1  // Copyright (c) 2018-2022 The Bitcoin Core developers
  2  // Distributed under the MIT software license, see the accompanying
  3  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  4  
  5  #ifndef BITCOIN_INDEX_BLOCKFILTERINDEX_H
  6  #define BITCOIN_INDEX_BLOCKFILTERINDEX_H
  7  
  8  #include <attributes.h>
  9  #include <blockfilter.h>
 10  #include <chain.h>
 11  #include <flatfile.h>
 12  #include <index/base.h>
 13  #include <util/hasher.h>
 14  
 15  #include <unordered_map>
 16  
 17  static const char* const DEFAULT_BLOCKFILTERINDEX = "0";
 18  
 19  /** Interval between compact filter checkpoints. See BIP 157. */
 20  static constexpr int CFCHECKPT_INTERVAL = 1000;
 21  
 22  /**
 23   * BlockFilterIndex is used to store and retrieve block filters, hashes, and headers for a range of
 24   * blocks by height. An index is constructed for each supported filter type with its own database
 25   * (ie. filter data for different types are stored in separate databases).
 26   *
 27   * This index is used to serve BIP 157 net requests.
 28   */
 29  class BlockFilterIndex final : public BaseIndex
 30  {
 31  private:
 32      BlockFilterType m_filter_type;
 33      std::unique_ptr<BaseIndex::DB> m_db;
 34  
 35      FlatFilePos m_next_filter_pos;
 36      std::unique_ptr<FlatFileSeq> m_filter_fileseq;
 37  
 38      bool ReadFilterFromDisk(const FlatFilePos& pos, const uint256& hash, BlockFilter& filter) const;
 39      size_t WriteFilterToDisk(FlatFilePos& pos, const BlockFilter& filter);
 40  
 41      Mutex m_cs_headers_cache;
 42      /** cache of block hash to filter header, to avoid disk access when responding to getcfcheckpt. */
 43      std::unordered_map<uint256, uint256, FilterHeaderHasher> m_headers_cache GUARDED_BY(m_cs_headers_cache);
 44  
 45      // Last computed header to avoid disk reads on every new block.
 46      uint256 m_last_header{};
 47  
 48      bool AllowPrune() const override { return true; }
 49  
 50      bool Write(const BlockFilter& filter, uint32_t block_height, const uint256& filter_header);
 51  
 52      std::optional<uint256> ReadFilterHeader(int height, const uint256& expected_block_hash);
 53  
 54  protected:
 55      bool CustomInit(const std::optional<interfaces::BlockKey>& block) override;
 56  
 57      bool CustomCommit(CDBBatch& batch) override;
 58  
 59      bool CustomAppend(const interfaces::BlockInfo& block) override;
 60  
 61      bool CustomRewind(const interfaces::BlockKey& current_tip, const interfaces::BlockKey& new_tip) override;
 62  
 63      BaseIndex::DB& GetDB() const LIFETIMEBOUND override { return *m_db; }
 64  
 65  public:
 66      /** Constructs the index, which becomes available to be queried. */
 67      explicit BlockFilterIndex(std::unique_ptr<interfaces::Chain> chain, BlockFilterType filter_type,
 68                                size_t n_cache_size, bool f_memory = false, bool f_wipe = false);
 69  
 70      BlockFilterType GetFilterType() const { return m_filter_type; }
 71  
 72      /** Get a single filter by block. */
 73      bool LookupFilter(const CBlockIndex* block_index, BlockFilter& filter_out) const;
 74  
 75      /** Get a single filter header by block. */
 76      bool LookupFilterHeader(const CBlockIndex* block_index, uint256& header_out) EXCLUSIVE_LOCKS_REQUIRED(!m_cs_headers_cache);
 77  
 78      /** Get a range of filters between two heights on a chain. */
 79      bool LookupFilterRange(int start_height, const CBlockIndex* stop_index,
 80                             std::vector<BlockFilter>& filters_out) const;
 81  
 82      /** Get a range of filter hashes between two heights on a chain. */
 83      bool LookupFilterHashRange(int start_height, const CBlockIndex* stop_index,
 84                                 std::vector<uint256>& hashes_out) const;
 85  };
 86  
 87  /**
 88   * Get a block filter index by type. Returns nullptr if index has not been initialized or was
 89   * already destroyed.
 90   */
 91  BlockFilterIndex* GetBlockFilterIndex(BlockFilterType filter_type);
 92  
 93  /** Iterate over all running block filter indexes, invoking fn on each. */
 94  void ForEachBlockFilterIndex(std::function<void (BlockFilterIndex&)> fn);
 95  
 96  /**
 97   * Initialize a block filter index for the given type if one does not already exist. Returns true if
 98   * a new index is created and false if one has already been initialized.
 99   */
100  bool InitBlockFilterIndex(std::function<std::unique_ptr<interfaces::Chain>()> make_chain, BlockFilterType filter_type,
101                            size_t n_cache_size, bool f_memory = false, bool f_wipe = false);
102  
103  /**
104   * Destroy the block filter index with the given type. Returns false if no such index exists. This
105   * just releases the allocated memory and closes the database connection, it does not delete the
106   * index data.
107   */
108  bool DestroyBlockFilterIndex(BlockFilterType filter_type);
109  
110  /** Destroy all open block filter indexes. */
111  void DestroyAllBlockFilterIndexes();
112  
113  #endif // BITCOIN_INDEX_BLOCKFILTERINDEX_H