flatfile.h

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2019 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 <fs.h>
#include <serialize.h>

#include <string>

struct FlatFilePos {
    int nFile;
    unsigned int nPos;

    ADD_SERIALIZE_METHODS;

    template <typename Stream, typename Operation>
    inline void SerializationOp(Stream &s, Operation ser_action) {
        READWRITE(VARINT_MODE(nFile, VarIntMode::NONNEGATIVE_SIGNED));
        READWRITE(VARINT(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