetAncestor(pindexDeepestChanged->nHeight) ==
	pindexDeepestChanged) {
	// reset pindexReset if it had a modified ancestor.
	pindexReset = nullptr;
	}

	// Update all blocks under modified blocks.
	for (auto &[_, block_index] : m_blockman.m_block_index) {
	UpdateFlagsForBlock(pindex, &block_index, fChild);
	UpdateFlagsForBlock(pindexDeepestChanged, &block_index,
	fAncestorWasChanged);
	}
	}

	void Chainstate::ResetBlockFailureFlags(CBlockIndex *pindex) {
	AssertLockHeld(cs_main);

	UpdateFlags(
	pindex, m_chainman.m_best_invalid,
	[](const BlockStatus status) {
	return status.withClearedFailureFlags();
	},
	[](const BlockStatus status) {
	return status.withClearedFailureFlags();
	},
	[](const BlockStatus status) {
	return status.withFailedParent(false);
	});
	}

	void Chainstate::TryAddBlockIndexCandidate(CBlockIndex *pindex) {
	AssertLockHeld(cs_main);
	// The block only is a candidate for the most-work-chain if it has the same
	// or more work than our current tip.
	if (m_chain.Tip() != nullptr &&
	setBlockIndexCandidates.value_comp()(pindex, m_chain.Tip())) {
	return;
	}

	bool is_active_chainstate = this == &m_chainman.ActiveChainstate();
	if (is_active_chainstate) {
	// The active chainstate should always add entries that have more
	// work than the tip.
	setBlockIndexCandidates.insert(pindex);
	} else if (!m_disabled) {
	// For the background chainstate, we only consider connecting blocks
	// towards the snapshot base (which can't be nullptr or else we'll
	// never make progress).
	const CBlockIndex *snapshot_base{
	Assert(m_chainman.GetSnapshotBaseBlock())};
	if (snapshot_base->GetAncestor(pindex->nHeight) == pindex) {
	setBlockIndexCandidates.insert(pindex);
	}
	}
	}

	void Chainstate::UnparkBlockImpl(CBlockIndex *pindex, bool fClearChildren) {
	AssertLockHeld(cs_main);

	UpdateFlags(
	pindex, m_chainman.m_best_parked,
	[](const BlockStatus status) {
	return status.withClearedParkedFlags();
	},
	[fClearChildren](const BlockStatus status) {
	return fClearChildren ? status.withClearedParkedFlags()
	: status.withParkedParent(false);
	},
	[](const BlockStatus status) {
	return status.withParkedParent(false);
	});
	}

	void Chainstate::UnparkBlockAndChildren(CBlockIndex *pindex) {
	return UnparkBlockImpl(pindex, true);
	}

	void Chainstate::UnparkBlock(CBlockIndex *pindex) {
	return UnparkBlockImpl(pindex, false);
	}

	bool Chainstate::AvalancheFinalizeBlock(CBlockIndex *pindex,
	avalanche::Processor &avalanche) {
	if (!pindex) {
	return false;
	}

	if (!m_chain.Contains(pindex)) {
	LogPrint(BCLog::AVALANCHE,
	"The block to mark finalized by avalanche is not on the "
	"active chain: %s\n",
	pindex->GetBlockHash().ToString());
	return false;
	}

	avalanche.cleanupStakingRewards(pindex->nHeight);

	if (IsBlockAvalancheFinalized(pindex)) {
	return true;
	}

	{
	LOCK(cs_avalancheFinalizedBlockIndex);
	m_avalancheFinalizedBlockIndex = pindex;
	}

	WITH_LOCK(cs_main, GetMainSignals().BlockFinalized(pindex));

	return true;
	}

	void Chainstate::ClearAvalancheFinalizedBlock() {
	LOCK(cs_avalancheFinalizedBlockIndex);
	m_avalancheFinalizedBlockIndex = nullptr;
	}

	bool Chainstate::IsBlockAvalancheFinalized(const CBlockIndex *pindex) const {
	LOCK(cs_avalancheFinalizedBlockIndex);
	return pindex && m_avalancheFinalizedBlockIndex &&
	m_avalancheFinalizedBlockIndex->GetAncestor(pindex->nHeight) ==
	pindex;
	}

	/**
	* Mark a block as having its data received and checked (up to
	* BLOCK_VALID_TRANSACTIONS).
	*/
	void ChainstateManager::ReceivedBlockTransactions(const CBlock &block,
	CBlockIndex *pindexNew,
	const FlatFilePos &pos) {
	pindexNew->nTx = block.vtx.size();
	pindexNew->MaybeResetChainStats(pindexNew == GetSnapshotBaseBlock());
	pindexNew->nSize = ::GetSerializeSize(block, PROTOCOL_VERSION);
	pindexNew->nFile = pos.nFile;
	pindexNew->nDataPos = pos.nPos;
	pindexNew->nUndoPos = 0;
	pindexNew->nStatus = pindexNew->nStatus.withData();
	pindexNew->RaiseValidity(BlockValidity::TRANSACTIONS);
	m_blockman.m_dirty_blockindex.insert(pindexNew);

	if (pindexNew->UpdateChainStats()) {
	// If pindexNew is the genesis block or all parents are
	// BLOCK_VALID_TRANSACTIONS.
	std::deque<CBlockIndex *> queue;
	queue.push_back(pindexNew);

	// Recursively process any descendant blocks that now may be eligible to
	// be connected.
	while (!queue.empty()) {
	CBlockIndex *pindex = queue.front();
	queue.pop_front();
	pindex->UpdateChainStats();
	if (pindex->nSequenceId == 0) {
	// We assign a sequence is when transaction are received to
	// prevent a miner from being able to broadcast a block but not
	// its content. However, a sequence id may have been set
	// manually, for instance via PreciousBlock, in which case, we
	// don't need to assign one.
	pindex->nSequenceId = nBlockSequenceId++;
	}
	for (Chainstate *c : GetAll()) {
	c->TryAddBlockIndexCandidate(pindex);
	}

	std::pair<std::multimap<CBlockIndex , CBlockIndex >::iterator,
	std::multimap<CBlockIndex , CBlockIndex >::iterator>
	range = m_blockman.m_blocks_unlinked.equal_range(pindex);
	while (range.first != range.second) {
	std::multimap<CBlockIndex , CBlockIndex >::iterator it =
	range.first;
	queue.push_back(it->second);
	range.first++;
	m_blockman.m_blocks_unlinked.erase(it);
	}
	}
	} else if (pindexNew->pprev &&
	pindexNew->pprev->IsValid(BlockValidity::TREE)) {
	m_blockman.m_blocks_unlinked.insert(
	std::make_pair(pindexNew->pprev, pindexNew));
	}
	}

	/**
	* Return true if the provided block header is valid.
	* Only verify PoW if blockValidationOptions is configured to do so.
	* This allows validation of headers on which the PoW hasn't been done.
	* For example: to validate template handed to mining software.
	* Do not call this for any check that depends on the context.
	* For context-dependent calls, see ContextualCheckBlockHeader.
	*/
	static bool CheckBlockHeader(const CBlockHeader &block,
	BlockValidationState &state,
	const Consensus::Params &params,
	BlockValidationOptions validationOptions) {
	// Check proof of work matches claimed amount
	if (validationOptions.shouldValidatePoW() &&
	!CheckProofOfWork(block.GetHash(), block.nBits, params)) {
	return state.Invalid(BlockValidationResult::BLOCK_INVALID_HEADER,
	"high-hash", "proof of work failed");
	}

	return true;
	}

	bool CheckBlock(const CBlock &block, BlockValidationState &state,
	const Consensus::Params &params,
	BlockValidationOptions validationOptions) {
	// These are checks that are independent of context.
	if (block.fChecked) {
	return true;
	}

	// Check that the header is valid (particularly PoW). This is mostly
	// redundant with the call in AcceptBlockHeader.
	if (!CheckBlockHeader(block, state, params, validationOptions)) {
	return false;
	}

	// Check the merkle root.
	if (validationOptions.shouldValidateMerkleRoot()) {
	bool mutated;
	uint256 hashMerkleRoot2 = BlockMerkleRoot(block, &mutated);
	if (block.hashMerkleRoot != hashMerkleRoot2) {
	return state.Invalid(BlockValidationResult::BLOCK_MUTATED,
	"bad-txnmrklroot", "hashMerkleRoot mismatch");
	}

	// Check for merkle tree malleability (CVE-2012-2459): repeating
	// sequences of transactions in a block without affecting the merkle
	// root of a block, while still invalidating it.
	if (mutated) {
	return state.Invalid(BlockValidationResult::BLOCK_MUTATED,
	"bad-txns-duplicate", "duplicate transaction");
	}
	}

	// All potential-corruption validation must be done before we do any
	// transaction validation, as otherwise we may mark the header as invalid
	// because we receive the wrong transactions for it.

	// First transaction must be coinbase.
	if (block.vtx.empty()) {
	return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
	"bad-cb-missing", "first tx is not coinbase");
	}

	// Size limits.
	auto nMaxBlockSize = validationOptions.getExcessiveBlockSize();

	// Bail early if there is no way this block is of reasonable size.
	if ((block.vtx.size() * MIN_TRANSACTION_SIZE) > nMaxBlockSize) {
	return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
	"bad-blk-length", "size limits failed");
	}

	auto currentBlockSize = ::GetSerializeSize(block, PROTOCOL_VERSION);
	if (currentBlockSize > nMaxBlockSize) {
	return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
	"bad-blk-length", "size limits failed");
	}

	// And a valid coinbase.
	TxValidationState tx_state;
	if (!CheckCoinbase(*block.vtx[0], tx_state)) {
	return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
	tx_state.GetRejectReason(),
	strprintf("Coinbase check failed (txid %s) %s",
	block.vtx[0]->GetId().ToString(),
	tx_state.GetDebugMessage()));
	}

	// Check transactions for regularity, skipping the first. Note that this
	// is the first time we check that all after the first are !IsCoinBase.
	for (size_t i = 1; i < block.vtx.size(); i++) {
	auto *tx = block.vtx[i].get();
	if (!CheckRegularTransaction(*tx, tx_state)) {
	return state.Invalid(
	BlockValidationResult::BLOCK_CONSENSUS,
	tx_state.GetRejectReason(),
	strprintf("Transaction check failed (txid %s) %s",
	tx->GetId().ToString(), tx_state.GetDebugMessage()));
	}
	}

	if (validationOptions.shouldValidatePoW() &&
	validationOptions.shouldValidateMerkleRoot()) {
	block.fChecked = true;
	}

	return true;
	}

	bool HasValidProofOfWork(const std::vector<CBlockHeader> &headers,
	const Consensus::Params &consensusParams) {
	return std::all_of(headers.cbegin(), headers.cend(),
	[&](const auto &header) {
	return CheckProofOfWork(
	header.GetHash(), header.nBits, consensusParams);
	});
	}

	arith_uint256 CalculateHeadersWork(const std::vector<CBlockHeader> &headers) {
	arith_uint256 total_work{0};
	for (const CBlockHeader &header : headers) {
	CBlockIndex dummy(header);
	total_work += GetBlockProof(dummy);
	}
	return total_work;
	}

	/**
	* Context-dependent validity checks.
	* By "context", we mean only the previous block headers, but not the UTXO
	* set; UTXO-related validity checks are done in ConnectBlock().
	* NOTE: This function is not currently invoked by ConnectBlock(), so we
	* should consider upgrade issues if we change which consensus rules are
	* enforced in this function (eg by adding a new consensus rule). See comment
	* in ConnectBlock().
	* Note that -reindex-chainstate skips the validation that happens here!
	*/
	static bool ContextualCheckBlockHeader(
	const CBlockHeader &block, BlockValidationState &state,
	BlockManager &blockman, ChainstateManager &chainman,
	const CBlockIndex *pindexPrev, NodeClock::time_point now,
	const std::optional<CCheckpointData> &test_checkpoints = std::nullopt)
	EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
	AssertLockHeld(::cs_main);
	assert(pindexPrev != nullptr);
	const int nHeight = pindexPrev->nHeight + 1;

	const CChainParams &params = chainman.GetParams();

	// Check proof of work
	if (block.nBits != GetNextWorkRequired(pindexPrev, &block, params)) {
	LogPrintf("bad bits after height: %d\n", pindexPrev->nHeight);
	return state.Invalid(BlockValidationResult::BLOCK_INVALID_HEADER,
	"bad-diffbits", "incorrect proof of work");
	}

	// Check against checkpoints
	if (chainman.m_options.checkpoints_enabled) {
	const CCheckpointData &checkpoints =
	test_checkpoints ? test_checkpoints.value() : params.Checkpoints();

	// Check that the block chain matches the known block chain up to a
	// checkpoint.
	if (!Checkpoints::CheckBlock(checkpoints, nHeight, block.GetHash())) {
	LogPrint(BCLog::VALIDATION,
	"ERROR: %s: rejected by checkpoint lock-in at %d\n",
	__func__, nHeight);
	return state.Invalid(BlockValidationResult::BLOCK_CHECKPOINT,
	"checkpoint mismatch");
	}

	// Don't accept any forks from the main chain prior to last checkpoint.
	// GetLastCheckpoint finds the last checkpoint in MapCheckpoints that's
	// in our BlockIndex().

	const CBlockIndex *pcheckpoint =
	blockman.GetLastCheckpoint(checkpoints);
	if (pcheckpoint && nHeight < pcheckpoint->nHeight) {
	LogPrint(BCLog::VALIDATION,
	"ERROR: %s: forked chain older than last checkpoint "
	"(height %d)\n",
	__func__, nHeight);
	return state.Invalid(BlockValidationResult::BLOCK_CHECKPOINT,
	"bad-fork-prior-to-checkpoint");
	}
	}

	// Check timestamp against prev
	if (block.GetBlockTime() <= pindexPrev->GetMedianTimePast()) {
	return state.Invalid(BlockValidationResult::BLOCK_INVALID_HEADER,
	"time-too-old", "block's timestamp is too early");
	}

	// Check timestamp
	if (block.Time() > now + std::chrono::seconds{MAX_FUTURE_BLOCK_TIME}) {
	return state.Invalid(BlockValidationResult::BLOCK_TIME_FUTURE,
	"time-too-new",
	"block timestamp too far in the future");
	}

