-
Notifications
You must be signed in to change notification settings - Fork 1.2k
/
SynchronizedFixedQueue.h
125 lines (101 loc) · 3.59 KB
/
SynchronizedFixedQueue.h
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
/*
* Copyright (C) 2016 Apple 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.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 INC. OR
* 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.
*/
#pragma once
#include <wtf/Condition.h>
#include <wtf/Deque.h>
#include <wtf/Lock.h>
#include <wtf/ThreadSafeRefCounted.h>
namespace WTF {
template<typename T, size_t BufferSize>
class SynchronizedFixedQueue : public ThreadSafeRefCounted<SynchronizedFixedQueue<T, BufferSize>> {
public:
static Ref<SynchronizedFixedQueue> create()
{
return adoptRef(*new SynchronizedFixedQueue());
}
void open()
{
LockHolder lockHolder(m_mutex);
if (m_open)
return;
// Restore the queue to its original state.
m_open = true;
m_queue.clear();
}
void close()
{
LockHolder lockHolder(m_mutex);
if (!m_open)
return;
// Wake all the sleeping threads up with a closing state.
m_open = false;
m_condition.notifyAll();
}
bool isOpen()
{
LockHolder lockHolder(m_mutex);
return m_open;
}
bool enqueue(const T& value)
{
LockHolder lockHolder(m_mutex);
// Wait for an empty place to be available in the queue.
m_condition.wait(m_mutex, [this]() { return !m_open || m_queue.size() < BufferSize; });
// The queue is closing, exit immediately.
if (!m_open)
return false;
// Add the item in the queue.
m_queue.append(value);
// Notify the other threads that an item was added to the queue.
m_condition.notifyAll();
return true;
}
bool dequeue(T& value)
{
LockHolder lockHolder(m_mutex);
// Wait for an item to be added.
m_condition.wait(m_mutex, [this]() { return !m_open || m_queue.size(); });
// The queue is closing, exit immediately.
if (!m_open)
return false;
// Get a copy from m_queue.first and then remove it.
value = m_queue.first();
m_queue.removeFirst();
// Notify the other threads that an item was removed from the queue.
m_condition.notifyAll();
return true;
}
private:
SynchronizedFixedQueue()
{
static_assert(!((BufferSize - 1) & BufferSize), "BufferSize must be power of 2.");
}
Lock m_mutex;
Condition m_condition;
bool m_open { true };
Deque<T, BufferSize> m_queue;
};
}
using WTF::SynchronizedFixedQueue;