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
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
|
//
// FileStreamRWLock.h
//
// Library: Foundation
// Package: Processes
// Module: FileStreamRWLock
//
// Definition of the FileStreamRWLock class.
//
// Copyright (c) 2004-2024, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier: BSL-1.0
//
#ifndef Foundation_FileStreamRWLock_INCLUDED
#define Foundation_FileStreamRWLock_INCLUDED
#include "Poco/Foundation.h"
#include "Poco/Exception.h"
#include "Poco/FileStream.h"
#include <atomic>
#if defined(POCO_OS_FAMILY_WINDOWS)
#include "Poco/FileStreamRWLock_WIN32.h"
#else
#include "Poco/FileStreamRWLock_POSIX.h"
#endif
namespace Poco {
class ScopedFStreamRWLock;
class ScopedFStreamReadRWLock;
class ScopedFStreamWriteRWLock;
class Foundation_API FileStreamRWLock: private FileStreamRWLockImpl
/// A reader writer lock on the file region allows multiple concurrent
/// process-readers or one exclusive process-writer.
{
public:
using ScopedLock = ScopedFStreamRWLock;
using ScopedReadLock = ScopedFStreamReadRWLock;
using ScopedWriteLock = ScopedFStreamWriteRWLock;
FileStreamRWLock(const FileStream &fs, Poco::UInt64 offset, Poco::UInt64 size);
/// Creates the Reader/Writer lock on the file region.
/// offset - from start of the file
/// size - size of the locker region
~FileStreamRWLock();
/// Destroys the Reader/Writer lock on the file region.
void readLock();
/// Acquires a read lock. If another process currently holds a write lock,
/// waits until the write lock is released.
bool tryReadLock();
/// Tries to acquire a read lock. Immediately returns true if successful, or
/// false if another process currently holds a write lock.
void writeLock();
/// Acquires a write lock on the file region. If one or more other processes currently hold
/// locks, waits until all locks are released.
bool tryWriteLock();
/// Tries to acquire a write lock on the file region. Immediately returns true if successful,
/// or false if one or more other processes currently hold
/// locks.
void unlock();
/// Releases the read or write lock.
private:
std::atomic_bool _locked = false;
FileStreamRWLock(const FileStreamRWLock&);
FileStreamRWLock& operator = (const FileStreamRWLock&);
};
class Foundation_API ScopedFStreamRWLock
/// A variant of ScopedLock for reader/writer locks.
{
public:
ScopedFStreamRWLock(FileStreamRWLock& rwl, bool write = false);
~ScopedFStreamRWLock();
private:
FileStreamRWLock& _rwl;
ScopedFStreamRWLock();
ScopedFStreamRWLock(const ScopedFStreamRWLock&);
ScopedFStreamRWLock& operator = (const ScopedFStreamRWLock&);
};
class Foundation_API ScopedFStreamReadRWLock : public ScopedFStreamRWLock
/// A variant of ScopedLock for reader locks.
{
public:
ScopedFStreamReadRWLock(FileStreamRWLock& rwl);
~ScopedFStreamReadRWLock();
};
class Foundation_API ScopedFStreamWriteRWLock : public ScopedFStreamRWLock
/// A variant of ScopedLock for writer locks.
{
public:
ScopedFStreamWriteRWLock(FileStreamRWLock& rwl);
~ScopedFStreamWriteRWLock();
};
//
// inlines
//
inline void FileStreamRWLock::readLock()
{
readLockImpl();
_locked = true;
}
inline bool FileStreamRWLock::tryReadLock()
{
bool locked = tryReadLockImpl();
if (locked) _locked = true; // assign only if success lock
return locked;
}
inline void FileStreamRWLock::writeLock()
{
writeLockImpl();
_locked = true;
}
inline bool FileStreamRWLock::tryWriteLock()
{
bool locked = tryWriteLockImpl();
if (locked) _locked = true; // assign only if success lock
return locked;
}
inline void FileStreamRWLock::unlock()
{
unlockImpl();
_locked = false;
}
inline ScopedFStreamRWLock::ScopedFStreamRWLock(FileStreamRWLock& rwl, bool write): _rwl(rwl)
{
if (write)
_rwl.writeLock();
else
_rwl.readLock();
}
inline ScopedFStreamRWLock::~ScopedFStreamRWLock()
{
try
{
_rwl.unlock();
}
catch (...)
{
poco_unexpected();
}
}
inline ScopedFStreamReadRWLock::ScopedFStreamReadRWLock(FileStreamRWLock& rwl): ScopedFStreamRWLock(rwl, false)
{
}
inline ScopedFStreamReadRWLock::~ScopedFStreamReadRWLock()
{
}
inline ScopedFStreamWriteRWLock::ScopedFStreamWriteRWLock(FileStreamRWLock& rwl): ScopedFStreamRWLock(rwl, true)
{
}
inline ScopedFStreamWriteRWLock::~ScopedFStreamWriteRWLock()
{
}
} // namespace Poco
#endif // Foundation_FileStreamRWLock_INCLUDED
|
