dash/src/validation.h

// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2020 The Bitcoin Core developers
// Copyright (c) 2014-2024 The Dash Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_VALIDATION_H
#define BITCOIN_VALIDATION_H

#if defined(HAVE_CONFIG_H)
#include <config/bitcoin-config.h>
#endif

#include <arith_uint256.h>
#include <attributes.h>
#include <chain.h>
#include <consensus/amount.h>
#include <fs.h>
#include <node/blockstorage.h>
#include <policy/feerate.h>
#include <policy/packages.h>
#include <script/script_error.h>
#include <serialize.h>
#include <sync.h>
#include <txdb.h>
#include <txmempool.h> // For CTxMemPool::cs
#include <uint256.h>
#include <util/check.h>
#include <util/hasher.h>
#include <util/translation.h>

#include <atomic>
#include <map>
#include <memory>
#include <optional>
#include <set>
#include <stdint.h>
#include <string>
#include <thread>
#include <utility>
#include <vector>

class CChainState;
class CBlockTreeDB;
class CChainParams;
class CEvoDB;
class CMNHFManager;
class CTxMemPool;
class TxValidationState;
class CChainstateHelper;
class ChainstateManager;
struct PrecomputedTransactionData;
class SnapshotMetadata;
struct ChainTxData;
struct DisconnectedBlockTransactions;
struct LockPoints;
struct AssumeutxoData;

namespace llmq {
class CChainLocksHandler;
class CInstantSendManager;
} // namespace llmq

/** Default for -minrelaytxfee, minimum relay fee for transactions */
static const unsigned int DEFAULT_MIN_RELAY_TX_FEE = 1000;
/** Default for -limitancestorcount, max number of in-mempool ancestors */
static const unsigned int DEFAULT_ANCESTOR_LIMIT = 25;
/** Default for -limitancestorsize, maximum kilobytes of tx + all in-mempool ancestors */
static const unsigned int DEFAULT_ANCESTOR_SIZE_LIMIT = 101;
/** Default for -limitdescendantcount, max number of in-mempool descendants */
static const unsigned int DEFAULT_DESCENDANT_LIMIT = 25;
/** Default for -limitdescendantsize, maximum kilobytes of in-mempool descendants */
static const unsigned int DEFAULT_DESCENDANT_SIZE_LIMIT = 101;
/**
 * An extra transaction can be added to a package, as long as it only has one
 * ancestor and is no larger than this. Not really any reason to make this
 * configurable as it doesn't materially change DoS parameters.
 */
static const unsigned int EXTRA_DESCENDANT_TX_SIZE_LIMIT = 10000;
/** Default for -mempoolexpiry, expiration time for mempool transactions in hours */
static const unsigned int DEFAULT_MEMPOOL_EXPIRY = 336;
/** Maximum number of dedicated script-checking threads allowed */
static const int MAX_SCRIPTCHECK_THREADS = 15;
/** -par default (number of script-checking threads, 0 = auto) */
static const int DEFAULT_SCRIPTCHECK_THREADS = 0;
/** Number of headers sent in one getheaders result. We rely on the assumption that if a peer sends
 *  less than this number, we reached its tip. Changing this value is a protocol upgrade. */
static const unsigned int MAX_HEADERS_UNCOMPRESSED_RESULT = 2000;
static const unsigned int MAX_HEADERS_COMPRESSED_RESULT = 8000;

static const int64_t DEFAULT_MAX_TIP_AGE = 6 * 60 * 60; // ~144 blocks behind -> 2 x fork detection time, was 24 * 60 * 60 in bitcoin

static const bool DEFAULT_CHECKPOINTS_ENABLED = true;
static const bool DEFAULT_TXINDEX = true;
static constexpr bool DEFAULT_COINSTATSINDEX{false};
static const char* const DEFAULT_BLOCKFILTERINDEX = "0";
/** Default for -persistmempool */
static const bool DEFAULT_PERSIST_MEMPOOL = true;
/** Default for -syncmempool */
static const bool DEFAULT_SYNC_MEMPOOL = true;

/** Default for -stopatheight */
static const int DEFAULT_STOPATHEIGHT = 0;
/** Block files containing a block-height within MIN_BLOCKS_TO_KEEP of ActiveChain().Tip() will not be pruned. */
static const unsigned int MIN_BLOCKS_TO_KEEP = 288;
static const signed int DEFAULT_CHECKBLOCKS = 6;
static constexpr int DEFAULT_CHECKLEVEL{3};

// Require that user allocate at least 945 MiB for block & undo files (blk???.dat and rev???.dat)
// At 2B MiB per block, 288 blocks = 576 MiB.
// Add 15% for Undo data = 662 MiB
// Add 20% for Orphan block rate = 794 MiB
// We want the low water mark after pruning to be at least 794 MiB and since we prune in
// full block file chunks, we need the high water mark which triggers the prune to be
// one 128 MiB block file + added 15% undo data = 147 MiB greater for a total of 941 MiB
// Setting the target to > than 945 MiB will make it likely we can respect the target.
static const uint64_t MIN_DISK_SPACE_FOR_BLOCK_FILES = 945 * 1024 * 1024;

/** Current sync state passed to tip changed callbacks. */
enum class SynchronizationState {
    INIT_REINDEX,
    INIT_DOWNLOAD,
    POST_INIT
};

extern RecursiveMutex cs_main;
extern Mutex g_best_block_mutex;
extern std::condition_variable g_best_block_cv;
/** Used to notify getblocktemplate RPC of new tips. */
extern uint256 g_best_block;
/** Whether there are dedicated script-checking threads running.
 * False indicates all script checking is done on the main threadMessageHandler thread.
 */
extern bool g_parallel_script_checks;
extern bool fRequireStandard;
extern bool fCheckBlockIndex;
extern bool fCheckpointsEnabled;
/** A fee rate smaller than this is considered zero fee (for relaying, mining and transaction creation) */
extern CFeeRate minRelayTxFee;
/** If the tip is older than this (in seconds), the node is considered to be in initial block download. */
extern int64_t nMaxTipAge;

extern bool fLargeWorkForkFound;
extern bool fLargeWorkInvalidChainFound;