	// Reject blocks with outdated version
	if ((block.nVersion < 2 &&
	DeploymentActiveAfter(pindexPrev, chainman,
	Consensus::DEPLOYMENT_HEIGHTINCB)) \|\|
	(block.nVersion < 3 &&
	DeploymentActiveAfter(pindexPrev, chainman,
	Consensus::DEPLOYMENT_DERSIG)) \|\|
	(block.nVersion < 4 &&
	DeploymentActiveAfter(pindexPrev, chainman,
	Consensus::DEPLOYMENT_CLTV))) {
	return state.Invalid(
	BlockValidationResult::BLOCK_INVALID_HEADER,
	strprintf("bad-version(0x%08x)", block.nVersion),
	strprintf("rejected nVersion=0x%08x block", block.nVersion));
	}

	return true;
	}

	bool ContextualCheckTransactionForCurrentBlock(
	const CBlockIndex &active_chain_tip, const Consensus::Params &params,
	const CTransaction &tx, TxValidationState &state) {
	AssertLockHeld(cs_main);

	// ContextualCheckTransactionForCurrentBlock() uses
	// active_chain_tip.Height()+1 to evaluate nLockTime because when
	// IsFinalTx() is called within 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
	// active_chain_tip.Height().
	const int nBlockHeight = active_chain_tip.nHeight + 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().
	// This time can also be used for consensus upgrades.
	const int64_t nMedianTimePast{active_chain_tip.GetMedianTimePast()};

	return ContextualCheckTransaction(params, tx, state, nBlockHeight,
	nMedianTimePast);
	}

	/**
	* NOTE: This function is not currently invoked by ConnectBlock(), so we
	* should consider upgrade issues if we change which consensus rules are
	* enforced in this function (eg by adding a new consensus rule). See comment
	* in ConnectBlock().
	* Note that -reindex-chainstate skips the validation that happens here!
	*/
	static bool ContextualCheckBlock(const CBlock &block,
	BlockValidationState &state,
	const ChainstateManager &chainman,
	const CBlockIndex *pindexPrev) {
	const int nHeight = pindexPrev == nullptr ? 0 : pindexPrev->nHeight + 1;

	// Enforce BIP113 (Median Time Past).
	bool enforce_locktime_median_time_past{false};
	if (DeploymentActiveAfter(pindexPrev, chainman,
	Consensus::DEPLOYMENT_CSV)) {
	assert(pindexPrev != nullptr);
	enforce_locktime_median_time_past = true;
	}

	const int64_t nMedianTimePast =
	pindexPrev == nullptr ? 0 : pindexPrev->GetMedianTimePast();

	const int64_t nLockTimeCutoff{enforce_locktime_median_time_past
	? nMedianTimePast
	: block.GetBlockTime()};

	const Consensus::Params params = chainman.GetConsensus();
	const bool fIsMagneticAnomalyEnabled =
	IsMagneticAnomalyEnabled(params, pindexPrev);

	// Check transactions:
	// - canonical ordering
	// - ensure they are finalized
	// - check they have the minimum size
	const CTransaction *prevTx = nullptr;
	for (const auto &ptx : block.vtx) {
	const CTransaction &tx = *ptx;
	if (fIsMagneticAnomalyEnabled) {
	if (prevTx && (tx.GetId() <= prevTx->GetId())) {
	if (tx.GetId() == prevTx->GetId()) {
	return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
	"tx-duplicate",
	strprintf("Duplicated transaction %s",
	tx.GetId().ToString()));
	}

	return state.Invalid(
	BlockValidationResult::BLOCK_CONSENSUS, "tx-ordering",
	strprintf("Transaction order is invalid (%s < %s)",
	tx.GetId().ToString(),
	prevTx->GetId().ToString()));
	}

	if (prevTx \|\| !tx.IsCoinBase()) {
	prevTx = &tx;
	}
	}

	TxValidationState tx_state;
	if (!ContextualCheckTransaction(params, tx, tx_state, nHeight,
	nLockTimeCutoff)) {
	return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
	tx_state.GetRejectReason(),
	tx_state.GetDebugMessage());
	}
	}

	// Enforce rule that the coinbase starts with serialized block height
	if (DeploymentActiveAfter(pindexPrev, chainman,
	Consensus::DEPLOYMENT_HEIGHTINCB)) {
	CScript expect = CScript() << nHeight;
	if (block.vtx[0]->vin[0].scriptSig.size() < expect.size() \|\|
	!std::equal(expect.begin(), expect.end(),
	block.vtx[0]->vin[0].scriptSig.begin())) {
	return state.Invalid(BlockValidationResult::BLOCK_CONSENSUS,
	"bad-cb-height",
	"block height mismatch in coinbase");
	}
	}

	return true;
	}

	/**
	* If the provided block header is valid, add it to the block index.
	*
	* Returns true if the block is successfully added to the block index.
	*/
	bool ChainstateManager::AcceptBlockHeader(
	const CBlockHeader &block, BlockValidationState &state,
	CBlockIndex **ppindex, bool min_pow_checked,
	const std::optional<CCheckpointData> &test_checkpoints) {
	AssertLockHeld(cs_main);
	const Config &config = this->GetConfig();
	const CChainParams &chainparams = config.GetChainParams();

	// Check for duplicate
	BlockHash hash = block.GetHash();
	BlockMap::iterator miSelf{m_blockman.m_block_index.find(hash)};
	if (hash != chainparams.GetConsensus().hashGenesisBlock) {
	if (miSelf != m_blockman.m_block_index.end()) {
	// Block header is already known.
	CBlockIndex *pindex = &(miSelf->second);
	if (ppindex) {
	*ppindex = pindex;
	}

	if (pindex->nStatus.isInvalid()) {
	LogPrint(BCLog::VALIDATION, "%s: block %s is marked invalid\n",
	__func__, hash.ToString());
	return state.Invalid(
	BlockValidationResult::BLOCK_CACHED_INVALID, "duplicate");
	}

	return true;
	}

	if (!CheckBlockHeader(block, state, chainparams.GetConsensus(),
	BlockValidationOptions(config))) {
	LogPrint(BCLog::VALIDATION,
	"%s: Consensus::CheckBlockHeader: %s, %s\n", __func__,
	hash.ToString(), state.ToString());
	return false;
	}

	// Get prev block index
	BlockMap::iterator mi{
	m_blockman.m_block_index.find(block.hashPrevBlock)};
	if (mi == m_blockman.m_block_index.end()) {
	LogPrint(BCLog::VALIDATION,
	"header %s has prev block not found: %s\n",
	hash.ToString(), block.hashPrevBlock.ToString());
	return state.Invalid(BlockValidationResult::BLOCK_MISSING_PREV,
	"prev-blk-not-found");
	}

	CBlockIndex pindexPrev = &((mi).second);
	assert(pindexPrev);
	if (pindexPrev->nStatus.isInvalid()) {
	LogPrint(BCLog::VALIDATION,
	"header %s has prev block invalid: %s\n", hash.ToString(),
	block.hashPrevBlock.ToString());
	return state.Invalid(BlockValidationResult::BLOCK_INVALID_PREV,
	"bad-prevblk");
	}

	if (!ContextualCheckBlockHeader(
	block, state, m_blockman, *this, pindexPrev,
	m_options.adjusted_time_callback(), test_checkpoints)) {
	LogPrint(BCLog::VALIDATION,
	"%s: Consensus::ContextualCheckBlockHeader: %s, %s\n",
	__func__, hash.ToString(), state.ToString());
	return false;
	}

	/* Determine if this block descends from any block which has been found
	* invalid (m_failed_blocks), then mark pindexPrev and any blocks
	* between them as failed. For example:
	*
	* D3
	* /
	* B2 - C2
	* / \
	* A D2 - E2 - F2
	* \
	* B1 - C1 - D1 - E1
	*
	* In the case that we attempted to reorg from E1 to F2, only to find
	* C2 to be invalid, we would mark D2, E2, and F2 as BLOCK_FAILED_CHILD
	* but NOT D3 (it was not in any of our candidate sets at the time).
	*
	* In any case D3 will also be marked as BLOCK_FAILED_CHILD at restart
	* in LoadBlockIndex.
	*/
	if (!pindexPrev->IsValid(BlockValidity::SCRIPTS)) {
	// The above does not mean "invalid": it checks if the previous
	// block hasn't been validated up to BlockValidity::SCRIPTS. This is
	// a performance optimization, in the common case of adding a new
	// block to the tip, we don't need to iterate over the failed blocks
	// list.
	for (const CBlockIndex *failedit : m_failed_blocks) {
	if (pindexPrev->GetAncestor(failedit->nHeight) == failedit) {
	assert(failedit->nStatus.hasFailed());
	CBlockIndex *invalid_walk = pindexPrev;
	while (invalid_walk != failedit) {
	invalid_walk->nStatus =
	invalid_walk->nStatus.withFailedParent();
	m_blockman.m_dirty_blockindex.insert(invalid_walk);
	invalid_walk = invalid_walk->pprev;
	}
	LogPrint(BCLog::VALIDATION,
	"header %s has prev block invalid: %s\n",
	hash.ToString(), block.hashPrevBlock.ToString());
	return state.Invalid(
	BlockValidationResult::BLOCK_INVALID_PREV,
	"bad-prevblk");
	}
	}
	}
	}
	if (!min_pow_checked) {
	LogPrint(BCLog::VALIDATION,
	"%s: not adding new block header %s, missing anti-dos "
	"proof-of-work validation\n",
	__func__, hash.ToString());
	return state.Invalid(BlockValidationResult::BLOCK_HEADER_LOW_WORK,
	"too-little-chainwork");
	}
	CBlockIndex *pindex{m_blockman.AddToBlockIndex(block, m_best_header)};

	if (ppindex) {
	*ppindex = pindex;
	}

	// Since this is the earliest point at which we have determined that a
	// header is both new and valid, log here.
	//
	// These messages are valuable for detecting potential selfish mining
	// behavior; if multiple displacing headers are seen near simultaneously
	// across many nodes in the network, this might be an indication of selfish
	// mining. Having this log by default when not in IBD ensures broad
	// availability of this data in case investigation is merited.
	const auto msg = strprintf("Saw new header hash=%s height=%d",
	hash.ToString(), pindex->nHeight);

	if (IsInitialBlockDownload()) {
	LogPrintLevel(BCLog::VALIDATION, BCLog::Level::Debug, "%s\n", msg);
	} else {
	LogPrintf("%s\n", msg);
	}

	return true;
	}

	// Exposed wrapper for AcceptBlockHeader
	bool ChainstateManager::ProcessNewBlockHeaders(
	const std::vector<CBlockHeader> &headers, bool min_pow_checked,
	BlockValidationState &state, const CBlockIndex **ppindex,
	const std::optional<CCheckpointData> &test_checkpoints) {
	AssertLockNotHeld(cs_main);
	{
	LOCK(cs_main);
	for (const CBlockHeader &header : headers) {
	// Use a temp pindex instead of ppindex to avoid a const_cast
	CBlockIndex *pindex = nullptr;
	bool accepted = AcceptBlockHeader(
	header, state, &pindex, min_pow_checked, test_checkpoints);
	CheckBlockIndex();

	if (!accepted) {
	return false;
	}

	if (ppindex) {
	*ppindex = pindex;
	}
	}
	}

	if (NotifyHeaderTip(*this)) {
	if (IsInitialBlockDownload() && ppindex && *ppindex) {
	const CBlockIndex &last_accepted{**ppindex};
	const int64_t blocks_left{
	(GetTime() - last_accepted.GetBlockTime()) /
	this->GetConsensus().nPowTargetSpacing};
	const double progress{100.0 * last_accepted.nHeight /
	(last_accepted.nHeight + blocks_left)};
	LogPrintf("Synchronizing blockheaders, height: %d (~%.2f%%)\n",
	last_accepted.nHeight, progress);
	}
	}
	return true;
	}

	void ChainstateManager::ReportHeadersPresync(const arith_uint256 &work,
	int64_t height,
	int64_t timestamp) {
	AssertLockNotHeld(cs_main);
	{
	LOCK(cs_main);
	// Don't report headers presync progress if we already have a
	// post-minchainwork header chain.
	// This means we lose reporting for potentially legimate, but unlikely,
	// deep reorgs, but prevent attackers that spam low-work headers from
	// filling our logs.
	if (m_best_header->nChainWork >=
	UintToArith256(GetConsensus().nMinimumChainWork)) {
	return;
	}
	// Rate limit headers presync updates to 4 per second, as these are not
	// subject to DoS protection.
	auto now = Now<SteadyMilliseconds>();
	if (now < m_last_presync_update + 250ms) {
	return;
	}
	m_last_presync_update = now;
	}
	bool initial_download = IsInitialBlockDownload();
	GetNotifications().headerTip(GetSynchronizationState(initial_download),
	height, timestamp, /presync=/true);
	if (initial_download) {
	const int64_t blocks_left{(GetTime() - timestamp) /
	GetConsensus().nPowTargetSpacing};
	const double progress{100.0 * height / (height + blocks_left)};
	LogPrintf("Pre-synchronizing blockheaders, height: %d (~%.2f%%)\n",
	height, progress);
	}
	}

	bool ChainstateManager::AcceptBlock(const std::shared_ptr<const CBlock> &pblock,
	BlockValidationState &state,
	bool fRequested, const FlatFilePos *dbp,
	bool *fNewBlock, bool min_pow_checked) {
	AssertLockHeld(cs_main);

	const CBlock &block = *pblock;
	if (fNewBlock) {
	*fNewBlock = false;
	}

	CBlockIndex *pindex = nullptr;

	bool accepted_header{
	AcceptBlockHeader(block, state, &pindex, min_pow_checked)};
	CheckBlockIndex();

	if (!accepted_header) {
	return false;
	}

	// Check all requested blocks that we do not already have for validity and
	// save them to disk. Skip processing of unrequested blocks as an anti-DoS
	// measure, unless the blocks have more work than the active chain tip, and
	// aren't too far ahead of it, so are likely to be attached soon.
	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 =
	ActiveTip() ? std::llabs(ActiveTip()->GetReceivedTimeDiff()) : 0;

	bool isSameHeight =
	ActiveTip() && (pindex->nChainWork == ActiveTip()->nChainWork);
	if (isSameHeight) {
	LogPrintf("Chain tip timestamp-to-received-time difference: hash=%s, "
	"diff=%d\n",
	ActiveTip()->GetBlockHash().ToString(), chainTipTimeDiff);
	LogPrintf("New block timestamp-to-received-time difference: hash=%s, "
	"diff=%d\n",
	pindex->GetBlockHash().ToString(), newBlockTimeDiff);
	}

	bool fHasMoreOrSameWork =
	(ActiveTip() ? pindex->nChainWork >= ActiveTip()->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 >
	ActiveHeight() + int(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.
	// Note that this would break the getblockfrompeer RPC

