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       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                 :          14 :     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                 :          13 :     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   [ +  +  +  - ]:         558 :     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