/** Block hash whose ancestors we will assume to have valid scripts without checking them. */
extern uint256 hashAssumeValid;

/** Minimum work we will assume exists on some valid chain. */
extern arith_uint256 nMinimumChainWork;

/** Documentation for argument 'checklevel'. */
extern const std::vector<std::string> CHECKLEVEL_DOC;

/** Run instances of script checking worker threads */
void StartScriptCheckWorkerThreads(int threads_num);
/** Stop all of the script checking worker threads */
void StopScriptCheckWorkerThreads();

CTransactionRef GetTransaction(const CBlockIndex* const block_index, const CTxMemPool* const mempool, const uint256& hash, const Consensus::Params& consensusParams, uint256& hashBlock);

double ConvertBitsToDouble(unsigned int nBits);
/**
 * Due to difference in logic, the GetBlockSubsidy() has also different list of
 * arguments.
 *
 * When pindex points to a genesis block GetBlockSubsidy() returns a pre-calculated value.
 * For other blocks it calls GetBlockSubsidyInner() using nBits and nHeight of a pindex->pprev block.
 */
CAmount GetBlockSubsidyInner(int nPrevBits, int nPrevHeight, const Consensus::Params& consensusParams, bool fV20Active);
CAmount GetSuperblockSubsidyInner(int nPrevBits, int nPrevHeight, const Consensus::Params& consensusParams, bool fV20Active);
CAmount GetBlockSubsidy(const CBlockIndex* const pindex, const Consensus::Params& consensusParams);
CAmount GetMasternodePayment(int nHeight, CAmount blockValue, bool fV20Active);

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

/** Guess verification progress (as a fraction between 0.0=genesis and 1.0=current tip). */
double GuessVerificationProgress(const ChainTxData& data, const CBlockIndex* pindex);

/** Prune block files up to a given height */
void PruneBlockFilesManual(CChainState& active_chainstate, int nManualPruneHeight);

/**
* Validation result for a single transaction mempool acceptance.
*/
struct MempoolAcceptResult {
    /** Used to indicate the results of mempool validation. */
    enum class ResultType {
        VALID, //!> Fully validated, valid.
        INVALID, //!> Invalid.
    };
    const ResultType m_result_type;
    const TxValidationState m_state;

    // The following fields are only present when m_result_type = ResultType::VALID
    /** Raw base fees in satoshis. */
    const std::optional<CAmount> m_base_fees;
    static MempoolAcceptResult Failure(TxValidationState state) {
        return MempoolAcceptResult(state);
    }

    static MempoolAcceptResult Success(CAmount fees) {
        return MempoolAcceptResult(fees);
    }

// Private constructors. Use static methods MempoolAcceptResult::Success, etc. to construct.
private:
    /** Constructor for failure case */
    explicit MempoolAcceptResult(TxValidationState state)
        : m_result_type(ResultType::INVALID), m_state(state), m_base_fees(std::nullopt) {
            Assume(!state.IsValid()); // Can be invalid or error
        }

    /** Constructor for success case */
    explicit MempoolAcceptResult(CAmount fees)
        : m_result_type(ResultType::VALID), m_base_fees(fees) {}
};

/**
* Validation result for package mempool acceptance.
*/
struct PackageMempoolAcceptResult
{
    const PackageValidationState m_state;
    /**
    * Map from txid to finished MempoolAcceptResults. The client is responsible
    * for keeping track of the transaction objects themselves. If a result is not
    * present, it means validation was unfinished for that transaction. If there
    * was a package-wide error (see result in m_state), m_tx_results will be empty.
    */
    std::map<const uint256, const MempoolAcceptResult> m_tx_results;

    explicit PackageMempoolAcceptResult(PackageValidationState state,
                                        std::map<const uint256, const MempoolAcceptResult>&& results)
        : m_state{state}, m_tx_results(std::move(results)) {}

    /** Constructor to create a PackageMempoolAcceptResult from a single MempoolAcceptResult */
    explicit PackageMempoolAcceptResult(const uint256 &txid, const MempoolAcceptResult& result)
        : m_tx_results{ {txid, result} } {}
};

/**
 * Try to add a transaction to the mempool. This is an internal function and is exposed only for testing.
 * Client code should use ChainstateManager::ProcessTransaction()
 *
 * @param[in]  active_chainstate  Reference to the active chainstate.
 * @param[in]  tx                 The transaction to submit for mempool acceptance.
 * @param[in]  accept_time        The timestamp for adding the transaction to the mempool.
 *                                It is also used to determine when the entry expires.
 * @param[in]  bypass_limits      When true, don't enforce mempool fee and capacity limits.
 * @param[in]  test_accept        When true, run validation checks but don't submit to mempool.
 *
 * @returns a MempoolAcceptResult indicating whether the transaction was accepted/rejected with reason.
 */
MempoolAcceptResult AcceptToMemoryPool(CChainState& active_chainstate, const CTransactionRef& tx,
                                       int64_t accept_time, bool bypass_limits, bool test_accept)
    EXCLUSIVE_LOCKS_REQUIRED(cs_main);