	// 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 < MinimumChainWork()) {
	return true;
	}
	}

	if (!CheckBlock(block, state,
	m_options.config.GetChainParams().GetConsensus(),
	BlockValidationOptions(m_options.config)) \|\|
	!ContextualCheckBlock(block, state, *this, pindex->pprev)) {
	if (state.IsInvalid() &&
	state.GetResult() != BlockValidationResult::BLOCK_MUTATED) {
	pindex->nStatus = pindex->nStatus.withFailed();
	m_blockman.m_dirty_blockindex.insert(pindex);
	}

	return error("%s: %s (block %s)", __func__, state.ToString(),
	block.GetHash().ToString());
	}

	// If connecting the new block would require rewinding more than one block
	// from the active chain (i.e., a "deep reorg"), then mark the new block as
	// parked. If it has enough work then it will be automatically unparked
	// later, during FindMostWorkChain. We mark the block as parked at the very
	// last minute so we can make sure everything is ready to be reorged if
	// needed.
	if (gArgs.GetBoolArg("-parkdeepreorg", true)) {
	+ // Blocks that are below the snapshot height can't cause reorgs, as the
	+ // active tip is at least thousands of blocks higher. Don't park them,
	+ // they will most likely connect on the tip of the background chain.
	+ std::optional<int> snapshot_base_height = GetSnapshotBaseHeight();
	+ const bool is_background_block =
	+ snapshot_base_height && BackgroundSyncInProgress() &&
	+ pindex->nHeight <= snapshot_base_height;
	const CBlockIndex *pindexFork = ActiveChain().FindFork(pindex);
	- if (pindexFork && pindexFork->nHeight + 1 < ActiveHeight()) {
	+ if (!is_background_block && pindexFork &&
	+ pindexFork->nHeight + 1 < ActiveHeight()) {
	LogPrintf("Park block %s as it would cause a deep reorg.\n",
	pindex->GetBlockHash().ToString());
	pindex->nStatus = pindex->nStatus.withParked();
	m_blockman.m_dirty_blockindex.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() && ActiveTip() == pindex->pprev) {
	GetMainSignals().NewPoWValidBlock(pindex, pblock);
	}

	// Write block to history file
	if (fNewBlock) {
	*fNewBlock = true;
	}
	try {
	FlatFilePos blockPos{
	m_blockman.SaveBlockToDisk(block, pindex->nHeight, dbp)};
	if (blockPos.IsNull()) {
	state.Error(strprintf(
	"%s: Failed to find position to write new block to disk",
	__func__));
	return false;
	}
	ReceivedBlockTransactions(block, pindex, blockPos);
	} catch (const std::runtime_error &e) {
	return AbortNode(state, std::string("System error: ") + e.what());
	}

	// TODO: FlushStateToDisk() handles flushing of both block and chainstate
	// data, so we should move this to ChainstateManager so that we can be more
	// intelligent about how we flush.
	// For now, since FlushStateMode::NONE is used, all that can happen is that
	// the block files may be pruned, so we can just call this on one
	// chainstate (particularly if we haven't implemented pruning with
	// background validation yet).
	ActiveChainstate().FlushStateToDisk(state, FlushStateMode::NONE);

	CheckBlockIndex();

	return true;
	}

	bool ChainstateManager::ProcessNewBlock(
	const std::shared_ptr<const CBlock> &block, bool force_processing,
	bool min_pow_checked, bool *new_block,
	avalanche::Processor *const avalanche) {
	AssertLockNotHeld(cs_main);

	{
	if (new_block) {
	*new_block = false;
	}

	BlockValidationState state;

	// CheckBlock() does not support multi-threaded block validation
	// because CBlock::fChecked can cause data race.
	// Therefore, the following critical section must include the
	// CheckBlock() call as well.
	LOCK(cs_main);

	// Skipping AcceptBlock() for CheckBlock() failures means that we will
	// never mark a block as invalid if CheckBlock() fails. This is
	// protective against consensus failure if there are any unknown form
	// s of block malleability that cause CheckBlock() to fail; see e.g.
	// CVE-2012-2459 and
	// https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2019-February/016697.html.
	// Because CheckBlock() is not very expensive, the anti-DoS benefits of
	// caching failure (of a definitely-invalid block) are not substantial.
	bool ret = CheckBlock(*block, state, this->GetConsensus(),
	BlockValidationOptions(this->GetConfig()));
	if (ret) {
	// Store to disk
	ret = AcceptBlock(block, state, force_processing, nullptr,
	new_block, min_pow_checked);
	}

	if (!ret) {
	GetMainSignals().BlockChecked(*block, state);
	return error("%s: AcceptBlock FAILED (%s)", __func__,
	state.ToString());
	}
	}

	NotifyHeaderTip(*this);

	// Only used to report errors, not invalidity - ignore it
	BlockValidationState state;
	if (!ActiveChainstate().ActivateBestChain(state, block, avalanche)) {
	return error("%s: ActivateBestChain failed (%s)", __func__,
	state.ToString());
	}

	Chainstate *bg_chain{WITH_LOCK(cs_main, return BackgroundSyncInProgress()
	? m_ibd_chainstate.get()
	: nullptr)};
	BlockValidationState bg_state;
	if (bg_chain && !bg_chain->ActivateBestChain(bg_state, block)) {
	return error("%s: [background] ActivateBestChain failed (%s)", __func__,
	bg_state.ToString());
	}

	return true;
	}

	MempoolAcceptResult
	ChainstateManager::ProcessTransaction(const CTransactionRef &tx,
	bool test_accept) {
	AssertLockHeld(cs_main);
	Chainstate &active_chainstate = ActiveChainstate();
	if (!active_chainstate.GetMempool()) {
	TxValidationState state;
	state.Invalid(TxValidationResult::TX_NO_MEMPOOL, "no-mempool");
	return MempoolAcceptResult::Failure(state);
	}
	auto result = AcceptToMemoryPool(active_chainstate, tx, GetTime(),
	/bypass_limits=/false, test_accept);
	active_chainstate.GetMempool()->check(
	active_chainstate.CoinsTip(), active_chainstate.m_chain.Height() + 1);
	return result;
	}

	bool TestBlockValidity(
	BlockValidationState &state, const CChainParams &params,
	Chainstate &chainstate, const CBlock &block, CBlockIndex *pindexPrev,
	const std::function<NodeClock::time_point()> &adjusted_time_callback,
	BlockValidationOptions validationOptions) {
	AssertLockHeld(cs_main);
	assert(pindexPrev && pindexPrev == chainstate.m_chain.Tip());
	CCoinsViewCache viewNew(&chainstate.CoinsTip());
	BlockHash block_hash(block.GetHash());
	CBlockIndex indexDummy(block);
	indexDummy.pprev = pindexPrev;
	indexDummy.nHeight = pindexPrev->nHeight + 1;
	indexDummy.phashBlock = &block_hash;

	// NOTE: CheckBlockHeader is called by CheckBlock
	if (!ContextualCheckBlockHeader(block, state, chainstate.m_blockman,
	chainstate.m_chainman, pindexPrev,
	adjusted_time_callback())) {
	return error("%s: Consensus::ContextualCheckBlockHeader: %s", __func__,
	state.ToString());
	}

	if (!CheckBlock(block, state, params.GetConsensus(), validationOptions)) {
	return error("%s: Consensus::CheckBlock: %s", __func__,
	state.ToString());
	}

	if (!ContextualCheckBlock(block, state, chainstate.m_chainman,
	pindexPrev)) {
	return error("%s: Consensus::ContextualCheckBlock: %s", __func__,
	state.ToString());
	}

	if (!chainstate.ConnectBlock(block, state, &indexDummy, viewNew,
	validationOptions, nullptr, true)) {
	return false;
	}

	assert(state.IsValid());
	return true;
	}

	/* This function is called from the RPC code for pruneblockchain */
	void PruneBlockFilesManual(Chainstate &active_chainstate,
	int nManualPruneHeight) {
	BlockValidationState state;
	if (active_chainstate.FlushStateToDisk(state, FlushStateMode::NONE,
	nManualPruneHeight)) {
	LogPrintf("%s: failed to flush state (%s)\n", __func__,
	state.ToString());
	}
	}

	void Chainstate::LoadMempool(const fs::path &load_path,
	FopenFn mockable_fopen_function) {
	if (!m_mempool) {
	return;
	}
	::LoadMempool(m_mempool, load_path, this, mockable_fopen_function);
	m_mempool->SetLoadTried(!ShutdownRequested());
	}

	bool Chainstate::LoadChainTip() {
	AssertLockHeld(cs_main);
	const CCoinsViewCache &coins_cache = CoinsTip();
	// Never called when the coins view is empty
	assert(!coins_cache.GetBestBlock().IsNull());
	const CBlockIndex *tip = m_chain.Tip();

	if (tip && tip->GetBlockHash() == coins_cache.GetBestBlock()) {
	return true;
	}

	// Load pointer to end of best chain
	CBlockIndex *pindex =
	m_blockman.LookupBlockIndex(coins_cache.GetBestBlock());
	if (!pindex) {
	return false;
	}
	m_chain.SetTip(*pindex);
	PruneBlockIndexCandidates();

	tip = m_chain.Tip();
	LogPrintf(
	"Loaded best chain: hashBestChain=%s height=%d date=%s progress=%f\n",
	tip->GetBlockHash().ToString(), m_chain.Height(),
	FormatISO8601DateTime(tip->GetBlockTime()),
	GuessVerificationProgress(m_chainman.GetParams().TxData(), tip));
	return true;
	}

	CVerifyDB::CVerifyDB(Notifications &notifications)
	: m_notifications{notifications} {
	m_notifications.progress(_("Verifying blocks…"), 0, false);
	}

	CVerifyDB::~CVerifyDB() {
	m_notifications.progress(bilingual_str{}, 100, false);
	}

	VerifyDBResult CVerifyDB::VerifyDB(Chainstate &chainstate,
	CCoinsView &coinsview, int nCheckLevel,
	int nCheckDepth) {
	AssertLockHeld(cs_main);

	const Config &config = chainstate.m_chainman.GetConfig();
	const CChainParams &params = config.GetChainParams();
	const Consensus::Params &consensusParams = params.GetConsensus();

	if (chainstate.m_chain.Tip() == nullptr \|\|
	chainstate.m_chain.Tip()->pprev == nullptr) {
	return VerifyDBResult::SUCCESS;
	}

	// Verify blocks in the best chain
	if (nCheckDepth <= 0 \|\| nCheckDepth > chainstate.m_chain.Height()) {
	nCheckDepth = chainstate.m_chain.Height();
	}

	nCheckLevel = std::max(0, std::min(4, nCheckLevel));
	LogPrintf("Verifying last %i blocks at level %i\n", nCheckDepth,
	nCheckLevel);

	CCoinsViewCache coins(&coinsview);
	CBlockIndex *pindex;
	CBlockIndex *pindexFailure = nullptr;
	int nGoodTransactions = 0;
	BlockValidationState state;
	int reportDone = 0;
	bool skipped_no_block_data{false};
	bool skipped_l3_checks{false};
	LogPrintf("Verification progress: 0%%\n");

	const bool is_snapshot_cs{chainstate.m_from_snapshot_blockhash};

	for (pindex = chainstate.m_chain.Tip(); pindex && pindex->pprev;
	pindex = pindex->pprev) {
	const int percentageDone = std::max(
	1, std::min(99, (int)(((double)(chainstate.m_chain.Height() -
	pindex->nHeight)) /
	(double)nCheckDepth *
	(nCheckLevel >= 4 ? 50 : 100))));
	if (reportDone < percentageDone / 10) {
	// report every 10% step
	LogPrintf("Verification progress: %d%%\n", percentageDone);
	reportDone = percentageDone / 10;
	}

	m_notifications.progress(_("Verifying blocks…"), percentageDone, false);
	if (pindex->nHeight <= chainstate.m_chain.Height() - nCheckDepth) {
	break;
	}

	if ((chainstate.m_blockman.IsPruneMode() \|\| is_snapshot_cs) &&
	!pindex->nStatus.hasData()) {
	// If pruning or running under an assumeutxo snapshot, only go
	// back as far as we have data.
	LogPrintf("VerifyDB(): block verification stopping at height %d "
	"(no data). This could be due to pruning or use of an "
	"assumeutxo snapshot.\n",
	pindex->nHeight);
	skipped_no_block_data = true;
	break;
	}

	CBlock block;

	// check level 0: read from disk
	if (!chainstate.m_blockman.ReadBlockFromDisk(block, *pindex)) {
	LogPrintf(
	"Verification error: ReadBlockFromDisk failed at %d, hash=%s\n",
	pindex->nHeight, pindex->GetBlockHash().ToString());
	return VerifyDBResult::CORRUPTED_BLOCK_DB;
	}

	// check level 1: verify block validity
	if (nCheckLevel >= 1 && !CheckBlock(block, state, consensusParams,
	BlockValidationOptions(config))) {
	LogPrintf(
	"Verification error: found bad block at %d, hash=%s (%s)\n",
	pindex->nHeight, pindex->GetBlockHash().ToString(),
	state.ToString());
	return VerifyDBResult::CORRUPTED_BLOCK_DB;
	}

