blockfilterindex.h

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// Copyright (c) 2018-present 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_BLOCKFILTERINDEX_H
#define BITCOIN_INDEX_BLOCKFILTERINDEX_H

#include <attributes.h>
#include <flatfile.h>
#include <index/base.h>
#include <interfaces/chain.h>
#include <sync.h>
#include <uint256.h>
#include <util/hasher.h>

#include <cstddef>
#include <cstdint>
#include <functional>
#include <memory>
#include <optional>
#include <unordered_map>
#include <vector>

class BlockFilter;
class CBlockIndex;
enum class BlockFilterType : uint8_t;

static const char* const DEFAULT_BLOCKFILTERINDEX = "0";

static constexpr int CFCHECKPT_INTERVAL = 1000;

class BlockFilterIndex final : public BaseIndex
{
private:
    BlockFilterType m_filter_type;
    std::unique_ptr<BaseIndex::DB> m_db;

    FlatFilePos m_next_filter_pos;
    std::unique_ptr<FlatFileSeq> m_filter_fileseq;

    bool ReadFilterFromDisk(const FlatFilePos& pos, const uint256& hash, BlockFilter& filter) const;
    size_t WriteFilterToDisk(FlatFilePos& pos, const BlockFilter& filter);

    Mutex m_cs_headers_cache;
    std::unordered_map<uint256, uint256, BlockHasher> m_headers_cache GUARDED_BY(m_cs_headers_cache);

    // Last computed header to avoid disk reads on every new block.
    uint256 m_last_header{};

    bool AllowPrune() const override { return true; }

    bool Write(const BlockFilter& filter, uint32_t block_height, const uint256& filter_header);

    std::optional<uint256> ReadFilterHeader(int height, const uint256& expected_block_hash);

protected:
    bool CustomInit(const std::optional<interfaces::BlockRef>& block) override;

    bool CustomCommit(CDBBatch& batch) override;

    bool CustomAppend(const interfaces::BlockInfo& block) override;

    bool CustomRemove(const interfaces::BlockInfo& block) override;

    BaseIndex::DB& GetDB() const LIFETIMEBOUND override { return *m_db; }

public:
    explicit BlockFilterIndex(std::unique_ptr<interfaces::Chain> chain, BlockFilterType filter_type,
                              size_t n_cache_size, bool f_memory = false, bool f_wipe = false);

    interfaces::Chain::NotifyOptions CustomOptions() override;

    BlockFilterType GetFilterType() const { return m_filter_type; }

    bool LookupFilter(const CBlockIndex* block_index, BlockFilter& filter_out) const;

    bool LookupFilterHeader(const CBlockIndex* block_index, uint256& header_out) EXCLUSIVE_LOCKS_REQUIRED(!m_cs_headers_cache);

    bool LookupFilterRange(int start_height, const CBlockIndex* stop_index,
                           std::vector<BlockFilter>& filters_out) const;

    bool LookupFilterHashRange(int start_height, const CBlockIndex* stop_index,
                               std::vector<uint256>& hashes_out) const;
};

BlockFilterIndex* GetBlockFilterIndex(BlockFilterType filter_type);

void ForEachBlockFilterIndex(std::function<void (BlockFilterIndex&)> fn);

bool InitBlockFilterIndex(std::function<std::unique_ptr<interfaces::Chain>()> make_chain, BlockFilterType filter_type,
                          size_t n_cache_size, bool f_memory = false, bool f_wipe = false);

bool DestroyBlockFilterIndex(BlockFilterType filter_type);

void DestroyAllBlockFilterIndexes();

#endif // BITCOIN_INDEX_BLOCKFILTERINDEX_H