git / moonbite-core / src/flatfile.h · raw

// Copyright (c) 2009-2010 Satoshi Nakamoto// Copyright (c) 2009-2020 The Bitcoin Core developers// Distributed under the MIT software license, see the accompanying// file COPYING or http://www.opensource.org/licenses/mit-license.php.#ifndef BITCOIN_FLATFILE_H#define BITCOIN_FLATFILE_H#include <string>#include <fs.h>#include <serialize.h>struct FlatFilePos{    int nFile;    unsigned int nPos;    SERIALIZE_METHODS(FlatFilePos, obj) { READWRITE(VARINT_MODE(obj.nFile, VarIntMode::NONNEGATIVE_SIGNED), VARINT(obj.nPos)); }    FlatFilePos() : nFile(-1), nPos(0) {}    FlatFilePos(int nFileIn, unsigned int nPosIn) :        nFile(nFileIn),        nPos(nPosIn)    {}    friend bool operator==(const FlatFilePos &a, const FlatFilePos &b) {        return (a.nFile == b.nFile && a.nPos == b.nPos);    }    friend bool operator!=(const FlatFilePos &a, const FlatFilePos &b) {        return !(a == b);    }    void SetNull() { nFile = -1; nPos = 0; }    bool IsNull() const { return (nFile == -1); }    std::string ToString() const;};/** * FlatFileSeq represents a sequence of numbered files storing raw data. This class facilitates * access to and efficient management of these files. */class FlatFileSeq{private:    const fs::path m_dir;    const char* const m_prefix;    const size_t m_chunk_size;public:    /**     * Constructor     *     * @param dir The base directory that all files live in.     * @param prefix A short prefix given to all file names.     * @param chunk_size Disk space is pre-allocated in multiples of this amount.     */    FlatFileSeq(fs::path dir, const char* prefix, size_t chunk_size);    /** Get the name of the file at the given position. */    fs::path FileName(const FlatFilePos& pos) const;    /** Open a handle to the file at the given position. */    FILE* Open(const FlatFilePos& pos, bool read_only = false);    /**     * Allocate additional space in a file after the given starting position. The amount allocated     * will be the minimum multiple of the sequence chunk size greater than add_size.     *     * @param[in] pos The starting position that bytes will be allocated after.     * @param[in] add_size The minimum number of bytes to be allocated.     * @param[out] out_of_space Whether the allocation failed due to insufficient disk space.     * @return The number of bytes successfully allocated.     */    size_t Allocate(const FlatFilePos& pos, size_t add_size, bool& out_of_space);    /**     * Commit a file to disk, and optionally truncate off extra pre-allocated bytes if final.     *     * @param[in] pos The first unwritten position in the file to be flushed.     * @param[in] finalize True if no more data will be written to this file.     * @return true on success, false on failure.     */    bool Flush(const FlatFilePos& pos, bool finalize = false);};#endif // BITCOIN_FLATFILE_H