flatfile.h

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// 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;
};

class FlatFileSeq
{
private:
    const fs::path m_dir;
    const char* const m_prefix;
    const size_t m_chunk_size;

public:
    FlatFileSeq(fs::path dir, const char* prefix, size_t chunk_size);

    fs::path FileName(const FlatFilePos& pos) const;

    FILE* Open(const FlatFilePos& pos, bool read_only = false);

    size_t Allocate(const FlatFilePos& pos, size_t add_size, bool& out_of_space);

    bool Flush(const FlatFilePos& pos, bool finalize = false);
};

#endif // BITCOIN_FLATFILE_H