1  // Copyright (c) 2018-present 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 <flatfile.h>
 10  #include <index/base.h>
 11  #include <interfaces/chain.h>
 12  #include <sync.h>
 13  #include <uint256.h>
 14  #include <util/hasher.h>
 15  
 16  #include <cstddef>
 17  #include <cstdint>
 18  #include <functional>
 19  #include <memory>
 20  #include <optional>
 21  #include <unordered_map>
 22  #include <vector>
 23  
 24  class BlockFilter;
 25  class CBlockIndex;
 26  enum class BlockFilterType : uint8_t;
 27  
 28  static const char* const DEFAULT_BLOCKFILTERINDEX = "0";
 29  
 30  /** Interval between compact filter checkpoints. See BIP 157. */
 31  static constexpr int CFCHECKPT_INTERVAL = 1000;
 32  
 33  /**
 34   * BlockFilterIndex is used to store and retrieve block filters, hashes, and headers for a range of
 35   * blocks by height. An index is constructed for each supported filter type with its own database
 36   * (ie. filter data for different types are stored in separate databases).
 37   *
 38   * This index is used to serve BIP 157 net requests.
 39   */
 40  class BlockFilterIndex final : public BaseIndex
 41  {
 42  private:
 43      BlockFilterType m_filter_type;
 44      std::unique_ptr<BaseIndex::DB> m_db;
 45  
 46      FlatFilePos m_next_filter_pos;
 47      std::unique_ptr<FlatFileSeq> m_filter_fileseq;
 48  
 49      bool ReadFilterFromDisk(const FlatFilePos& pos, const uint256& hash, BlockFilter& filter) const;
 50      size_t WriteFilterToDisk(FlatFilePos& pos, const BlockFilter& filter);
 51  
 52      Mutex m_cs_headers_cache;
 53      /** cache of block hash to filter header, to avoid disk access when responding to getcfcheckpt. */
 54      std::unordered_map<uint256, uint256, BlockHasher> m_headers_cache GUARDED_BY(m_cs_headers_cache);
 55  
 56      // Last computed header to avoid disk reads on every new block.
 57      uint256 m_last_header{};
 58  
 59      bool AllowPrune() const override { return true; }
 60  
 61      bool Write(const BlockFilter& filter, uint32_t block_height, const uint256& filter_header);
 62  
 63      std::optional<uint256> ReadFilterHeader(int height, const uint256& expected_block_hash);
 64  
 65  protected:
 66      bool CustomInit(const std::optional<interfaces::BlockRef>& block) override;
 67  
 68      bool CustomCommit(CDBBatch& batch) override;
 69  
 70      bool CustomAppend(const interfaces::BlockInfo& block) override;
 71  
 72      bool CustomRemove(const interfaces::BlockInfo& block) override;
 73  
 74      BaseIndex::DB& GetDB() const LIFETIMEBOUND override { return *m_db; }
 75  
 76  public:
 77      /** Constructs the index, which becomes available to be queried. */
 78      explicit BlockFilterIndex(std::unique_ptr<interfaces::Chain> chain, BlockFilterType filter_type,
 79                                size_t n_cache_size, bool f_memory = false, bool f_wipe = false);
 80  
 81      interfaces::Chain::NotifyOptions CustomOptions() override;
 82  
 83      BlockFilterType GetFilterType() const { return m_filter_type; }
 84  
 85      /** Get a single filter by block. */
 86      bool LookupFilter(const CBlockIndex* block_index, BlockFilter& filter_out) const;
 87  
 88      /** Get a single filter header by block. */
 89      bool LookupFilterHeader(const CBlockIndex* block_index, uint256& header_out) EXCLUSIVE_LOCKS_REQUIRED(!m_cs_headers_cache);
 90  
 91      /** Get a range of filters between two heights on a chain. */
 92      bool LookupFilterRange(int start_height, const CBlockIndex* stop_index,
 93                             std::vector<BlockFilter>& filters_out) const;
 94  
 95      /** Get a range of filter hashes between two heights on a chain. */
 96      bool LookupFilterHashRange(int start_height, const CBlockIndex* stop_index,
 97                                 std::vector<uint256>& hashes_out) const;
 98  };
 99  
100  /**
101   * Get a block filter index by type. Returns nullptr if index has not been initialized or was
102   * already destroyed.
103   */
104  BlockFilterIndex* GetBlockFilterIndex(BlockFilterType filter_type);
105  
106  /** Iterate over all running block filter indexes, invoking fn on each. */
107  void ForEachBlockFilterIndex(std::function<void (BlockFilterIndex&)> fn);
108  
109  /**
110   * Initialize a block filter index for the given type if one does not already exist. Returns true if
111   * a new index is created and false if one has already been initialized.
112   */
113  bool InitBlockFilterIndex(std::function<std::unique_ptr<interfaces::Chain>()> make_chain, BlockFilterType filter_type,
114                            size_t n_cache_size, bool f_memory = false, bool f_wipe = false);
115  
116  /**
117   * Destroy the block filter index with the given type. Returns false if no such index exists. This
118   * just releases the allocated memory and closes the database connection, it does not delete the
119   * index data.
120   */
121  bool DestroyBlockFilterIndex(BlockFilterType filter_type);
122  
123  /** Destroy all open block filter indexes. */
124  void DestroyAllBlockFilterIndexes();
125  
126  #endif // BITCOIN_INDEX_BLOCKFILTERINDEX_H