	// check level 2: verify undo validity
	if (nCheckLevel >= 2 && pindex) {
	CBlockUndo undo;
	if (!pindex->GetUndoPos().IsNull()) {
	if (!chainstate.m_blockman.UndoReadFromDisk(undo, *pindex)) {
	LogPrintf("Verification error: found bad undo data at %d, "
	"hash=%s\n",
	pindex->nHeight,
	pindex->GetBlockHash().ToString());
	return VerifyDBResult::CORRUPTED_BLOCK_DB;
	}
	}
	}
	// check level 3: check for inconsistencies during memory-only
	// disconnect of tip blocks
	size_t curr_coins_usage = coins.DynamicMemoryUsage() +
	chainstate.CoinsTip().DynamicMemoryUsage();

	if (nCheckLevel >= 3) {
	if (curr_coins_usage <= chainstate.m_coinstip_cache_size_bytes) {
	assert(coins.GetBestBlock() == pindex->GetBlockHash());
	DisconnectResult res =
	chainstate.DisconnectBlock(block, pindex, coins);
	if (res == DisconnectResult::FAILED) {
	LogPrintf("Verification error: irrecoverable inconsistency "
	"in block data at %d, hash=%s\n",
	pindex->nHeight,
	pindex->GetBlockHash().ToString());
	return VerifyDBResult::CORRUPTED_BLOCK_DB;
	}
	if (res == DisconnectResult::UNCLEAN) {
	nGoodTransactions = 0;
	pindexFailure = pindex;
	} else {
	nGoodTransactions += block.vtx.size();
	}
	} else {
	skipped_l3_checks = true;
	}
	}

	if (ShutdownRequested()) {
	return VerifyDBResult::INTERRUPTED;
	}
	}

	if (pindexFailure) {
	LogPrintf("Verification error: coin database inconsistencies found "
	"(last %i blocks, %i good transactions before that)\n",
	chainstate.m_chain.Height() - pindexFailure->nHeight + 1,
	nGoodTransactions);
	return VerifyDBResult::CORRUPTED_BLOCK_DB;
	}
	if (skipped_l3_checks) {
	LogPrintf("Skipped verification of level >=3 (insufficient database "
	"cache size). Consider increasing -dbcache.\n");
	}

	// store block count as we move pindex at check level >= 4
	int block_count = chainstate.m_chain.Height() - pindex->nHeight;

	// check level 4: try reconnecting blocks
	if (nCheckLevel >= 4 && !skipped_l3_checks) {
	while (pindex != chainstate.m_chain.Tip()) {
	const int percentageDone = std::max(
	1, std::min(99, 100 - int(double(chainstate.m_chain.Height() -
	pindex->nHeight) /
	double(nCheckDepth) * 50)));
	if (reportDone < percentageDone / 10) {
	// report every 10% step
	LogPrintf("Verification progress: %d%%\n", percentageDone);
	reportDone = percentageDone / 10;
	}
	m_notifications.progress(_("Verifying blocks…"), percentageDone,
	false);
	pindex = chainstate.m_chain.Next(pindex);
	CBlock block;
	if (!chainstate.m_blockman.ReadBlockFromDisk(block, *pindex)) {
	LogPrintf("Verification error: ReadBlockFromDisk failed at %d, "
	"hash=%s\n",
	pindex->nHeight, pindex->GetBlockHash().ToString());
	return VerifyDBResult::CORRUPTED_BLOCK_DB;
	}
	if (!chainstate.ConnectBlock(block, state, pindex, coins,
	BlockValidationOptions(config))) {
	LogPrintf("Verification error: found unconnectable block at "
	"%d, hash=%s (%s)\n",
	pindex->nHeight, pindex->GetBlockHash().ToString(),
	state.ToString());
	return VerifyDBResult::CORRUPTED_BLOCK_DB;
	}
	if (ShutdownRequested()) {
	return VerifyDBResult::INTERRUPTED;
	}
	}
	}

	LogPrintf("Verification: No coin database inconsistencies in last %i "
	"blocks (%i transactions)\n",
	block_count, nGoodTransactions);

	if (skipped_l3_checks) {
	return VerifyDBResult::SKIPPED_L3_CHECKS;
	}
	if (skipped_no_block_data) {
	return VerifyDBResult::SKIPPED_MISSING_BLOCKS;
	}
	return VerifyDBResult::SUCCESS;
	}

	/**
	* Apply the effects of a block on the utxo cache, ignoring that it may already
	* have been applied.
	*/
	bool Chainstate::RollforwardBlock(const CBlockIndex *pindex,
	CCoinsViewCache &view) {
	AssertLockHeld(cs_main);
	// TODO: merge with ConnectBlock
	CBlock block;
	if (!m_blockman.ReadBlockFromDisk(block, *pindex)) {
	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 Chainstate::ReplayBlocks() {
	LOCK(cs_main);

	CCoinsView &db = this->CoinsDB();
	CCoinsViewCache cache(&db);

	std::vector<BlockHash> hashHeads = db.GetHeadBlocks();
	if (hashHeads.empty()) {
	// We're already in a consistent state.
	return true;
	}
	if (hashHeads.size() != 2) {
	return error("ReplayBlocks(): unknown inconsistent state");
	}

	m_chainman.GetNotifications().progress(_("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 (m_blockman.m_block_index.count(hashHeads[0]) == 0) {
	return error(
	"ReplayBlocks(): reorganization to unknown block requested");
	}

	pindexNew = &(m_blockman.m_block_index[hashHeads[0]]);

	if (!hashHeads[1].IsNull()) {
	// The old tip is allowed to be 0, indicating it's the first flush.
	if (m_blockman.m_block_index.count(hashHeads[1]) == 0) {
	return error(
	"ReplayBlocks(): reorganization from unknown block requested");
	}

	pindexOld = &(m_blockman.m_block_index[hashHeads[1]]);
	pindexFork = LastCommonAncestor(pindexOld, pindexNew);
	assert(pindexFork != nullptr);
	}

	// Rollback along the old branch.
	while (pindexOld != pindexFork) {
	if (pindexOld->nHeight > 0) {
	// Never disconnect the genesis block.
	CBlock block;
	if (!m_blockman.ReadBlockFromDisk(block, *pindexOld)) {
	return error("RollbackBlock(): ReadBlockFromDisk() failed at "
	"%d, hash=%s",
	pindexOld->nHeight,
	pindexOld->GetBlockHash().ToString());
	}

	LogPrintf("Rolling back %s (%i)\n",
	pindexOld->GetBlockHash().ToString(), pindexOld->nHeight);
	DisconnectResult res = DisconnectBlock(block, pindexOld, cache);
	if (res == DisconnectResult::FAILED) {
	return error(
	"RollbackBlock(): DisconnectBlock failed at %d, hash=%s",
	pindexOld->nHeight, pindexOld->GetBlockHash().ToString());
	}

	// If DisconnectResult::UNCLEAN is returned, it means a non-existing
	// UTXO was deleted, or an existing UTXO was overwritten. It
	// corresponds to cases where the block-to-be-disconnect never had
	// all its operations applied to the UTXO set. However, as both
	// writing a UTXO and deleting a UTXO are idempotent operations, the
	// result is still a version of the UTXO set with the effects of
	// that block undone.
	}
	pindexOld = pindexOld->pprev;
	}

	// Roll forward from the forking point to the new tip.
	int nForkHeight = pindexFork ? pindexFork->nHeight : 0;
	for (int nHeight = nForkHeight + 1; nHeight <= pindexNew->nHeight;
	++nHeight) {
	const CBlockIndex &pindex{*Assert(pindexNew->GetAncestor(nHeight))};
	LogPrintf("Rolling forward %s (%i)\n", pindex.GetBlockHash().ToString(),
	nHeight);
	m_chainman.GetNotifications().progress(
	_("Replaying blocks…"),
	(int)((nHeight - nForkHeight) * 100.0 /
	(pindexNew->nHeight - nForkHeight)),
	false);
	if (!RollforwardBlock(&pindex, cache)) {
	return false;
	}
	}

	cache.SetBestBlock(pindexNew->GetBlockHash());
	cache.Flush();
	m_chainman.GetNotifications().progress(bilingual_str{}, 100, false);
	return true;
	}

	// May NOT be used after any connections are up as much of the peer-processing
	// logic assumes a consistent block index state
	void Chainstate::ClearBlockIndexCandidates() {
	AssertLockHeld(::cs_main);
	m_best_fork_tip = nullptr;
	m_best_fork_base = nullptr;
	setBlockIndexCandidates.clear();
	}

	bool ChainstateManager::DumpRecentHeadersTime(const fs::path &filePath) const {
	AssertLockHeld(cs_main);

	if (!m_options.store_recent_headers_time) {
	return false;
	}

	// Dump enough headers for RTT computation, with a few extras in case a
	// reorg occurs.
	const uint64_t numHeaders{20};

	try {
	const fs::path filePathTmp = filePath + ".new";
	FILE *filestr = fsbridge::fopen(filePathTmp, "wb");
	if (!filestr) {
	return false;
	}

	CAutoFile file(filestr, SER_DISK, CLIENT_VERSION);
	file << HEADERS_TIME_VERSION;
	file << numHeaders;

	const CBlockIndex *index = ActiveTip();
	bool missingIndex{false};
	for (uint64_t i = 0; i < numHeaders; i++) {
	if (!index) {
	LogPrintf("Missing block index, stopping the headers time "
	"dumping after %d blocks.\n",
	i);
	missingIndex = true;
	break;
	}

	file << index->GetBlockHash();
	file << index->GetHeaderReceivedTime();

	index = index->pprev;
	}

	if (!FileCommit(file.Get())) {
	throw std::runtime_error(strprintf("Failed to commit to file %s",
	PathToString(filePathTmp)));
	}
	file.fclose();

	if (missingIndex) {
	fs::remove(filePathTmp);
	return false;
	}

	if (!RenameOver(filePathTmp, filePath)) {
	throw std::runtime_error(strprintf("Rename failed from %s to %s",
	PathToString(filePathTmp),
	PathToString(filePath)));
	}
	} catch (const std::exception &e) {
	LogPrintf("Failed to dump the headers time: %s.\n", e.what());
	return false;
	}

	LogPrintf("Successfully dumped the last %d headers time to %s.\n",
	numHeaders, PathToString(filePath));

	return true;
	}

	bool ChainstateManager::LoadRecentHeadersTime(const fs::path &filePath) {
	AssertLockHeld(cs_main);

	if (!m_options.store_recent_headers_time) {
	return false;
	}

	FILE *filestr = fsbridge::fopen(filePath, "rb");
	CAutoFile file(filestr, SER_DISK, CLIENT_VERSION);
	if (file.IsNull()) {
	LogPrintf("Failed to open header times from disk, skipping.\n");
	return false;
	}

	try {
	uint64_t version;
	file >> version;

	if (version != HEADERS_TIME_VERSION) {
	LogPrintf("Unsupported header times file version, skipping.\n");
	return false;
	}

	uint64_t numBlocks;
	file >> numBlocks;

	for (uint64_t i = 0; i < numBlocks; i++) {
	BlockHash blockHash;
	int64_t receiveTime;

	file >> blockHash;
	file >> receiveTime;

	CBlockIndex *index = m_blockman.LookupBlockIndex(blockHash);
	if (!index) {
	LogPrintf("Missing index for block %s, stopping the headers "
	"time loading after %d blocks.\n",
	blockHash.ToString(), i);
	return false;
	}

	index->nTimeReceived = receiveTime;
	}
	} catch (const std::exception &e) {
	LogPrintf("Failed to read the headers time file data on disk: %s.\n",
	e.what());
	return false;
	}

	return true;
	}

	bool ChainstateManager::LoadBlockIndex() {
	AssertLockHeld(cs_main);
	// Load block index from databases
	bool needs_init = fReindex;
	if (!fReindex) {
	bool ret{m_blockman.LoadBlockIndexDB(SnapshotBlockhash())};
	if (!ret) {
	return false;
	}

	m_blockman.ScanAndUnlinkAlreadyPrunedFiles();

	std::vector<CBlockIndex *> vSortedByHeight{
	m_blockman.GetAllBlockIndices()};
	std::sort(vSortedByHeight.begin(), vSortedByHeight.end(),
	CBlockIndexHeightOnlyComparator());

	for (CBlockIndex *pindex : vSortedByHeight) {
	if (ShutdownRequested()) {
	return false;
	}
	// If we have an assumeutxo-based chainstate, then the snapshot
	// block will be a candidate for the tip, but it may not be
	// VALID_TRANSACTIONS (eg if we haven't yet downloaded the block),
	// so we special-case the snapshot block as a potential candidate
	// here.
	if (pindex == GetSnapshotBaseBlock() \|\|
	(pindex->IsValid(BlockValidity::TRANSACTIONS) &&
	(pindex->HaveNumChainTxs() \|\| pindex->pprev == nullptr))) {
	for (Chainstate *chainstate : GetAll()) {
	chainstate->TryAddBlockIndexCandidate(pindex);
	}
	}

	if (pindex->nStatus.isInvalid() &&
	(!m_best_invalid \|\|
	pindex->nChainWork > m_best_invalid->nChainWork)) {
	m_best_invalid = pindex;
	}

	if (pindex->nStatus.isOnParkedChain() &&
	(!m_best_parked \|\|
	pindex->nChainWork > m_best_parked->nChainWork)) {
	m_best_parked = pindex;
	}

	if (pindex->IsValid(BlockValidity::TREE) &&
	(m_best_header == nullptr \|\|
	CBlockIndexWorkComparator()(m_best_header, pindex))) {
	m_best_header = pindex;
	}
	}

	needs_init = m_blockman.m_block_index.empty();
	}

	if (needs_init) {
	// Everything here is for new reindex/DBs. Thus, though
	// LoadBlockIndexDB may have set fReindex if we shut down
	// mid-reindex previously, we don't check fReindex and
	// instead only check it prior to LoadBlockIndexDB to set
	// needs_init.