/**
* Atomically test acceptance of a package. If the package only contains one tx, package rules still
* apply. The transaction(s) cannot spend the same inputs as any transaction in the mempool.
* @param[in]    txns                Group of transactions which may be independent or contain
*                                   parent-child dependencies. The transactions must not conflict
*                                   with each other, i.e., must not spend the same inputs. If any
*                                   dependencies exist, parents must appear anywhere in the list
*                                   before their children.
* @returns a PackageMempoolAcceptResult which includes a MempoolAcceptResult for each transaction.
* If a transaction fails, validation will exit early and some results may be missing.
*/
PackageMempoolAcceptResult ProcessNewPackage(CChainState& active_chainstate, CTxMemPool& pool,
                                             const Package& txns, bool test_accept)
                                             EXCLUSIVE_LOCKS_REQUIRED(cs_main);

bool GetUTXOCoin(CChainState& active_chainstate, const COutPoint& outpoint, Coin& coin);
int GetUTXOHeight(CChainState& active_chainstate, const COutPoint& outpoint);
int GetUTXOConfirmations(CChainState& active_chainstate, const COutPoint& outpoint);

/* Mempool validation helper functions */

/**
 * Check if transaction will be final in the next block to be created.
 */
bool CheckFinalTxAtTip(const CBlockIndex& active_chain_tip, const CTransaction& tx) EXCLUSIVE_LOCKS_REQUIRED(::cs_main);

/**
 * Check if transaction will be BIP68 final in the next block to be created on top of tip.
 * @param[in]   tip             Chain tip to check tx sequence locks against. For example,
 *                              the tip of the current active chain.
 * @param[in]   coins_view      Any CCoinsView that provides access to the relevant coins for
 *                              checking sequence locks. For example, it can be a CCoinsViewCache
 *                              that isn't connected to anything but contains all the relevant
 *                              coins, or a CCoinsViewMemPool that is connected to the
 *                              mempool and chainstate UTXO set. In the latter case, the caller is
 *                              responsible for holding the appropriate locks to ensure that
 *                              calls to GetCoin() return correct coins.
 * Simulates calling SequenceLocks() with data from the tip passed in.
 * Optionally stores in LockPoints the resulting height and time calculated and the hash
 * of the block needed for calculation or skips the calculation and uses the LockPoints
 * passed in for evaluation.
 * The LockPoints should not be considered valid if CheckSequenceLocksAtTip returns false.
 */
bool CheckSequenceLocksAtTip(CBlockIndex* tip,
                        const CCoinsView& coins_view,
                        const CTransaction& tx,
                        LockPoints* lp = nullptr,
                        bool useExistingLockPoints = false);

/**
 * Closure representing one script verification
 * Note that this stores references to the spending transaction
 */
class CScriptCheck
{
private:
    CTxOut m_tx_out;
    const CTransaction *ptxTo;
    unsigned int nIn;
    unsigned int nFlags;
    bool cacheStore;
    ScriptError error;
    PrecomputedTransactionData *txdata;

public:
    CScriptCheck(): ptxTo(nullptr), nIn(0), nFlags(0), cacheStore(false), error(SCRIPT_ERR_UNKNOWN_ERROR) {}
    CScriptCheck(const CTxOut& outIn, const CTransaction& txToIn, unsigned int nInIn, unsigned int nFlagsIn, bool cacheIn, PrecomputedTransactionData* txdataIn) :
        m_tx_out(outIn), ptxTo(&txToIn), nIn(nInIn), nFlags(nFlagsIn), cacheStore(cacheIn), error(SCRIPT_ERR_UNKNOWN_ERROR), txdata(txdataIn) { }

    bool operator()();

    void swap(CScriptCheck& check) noexcept
    {
        std::swap(ptxTo, check.ptxTo);
        std::swap(m_tx_out, check.m_tx_out);
        std::swap(nIn, check.nIn);
        std::swap(nFlags, check.nFlags);
        std::swap(cacheStore, check.cacheStore);
        std::swap(error, check.error);
        std::swap(txdata, check.txdata);
    }

    ScriptError GetScriptError() const { return error; }
};

/** Initializes the script-execution cache */
void InitScriptExecutionCache();

/** Functions for validating blocks and updating the block tree */

/** Context-independent validity checks */
bool CheckBlock(const CBlock& block, BlockValidationState& state, const Consensus::Params& consensusParams, bool fCheckPOW = true, bool fCheckMerkleRoot = true);

/** Check a block is completely valid from start to finish (only works on top of our current best block) */
bool TestBlockValidity(BlockValidationState& state,
                       llmq::CChainLocksHandler& clhandler,
                       CEvoDB& evoDb,
                       const CChainParams& chainparams,
                       CChainState& chainstate,
                       const CBlock& block,
                       CBlockIndex* pindexPrev,
                       bool fCheckPOW = true,
                       bool fCheckMerkleRoot = true) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

/** RAII wrapper for VerifyDB: Verify consistency of the block and coin databases */
class CVerifyDB {
public:
    CVerifyDB();
    ~CVerifyDB();
    bool VerifyDB(
        CChainState& chainstate,
        const Consensus::Params& consensus_params,
        CCoinsView& coinsview,
        CEvoDB& evoDb,
        int nCheckLevel,
        int nCheckDepth) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
};

enum DisconnectResult {
    DISCONNECT_OK,      // All good.
    DISCONNECT_UNCLEAN, // Rolled back, but UTXO set was inconsistent with block.
    DISCONNECT_FAILED   // Something else went wrong.
};

class ConnectTrace;

/** @see CChainState::FlushStateToDisk */
enum class FlushStateMode {
    NONE,
    IF_NEEDED,
    PERIODIC,
    ALWAYS
};

/**
 * A convenience class for constructing the CCoinsView* hierarchy used
 * to facilitate access to the UTXO set.
 *
 * This class consists of an arrangement of layered CCoinsView objects,
 * preferring to store and retrieve coins in memory via `m_cacheview` but
 * ultimately falling back on cache misses to the canonical store of UTXOs on
 * disk, `m_dbview`.
 */
class CoinsViews {

public:
    //! The lowest level of the CoinsViews cache hierarchy sits in a leveldb database on disk.
    //! All unspent coins reside in this store.
    CCoinsViewDB m_dbview GUARDED_BY(cs_main);

