blob: ca6b529930d617ffe7756376063521d2f3ff1253 (
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
|
#ifndef QPID_SYS_BLOCKINGQUEUE_H
#define QPID_SYS_BLOCKINGQUEUE_H
/*
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*
*/
#include "qpid/sys/Waitable.h"
#include <queue>
namespace qpid {
namespace sys {
/**
* A simple blocking queue template
*/
template <class T>
class BlockingQueue
{
mutable sys::Waitable waitable;
std::queue<T> queue;
public:
BlockingQueue() {}
~BlockingQueue() { close(); }
/** Pop from the queue, block up to timeout if empty.
*@param result Set to value popped from queue.
*@param timeout Defaults to infinite.
*@return true if result was set, false if queue empty after timeout.
*/
bool pop(T& result, Duration timeout=TIME_INFINITE) {
Mutex::ScopedLock l(waitable);
{
Waitable::ScopedWait w(waitable);
if (timeout == TIME_INFINITE) {
while (queue.empty()) waitable.wait();
} else if (timeout) {
AbsTime deadline(now(),timeout);
while (queue.empty() && deadline > now()) waitable.wait(deadline);
} else {
//ensure zero timeout pop does not miss the fact that
//queue is closed
waitable.checkException();
}
}
if (queue.empty()) return false;
result = queue.front();
queue.pop();
if (!queue.empty())
waitable.notify(); // Notify another waiter.
return true;
}
T pop(Duration timeout=TIME_INFINITE) {
T result;
bool ok = pop(result, timeout);
if (!ok)
throw Exception("Timed out waiting on a blocking queue");
return result;
}
/** Push a value onto the queue.
* Note it is not an error to push onto a closed queue.
*/
void push(const T& t) {
Mutex::ScopedLock l(waitable);
queue.push(t);
waitable.notify(); // Notify a waiter.
}
/**
* Close the queue.
*@ex exception to throw to waiting threads. ClosedException by default.
*/
void close(const ExceptionHolder& ex=ExceptionHolder(new ClosedException()))
{
Mutex::ScopedLock l(waitable);
if (!waitable.hasException()) {
waitable.setException(ex);
waitable.notifyAll();
waitable.waitWaiters(); // Ensure no threads are still waiting.
}
}
/** Open a closed queue. */
void open() {
Mutex::ScopedLock l(waitable);
waitable.resetException();
}
bool isClosed() const {
Mutex::ScopedLock l(waitable);
return waitable.hasException();
}
bool empty() const {
Mutex::ScopedLock l(waitable);
return queue.empty();
}
size_t size() const {
Mutex::ScopedLock l(waitable);
return queue.size();
}
};
}}
#endif /*!QPID_SYS_BLOCKINGQUEUE_H*/
|
