1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
|
// 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 <string>
#include <fs.h>
#include <serialize.h>
struct CDiskBlockPos
{
int nFile;
unsigned int nPos;
ADD_SERIALIZE_METHODS;
template <typename Stream, typename Operation>
inline void SerializationOp(Stream& s, Operation ser_action) {
READWRITE(VARINT(nFile, VarIntMode::NONNEGATIVE_SIGNED));
READWRITE(VARINT(nPos));
}
CDiskBlockPos() {
SetNull();
}
CDiskBlockPos(int nFileIn, unsigned int nPosIn) {
nFile = nFileIn;
nPos = nPosIn;
}
friend bool operator==(const CDiskBlockPos &a, const CDiskBlockPos &b) {
return (a.nFile == b.nFile && a.nPos == b.nPos);
}
friend bool operator!=(const CDiskBlockPos &a, const CDiskBlockPos &b) {
return !(a == b);
}
void SetNull() { nFile = -1; nPos = 0; }
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 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
|
