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
|
/*
* Copyright (C) 2008 Apple Inc. All rights reserved.
* Copyright (C) 2009 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef MessageQueue_h
#define MessageQueue_h
#include <limits>
#include <wtf/Assertions.h>
#include <wtf/Deque.h>
#include <wtf/Noncopyable.h>
#include <wtf/Threading.h>
namespace WTF {
enum MessageQueueWaitResult {
MessageQueueTerminated, // Queue was destroyed while waiting for message.
MessageQueueTimeout, // Timeout was specified and it expired.
MessageQueueMessageReceived, // A message was successfully received and returned.
};
template<typename DataType>
class MessageQueue : public Noncopyable {
public:
MessageQueue() : m_killed(false) { }
void append(const DataType&);
bool appendAndCheckEmpty(const DataType&);
void prepend(const DataType&);
bool waitForMessage(DataType&);
template<typename Predicate>
MessageQueueWaitResult waitForMessageFilteredWithTimeout(DataType&, Predicate&, double absoluteTime);
void kill();
bool tryGetMessage(DataType&);
bool killed() const;
// The result of isEmpty() is only valid if no other thread is manipulating the queue at the same time.
bool isEmpty();
static double infiniteTime() { return std::numeric_limits<double>::max(); }
private:
static bool alwaysTruePredicate(DataType&) { return true; }
mutable Mutex m_mutex;
ThreadCondition m_condition;
Deque<DataType> m_queue;
bool m_killed;
};
template<typename DataType>
inline void MessageQueue<DataType>::append(const DataType& message)
{
MutexLocker lock(m_mutex);
m_queue.append(message);
m_condition.signal();
}
// Returns true if the queue was empty before the item was added.
template<typename DataType>
inline bool MessageQueue<DataType>::appendAndCheckEmpty(const DataType& message)
{
MutexLocker lock(m_mutex);
bool wasEmpty = m_queue.isEmpty();
m_queue.append(message);
m_condition.signal();
return wasEmpty;
}
template<typename DataType>
inline void MessageQueue<DataType>::prepend(const DataType& message)
{
MutexLocker lock(m_mutex);
m_queue.prepend(message);
m_condition.signal();
}
template<typename DataType>
inline bool MessageQueue<DataType>::waitForMessage(DataType& result)
{
MessageQueueWaitResult exitReason = waitForMessageFilteredWithTimeout(result, MessageQueue<DataType>::alwaysTruePredicate, infiniteTime());
ASSERT(exitReason == MessageQueueTerminated || exitReason == MessageQueueMessageReceived);
return exitReason == MessageQueueMessageReceived;
}
template<typename DataType>
template<typename Predicate>
inline MessageQueueWaitResult MessageQueue<DataType>::waitForMessageFilteredWithTimeout(DataType& result, Predicate& predicate, double absoluteTime)
{
MutexLocker lock(m_mutex);
bool timedOut = false;
DequeConstIterator<DataType> found = m_queue.end();
while (!m_killed && !timedOut && (found = m_queue.findIf(predicate)) == m_queue.end())
timedOut = !m_condition.timedWait(m_mutex, absoluteTime);
ASSERT(!timedOut || absoluteTime != infiniteTime());
if (m_killed)
return MessageQueueTerminated;
if (timedOut)
return MessageQueueTimeout;
ASSERT(found != m_queue.end());
result = *found;
m_queue.remove(found);
return MessageQueueMessageReceived;
}
template<typename DataType>
inline bool MessageQueue<DataType>::tryGetMessage(DataType& result)
{
MutexLocker lock(m_mutex);
if (m_killed)
return false;
if (m_queue.isEmpty())
return false;
result = m_queue.first();
m_queue.removeFirst();
return true;
}
template<typename DataType>
inline bool MessageQueue<DataType>::isEmpty()
{
MutexLocker lock(m_mutex);
if (m_killed)
return true;
return m_queue.isEmpty();
}
template<typename DataType>
inline void MessageQueue<DataType>::kill()
{
MutexLocker lock(m_mutex);
m_killed = true;
m_condition.broadcast();
}
template<typename DataType>
inline bool MessageQueue<DataType>::killed() const
{
MutexLocker lock(m_mutex);
return m_killed;
}
} // namespace WTF
using WTF::MessageQueue;
// MessageQueueWaitResult enum and all its values.
using WTF::MessageQueueWaitResult;
using WTF::MessageQueueTerminated;
using WTF::MessageQueueTimeout;
using WTF::MessageQueueMessageReceived;
#endif // MessageQueue_h
|
