// 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)); }

Unexecuted instantiation: void FlatFilePos::SerializationOps<DataStream, FlatFilePos, ActionUnserialize>(FlatFilePos&, DataStream&, ActionUnserialize)

Unexecuted instantiation: void FlatFilePos::SerializationOps<DataStream, FlatFilePos const, ActionSerialize>(FlatFilePos const&, DataStream&, ActionSerialize)

    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);

  Branch (29:17): [True: 0, False: 0]
  Branch (29:39): [True: 0, False: 0]

    }

    friend bool operator!=(const FlatFilePos &a, const FlatFilePos &b) {

        return !(a == b);

    }

    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) const;

    /**

     * 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) const;

    /**

     * 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) const;

};

#endif // BITCOIN_FLATFILE_H