f90c3a62f5
In order to preserve getrawtransaction RPC behavior, there needs to be a way for a thread to ensure the transaction index is in sync with the current state of the blockchain.
85 lines
3.1 KiB
C++
85 lines
3.1 KiB
C++
// Copyright (c) 2017-2018 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_INDEX_TXINDEX_H
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#define BITCOIN_INDEX_TXINDEX_H
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#include <primitives/block.h>
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#include <threadinterrupt.h>
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#include <txdb.h>
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#include <uint256.h>
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#include <validationinterface.h>
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class CBlockIndex;
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/**
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* TxIndex is used to look up transactions included in the blockchain by hash.
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* The index is written to a LevelDB database and records the filesystem
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* location of each transaction by transaction hash.
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*/
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class TxIndex final : public CValidationInterface
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{
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private:
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const std::unique_ptr<TxIndexDB> m_db;
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/// Whether the index is in sync with the main chain. The flag is flipped
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/// from false to true once, after which point this starts processing
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/// ValidationInterface notifications to stay in sync.
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std::atomic<bool> m_synced;
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/// The last block in the chain that the TxIndex is in sync with.
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std::atomic<const CBlockIndex*> m_best_block_index;
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std::thread m_thread_sync;
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CThreadInterrupt m_interrupt;
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/// Initialize internal state from the database and block index.
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bool Init();
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/// Sync the tx index with the block index starting from the current best
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/// block. Intended to be run in its own thread, m_thread_sync, and can be
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/// interrupted with m_interrupt. Once the txindex gets in sync, the
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/// m_synced flag is set and the BlockConnected ValidationInterface callback
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/// takes over and the sync thread exits.
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void ThreadSync();
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/// Write update index entries for a newly connected block.
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bool WriteBlock(const CBlock& block, const CBlockIndex* pindex);
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/// Write the current chain block locator to the DB.
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bool WriteBestBlock(const CBlockIndex* block_index);
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protected:
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void BlockConnected(const std::shared_ptr<const CBlock>& block, const CBlockIndex* pindex,
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const std::vector<CTransactionRef>& txn_conflicted) override;
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void SetBestChain(const CBlockLocator& locator) override;
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public:
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/// Constructs the TxIndex, which becomes available to be queried.
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explicit TxIndex(std::unique_ptr<TxIndexDB> db);
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/// Destructor interrupts sync thread if running and blocks until it exits.
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~TxIndex();
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/// Blocks the current thread until the transaction index is caught up to
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/// the current state of the block chain. This only blocks if the index has gotten in sync once
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/// and only needs to process blocks in the ValidationInterface queue. If the index is catching
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/// up from far behind, this method does not block and immediately returns false.
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bool BlockUntilSyncedToCurrentChain();
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/// Look up the on-disk location of a transaction by hash.
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bool FindTx(const uint256& txid, CDiskTxPos& pos) const;
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void Interrupt();
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/// Start initializes the sync state and registers the instance as a
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/// ValidationInterface so that it stays in sync with blockchain updates.
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void Start();
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/// Stops the instance from staying in sync with blockchain updates.
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void Stop();
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};
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#endif // BITCOIN_INDEX_TXINDEX_H
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