    //! This view wraps access to the leveldb instance and handles read errors gracefully.
    CCoinsViewErrorCatcher m_catcherview GUARDED_BY(cs_main);

    //! This is the top layer of the cache hierarchy - it keeps as many coins in memory as
    //! can fit per the dbcache setting.
    std::unique_ptr<CCoinsViewCache> m_cacheview GUARDED_BY(cs_main);

    //! This constructor initializes CCoinsViewDB and CCoinsViewErrorCatcher instances, but it
    //! *does not* create a CCoinsViewCache instance by default. This is done separately because the
    //! presence of the cache has implications on whether or not we're allowed to flush the cache's
    //! state to disk, which should not be done until the health of the database is verified.
    //!
    //! All arguments forwarded onto CCoinsViewDB.
    CoinsViews(std::string ldb_name, size_t cache_size_bytes, bool in_memory, bool should_wipe);

    //! Initialize the CCoinsViewCache member.
    void InitCache() EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
};

enum class CoinsCacheSizeState
{
    //! The coins cache is in immediate need of a flush.
    CRITICAL = 2,
    //! The cache is at >= 90% capacity.
    LARGE = 1,
    OK = 0
};

/**
 * CChainState stores and provides an API to update our local knowledge of the
 * current best chain.
 *
 * Eventually, the API here is targeted at being exposed externally as a
 * consumable libconsensus library, so any functions added must only call
 * other class member functions, pure functions in other parts of the consensus
 * library, callbacks via the validation interface, or read/write-to-disk
 * functions (eventually this will also be via callbacks).
 *
 * Anything that is contingent on the current tip of the chain is stored here,
 * whereas block information and metadata independent of the current tip is
 * kept in `BlockManager`.
 */
class CChainState
{
protected:
    /**
     * Every received block is assigned a unique and increasing identifier, so we
     * know which one to give priority in case of a fork.
     */
    /** Blocks loaded from disk are assigned id 0, so start the counter at 1. */
    int32_t nBlockSequenceId GUARDED_BY(::cs_main) = 1;
    /** Decreasing counter (used by subsequent preciousblock calls). */
    int32_t nBlockReverseSequenceId = -1;
    /** chainwork for the last block that preciousblock has been applied to. */
    arith_uint256 nLastPreciousChainwork = 0;

    /**
     * The ChainState Mutex
     * A lock that must be held when modifying this ChainState - held in ActivateBestChain() and
     * InvalidateBlock()
     */
    Mutex m_chainstate_mutex;

    /**
     * Whether this chainstate is undergoing initial block download.
     *
     * Mutable because we need to be able to mark IsInitialBlockDownload()
     * const, which latches this for caching purposes.
     */
    mutable std::atomic<bool> m_cached_finished_ibd{false};

    //! Optional mempool that is kept in sync with the chain.
    //! Only the active chainstate has a mempool.
    CTxMemPool* m_mempool;

    //! Manages the UTXO set, which is a reflection of the contents of `m_chain`.
    std::unique_ptr<CoinsViews> m_coins_views;

    //! Dash
    const std::unique_ptr<CChainstateHelper>& m_chain_helper;
    const std::unique_ptr<llmq::CChainLocksHandler>& m_clhandler;
    const std::unique_ptr<llmq::CInstantSendManager>& m_isman;
    CEvoDB& m_evoDb;

public:
    //! Reference to a BlockManager instance which itself is shared across all
    //! CChainState instances.
    BlockManager& m_blockman;

    /** Chain parameters for this chainstate */
    const CChainParams& m_params;

    //! The chainstate manager that owns this chainstate. The reference is
    //! necessary so that this instance can check whether it is the active
    //! chainstate within deeply nested method calls.
    ChainstateManager& m_chainman;

    explicit CChainState(CTxMemPool* mempool,
                         BlockManager& blockman,
                         ChainstateManager& chainman,
                         CEvoDB& evoDb,
                         const std::unique_ptr<CChainstateHelper>& chain_helper,
                         const std::unique_ptr<llmq::CChainLocksHandler>& clhandler,
                         const std::unique_ptr<llmq::CInstantSendManager>& isman,
                         std::optional<uint256> from_snapshot_blockhash = std::nullopt);

    /**
     * Initialize the CoinsViews UTXO set database management data structures. The in-memory
     * cache is initialized separately.
     *
     * All parameters forwarded to CoinsViews.
     */
    void InitCoinsDB(
        size_t cache_size_bytes,
        bool in_memory,
        bool should_wipe,
        std::string leveldb_name = "chainstate");

    //! Initialize the in-memory coins cache (to be done after the health of the on-disk database
    //! is verified).
    void InitCoinsCache(size_t cache_size_bytes) EXCLUSIVE_LOCKS_REQUIRED(::cs_main);

    //! @returns whether or not the CoinsViews object has been fully initialized and we can
    //!          safely flush this object to disk.
    bool CanFlushToDisk() const EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
    {
        AssertLockHeld(::cs_main);
        return m_coins_views && m_coins_views->m_cacheview;
    }

    //! The current chain of blockheaders we consult and build on.
    //! @see CChain, CBlockIndex.
    CChain m_chain;

    /**
     * The blockhash which is the base of the snapshot this chainstate was created from.
     *
     * std::nullopt if this chainstate was not created from a snapshot.
     */
    const std::optional<uint256> m_from_snapshot_blockhash;

    //! Return true if this chainstate relies on blocks that are assumed-valid. In
    //! practice this means it was created based on a UTXO snapshot.
    bool reliesOnAssumedValid() { return m_from_snapshot_blockhash.has_value(); }