	LogPrintf("Initializing databases...\n");
	}
	return true;
	}

	bool Chainstate::LoadGenesisBlock() {
	LOCK(cs_main);

	const CChainParams &params{m_chainman.GetParams()};

	// Check whether we're already initialized by checking for genesis in
	// m_blockman.m_block_index. Note that we can't use m_chain here, since it
	// is set based on the coins db, not the block index db, which is the only
	// thing loaded at this point.
	if (m_blockman.m_block_index.count(params.GenesisBlock().GetHash())) {
	return true;
	}

	try {
	const CBlock &block = params.GenesisBlock();
	FlatFilePos blockPos{m_blockman.SaveBlockToDisk(block, 0, nullptr)};
	if (blockPos.IsNull()) {
	return error("%s: writing genesis block to disk failed", __func__);
	}
	CBlockIndex *pindex =
	m_blockman.AddToBlockIndex(block, m_chainman.m_best_header);
	m_chainman.ReceivedBlockTransactions(block, pindex, blockPos);
	} catch (const std::runtime_error &e) {
	return error("%s: failed to write genesis block: %s", __func__,
	e.what());
	}

	return true;
	}

	void ChainstateManager::LoadExternalBlockFile(
	FILE fileIn, FlatFilePos dbp,
	std::multimap<BlockHash, FlatFilePos> *blocks_with_unknown_parent,
	avalanche::Processor *const avalanche) {
	// Either both should be specified (-reindex), or neither (-loadblock).
	assert(!dbp == !blocks_with_unknown_parent);

	int64_t nStart = GetTimeMillis();
	const CChainParams &params{GetParams()};

	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);
	// nRewind indicates where to resume scanning in case something goes
	// wrong, such as a block fails to deserialize.
	uint64_t nRewind = blkdat.GetPos();
	while (!blkdat.eof()) {
	if (ShutdownRequested()) {
	return;
	}

	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(std::byte(params.DiskMagic()[0]));
	nRewind = blkdat.GetPos() + 1;
	blkdat >> buf;
	if (memcmp(buf, params.DiskMagic().data(),
	CMessageHeader::MESSAGE_START_SIZE)) {
	continue;
	}

	// Read size.
	blkdat >> nSize;
	if (nSize < 80) {
	continue;
	}
	} catch (const std::exception &) {
	// No valid block header found; don't complain.
	// (this happens at the end of every blk.dat file)
	break;
	}

	try {
	// read block header
	const uint64_t nBlockPos{blkdat.GetPos()};
	if (dbp) {
	dbp->nPos = nBlockPos;
	}
	blkdat.SetLimit(nBlockPos + nSize);
	CBlockHeader header;
	blkdat >> header;
	const BlockHash hash{header.GetHash()};
	// Skip the rest of this block (this may read from disk
	// into memory); position to the marker before the next block,
	// but it's still possible to rewind to the start of the
	// current block (without a disk read).
	nRewind = nBlockPos + nSize;
	blkdat.SkipTo(nRewind);

	// needs to remain available after the cs_main lock is released
	// to avoid duplicate reads from disk
	std::shared_ptr<CBlock> pblock{};

	{
	LOCK(cs_main);
	// detect out of order blocks, and store them for later
	if (hash != params.GetConsensus().hashGenesisBlock &&
	!m_blockman.LookupBlockIndex(header.hashPrevBlock)) {
	LogPrint(
	BCLog::REINDEX,
	"%s: Out of order block %s, parent %s not known\n",
	__func__, hash.ToString(),
	header.hashPrevBlock.ToString());
	if (dbp && blocks_with_unknown_parent) {
	blocks_with_unknown_parent->emplace(
	header.hashPrevBlock, *dbp);
	}
	continue;
	}

	// process in case the block isn't known yet
	const CBlockIndex *pindex =
	m_blockman.LookupBlockIndex(hash);
	if (!pindex \|\| !pindex->nStatus.hasData()) {
	// This block can be processed immediately; rewind to
	// its start, read and deserialize it.
	blkdat.SetPos(nBlockPos);
	pblock = std::make_shared<CBlock>();
	blkdat >> *pblock;
	nRewind = blkdat.GetPos();

	BlockValidationState state;
	if (AcceptBlock(pblock, state, true, dbp, nullptr,
	true)) {
	nLoaded++;
	}
	if (state.IsError()) {
	break;
	}
	} else if (hash != params.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 == params.GetConsensus().hashGenesisBlock) {
	bool genesis_activation_failure = false;
	for (auto c : GetAll()) {
	BlockValidationState state;
	if (!c->ActivateBestChain(state, nullptr, avalanche)) {
	genesis_activation_failure = true;
	break;
	}
	}
	if (genesis_activation_failure) {
	break;
	}
	}

	if (m_blockman.IsPruneMode() && !fReindex && pblock) {
	// Must update the tip for pruning to work while importing
	// with -loadblock. This is a tradeoff to conserve disk
	// space at the expense of time spent updating the tip to be
	// able to prune. Otherwise, ActivateBestChain won't be
	// called by the import process until after all of the block
	// files are loaded. ActivateBestChain can be called by
	// concurrent network message processing, but that is not
	// reliable for the purpose of pruning while importing.
	bool activation_failure = false;
	for (auto c : GetAll()) {
	BlockValidationState state;
	if (!c->ActivateBestChain(state, pblock, avalanche)) {
	LogPrint(BCLog::REINDEX,
	"failed to activate chain (%s)\n",
	state.ToString());
	activation_failure = true;
	break;
	}
	}
	if (activation_failure) {
	break;
	}
	}

	NotifyHeaderTip(*this);

	if (!blocks_with_unknown_parent) {
	continue;
	}

	// Recursively process earlier encountered successors of this
	// block
	std::deque<BlockHash> queue;
	queue.push_back(hash);
	while (!queue.empty()) {
	BlockHash head = queue.front();
	queue.pop_front();
	auto range = blocks_with_unknown_parent->equal_range(head);
	while (range.first != range.second) {
	std::multimap<BlockHash, FlatFilePos>::iterator it =
	range.first;
	std::shared_ptr<CBlock> pblockrecursive =
	std::make_shared<CBlock>();
	if (m_blockman.ReadBlockFromDisk(*pblockrecursive,
	it->second)) {
	LogPrint(
	BCLog::REINDEX,
	"%s: Processing out of order child %s of %s\n",
	__func__, pblockrecursive->GetHash().ToString(),
	head.ToString());
	LOCK(cs_main);
	BlockValidationState dummy;
	if (AcceptBlock(pblockrecursive, dummy, true,
	&it->second, nullptr, true)) {
	nLoaded++;
	queue.push_back(pblockrecursive->GetHash());
	}
	}
	range.first++;
	blocks_with_unknown_parent->erase(it);
	NotifyHeaderTip(*this);
	}
	}
	} catch (const std::exception &e) {
	// Historical bugs added extra data to the block files that does
	// not deserialize cleanly. Commonly this data is between
	// readable blocks, but it does not really matter. Such data is
	// not fatal to the import process. The code that reads the
	// block files deals with invalid data by simply ignoring it. It
	// continues to search for the next {4 byte magic message start
	// bytes + 4 byte length + block} that does deserialize cleanly
	// and passes all of the other block validation checks dealing
	// with POW and the merkle root, etc... We merely note with this
	// informational log message when unexpected data is
	// encountered. We could also be experiencing a storage system
	// read error, or a read of a previous bad write. These are
	// possible, but less likely scenarios. We don't have enough
	// information to tell a difference here. The reindex process is
	// not the place to attempt to clean and/or compact the block
	// files. If so desired, a studious node operator may use
	// knowledge of the fact that the block files are not entirely
	// pristine in order to prepare a set of pristine, and perhaps
	// ordered, block files for later reindexing.
	LogPrint(BCLog::REINDEX,
	"%s: unexpected data at file offset 0x%x - %s. "
	"continuing\n",
	__func__, (nRewind - 1), e.what());
	}
	}
	} catch (const std::runtime_error &e) {
	AbortNode(std::string("System error: ") + e.what());
	}

	LogPrintf("Loaded %i blocks from external file in %dms\n", nLoaded,
	GetTimeMillis() - nStart);
	}

	void ChainstateManager::CheckBlockIndex() {
	if (!ShouldCheckBlockIndex()) {
	return;
	}

	LOCK(cs_main);

	// During a reindex, we read the genesis block and call CheckBlockIndex
	// before ActivateBestChain, so we have the genesis block in
	// m_blockman.m_block_index but no active chain. (A few of the tests when
	// iterating the block tree require that m_chain has been initialized.)
	if (ActiveChain().Height() < 0) {
	assert(m_blockman.m_block_index.size() <= 1);
	return;
	}

	// Build forward-pointing map of the entire block tree.
	std::multimap<CBlockIndex , CBlockIndex > forward;
	for (auto &[_, block_index] : m_blockman.m_block_index) {
	forward.emplace(block_index.pprev, &block_index);
	}

	assert(forward.size() == m_blockman.m_block_index.size());

	std::pair<std::multimap<CBlockIndex , CBlockIndex >::iterator,
	std::multimap<CBlockIndex , CBlockIndex >::iterator>
	rangeGenesis = forward.equal_range(nullptr);
	CBlockIndex *pindex = rangeGenesis.first->second;
	rangeGenesis.first++;
	// There is only one index entry with parent nullptr.
	assert(rangeGenesis.first == rangeGenesis.second);

	// Iterate over the entire block tree, using depth-first search.
	// Along the way, remember whether there are blocks on the path from genesis
	// block being explored which are the first to have certain properties.
	size_t nNodes = 0;
	int nHeight = 0;
	// Oldest ancestor of pindex which is invalid.
	CBlockIndex *pindexFirstInvalid = nullptr;
	// Oldest ancestor of pindex which is parked.
	CBlockIndex *pindexFirstParked = nullptr;
	// Oldest ancestor of pindex which does not have data available, since
	// assumeutxo snapshot if used.
	CBlockIndex *pindexFirstMissing = nullptr;
	// Oldest ancestor of pindex for which nTx == 0, since assumeutxo snapshot
	// if used..
	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), since assumeutxo snapshot if used.
	CBlockIndex *pindexFirstNotTransactionsValid = nullptr;
	// Oldest ancestor of pindex which does not have BLOCK_VALID_CHAIN
	// (regardless of being valid or not), since assumeutxo snapshot if used.
	CBlockIndex *pindexFirstNotChainValid = nullptr;
	// Oldest ancestor of pindex which does not have BLOCK_VALID_SCRIPTS
	// (regardless of being valid or not), since assumeutxo snapshot if used.
	CBlockIndex *pindexFirstNotScriptsValid = nullptr;

	// After checking an assumeutxo snapshot block, reset pindexFirst pointers
	// to earlier blocks that have not been downloaded or validated yet, so
	// checks for later blocks can assume the earlier blocks were validated and
	// be stricter, testing for more requirements.
	const CBlockIndex *snap_base{GetSnapshotBaseBlock()};
	CBlockIndex snap_first_missing{}, snap_first_notx{}, *snap_first_notv{},
	snap_first_nocv{}, snap_first_nosv{};
	auto snap_update_firsts = [&] {
	if (pindex == snap_base) {
	std::swap(snap_first_missing, pindexFirstMissing);
	std::swap(snap_first_notx, pindexFirstNeverProcessed);
	std::swap(snap_first_notv, pindexFirstNotTransactionsValid);
	std::swap(snap_first_nocv, pindexFirstNotChainValid);
	std::swap(snap_first_nosv, pindexFirstNotScriptsValid);
	}
	};

	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) {
	if (pindexFirstNotTransactionsValid == nullptr &&
	pindex->nStatus.getValidity() < BlockValidity::TRANSACTIONS) {
	pindexFirstNotTransactionsValid = pindex;
	}
	if (pindexFirstNotChainValid == nullptr &&
	pindex->nStatus.getValidity() < BlockValidity::CHAIN) {
	pindexFirstNotChainValid = pindex;
	}
	if (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() == GetConsensus().hashGenesisBlock);
	for (auto c : GetAll()) {
	if (c->m_chain.Genesis() != nullptr) {
	// The chain's genesis block must be this block.
	assert(pindex == c->m_chain.Genesis());
	}
	}
	}
	if (!pindex->HaveNumChainTxs()) {
	// 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 (!m_blockman.m_have_pruned) {
	// 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());
	}
	if (snap_base && snap_base->GetAncestor(pindex->nHeight) == pindex) {
	// Assumed-valid blocks should connect to the main chain.
	assert(pindex->nStatus.getValidity() >= BlockValidity::TREE);
	}
	// There should only be an nTx value if we have
	// actually seen a block's transactions.
	// 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
	// HaveNumChainTxs().
	assert((pindexFirstNeverProcessed == nullptr \|\| pindex == snap_base) ==
	(pindex->HaveNumChainTxs()));
	assert((pindexFirstNotTransactionsValid == nullptr \|\|
	pindex == snap_base) == (pindex->HaveNumChainTxs()));
	// nHeight must be consistent.
	assert(pindex->nHeight == nHeight);
	// For every block except the genesis block, the chainwork must be
	// larger than the parent's.
	assert(pindex->pprev == nullptr \|\|
	pindex->nChainWork >= pindex->pprev->nChainWork);
	// The pskip pointer must point back for all but the first 2 blocks.
	assert(nHeight < 2 \|\|
	(pindex->pskip && (pindex->pskip->nHeight < nHeight)));
	// All m_blockman.m_block_index entries must at least be TREE valid
	assert(pindexFirstNotTreeValid == nullptr);
	if (pindex->nStatus.getValidity() >= BlockValidity::TREE) {
	// TREE valid implies all parents are TREE valid
	assert(pindexFirstNotTreeValid == nullptr);
	}
	if (pindex->nStatus.getValidity() >= BlockValidity::CHAIN) {
	// CHAIN valid implies all parents are CHAIN valid
	assert(pindexFirstNotChainValid == nullptr);
	}
	if (pindex->nStatus.getValidity() >= BlockValidity::SCRIPTS) {
	// SCRIPTS valid implies all parents are SCRIPTS valid
	assert(pindexFirstNotScriptsValid == nullptr);
	}
	if (pindexFirstInvalid == nullptr) {
	// Checks for not-invalid blocks.
	// The failed mask cannot be set for blocks without invalid parents.
	assert(!pindex->nStatus.isInvalid());
	}
	if (pindexFirstParked == nullptr) {
	// Checks for not-parked blocks.
	// The parked mask cannot be set for blocks without parked parents.
	// (i.e., hasParkedParent only if an ancestor is properly parked).
	assert(!pindex->nStatus.isOnParkedChain());
	}
	// Make sure nChainTx sum is correctly computed.
	if (!pindex->pprev) {
	// If no previous block, nTx and nChainTx must be the same.
	assert(pindex->nChainTx == pindex->nTx);
	} else if (pindex->pprev->nChainTx > 0 && pindex->nTx > 0) {
	// If previous nChainTx is set and number of transactions in block
	// is known, sum must be set.
	assert(pindex->nChainTx == pindex->nTx + pindex->pprev->nChainTx);
	} else {
	// Otherwise nChainTx should only be set if this is a snapshot
	// block, and must be set if it is.
	assert((pindex->nChainTx != 0) == (pindex == snap_base));
	}

