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// Copyright (c) 2017-2018 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_INDEX_TXINDEX_H
#define BITCOIN_INDEX_TXINDEX_H
#include <primitives/block.h>
#include <primitives/transaction.h>
#include <threadinterrupt.h>
#include <txdb.h>
#include <uint256.h>
#include <validationinterface.h>
class CBlockIndex;
/**
* TxIndex is used to look up transactions included in the blockchain by hash.
* The index is written to a LevelDB database and records the filesystem
* location of each transaction by transaction hash.
*/
class TxIndex final : public CValidationInterface
{
private:
const std::unique_ptr<TxIndexDB> m_db;
/// Whether the index is in sync with the main chain. The flag is flipped
/// from false to true once, after which point this starts processing
/// ValidationInterface notifications to stay in sync.
std::atomic<bool> m_synced;
/// The last block in the chain that the TxIndex is in sync with.
std::atomic<const CBlockIndex*> m_best_block_index;
std::thread m_thread_sync;
CThreadInterrupt m_interrupt;
/// Initialize internal state from the database and block index.
bool Init();
/// Sync the tx index with the block index starting from the current best
/// block. Intended to be run in its own thread, m_thread_sync, and can be
/// interrupted with m_interrupt. Once the txindex gets in sync, the
/// m_synced flag is set and the BlockConnected ValidationInterface callback
/// takes over and the sync thread exits.
void ThreadSync();
/// Write update index entries for a newly connected block.
bool WriteBlock(const CBlock& block, const CBlockIndex* pindex);
/// Write the current chain block locator to the DB.
bool WriteBestBlock(const CBlockIndex* block_index);
protected:
void BlockConnected(const std::shared_ptr<const CBlock>& block, const CBlockIndex* pindex,
const std::vector<CTransactionRef>& txn_conflicted) override;
void ChainStateFlushed(const CBlockLocator& locator) override;
public:
/// Constructs the TxIndex, which becomes available to be queried.
explicit TxIndex(std::unique_ptr<TxIndexDB> db);
/// Destructor interrupts sync thread if running and blocks until it exits.
~TxIndex();
/// Blocks the current thread until the transaction index is caught up to
/// the current state of the block chain. This only blocks if the index has gotten in sync once
/// and only needs to process blocks in the ValidationInterface queue. If the index is catching
/// up from far behind, this method does not block and immediately returns false.
bool BlockUntilSyncedToCurrentChain();
/// Look up a transaction by hash.
///
/// @param[in] tx_hash The hash of the transaction to be returned.
/// @param[out] block_hash The hash of the block the transaction is found in.
/// @param[out] tx The transaction itself.
/// @return true if transaction is found, false otherwise
bool FindTx(const uint256& tx_hash, uint256& block_hash, CTransactionRef& tx) const;
void Interrupt();
/// Start initializes the sync state and registers the instance as a
/// ValidationInterface so that it stays in sync with blockchain updates.
void Start();
/// Stops the instance from staying in sync with blockchain updates.
void Stop();
};
/// The global transaction index, used in GetTransaction. May be null.
extern std::unique_ptr<TxIndex> g_txindex;
#endif // BITCOIN_INDEX_TXINDEX_H
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