    /**
     * The set of all CBlockIndex entries with either BLOCK_VALID_TRANSACTIONS (for
     * itself and all ancestors) *or* BLOCK_ASSUMED_VALID (if using background
     * chainstates) and as good as our current tip or better. Entries may be failed,
     * though, and pruning nodes may be missing the data for the block.
     */
    std::set<CBlockIndex*, CBlockIndexWorkComparator> setBlockIndexCandidates;

    CChainstateHelper& ChainHelper()
    {
        assert(m_chain_helper);
        return *m_chain_helper;
    }

    //! @returns A reference to the in-memory cache of the UTXO set.
    CCoinsViewCache& CoinsTip() EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
    {
        AssertLockHeld(::cs_main);
        assert(m_coins_views->m_cacheview);
        return *m_coins_views->m_cacheview.get();
    }

    //! @returns A reference to the on-disk UTXO set database.
    CCoinsViewDB& CoinsDB() EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
    {
        AssertLockHeld(::cs_main);
        return m_coins_views->m_dbview;
    }

    //! @returns A pointer to the mempool.
    CTxMemPool* GetMempool()
    {
        return m_mempool;
    }

    //! @returns A reference to a wrapped view of the in-memory UTXO set that
    //!     handles disk read errors gracefully.
    CCoinsViewErrorCatcher& CoinsErrorCatcher() EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
    {
        AssertLockHeld(::cs_main);
        return m_coins_views->m_catcherview;
    }

    //! Destructs all objects related to accessing the UTXO set.
    void ResetCoinsViews() { m_coins_views.reset(); }

    //! The cache size of the on-disk coins view.
    size_t m_coinsdb_cache_size_bytes{0};

    //! The cache size of the in-memory coins view.
    size_t m_coinstip_cache_size_bytes{0};

    //! Resize the CoinsViews caches dynamically and flush state to disk.
    //! @returns true unless an error occurred during the flush.
    bool ResizeCoinsCaches(size_t coinstip_size, size_t coinsdb_size)
        EXCLUSIVE_LOCKS_REQUIRED(::cs_main);

    /**
     * Import blocks from an external file
     *
     * During reindexing, this function is called for each block file (datadir/blocks/blk?????.dat).
     * It reads all blocks contained in the given file and attempts to process them (add them to the
     * block index). The blocks may be out of order within each file and across files. Often this
     * function reads a block but finds that its parent hasn't been read yet, so the block can't be
     * processed yet. The function will add an entry to the blocks_with_unknown_parent map (which is
     * passed as an argument), so that when the block's parent is later read and processed, this
     * function can re-read the child block from disk and process it.
     *
     * Because a block's parent may be in a later file, not just later in the same file, the
     * blocks_with_unknown_parent map must be passed in and out with each call. It's a multimap,
     * rather than just a map, because multiple blocks may have the same parent (when chain splits
     * or stale blocks exist). It maps from parent-hash to child-disk-position.
     *
     * This function can also be used to read blocks from user-specified block files using the
     * -loadblock= option. There's no unknown-parent tracking, so the last two arguments are omitted.
     *
     *
     * @param[in]     fileIn                        FILE handle to file containing blocks to read
     * @param[in]     dbp                           (optional) Disk block position (only for reindex)
     * @param[in,out] blocks_with_unknown_parent    (optional) Map of disk positions for blocks with
     *                                              unknown parent, key is parent block hash
     *                                              (only used for reindex)
     * */
    void LoadExternalBlockFile(
        FILE* fileIn,
        FlatFilePos* dbp = nullptr,
        std::multimap<uint256, FlatFilePos>* blocks_with_unknown_parent = nullptr)
        EXCLUSIVE_LOCKS_REQUIRED(!m_chainstate_mutex);

    /**
     * Update the on-disk chain state.
     * The caches and indexes are flushed depending on the mode we're called with
     * if they're too large, if it's been a while since the last write,
     * or always and in all cases if we're in prune mode and are deleting files.
     *
     * If FlushStateMode::NONE is used, then FlushStateToDisk(...) won't do anything
     * besides checking if we need to prune.
     *
     * @returns true unless a system error occurred
     */
    bool FlushStateToDisk(
        BlockValidationState& state,
        FlushStateMode mode,
        int nManualPruneHeight = 0);

    //! Unconditionally flush all changes to disk.
    void ForceFlushStateToDisk();

    //! Prune blockfiles from the disk if necessary and then flush chainstate changes
    //! if we pruned.
    void PruneAndFlush();

    /**
     * Find the best known block, and make it the tip of the block chain. The
     * result is either failure or an activated best chain. pblock is either
     * nullptr or a pointer to a block that is already loaded (to avoid loading
     * it again from disk).
     *
     * ActivateBestChain is split into steps (see ActivateBestChainStep) so that
     * we avoid holding cs_main for an extended period of time; the length of this
     * call may be quite long during reindexing or a substantial reorg.
     *
     * May not be called with cs_main held. May not be called in a
     * validationinterface callback.
     *
     * @returns true unless a system error occurred
     */
    bool ActivateBestChain(
        BlockValidationState& state,
        std::shared_ptr<const CBlock> pblock = nullptr)
        EXCLUSIVE_LOCKS_REQUIRED(!m_chainstate_mutex)
        LOCKS_EXCLUDED(::cs_main);

    bool AcceptBlock(const std::shared_ptr<const CBlock>& pblock, BlockValidationState& state, CBlockIndex** ppindex, bool fRequested, const FlatFilePos* dbp, bool* fNewBlock) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    // Block (dis)connection on a given view:
    DisconnectResult DisconnectBlock(const CBlock& block, const CBlockIndex* pindex, CCoinsViewCache& view) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
    bool ConnectBlock(const CBlock& block, BlockValidationState& state, CBlockIndex* pindex, CCoinsViewCache& view, bool fJustCheck = false) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    // Apply the effects of a block disconnection on the UTXO set.
    bool DisconnectTip(BlockValidationState& state, DisconnectedBlockTransactions* disconnectpool) EXCLUSIVE_LOCKS_REQUIRED(cs_main, m_mempool->cs);