	// Chainstate-specific checks on setBlockIndexCandidates
	for (auto c : GetAll()) {
	if (c->m_chain.Tip() == nullptr) {
	continue;
	}
	// Two main factors determine whether pindex is a candidate in
	// setBlockIndexCandidates:
	//
	// - If pindex has less work than the chain tip, it should not be a
	// candidate, and this will be asserted below. Otherwise it is a
	// potential candidate.
	//
	// - If pindex or one of its parent blocks back to the genesis block
	// or an assumeutxo snapshot never downloaded transactions
	// (pindexFirstNeverProcessed is non-null), it should not be a
	// candidate, and this will be asserted below. The only exception
	// is if pindex itself is an assumeutxo snapshot block. Then it is
	// also a potential candidate.
	if (!CBlockIndexWorkComparator()(pindex, c->m_chain.Tip()) &&
	(pindexFirstNeverProcessed == nullptr \|\| pindex == snap_base)) {
	// If pindex was detected as invalid (pindexFirstInvalid is
	// non-null), it is not required to be in
	// setBlockIndexCandidates.
	if (pindexFirstInvalid == nullptr) {
	// If this chainstate is the active chainstate, pindex
	// must be in setBlockIndexCandidates. Otherwise, this
	// chainstate is a background validation chainstate, and
	// pindex only needs to be added if it is an ancestor of
	// the snapshot that is being validated.
	if (c == &ActiveChainstate() \|\|
	GetSnapshotBaseBlock()->GetAncestor(pindex->nHeight) ==
	pindex) {
	// If pindex and all its parents back to the genesis
	// block or an assumeutxo snapshot block downloaded
	// transactions, transactions, and the transactions were
	// not pruned (pindexFirstMissing is null), it is a
	// potential candidate or was parked. The check excludes
	// pruned blocks, because if any blocks were pruned
	// between pindex the current chain tip, pindex will
	// only temporarily be added to setBlockIndexCandidates,
	// before being moved to m_blocks_unlinked. This check
	// could be improved to verify that if all blocks
	// between the chain tip and pindex have data, pindex
	// must be a candidate.
	if (pindexFirstMissing == nullptr) {
	assert(pindex->nStatus.isOnParkedChain() \|\|
	c->setBlockIndexCandidates.count(pindex));
	}
	// If pindex is the chain tip, it also is a potential
	// candidate.
	//
	// If the chainstate was loaded from a snapshot and
	// pindex is the base of the snapshot, pindex is also a
	// potential candidate.
	if (pindex == c->m_chain.Tip() \|\|
	pindex == c->SnapshotBase()) {
	assert(c->setBlockIndexCandidates.count(pindex));
	}
	}
	// If some parent is missing, then it could be that this
	// block was in setBlockIndexCandidates but had to be
	// removed because of the missing data. In this case it must
	// be in m_blocks_unlinked -- see test below.
	}
	} else {
	// If this block sorts worse than the current tip or some
	// ancestor's block has never been seen, it cannot be in
	// setBlockIndexCandidates.
	assert(c->setBlockIndexCandidates.count(pindex) == 0);
	}
	}
	// Check whether this block is in m_blocks_unlinked.
	std::pair<std::multimap<CBlockIndex , CBlockIndex >::iterator,
	std::multimap<CBlockIndex , CBlockIndex >::iterator>
	rangeUnlinked =
	m_blockman.m_blocks_unlinked.equal_range(pindex->pprev);
	bool foundInUnlinked = false;
	while (rangeUnlinked.first != rangeUnlinked.second) {
	assert(rangeUnlinked.first->first == pindex->pprev);
	if (rangeUnlinked.first->second == pindex) {
	foundInUnlinked = true;
	break;
	}
	rangeUnlinked.first++;
	}
	if (pindex->pprev && pindex->nStatus.hasData() &&
	pindexFirstNeverProcessed != nullptr &&
	pindexFirstInvalid == nullptr) {
	// If this block has block data available, some parent was never
	// received, and has no invalid parents, it must be in
	// m_blocks_unlinked.
	assert(foundInUnlinked);
	}
	if (!pindex->nStatus.hasData()) {
	// Can't be in m_blocks_unlinked if we don't HAVE_DATA
	assert(!foundInUnlinked);
	}
	if (pindexFirstMissing == nullptr) {
	// We aren't missing data for any parent -- cannot be in
	// m_blocks_unlinked.
	assert(!foundInUnlinked);
	}
	if (pindex->pprev && pindex->nStatus.hasData() &&
	pindexFirstNeverProcessed == nullptr &&
	pindexFirstMissing != nullptr) {
	// We HAVE_DATA for this block, have received data for all parents
	// at some point, but we're currently missing data for some parent.
	assert(m_blockman.m_have_pruned);
	// This block may have entered m_blocks_unlinked if:
	// - it has a descendant that at some point had more work than the
	// tip, and
	// - we tried switching to that descendant but were missing
	// data for some intermediate block between m_chain and the
	// tip.
	// So if this block is itself better than any m_chain.Tip() and it
	// wasn't in setBlockIndexCandidates, then it must be in
	// m_blocks_unlinked.
	for (auto c : GetAll()) {
	const bool is_active = c == &ActiveChainstate();
	if (!CBlockIndexWorkComparator()(pindex, c->m_chain.Tip()) &&
	c->setBlockIndexCandidates.count(pindex) == 0) {
	if (pindexFirstInvalid == nullptr) {
	if (is_active \|\|
	snap_base->GetAncestor(pindex->nHeight) == pindex) {
	assert(foundInUnlinked);
	}
	}
	}
	}
	}
	// Perhaps too slow
	// assert(pindex->GetBlockHash() == pindex->GetBlockHeader().GetHash());
	// End: actual consistency checks.

	// Try descending into the first subnode.
	snap_update_firsts();
	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.
	snap_update_firsts();
	// 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 Chainstate::ToString() {
	AssertLockHeld(::cs_main);
	CBlockIndex *tip = m_chain.Tip();
	return strprintf("Chainstate [%s] @ height %d (%s)",
	m_from_snapshot_blockhash ? "snapshot" : "ibd",
	tip ? tip->nHeight : -1,
	tip ? tip->GetBlockHash().ToString() : "null");
	}

	bool Chainstate::ResizeCoinsCaches(size_t coinstip_size, size_t coinsdb_size) {
	AssertLockHeld(::cs_main);
	if (coinstip_size == m_coinstip_cache_size_bytes &&
	coinsdb_size == m_coinsdb_cache_size_bytes) {
	// Cache sizes are unchanged, no need to continue.
	return true;
	}
	size_t old_coinstip_size = m_coinstip_cache_size_bytes;
	m_coinstip_cache_size_bytes = coinstip_size;
	m_coinsdb_cache_size_bytes = coinsdb_size;
	CoinsDB().ResizeCache(coinsdb_size);

	LogPrintf("[%s] resized coinsdb cache to %.1f MiB\n", this->ToString(),
	coinsdb_size * (1.0 / 1024 / 1024));
	LogPrintf("[%s] resized coinstip cache to %.1f MiB\n", this->ToString(),
	coinstip_size * (1.0 / 1024 / 1024));

	BlockValidationState state;
	bool ret;

	if (coinstip_size > old_coinstip_size) {
	// Likely no need to flush if cache sizes have grown.
	ret = FlushStateToDisk(state, FlushStateMode::IF_NEEDED);
	} else {
	// Otherwise, flush state to disk and deallocate the in-memory coins
	// map.
	ret = FlushStateToDisk(state, FlushStateMode::ALWAYS);
	}
	return ret;
	}

	//! Guess how far we are in the verification process at the given block index
	//! require cs_main if pindex has not been validated yet (because the chain's
	//! transaction count might be unset) This conditional lock requirement might be
	//! confusing, see: https://github.com/bitcoin/bitcoin/issues/15994
	double GuessVerificationProgress(const ChainTxData &data,
	const CBlockIndex *pindex) {
	if (pindex == nullptr) {
	return 0.0;
	}

	if (!Assume(pindex->nChainTx > 0)) {
	LogPrintf("Internal bug detected: block %d has unset nChainTx (%s %s). "
	"Please report this issue here: %s\n",
	pindex->nHeight, PACKAGE_NAME, FormatFullVersion(),
	PACKAGE_BUGREPORT);
	return 0.0;
	}

	int64_t nNow = time(nullptr);

	double fTxTotal;
	if (pindex->GetChainTxCount() <= data.nTxCount) {
	fTxTotal = data.nTxCount + (nNow - data.nTime) * data.dTxRate;
	} else {
	fTxTotal = pindex->GetChainTxCount() +
	(nNow - pindex->GetBlockTime()) * data.dTxRate;
	}

	return std::min<double>(pindex->GetChainTxCount() / fTxTotal, 1.0);
	}

	std::optional<BlockHash> ChainstateManager::SnapshotBlockhash() const {
	LOCK(::cs_main);
	if (m_active_chainstate && m_active_chainstate->m_from_snapshot_blockhash) {
	// If a snapshot chainstate exists, it will always be our active.
	return m_active_chainstate->m_from_snapshot_blockhash;
	}
	return std::nullopt;
	}

	std::vector<Chainstate *> ChainstateManager::GetAll() {
	LOCK(::cs_main);
	std::vector<Chainstate *> out;

	for (Chainstate *pchainstate :
	{m_ibd_chainstate.get(), m_snapshot_chainstate.get()}) {
	if (this->IsUsable(pchainstate)) {
	out.push_back(pchainstate);
	}
	}

	return out;
	}

	Chainstate &ChainstateManager::InitializeChainstate(CTxMemPool *mempool) {
	AssertLockHeld(::cs_main);
	assert(!m_ibd_chainstate);
	assert(!m_active_chainstate);

	m_ibd_chainstate = std::make_unique<Chainstate>(mempool, m_blockman, *this);
	m_active_chainstate = m_ibd_chainstate.get();
	return *m_active_chainstate;
	}

	[[nodiscard]] static bool DeleteCoinsDBFromDisk(const fs::path &db_path,
	bool is_snapshot)
	EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
	AssertLockHeld(::cs_main);

	if (is_snapshot) {
	fs::path base_blockhash_path =
	db_path / node::SNAPSHOT_BLOCKHASH_FILENAME;

	try {
	const bool existed{fs::remove(base_blockhash_path)};
	if (!existed) {
	LogPrintf("[snapshot] snapshot chainstate dir being removed "
	"lacks %s file\n",
	fs::PathToString(node::SNAPSHOT_BLOCKHASH_FILENAME));
	}
	} catch (const fs::filesystem_error &e) {
	LogPrintf("[snapshot] failed to remove file %s: %s\n",
	fs::PathToString(base_blockhash_path),
	fsbridge::get_filesystem_error_message(e));
	}
	}

	std::string path_str = fs::PathToString(db_path);
	LogPrintf("Removing leveldb dir at %s\n", path_str);

	// We have to destruct before this call leveldb::DB in order to release the
	// db lock, otherwise `DestroyDB` will fail. See `leveldb::~DBImpl()`.
	const bool destroyed = dbwrapper::DestroyDB(path_str, {}).ok();

	if (!destroyed) {
	LogPrintf("error: leveldb DestroyDB call failed on %s\n", path_str);
	}

	// Datadir should be removed from filesystem; otherwise initialization may
	// detect it on subsequent statups and get confused.
	//
	// If the base_blockhash_path removal above fails in the case of snapshot
	// chainstates, this will return false since leveldb won't remove a
	// non-empty directory.
	return destroyed && !fs::exists(db_path);
	}

	bool ChainstateManager::ActivateSnapshot(AutoFile &coins_file,
	const SnapshotMetadata &metadata,
	bool in_memory) {
	BlockHash base_blockhash = metadata.m_base_blockhash;

	if (this->SnapshotBlockhash()) {
	LogPrintf("[snapshot] can't activate a snapshot-based chainstate more "
	"than once\n");
	return false;
	}

	int64_t current_coinsdb_cache_size{0};
	int64_t current_coinstip_cache_size{0};

	// Cache percentages to allocate to each chainstate.
	//
	// These particular percentages don't matter so much since they will only be
	// relevant during snapshot activation; caches are rebalanced at the
	// conclusion of this function. We want to give (essentially) all available
	// cache capacity to the snapshot to aid the bulk load later in this
	// function.
	static constexpr double IBD_CACHE_PERC = 0.01;
	static constexpr double SNAPSHOT_CACHE_PERC = 0.99;

	{
	LOCK(::cs_main);
	// Resize the coins caches to ensure we're not exceeding memory limits.
	//
	// Allocate the majority of the cache to the incoming snapshot
	// chainstate, since (optimistically) getting to its tip will be the top
	// priority. We'll need to call `MaybeRebalanceCaches()` once we're done
	// with this function to ensure the right allocation (including the
	// possibility that no snapshot was activated and that we should restore
	// the active chainstate caches to their original size).
	//
	current_coinsdb_cache_size =
	this->ActiveChainstate().m_coinsdb_cache_size_bytes;
	current_coinstip_cache_size =
	this->ActiveChainstate().m_coinstip_cache_size_bytes;

	// Temporarily resize the active coins cache to make room for the
	// newly-created snapshot chain.
	this->ActiveChainstate().ResizeCoinsCaches(
	static_cast<size_t>(current_coinstip_cache_size * IBD_CACHE_PERC),
	static_cast<size_t>(current_coinsdb_cache_size * IBD_CACHE_PERC));
	}

	auto snapshot_chainstate =
	WITH_LOCK(::cs_main, return std::make_unique<Chainstate>(
	/* mempool / nullptr, m_blockman, this,
	base_blockhash));

