1  // Copyright (c) 2017-2022 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_TXINDEX_H
 6  #define BITCOIN_INDEX_TXINDEX_H
 7  
 8  #include <index/base.h>
 9  
10  static constexpr bool DEFAULT_TXINDEX{false};
11  
12  /**
13   * TxIndex is used to look up transactions included in the blockchain by hash.
14   * The index is written to a LevelDB database and records the filesystem
15   * location of each transaction by transaction hash.
16   */
17  class TxIndex final : public BaseIndex
18  {
19  protected:
20      class DB;
21  
22  private:
23      const std::unique_ptr<DB> m_db;
24  
25      bool AllowPrune() const override { return false; }
26  
27  protected:
28      bool CustomAppend(const interfaces::BlockInfo& block) override;
29  
30      BaseIndex::DB& GetDB() const override;
31  
32  public:
33      /// Constructs the index, which becomes available to be queried.
34      explicit TxIndex(std::unique_ptr<interfaces::Chain> chain, size_t n_cache_size, bool f_memory = false, bool f_wipe = false);
35  
36      // Destructor is declared because this class contains a unique_ptr to an incomplete type.
37      virtual ~TxIndex() override;
38  
39      /// Look up a transaction by hash.
40      ///
41      /// @param[in]   tx_hash  The hash of the transaction to be returned.
42      /// @param[out]  block_hash  The hash of the block the transaction is found in.
43      /// @param[out]  tx  The transaction itself.
44      /// @return  true if transaction is found, false otherwise
45      bool FindTx(const uint256& tx_hash, uint256& block_hash, CTransactionRef& tx) const;
46  };
47  
48  /// The global transaction index, used in GetTransaction. May be null.
49  extern std::unique_ptr<TxIndex> g_txindex;
50  
51  #endif // BITCOIN_INDEX_TXINDEX_H