blob: 9e47bdba894f33e051dac384a1dc37cf4237f08f (
plain)
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
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
|
// **********************************************************************
//
// Copyright (c) 2003
// ZeroC, Inc.
// Billerica, MA, USA
//
// All Rights Reserved.
//
// Ice is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License version 2 as published by
// the Free Software Foundation.
//
// **********************************************************************
#ifndef ICE_UTIL_RW_REC_MUTEX_H
#define ICE_UTIL_RW_REC_MUTEX_H
#include <IceUtil/Mutex.h>
#include <IceUtil/Cond.h>
#include <IceUtil/Thread.h>
namespace IceUtil
{
template <typename T>
class RLock
{
public:
RLock(const T& mutex) :
_mutex(mutex)
{
_mutex.readlock();
}
~RLock()
{
_mutex.unlock();
}
void
upgrade()
{
_mutex.upgrade();
}
void
timedUpgrade(const Time& timeout)
{
_mutex.timedUpgrade(timeout);
}
private:
const T& _mutex;
};
template <typename T>
class TryRLock
{
public:
TryRLock(const T& mutex) :
_mutex(mutex)
{
_mutex.tryReadlock();
}
TryRLock(const T& mutex, const Time& timeout) :
_mutex(mutex)
{
_mutex.timedTryReadlock(timeout);
}
~TryRLock()
{
_mutex.unlock();
}
void
upgrade()
{
_mutex.upgrade();
}
void
timedUpgrade(const Time& timeout)
{
_mutex.timedUpgrade(timeout);
}
private:
const T& _mutex;
};
template <typename T>
class WLock
{
public:
WLock(const T& mutex) :
_mutex(mutex)
{
_mutex.writelock();
}
~WLock()
{
_mutex.unlock();
}
private:
const T& _mutex;
};
template <typename T>
class TryWLock
{
public:
TryWLock(const T& mutex) :
_mutex(mutex)
{
_mutex.tryWritelock();
}
TryWLock(const T& mutex, const Time& timeout) :
_mutex(mutex)
{
_mutex.timedTryWritelock(timeout);
}
~TryWLock()
{
_mutex.unlock();
}
private:
const T& _mutex;
};
//
// Concurrency primitive that allows many readers & one writer access
// to a data structure. Writers have priority over readers. The
// structure is not strictly fair in that there is no absolute queue
// of waiting writers - that is managed by a condition variable.
//
// Both Reader & Writer mutexes can be recursively locked. Calling
// upgrade() or timedUpgrade() while holding a read lock promotes
// the reader to a writer lock.
//
class ICE_UTIL_API RWRecMutex
{
public:
//
// RLock (reader) & WLock (writer) typedefs.
//
typedef RLock<RWRecMutex> RLock;
typedef TryRLock<RWRecMutex> TryRLock;
typedef WLock<RWRecMutex> WLock;
typedef TryWLock<RWRecMutex> TryWLock;
RWRecMutex();
~RWRecMutex();
//
// Note that readlock/writelock & unlock in general should not be
// used directly. Instead use RLock & WLock.
//
//
// Acquire a read lock.
//
void readlock() const;
//
// Try to acquire a read lock.
//
void tryReadlock() const;
//
// Try to acquire a read lock for upto the given timeout.
//
void timedTryReadlock(const Time&) const;
//
// Acquire a write lock.
//
void writelock() const;
//
// Acquire a write lock.
//
void tryWritelock() const;
//
// Acquire a write lock for up to the given timeout.
//
void timedTryWritelock(const Time&) const;
//
// Unlock the reader/writer lock.
//
void unlock() const;
//
// Upgrade the read lock to a writer lock. Note that this method
// can only be called if the reader lock is not held recursively.
//
void upgrade() const;
//
// Upgrade the read lock to a writer lock for up to the given
// timeout Note that this method can only be called if the reader
// lock is not held recursively.
//
void timedUpgrade(const Time&) const;
private:
// noncopyable
RWRecMutex(const RWRecMutex&);
void operator=(const RWRecMutex&);
//
// Number of readers holding the lock. A positive number indicates
// readers are active. A negative number means that a writer is
// active.
//
mutable int _count;
//
// If there is an active writer this is the ID of the writer thread.
//
mutable ThreadId _writerId;
//
// Number of waiting writers.
//
mutable unsigned int _waitingWriters;
//
// Internal mutex.
//
Mutex _mutex;
//
// Two condition variables for waiting readers & writers.
//
mutable Cond _readers;
mutable Cond _writers;
};
} // End namespace IceUtil
#endif
|