    // Manual block validity manipulation:
    /** Mark a block as precious and reorganize.
     *
     * May not be called in a validationinterface callback.
     */
    bool PreciousBlock(BlockValidationState& state, CBlockIndex* pindex)
        EXCLUSIVE_LOCKS_REQUIRED(!m_chainstate_mutex)
        LOCKS_EXCLUDED(::cs_main);

    /** Mark a block as invalid. */
    bool InvalidateBlock(BlockValidationState& state, CBlockIndex* pindex)
        EXCLUSIVE_LOCKS_REQUIRED(!m_chainstate_mutex)
        LOCKS_EXCLUDED(::cs_main);

    /** Enforce a block marking all the other chains as conflicting. */
    void EnforceBlock(BlockValidationState& state, const CBlockIndex* pindex)
        EXCLUSIVE_LOCKS_REQUIRED(!m_chainstate_mutex)
        LOCKS_EXCLUDED(::cs_main);

    /** Remove invalidity status from a block and its descendants. */
    void ResetBlockFailureFlags(CBlockIndex* pindex) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    /** Replay blocks that aren't fully applied to the database. */
    bool ReplayBlocks();
    /** Ensures we have a genesis block in the block tree, possibly writing one to disk. */
    bool LoadGenesisBlock();
    bool AddGenesisBlock(const CBlock& block, BlockValidationState& state) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    void PruneBlockIndexCandidates();

    void UnloadBlockIndex() EXCLUSIVE_LOCKS_REQUIRED(::cs_main);

    /** Check whether we are doing an initial block download (synchronizing from disk or network) */
    bool IsInitialBlockDownload() const;

    /** Find the last common block of this chain and a locator. */
    const CBlockIndex* FindForkInGlobalIndex(const CBlockLocator& locator) const EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    /**
     * Make various assertions about the state of the block index.
     *
     * By default this only executes fully when using the Regtest chain; see: fCheckBlockIndex.
     */
    void CheckBlockIndex();

    /** Load the persisted mempool from disk */
    void LoadMempool(const ArgsManager& args);

    /** Update the chain tip based on database information, i.e. CoinsTip()'s best block. */
    bool LoadChainTip() EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    //! Dictates whether we need to flush the cache to disk or not.
    //!
    //! @return the state of the size of the coins cache.
    CoinsCacheSizeState GetCoinsCacheSizeState() EXCLUSIVE_LOCKS_REQUIRED(::cs_main);

    CoinsCacheSizeState GetCoinsCacheSizeState(
        size_t max_coins_cache_size_bytes,
        size_t max_mempool_size_bytes) EXCLUSIVE_LOCKS_REQUIRED(::cs_main);

    std::string ToString() EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
private:
    bool ActivateBestChainStep(BlockValidationState& state, CBlockIndex* pindexMostWork, const std::shared_ptr<const CBlock>& pblock, bool& fInvalidFound, ConnectTrace& connectTrace) EXCLUSIVE_LOCKS_REQUIRED(cs_main, m_mempool->cs);
    bool ConnectTip(BlockValidationState& state, CBlockIndex* pindexNew, const std::shared_ptr<const CBlock>& pblock, ConnectTrace& connectTrace, DisconnectedBlockTransactions& disconnectpool) EXCLUSIVE_LOCKS_REQUIRED(cs_main, m_mempool->cs);

    void InvalidBlockFound(CBlockIndex* pindex, const BlockValidationState& state) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
    CBlockIndex* FindMostWorkChain() EXCLUSIVE_LOCKS_REQUIRED(cs_main);
    void ReceivedBlockTransactions(const CBlock& block, CBlockIndex* pindexNew, const FlatFilePos& pos) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    bool RollforwardBlock(const CBlockIndex* pindex, CCoinsViewCache& inputs) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    //! Mark a block as conflicting
    bool MarkConflictingBlock(BlockValidationState& state, CBlockIndex* pindex) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    void CheckForkWarningConditions() EXCLUSIVE_LOCKS_REQUIRED(cs_main);
    void InvalidChainFound(CBlockIndex* pindexNew) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
    void ConflictingChainFound(CBlockIndex* pindexNew) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    //! Indirection necessary to make lock annotations work with an optional mempool.
    RecursiveMutex* MempoolMutex() const LOCK_RETURNED(m_mempool->cs)
    {
        return m_mempool ? &m_mempool->cs : nullptr;
    }

    /**
     * Make mempool consistent after a reorg, by re-adding or recursively erasing
     * disconnected block transactions from the mempool, and also removing any
     * other transactions from the mempool that are no longer valid given the new
     * tip/height.
     *
     * Note: we assume that disconnectpool only contains transactions that are NOT
     * confirmed in the current chain nor already in the mempool (otherwise,
     * in-mempool descendants of such transactions would be removed).
     *
     * Passing fAddToMempool=false will skip trying to add the transactions back,
     * and instead just erase from the mempool as needed.
     */
    void MaybeUpdateMempoolForReorg(
        DisconnectedBlockTransactions& disconnectpool,
        bool fAddToMempool) EXCLUSIVE_LOCKS_REQUIRED(cs_main, m_mempool->cs);

    /** Check warning conditions and do some notifications on new chain tip set. */
    void UpdateTip(const CBlockIndex* pindexNew)
        EXCLUSIVE_LOCKS_REQUIRED(::cs_main);

    friend ChainstateManager;
};

