Line data    Source code

       1             : // Copyright (c) 2009-2010 Satoshi Nakamoto
       2             : // Copyright (c) 2009-2020 The Bitcoin Core developers
       3             : // Distributed under the MIT software license, see the accompanying
       4             : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       5             : 
       6             : #ifndef BITCOIN_FLATFILE_H
       7             : #define BITCOIN_FLATFILE_H
       8             : 
       9             : #include <string>
      10             : 
      11             : #include <fs.h>
      12             : #include <serialize.h>
      13             : 
      14             : struct FlatFilePos
      15             : {
      16     2352149 :     int nFile{-1};
      17     2352149 :     unsigned int nPos{0};
      18             : 
      19     2909672 :     SERIALIZE_METHODS(FlatFilePos, obj)
      20             :     {
      21      969892 :         READWRITE(VARINT_MODE(obj.nFile, VarIntMode::NONNEGATIVE_SIGNED), VARINT(obj.nPos));
      22      969892 :     }
      23             : 
      24     6962975 :     FlatFilePos() {}
      25             : 
      26      350389 :     FlatFilePos(int nFileIn, unsigned int nPosIn) :
      27      318051 :         nFile(nFileIn),
      28      318051 :         nPos(nPosIn)
      29      350389 :     {}
      30             : 
      31             :     friend bool operator==(const FlatFilePos &a, const FlatFilePos &b) {
      32             :         return (a.nFile == b.nFile && a.nPos == b.nPos);
      33             :     }
      34             : 
      35             :     friend bool operator!=(const FlatFilePos &a, const FlatFilePos &b) {
      36             :         return !(a == b);
      37             :     }
      38             : 
      39     2294262 :     bool IsNull() const { return (nFile == -1); }
      40             : 
      41             :     std::string ToString() const;
      42             : };
      43             : 
      44             : /**
      45             :  * FlatFileSeq represents a sequence of numbered files storing raw data. This class facilitates
      46             :  * access to and efficient management of these files.
      47             :  */
      48             : class FlatFileSeq
      49             : {
      50             : private:
      51             :     const fs::path m_dir;
      52             :     const char* const m_prefix;
      53             :     const size_t m_chunk_size;
      54             : 
      55             : public:
      56             :     /**
      57             :      * Constructor
      58             :      *
      59             :      * @param dir The base directory that all files live in.
      60             :      * @param prefix A short prefix given to all file names.
      61             :      * @param chunk_size Disk space is pre-allocated in multiples of this amount.
      62             :      */
      63             :     FlatFileSeq(fs::path dir, const char* prefix, size_t chunk_size);
      64             : 
      65             :     /** Get the name of the file at the given position. */
      66             :     fs::path FileName(const FlatFilePos& pos) const;
      67             : 
      68             :     /** Open a handle to the file at the given position. */
      69             :     FILE* Open(const FlatFilePos& pos, bool read_only = false);
      70             : 
      71             :     /**
      72             :      * Allocate additional space in a file after the given starting position. The amount allocated
      73             :      * will be the minimum multiple of the sequence chunk size greater than add_size.
      74             :      *
      75             :      * @param[in] pos The starting position that bytes will be allocated after.
      76             :      * @param[in] add_size The minimum number of bytes to be allocated.
      77             :      * @param[out] out_of_space Whether the allocation failed due to insufficient disk space.
      78             :      * @return The number of bytes successfully allocated.
      79             :      */
      80             :     size_t Allocate(const FlatFilePos& pos, size_t add_size, bool& out_of_space);
      81             : 
      82             :     /**
      83             :      * Commit a file to disk, and optionally truncate off extra pre-allocated bytes if final.
      84             :      *
      85             :      * @param[in] pos The first unwritten position in the file to be flushed.
      86             :      * @param[in] finalize True if no more data will be written to this file.
      87             :      * @return true on success, false on failure.
      88             :      */
      89             :     bool Flush(const FlatFilePos& pos, bool finalize = false);
      90             : };
      91             : 
      92             : #endif // BITCOIN_FLATFILE_H