mirror of https://github.com/bitcoin/bitcoin
113 lines
4.4 KiB
C++
113 lines
4.4 KiB
C++
// Copyright (c) 2017-2019 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_BASE_H
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#define BITCOIN_INDEX_BASE_H
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#include <dbwrapper.h>
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#include <primitives/block.h>
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#include <primitives/transaction.h>
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#include <threadinterrupt.h>
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#include <validationinterface.h>
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class CBlockIndex;
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/**
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* Base class for indices of blockchain data. This implements
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* CValidationInterface and ensures blocks are indexed sequentially according
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* to their position in the active chain.
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*/
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class BaseIndex : public CValidationInterface
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{
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protected:
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class DB : public CDBWrapper
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{
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public:
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DB(const fs::path& path, size_t n_cache_size,
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bool f_memory = false, bool f_wipe = false, bool f_obfuscate = false);
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/// Read block locator of the chain that the txindex is in sync with.
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bool ReadBestBlock(CBlockLocator& locator) const;
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/// Write block locator of the chain that the txindex is in sync with.
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void WriteBestBlock(CDBBatch& batch, const CBlockLocator& locator);
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};
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private:
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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{false};
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/// The last block in the chain that the index is in sync with.
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std::atomic<const CBlockIndex*> m_best_block_index{nullptr};
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std::thread m_thread_sync;
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CThreadInterrupt m_interrupt;
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/// Sync the index with the block index starting from the current best block.
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/// Intended to be run in its own thread, m_thread_sync, and can be
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/// interrupted with m_interrupt. Once the index gets in sync, the m_synced
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/// flag is set and the BlockConnected ValidationInterface callback takes
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/// over and the sync thread exits.
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void ThreadSync();
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/// Write the current index state (eg. chain block locator and subclass-specific items) to disk.
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///
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/// Recommendations for error handling:
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/// If called on a successor of the previous committed best block in the index, the index can
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/// continue processing without risk of corruption, though the index state will need to catch up
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/// from further behind on reboot. If the new state is not a successor of the previous state (due
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/// to a chain reorganization), the index must halt until Commit succeeds or else it could end up
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/// getting corrupted.
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bool Commit();
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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 ChainStateFlushed(const CBlockLocator& locator) override;
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/// Initialize internal state from the database and block index.
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virtual bool Init();
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/// Write update index entries for a newly connected block.
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virtual bool WriteBlock(const CBlock& block, const CBlockIndex* pindex) { return true; }
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/// Virtual method called internally by Commit that can be overridden to atomically
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/// commit more index state.
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virtual bool CommitInternal(CDBBatch& batch);
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/// Rewind index to an earlier chain tip during a chain reorg. The tip must
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/// be an ancestor of the current best block.
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virtual bool Rewind(const CBlockIndex* current_tip, const CBlockIndex* new_tip);
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virtual DB& GetDB() const = 0;
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/// Get the name of the index for display in logs.
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virtual const char* GetName() const = 0;
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public:
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/// Destructor interrupts sync thread if running and blocks until it exits.
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virtual ~BaseIndex();
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/// Blocks the current thread until the index is caught up to the current
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/// state of the block chain. This only blocks if the index has gotten in
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/// sync once and only needs to process blocks in the ValidationInterface
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/// queue. If the index is catching up from far behind, this method does
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/// not block and immediately returns false.
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bool BlockUntilSyncedToCurrentChain();
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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_BASE_H
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