/**
 * Provides an interface for creating and interacting with one or two
 * chainstates: an IBD chainstate generated by downloading blocks, and
 * an optional snapshot chainstate loaded from a UTXO snapshot. Managed
 * chainstates can be maintained at different heights simultaneously.
 *
 * This class provides abstractions that allow the retrieval of the current
 * most-work chainstate ("Active") as well as chainstates which may be in
 * background use to validate UTXO snapshots.
 *
 * Definitions:
 *
 * *IBD chainstate*: a chainstate whose current state has been "fully"
 *   validated by the initial block download process.
 *
 * *Snapshot chainstate*: a chainstate populated by loading in an
 *    assumeutxo UTXO snapshot.
 *
 * *Active chainstate*: the chainstate containing the current most-work
 *    chain. Consulted by most parts of the system (net_processing,
 *    wallet) as a reflection of the current chain and UTXO set.
 *    This may either be an IBD chainstate or a snapshot chainstate.
 *
 * *Background IBD chainstate*: an IBD chainstate for which the
 *    IBD process is happening in the background while use of the
 *    active (snapshot) chainstate allows the rest of the system to function.
 */
class ChainstateManager
{
private:
    //! The chainstate used under normal operation (i.e. "regular" IBD) or, if
    //! a snapshot is in use, for background validation.
    //!
    //! Its contents (including on-disk data) will be deleted *upon shutdown*
    //! after background validation of the snapshot has completed. We do not
    //! free the chainstate contents immediately after it finishes validation
    //! to cautiously avoid a case where some other part of the system is still
    //! using this pointer (e.g. net_processing).
    //!
    //! Once this pointer is set to a corresponding chainstate, it will not
    //! be reset until init.cpp:Shutdown().
    //!
    //! This is especially important when, e.g., calling ActivateBestChain()
    //! on all chainstates because we are not able to hold ::cs_main going into
    //! that call.
    std::unique_ptr<CChainState> m_ibd_chainstate GUARDED_BY(::cs_main);

    //! A chainstate initialized on the basis of a UTXO snapshot. If this is
    //! non-null, it is always our active chainstate.
    //!
    //! Once this pointer is set to a corresponding chainstate, it will not
    //! be reset until init.cpp:Shutdown().
    //!
    //! This is especially important when, e.g., calling ActivateBestChain()
    //! on all chainstates because we are not able to hold ::cs_main going into
    //! that call.
    std::unique_ptr<CChainState> m_snapshot_chainstate GUARDED_BY(::cs_main);

    //! Points to either the ibd or snapshot chainstate; indicates our
    //! most-work chain.
    //!
    //! Once this pointer is set to a corresponding chainstate, it will not
    //! be reset until init.cpp:Shutdown().
    //!
    //! This is especially important when, e.g., calling ActivateBestChain()
    //! on all chainstates because we are not able to hold ::cs_main going into
    //! that call.
    CChainState* m_active_chainstate GUARDED_BY(::cs_main) {nullptr};

    //! If true, the assumed-valid chainstate has been fully validated
    //! by the background validation chainstate.
    bool m_snapshot_validated GUARDED_BY(::cs_main){false};

    CBlockIndex* m_best_invalid GUARDED_BY(::cs_main){nullptr};

    //! Internal helper for ActivateSnapshot().
    [[nodiscard]] bool PopulateAndValidateSnapshot(
        CChainState& snapshot_chainstate,
        CAutoFile& coins_file,
        const SnapshotMetadata& metadata);

    /**
     * If a block header hasn't already been seen, call CheckBlockHeader on it, ensure
     * that it doesn't descend from an invalid block, and then add it to m_block_index.
     */
    bool AcceptBlockHeader(
        const CBlockHeader& block,
        BlockValidationState& state,
        const CChainParams& chainparams,
        CBlockIndex** ppindex) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
    friend CChainState;

public:
    std::thread m_load_block;
    //! A single BlockManager instance is shared across each constructed
    //! chainstate to avoid duplicating block metadata.
    BlockManager m_blockman;

    /**
     * In order to efficiently track invalidity of headers, we keep the set of
     * blocks which we tried to connect and found to be invalid here (ie which
     * were set to BLOCK_FAILED_VALID since the last restart). We can then
     * walk this set and check if a new header is a descendant of something in
     * this set, preventing us from having to walk m_block_index when we try
     * to connect a bad block and fail.
     *
     * While this is more complicated than marking everything which descends
     * from an invalid block as invalid at the time we discover it to be
     * invalid, doing so would require walking all of m_block_index to find all
     * descendants. Since this case should be very rare, keeping track of all
     * BLOCK_FAILED_VALID blocks in a set should be just fine and work just as
     * well.
     *
     * Because we already walk m_block_index in height-order at startup, we go
     * ahead and mark descendants of invalid blocks as FAILED_CHILD at that time,
     * instead of putting things in this set.
     */
    std::set<CBlockIndex*> m_failed_blocks;

    /** Best header we've seen so far (used for getheaders queries' starting points). */
    CBlockIndex* m_best_header = nullptr;

    //! The total number of bytes available for us to use across all in-memory
    //! coins caches. This will be split somehow across chainstates.
    int64_t m_total_coinstip_cache{0};
    //
    //! The total number of bytes available for us to use across all leveldb
    //! coins databases. This will be split somehow across chainstates.
    int64_t m_total_coinsdb_cache{0};

    //! Instantiate a new chainstate and assign it based upon whether it is
    //! from a snapshot.
    //!
    //! @param[in] mempool              The mempool to pass to the chainstate
    //                                  constructor
    //! @param[in] snapshot_blockhash   If given, signify that this chainstate
    //!                                 is based on a snapshot.
    CChainState& InitializeChainstate(CTxMemPool* mempool,
                                      CEvoDB& evoDb,
                                      const std::unique_ptr<CChainstateHelper>& chain_helper,
                                      const std::unique_ptr<llmq::CChainLocksHandler>& clhandler,
                                      const std::unique_ptr<llmq::CInstantSendManager>& isman,
                                      const std::optional<uint256>& snapshot_blockhash = std::nullopt)
        LIFETIMEBOUND EXCLUSIVE_LOCKS_REQUIRED(::cs_main);