	{
	LOCK(::cs_main);
	snapshot_chainstate->InitCoinsDB(
	static_cast<size_t>(current_coinsdb_cache_size *
	SNAPSHOT_CACHE_PERC),
	in_memory, false, "chainstate");
	snapshot_chainstate->InitCoinsCache(static_cast<size_t>(
	current_coinstip_cache_size * SNAPSHOT_CACHE_PERC));
	}

	bool snapshot_ok = this->PopulateAndValidateSnapshot(*snapshot_chainstate,
	coins_file, metadata);

	// If not in-memory, persist the base blockhash for use during subsequent
	// initialization.
	if (!in_memory) {
	LOCK(::cs_main);
	if (!node::WriteSnapshotBaseBlockhash(*snapshot_chainstate)) {
	snapshot_ok = false;
	}
	}
	if (!snapshot_ok) {
	LOCK(::cs_main);
	this->MaybeRebalanceCaches();

	// PopulateAndValidateSnapshot can return (in error) before the leveldb
	// datadir has been created, so only attempt removal if we got that far.
	if (auto snapshot_datadir = node::FindSnapshotChainstateDir()) {
	// We have to destruct leveldb::DB in order to release the db lock,
	// otherwise DestroyDB() (in DeleteCoinsDBFromDisk()) will fail. See
	// `leveldb::~DBImpl()`. Destructing the chainstate (and so
	// resetting the coinsviews object) does this.
	snapshot_chainstate.reset();
	bool removed =
	DeleteCoinsDBFromDisk(snapshot_datadir, /is_snapshot=*/true);
	if (!removed) {
	AbortNode(
	strprintf("Failed to remove snapshot chainstate dir (%s). "
	"Manually remove it before restarting.\n",
	fs::PathToString(*snapshot_datadir)));
	}
	}
	return false;
	}

	{
	LOCK(::cs_main);
	assert(!m_snapshot_chainstate);
	m_snapshot_chainstate.swap(snapshot_chainstate);
	const bool chaintip_loaded = m_snapshot_chainstate->LoadChainTip();
	assert(chaintip_loaded);

	m_active_chainstate = m_snapshot_chainstate.get();

	LogPrintf("[snapshot] successfully activated snapshot %s\n",
	base_blockhash.ToString());
	LogPrintf("[snapshot] (%.2f MB)\n",
	m_snapshot_chainstate->CoinsTip().DynamicMemoryUsage() /
	(1000 * 1000));

	this->MaybeRebalanceCaches();
	}
	return true;
	}

	static void FlushSnapshotToDisk(CCoinsViewCache &coins_cache,
	bool snapshot_loaded) {
	LOG_TIME_MILLIS_WITH_CATEGORY_MSG_ONCE(
	strprintf("%s (%.2f MB)",
	snapshot_loaded ? "saving snapshot chainstate"
	: "flushing coins cache",
	coins_cache.DynamicMemoryUsage() / (1000 * 1000)),
	BCLog::LogFlags::ALL);

	coins_cache.Flush();
	}

	struct StopHashingException : public std::exception {
	const char *what() const throw() override {
	return "ComputeUTXOStats interrupted by shutdown.";
	}
	};

	static void SnapshotUTXOHashBreakpoint() {
	if (ShutdownRequested()) {
	throw StopHashingException();
	}
	}

	bool ChainstateManager::PopulateAndValidateSnapshot(
	Chainstate &snapshot_chainstate, AutoFile &coins_file,
	const SnapshotMetadata &metadata) {
	// It's okay to release cs_main before we're done using `coins_cache`
	// because we know that nothing else will be referencing the newly created
	// snapshot_chainstate yet.
	CCoinsViewCache &coins_cache =
	*WITH_LOCK(::cs_main, return &snapshot_chainstate.CoinsTip());

	BlockHash base_blockhash = metadata.m_base_blockhash;

	CBlockIndex *snapshot_start_block = WITH_LOCK(
	::cs_main, return m_blockman.LookupBlockIndex(base_blockhash));

	if (!snapshot_start_block) {
	// Needed for ComputeUTXOStats to determine the
	// height and to avoid a crash when base_blockhash.IsNull()
	LogPrintf("[snapshot] Did not find snapshot start blockheader %s\n",
	base_blockhash.ToString());
	return false;
	}

	int base_height = snapshot_start_block->nHeight;
	const auto &maybe_au_data = GetParams().AssumeutxoForHeight(base_height);

	if (!maybe_au_data) {
	LogPrintf("[snapshot] assumeutxo height in snapshot metadata not "
	"recognized (%d) - refusing to load snapshot\n",
	base_height);
	return false;
	}

	const AssumeutxoData &au_data = *maybe_au_data;

	COutPoint outpoint;
	Coin coin;
	const uint64_t coins_count = metadata.m_coins_count;
	uint64_t coins_left = metadata.m_coins_count;

	LogPrintf("[snapshot] loading coins from snapshot %s\n",
	base_blockhash.ToString());
	int64_t coins_processed{0};

	while (coins_left > 0) {
	try {
	coins_file >> outpoint;
	coins_file >> coin;
	} catch (const std::ios_base::failure &) {
	LogPrintf("[snapshot] bad snapshot format or truncated snapshot "
	"after deserializing %d coins\n",
	coins_count - coins_left);
	return false;
	}
	if (coin.GetHeight() > uint32_t(base_height) \|\|
	// Avoid integer wrap-around in coinstats.cpp:ApplyHash
	outpoint.GetN() >=
	std::numeric_limits<decltype(outpoint.GetN())>::max()) {
	LogPrintf(
	"[snapshot] bad snapshot data after deserializing %d coins\n",
	coins_count - coins_left);
	return false;
	}
	coins_cache.EmplaceCoinInternalDANGER(std::move(outpoint),
	std::move(coin));

	--coins_left;
	++coins_processed;

	if (coins_processed % 1000000 == 0) {
	LogPrintf("[snapshot] %d coins loaded (%.2f%%, %.2f MB)\n",
	coins_processed,
	static_cast<float>(coins_processed) * 100 /
	static_cast<float>(coins_count),
	coins_cache.DynamicMemoryUsage() / (1000 * 1000));
	}

	// Batch write and flush (if we need to) every so often.
	//
	// If our average Coin size is roughly 41 bytes, checking every 120,000
	// coins means <5MB of memory imprecision.
	if (coins_processed % 120000 == 0) {
	if (ShutdownRequested()) {
	return false;
	}

	const auto snapshot_cache_state = WITH_LOCK(
	::cs_main, return snapshot_chainstate.GetCoinsCacheSizeState());

	if (snapshot_cache_state >= CoinsCacheSizeState::CRITICAL) {
	// This is a hack - we don't know what the actual best block is,
	// but that doesn't matter for the purposes of flushing the
	// cache here. We'll set this to its correct value
	// (`base_blockhash`) below after the coins are loaded.
	coins_cache.SetBestBlock(BlockHash{GetRandHash()});

	// No need to acquire cs_main since this chainstate isn't being
	// used yet.
	FlushSnapshotToDisk(coins_cache, /snapshot_loaded=/false);
	}
	}
	}

	// Important that we set this. This and the coins_cache accesses above are
	// sort of a layer violation, but either we reach into the innards of
	// CCoinsViewCache here or we have to invert some of the Chainstate to
	// embed them in a snapshot-activation-specific CCoinsViewCache bulk load
	// method.
	coins_cache.SetBestBlock(base_blockhash);

	bool out_of_coins{false};
	try {
	coins_file >> outpoint;
	} catch (const std::ios_base::failure &) {
	// We expect an exception since we should be out of coins.
	out_of_coins = true;
	}
	if (!out_of_coins) {
	LogPrintf("[snapshot] bad snapshot - coins left over after "
	"deserializing %d coins\n",
	coins_count);
	return false;
	}

	LogPrintf("[snapshot] loaded %d (%.2f MB) coins from snapshot %s\n",
	coins_count, coins_cache.DynamicMemoryUsage() / (1000 * 1000),
	base_blockhash.ToString());

	// No need to acquire cs_main since this chainstate isn't being used yet.
	FlushSnapshotToDisk(coins_cache, /snapshot_loaded=/true);

	assert(coins_cache.GetBestBlock() == base_blockhash);

	// As above, okay to immediately release cs_main here since no other context
	// knows about the snapshot_chainstate.
	CCoinsViewDB *snapshot_coinsdb =
	WITH_LOCK(::cs_main, return &snapshot_chainstate.CoinsDB());

	std::optional<CCoinsStats> maybe_stats;

	try {
	maybe_stats = ComputeUTXOStats(CoinStatsHashType::HASH_SERIALIZED,
	snapshot_coinsdb, m_blockman,
	SnapshotUTXOHashBreakpoint);
	} catch (StopHashingException const &) {
	return false;
	}
	if (!maybe_stats.has_value()) {
	LogPrintf("[snapshot] failed to generate coins stats\n");
	return false;
	}

	// Assert that the deserialized chainstate contents match the expected
	// assumeutxo value.
	if (AssumeutxoHash{maybe_stats->hashSerialized} !=
	au_data.hash_serialized) {
	LogPrintf("[snapshot] bad snapshot content hash: expected %s, got %s\n",
	au_data.hash_serialized.ToString(),
	maybe_stats->hashSerialized.ToString());
	return false;
	}

	snapshot_chainstate.m_chain.SetTip(*snapshot_start_block);

	// The remainder of this function requires modifying data protected by
	// cs_main.
	LOCK(::cs_main);

	// Fake various pieces of CBlockIndex state:
	CBlockIndex *index = nullptr;

	// Don't make any modifications to the genesis block since it shouldn't be
	// necessary, and since the genesis block doesn't have normal flags like
	// BLOCK_VALID_SCRIPTS set.
	constexpr int AFTER_GENESIS_START{1};

	for (int i = AFTER_GENESIS_START; i <= snapshot_chainstate.m_chain.Height();
	++i) {
	index = snapshot_chainstate.m_chain[i];

	m_blockman.m_dirty_blockindex.insert(index);
	// Changes to the block index will be flushed to disk after this call
	// returns in `ActivateSnapshot()`, when `MaybeRebalanceCaches()` is
	// called, since we've added a snapshot chainstate and therefore will
	// have to downsize the IBD chainstate, which will result in a call to
	// `FlushStateToDisk(ALWAYS)`.
	}

	assert(index);
	assert(index == snapshot_start_block);
	index->nChainTx = au_data.nChainTx;
	snapshot_chainstate.setBlockIndexCandidates.insert(snapshot_start_block);

	LogPrintf("[snapshot] validated snapshot (%.2f MB)\n",
	coins_cache.DynamicMemoryUsage() / (1000 * 1000));
	return true;
	}

	// Currently, this function holds cs_main for its duration, which could be for
	// multiple minutes due to the ComputeUTXOStats call. This hold is necessary
	// because we need to avoid advancing the background validation chainstate
	// farther than the snapshot base block - and this function is also invoked
	// from within ConnectTip, i.e. from within ActivateBestChain, so cs_main is
	// held anyway.
	//
	// Eventually (TODO), we could somehow separate this function's runtime from
	// maintenance of the active chain, but that will either require
	//
	// (i) setting `m_disabled` immediately and ensuring all chainstate accesses go
	// through IsUsable() checks, or
	//
	// (ii) giving each chainstate its own lock instead of using cs_main for
	// everything.
	SnapshotCompletionResult ChainstateManager::MaybeCompleteSnapshotValidation(
	std::function<void(bilingual_str)> shutdown_fnc) {
	AssertLockHeld(cs_main);
	if (m_ibd_chainstate.get() == &this->ActiveChainstate() \|\|
	!this->IsUsable(m_snapshot_chainstate.get()) \|\|
	!this->IsUsable(m_ibd_chainstate.get()) \|\|
	!m_ibd_chainstate->m_chain.Tip()) {
	// Nothing to do - this function only applies to the background
	// validation chainstate.
	return SnapshotCompletionResult::SKIPPED;
	}
	const int snapshot_tip_height = this->ActiveHeight();
	const int snapshot_base_height = *Assert(this->GetSnapshotBaseHeight());
	const CBlockIndex &index_new = *Assert(m_ibd_chainstate->m_chain.Tip());

	if (index_new.nHeight < snapshot_base_height) {
	// Background IBD not complete yet.
	return SnapshotCompletionResult::SKIPPED;
	}

	assert(SnapshotBlockhash());
	BlockHash snapshot_blockhash = *Assert(SnapshotBlockhash());

	auto handle_invalid_snapshot = [&]() EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
	bilingual_str user_error = strprintf(
	_("%s failed to validate the -assumeutxo snapshot state. "
	"This indicates a hardware problem, or a bug in the software, or "
	"a bad software modification that allowed an invalid snapshot to "
	"be loaded. As a result of this, the node will shut down and "
	"stop using any state that was built on the snapshot, resetting "
	"the chain height from %d to %d. On the next restart, the node "
	"will resume syncing from %d without using any snapshot data. "
	"Please report this incident to %s, including how you obtained "
	"the snapshot. The invalid snapshot chainstate will be left on "
	"disk in case it is helpful in diagnosing the issue that caused "
	"this error."),
	PACKAGE_NAME, snapshot_tip_height, snapshot_base_height,
	snapshot_base_height, PACKAGE_BUGREPORT);

	LogPrintf("[snapshot] !!! %s\n", user_error.original);
	LogPrintf("[snapshot] deleting snapshot, reverting to validated chain, "
	"and stopping node\n");

	m_active_chainstate = m_ibd_chainstate.get();
	m_snapshot_chainstate->m_disabled = true;
	assert(!this->IsUsable(m_snapshot_chainstate.get()));
	assert(this->IsUsable(m_ibd_chainstate.get()));

	auto rename_result = m_snapshot_chainstate->InvalidateCoinsDBOnDisk();
	if (!rename_result) {
	user_error = strprintf(Untranslated("%s\n%s"), user_error,
	util::ErrorString(rename_result));
	}

	shutdown_fnc(user_error);
	};

	if (index_new.GetBlockHash() != snapshot_blockhash) {
	LogPrintf(
	"[snapshot] supposed base block %s does not match the "
	"snapshot base block %s (height %d). Snapshot is not valid.\n",
	index_new.ToString(), snapshot_blockhash.ToString(),
	snapshot_base_height);
	handle_invalid_snapshot();
	return SnapshotCompletionResult::BASE_BLOCKHASH_MISMATCH;
	}

	assert(index_new.nHeight == snapshot_base_height);

	int curr_height = m_ibd_chainstate->m_chain.Height();

	assert(snapshot_base_height == curr_height);
	assert(snapshot_base_height == index_new.nHeight);
	assert(this->IsUsable(m_snapshot_chainstate.get()));
	assert(this->GetAll().size() == 2);

