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 <serialize.h>
#include <util/fs.h>
 
struct FlatFilePos
{
    int nFile{-1};
    unsigned int nPos{0};
 
    SERIALIZE_METHODS(FlatFilePos, obj) { READWRITE(VARINT_MODE(obj.nFile, VarIntMode::NONNEGATIVE_SIGNED), VARINT(obj.nPos)); }
 
    FlatFilePos() = default;
 
    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);
    }
 
    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) const;
 
    size_t Allocate(const FlatFilePos& pos, size_t add_size, bool& out_of_space) const;
 
    bool Flush(const FlatFilePos& pos, bool finalize = false) const;
};
 
#endif // BITCOIN_FLATFILE_H