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src/flatfile.h
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// Copyright (c) 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 <chain.h> | |||||
#include <fs.h> | |||||
/** | |||||
* 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 CDiskBlockPos &pos) const; | |||||
/** Open a handle to the file at the given position. */ | |||||
FILE *Open(const CDiskBlockPos &pos, bool fReadOnly = 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 CDiskBlockPos &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 CDiskBlockPos &pos, bool finalize = false); | |||||
}; | |||||
#endif // BITCOIN_FLATFILE_H |