	CCoinsViewDB &ibd_coins_db = m_ibd_chainstate->CoinsDB();
	m_ibd_chainstate->ForceFlushStateToDisk();

	const auto &maybe_au_data =
	this->GetParams().AssumeutxoForHeight(curr_height);
	if (!maybe_au_data) {
	LogPrintf("[snapshot] assumeutxo data not found for height "
	"(%d) - refusing to validate snapshot\n",
	curr_height);
	handle_invalid_snapshot();
	return SnapshotCompletionResult::MISSING_CHAINPARAMS;
	}

	const AssumeutxoData &au_data = *maybe_au_data;
	std::optional<CCoinsStats> maybe_ibd_stats;
	LogPrintf(
	"[snapshot] computing UTXO stats for background chainstate to validate "
	"snapshot - this could take a few minutes\n");
	try {
	maybe_ibd_stats =
	ComputeUTXOStats(CoinStatsHashType::HASH_SERIALIZED, &ibd_coins_db,
	m_blockman, SnapshotUTXOHashBreakpoint);
	} catch (StopHashingException const &) {
	return SnapshotCompletionResult::STATS_FAILED;
	}

	if (!maybe_ibd_stats) {
	LogPrintf(
	"[snapshot] failed to generate stats for validation coins db\n");
	// While this isn't a problem with the snapshot per se, this condition
	// prevents us from validating the snapshot, so we should shut down and
	// let the user handle the issue manually.
	handle_invalid_snapshot();
	return SnapshotCompletionResult::STATS_FAILED;
	}
	const auto &ibd_stats = *maybe_ibd_stats;

	// Compare the background validation chainstate's UTXO set hash against the
	// hard-coded assumeutxo hash we expect.
	//
	// TODO: For belt-and-suspenders, we could cache the UTXO set
	// hash for the snapshot when it's loaded in its chainstate's leveldb. We
	// could then reference that here for an additional check.
	if (AssumeutxoHash{ibd_stats.hashSerialized} != au_data.hash_serialized) {
	LogPrintf("[snapshot] hash mismatch: actual=%s, expected=%s\n",
	ibd_stats.hashSerialized.ToString(),
	au_data.hash_serialized.ToString());
	handle_invalid_snapshot();
	return SnapshotCompletionResult::HASH_MISMATCH;
	}

	LogPrintf("[snapshot] snapshot beginning at %s has been fully validated\n",
	snapshot_blockhash.ToString());

	m_ibd_chainstate->m_disabled = true;
	this->MaybeRebalanceCaches();

	return SnapshotCompletionResult::SUCCESS;
	}

	Chainstate &ChainstateManager::ActiveChainstate() const {
	LOCK(::cs_main);
	assert(m_active_chainstate);
	return *m_active_chainstate;
	}

	bool ChainstateManager::IsSnapshotActive() const {
	LOCK(::cs_main);
	return m_snapshot_chainstate &&
	m_active_chainstate == m_snapshot_chainstate.get();
	}
	void ChainstateManager::MaybeRebalanceCaches() {
	AssertLockHeld(::cs_main);
	bool ibd_usable = this->IsUsable(m_ibd_chainstate.get());
	bool snapshot_usable = this->IsUsable(m_snapshot_chainstate.get());
	assert(ibd_usable \|\| snapshot_usable);

	if (ibd_usable && !snapshot_usable) {
	LogPrintf("[snapshot] allocating all cache to the IBD chainstate\n");
	// Allocate everything to the IBD chainstate.
	m_ibd_chainstate->ResizeCoinsCaches(m_total_coinstip_cache,
	m_total_coinsdb_cache);
	} else if (snapshot_usable && !ibd_usable) {
	// If background validation has completed and snapshot is our active
	// chain...
	LogPrintf(
	"[snapshot] allocating all cache to the snapshot chainstate\n");
	// Allocate everything to the snapshot chainstate.
	m_snapshot_chainstate->ResizeCoinsCaches(m_total_coinstip_cache,
	m_total_coinsdb_cache);
	} else if (ibd_usable && snapshot_usable) {
	// If both chainstates exist, determine who needs more cache based on
	// IBD status.
	//
	// Note: shrink caches first so that we don't inadvertently overwhelm
	// available memory.
	if (IsInitialBlockDownload()) {
	m_ibd_chainstate->ResizeCoinsCaches(m_total_coinstip_cache * 0.05,
	m_total_coinsdb_cache * 0.05);
	m_snapshot_chainstate->ResizeCoinsCaches(
	m_total_coinstip_cache * 0.95, m_total_coinsdb_cache * 0.95);
	} else {
	m_snapshot_chainstate->ResizeCoinsCaches(
	m_total_coinstip_cache * 0.05, m_total_coinsdb_cache * 0.05);
	m_ibd_chainstate->ResizeCoinsCaches(m_total_coinstip_cache * 0.95,
	m_total_coinsdb_cache * 0.95);
	}
	}
	}

	void ChainstateManager::ResetChainstates() {
	m_ibd_chainstate.reset();
	m_snapshot_chainstate.reset();
	m_active_chainstate = nullptr;
	}

	/**
	* Apply default chain params to nullopt members.
	* This helps to avoid coding errors around the accidental use of the compare
	* operators that accept nullopt, thus ignoring the intended default value.
	*/
	static ChainstateManager::Options &&Flatten(ChainstateManager::Options &&opts) {
	if (!opts.check_block_index.has_value()) {
	opts.check_block_index =
	opts.config.GetChainParams().DefaultConsistencyChecks();
	}

	if (!opts.minimum_chain_work.has_value()) {
	opts.minimum_chain_work = UintToArith256(
	opts.config.GetChainParams().GetConsensus().nMinimumChainWork);
	}
	if (!opts.assumed_valid_block.has_value()) {
	opts.assumed_valid_block =
	opts.config.GetChainParams().GetConsensus().defaultAssumeValid;
	}
	Assert(opts.adjusted_time_callback);
	return std::move(opts);
	}

	ChainstateManager::ChainstateManager(
	Options options, node::BlockManager::Options blockman_options)
	: m_options{Flatten(std::move(options))},
	m_blockman{std::move(blockman_options)} {}

	bool ChainstateManager::DetectSnapshotChainstate(CTxMemPool *mempool) {
	assert(!m_snapshot_chainstate);
	std::optional<fs::path> path = node::FindSnapshotChainstateDir();
	if (!path) {
	return false;
	}
	std::optional<BlockHash> base_blockhash =
	node::ReadSnapshotBaseBlockhash(*path);
	if (!base_blockhash) {
	return false;
	}
	LogPrintf("[snapshot] detected active snapshot chainstate (%s) - loading\n",
	fs::PathToString(*path));

	this->ActivateExistingSnapshot(mempool, *base_blockhash);
	return true;
	}

	Chainstate &
	ChainstateManager::ActivateExistingSnapshot(CTxMemPool *mempool,
	BlockHash base_blockhash) {
	assert(!m_snapshot_chainstate);
	m_snapshot_chainstate = std::make_unique<Chainstate>(mempool, m_blockman,
	*this, base_blockhash);
	LogPrintf("[snapshot] switching active chainstate to %s\n",
	m_snapshot_chainstate->ToString());
	m_active_chainstate = m_snapshot_chainstate.get();
	return *m_snapshot_chainstate;
	}

	static fs::path GetSnapshotCoinsDBPath(Chainstate &cs)
	EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
	AssertLockHeld(::cs_main);
	// Should never be called on a non-snapshot chainstate.
	assert(cs.m_from_snapshot_blockhash);
	auto storage_path_maybe = cs.CoinsDB().StoragePath();
	// Should never be called with a non-existent storage path.
	assert(storage_path_maybe);
	return *storage_path_maybe;
	}

	util::Result<void> Chainstate::InvalidateCoinsDBOnDisk() {
	fs::path snapshot_datadir = GetSnapshotCoinsDBPath(*this);

	// Coins views no longer usable.
	m_coins_views.reset();

	auto invalid_path = snapshot_datadir + "_INVALID";
	std::string dbpath = fs::PathToString(snapshot_datadir);
	std::string target = fs::PathToString(invalid_path);
	LogPrintf("[snapshot] renaming snapshot datadir %s to %s\n", dbpath,
	target);

	// The invalid snapshot datadir is simply moved and not deleted because we
	// may want to do forensics later during issue investigation. The user is
	// instructed accordingly in MaybeCompleteSnapshotValidation().
	try {
	fs::rename(snapshot_datadir, invalid_path);
	} catch (const fs::filesystem_error &e) {
	auto src_str = fs::PathToString(snapshot_datadir);
	auto dest_str = fs::PathToString(invalid_path);

	LogPrintf("%s: error renaming file '%s' -> '%s': %s\n", __func__,
	src_str, dest_str, e.what());
	return util::Error{strprintf(_("Rename of '%s' -> '%s' failed. "
	"You should resolve this by manually "
	"moving or deleting the invalid "
	"snapshot directory %s, otherwise you "
	"will encounter the same error again "
	"on the next startup."),
	src_str, dest_str, src_str)};
	}
	return {};
	}

	bool ChainstateManager::DeleteSnapshotChainstate() {
	AssertLockHeld(::cs_main);
	Assert(m_snapshot_chainstate);
	Assert(m_ibd_chainstate);

	fs::path snapshot_datadir = GetSnapshotCoinsDBPath(*m_snapshot_chainstate);
	if (!DeleteCoinsDBFromDisk(snapshot_datadir, /is_snapshot=/true)) {
	LogPrintf("Deletion of %s failed. Please remove it manually to "
	"continue reindexing.\n",
	fs::PathToString(snapshot_datadir));
	return false;
	}
	m_active_chainstate = m_ibd_chainstate.get();
	m_snapshot_chainstate.reset();
	return true;
	}

	const CBlockIndex *ChainstateManager::GetSnapshotBaseBlock() const {
	return m_active_chainstate ? m_active_chainstate->SnapshotBase() : nullptr;
	}

	std::optional<int> ChainstateManager::GetSnapshotBaseHeight() const {
	const CBlockIndex *base = this->GetSnapshotBaseBlock();
	return base ? std::make_optional(base->nHeight) : std::nullopt;
	}

	bool ChainstateManager::ValidatedSnapshotCleanup() {
	AssertLockHeld(::cs_main);
	auto get_storage_path = [](auto &chainstate) EXCLUSIVE_LOCKS_REQUIRED(
	::cs_main) -> std::optional<fs::path> {
	if (!(chainstate && chainstate->HasCoinsViews())) {
	return {};
	}
	return chainstate->CoinsDB().StoragePath();
	};
	std::optional<fs::path> ibd_chainstate_path_maybe =
	get_storage_path(m_ibd_chainstate);
	std::optional<fs::path> snapshot_chainstate_path_maybe =
	get_storage_path(m_snapshot_chainstate);

	if (!this->IsSnapshotValidated()) {
	// No need to clean up.
	return false;
	}
	// If either path doesn't exist, that means at least one of the chainstates
	// is in-memory, in which case we can't do on-disk cleanup. You'd better be
	// in a unittest!
	if (!ibd_chainstate_path_maybe \|\| !snapshot_chainstate_path_maybe) {
	LogPrintf("[snapshot] snapshot chainstate cleanup cannot happen with "
	"in-memory chainstates. You are testing, right?\n");
	return false;
	}

	const auto &snapshot_chainstate_path = *snapshot_chainstate_path_maybe;
	const auto &ibd_chainstate_path = *ibd_chainstate_path_maybe;

	// Since we're going to be moving around the underlying leveldb filesystem
	// content for each chainstate, make sure that the chainstates (and their
	// constituent CoinsViews members) have been destructed first.
	//
	// The caller of this method will be responsible for reinitializing
	// chainstates if they want to continue operation.
	this->ResetChainstates();

	// No chainstates should be considered usable.
	assert(this->GetAll().size() == 0);

	LogPrintf("[snapshot] deleting background chainstate directory (now "
	"unnecessary) (%s)\n",
	fs::PathToString(ibd_chainstate_path));

	fs::path tmp_old{ibd_chainstate_path + "_todelete"};

	auto rename_failed_abort = [](fs::path p_old, fs::path p_new,
	const fs::filesystem_error &err) {
	LogPrintf("Error renaming file (%s): %s\n", fs::PathToString(p_old),
	err.what());
	AbortNode(strprintf(
	"Rename of '%s' -> '%s' failed. "
	"Cannot clean up the background chainstate leveldb directory.",
	fs::PathToString(p_old), fs::PathToString(p_new)));
	};

	try {
	fs::rename(ibd_chainstate_path, tmp_old);
	} catch (const fs::filesystem_error &e) {
	rename_failed_abort(ibd_chainstate_path, tmp_old, e);
	throw;
	}

	LogPrintf("[snapshot] moving snapshot chainstate (%s) to "
	"default chainstate directory (%s)\n",
	fs::PathToString(snapshot_chainstate_path),
	fs::PathToString(ibd_chainstate_path));

	try {
	fs::rename(snapshot_chainstate_path, ibd_chainstate_path);
	} catch (const fs::filesystem_error &e) {
	rename_failed_abort(snapshot_chainstate_path, ibd_chainstate_path, e);
	throw;
	}

	if (!DeleteCoinsDBFromDisk(tmp_old, /is_snapshot=/false)) {
	// No need to AbortNode because once the unneeded bg chainstate data is
	// moved, it will not interfere with subsequent initialization.
	LogPrintf("Deletion of %s failed. Please remove it manually, as the "
	"directory is now unnecessary.\n",
	fs::PathToString(tmp_old));
	} else {
	LogPrintf("[snapshot] deleted background chainstate directory (%s)\n",
	fs::PathToString(ibd_chainstate_path));
	}
	return true;
	}

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