    //! Get all chainstates currently being used.
    std::vector<CChainState*> GetAll();

    //! Construct and activate a Chainstate on the basis of UTXO snapshot data.
    //!
    //! Steps:
    //!
    //! - Initialize an unused CChainState.
    //! - Load its `CoinsViews` contents from `coins_file`.
    //! - Verify that the hash of the resulting coinsdb matches the expected hash
    //!   per assumeutxo chain parameters.
    //! - Wait for our headers chain to include the base block of the snapshot.
    //! - "Fast forward" the tip of the new chainstate to the base of the snapshot,
    //!   faking nTx* block index data along the way.
    //! - Move the new chainstate to `m_snapshot_chainstate` and make it our
    //!   ChainstateActive().
    [[nodiscard]] bool ActivateSnapshot(
        CAutoFile& coins_file, const SnapshotMetadata& metadata, bool in_memory);

    //! The most-work chain.
    CChainState& ActiveChainstate() const;
    CChain& ActiveChain() const { return ActiveChainstate().m_chain; }
    int ActiveHeight() const { return ActiveChain().Height(); }
    CBlockIndex* ActiveTip() const { return ActiveChain().Tip(); }

    BlockMap& BlockIndex() EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
    {
        AssertLockHeld(::cs_main);
        return m_blockman.m_block_index;
    }

    PrevBlockMap& PrevBlockIndex() EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
    {
        return m_blockman.m_prev_block_index;
    }

    //! @returns true if a snapshot-based chainstate is in use. Also implies
    //!          that a background validation chainstate is also in use.
    bool IsSnapshotActive() const;

    std::optional<uint256> SnapshotBlockhash() const;

    //! Is there a snapshot in use and has it been fully validated?
    bool IsSnapshotValidated() const EXCLUSIVE_LOCKS_REQUIRED(::cs_main) { return m_snapshot_validated; }

    /**
     * Process an incoming block. This only returns after the best known valid
     * block is made active. Note that it does not, however, guarantee that the
     * specific block passed to it has been checked for validity!
     *
     * If you want to *possibly* get feedback on whether block is valid, you must
     * install a CValidationInterface (see validationinterface.h) - this will have
     * its BlockChecked method called whenever *any* block completes validation.
     *
     * Note that we guarantee that either the proof-of-work is valid on block, or
     * (and possibly also) BlockChecked will have been called.
     *
     * May not be called in a validationinterface callback.
     *
     * @param[in]   block The block we want to process.
     * @param[in]   force_processing Process this block even if unrequested; used for non-network block sources.
     * @param[out]  new_block A boolean which is set to indicate if the block was first received via this call
     * @returns     If the block was processed, independently of block validity
     */
    bool ProcessNewBlock(const CChainParams& chainparams, const std::shared_ptr<const CBlock>& block, bool force_processing, bool* new_block) LOCKS_EXCLUDED(cs_main);

    /**
     * Process incoming block headers.
     *
     * May not be called in a
     * validationinterface callback.
     *
     * @param[in]  block The block headers themselves
     * @param[out] state This may be set to an Error state if any error occurred processing them
     * @param[in]  chainparams The params for the chain we want to connect to
     * @param[out] ppindex If set, the pointer will be set to point to the last new block index object for the given headers
     */
    bool ProcessNewBlockHeaders(const std::vector<CBlockHeader>& block, BlockValidationState& state, const CChainParams& chainparams, const CBlockIndex** ppindex = nullptr) LOCKS_EXCLUDED(cs_main);

    /**
     * Try to add a transaction to the memory pool.
     *
     * @param[in]  tx              The transaction to submit for mempool acceptance.
     * @param[in]  test_accept     When true, run validation checks but don't submit to mempool.
     * @param[in]  bypass_limits   When true, don't enforce mempool fee and capacity limits.
     */
    [[nodiscard]] MempoolAcceptResult ProcessTransaction(const CTransactionRef& tx, bool test_accept=false, bool bypass_limits=false)
        EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    //! Load the block tree and coins database from disk, initializing state if we're running with -reindex
    bool LoadBlockIndex() EXCLUSIVE_LOCKS_REQUIRED(cs_main);
    //! Initialize additional indexes and store their flags to disk
    void InitAdditionalIndexes() EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    //! Check to see if caches are out of balance and if so, call
    //! ResizeCoinsCaches() as needed.
    void MaybeRebalanceCaches() EXCLUSIVE_LOCKS_REQUIRED(::cs_main);

    ~ChainstateManager();
};

/**
 * Return true if hash can be found in active_chain at nBlockHeight height.
 * Fills hashRet with found hash, if no nBlockHeight is specified - active_chain.Height() is used.
 */
bool GetBlockHash(const CChain& active_chain, uint256& hashRet, int nBlockHeight = -1);

using FopenFn = std::function<FILE*(const fs::path&, const char*)>;

/** Dump the mempool to disk. */
bool DumpMempool(const CTxMemPool& pool, FopenFn mockable_fopen_function = fsbridge::fopen, bool skip_file_commit = false);

/** Load the mempool from disk. */
bool LoadMempool(CTxMemPool& pool, CChainState& active_chainstate, FopenFn mockable_fopen_function = fsbridge::fopen);

/**
 * Return the expected assumeutxo value for a given height, if one exists.
 *
 * @param[in] height Get the assumeutxo value for this height.
 *
 * @returns empty if no assumeutxo configuration exists for the given height.
 */
const AssumeutxoData* ExpectedAssumeutxo(const int height, const CChainParams& params);

#endif // BITCOIN_VALIDATION_H