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src/index/txindex.h
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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 <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 SetBestChain(const CBlockLocator &locator) override; | |||||
public: | |||||
/// Constructs the TxIndex, which becomes available to be queried. | |||||
explicit TxIndex(std::unique_ptr<TxIndexDB> db); | |||||
/// Destructor interrupts sync thread if running and blocks until it exits. | |||||
~TxIndex(); | |||||
/// Blocks the current thread until the transaction index is caught up to | |||||
/// the current state of the block chain. This only blocks if the index has | |||||
/// gotten in sync once and only needs to process blocks in the | |||||
/// ValidationInterface queue. If the index is catching up from far behind, | |||||
/// this method does not block and immediately returns false. | |||||
bool BlockUntilSyncedToCurrentChain(); | |||||
/// Look up the on-disk location of a transaction by hash. | |||||
bool FindTx(const uint256 &txid, CDiskTxPos &pos) const; | |||||
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(); | |||||
}; | |||||
#endif // BITCOIN_INDEX_TXINDEX_H |