1/*
2 * Copyright (C) 2016 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#pragma once
27
28#include <limits>
29#include <wtf/Assertions.h>
30#include <wtf/Condition.h>
31#include <wtf/Deque.h>
32#include <wtf/Lock.h>
33#include <wtf/Noncopyable.h>
34#include <wtf/Optional.h>
35
36namespace WTF {
37
38template<typename DataType>
39class CrossThreadQueue final {
40 WTF_MAKE_FAST_ALLOCATED;
41 WTF_MAKE_NONCOPYABLE(CrossThreadQueue);
42public:
43 CrossThreadQueue() = default;
44
45 void append(DataType&&);
46
47 DataType waitForMessage();
48 Optional<DataType> tryGetMessage();
49
50 void kill();
51 bool isKilled() const;
52 bool isEmpty() const;
53
54private:
55 Deque<DataType> m_queue;
56 mutable Lock m_lock;
57 Condition m_condition;
58 bool m_killed { false };
59};
60
61template<typename DataType>
62void CrossThreadQueue<DataType>::append(DataType&& message)
63{
64 LockHolder lock(m_lock);
65 ASSERT(!m_killed);
66 m_queue.append(WTFMove(message));
67 m_condition.notifyOne();
68}
69
70template<typename DataType>
71DataType CrossThreadQueue<DataType>::waitForMessage()
72{
73 LockHolder lock(m_lock);
74
75 auto found = m_queue.end();
76 while (found == m_queue.end()) {
77 found = m_queue.begin();
78 if (found != m_queue.end())
79 break;
80
81 m_condition.wait(m_lock);
82 }
83
84 return m_queue.takeFirst();
85}
86
87template<typename DataType>
88Optional<DataType> CrossThreadQueue<DataType>::tryGetMessage()
89{
90 LockHolder lock(m_lock);
91
92 if (m_queue.isEmpty())
93 return { };
94
95 return m_queue.takeFirst();
96}
97
98template<typename DataType>
99void CrossThreadQueue<DataType>::kill()
100{
101 LockHolder lock(m_lock);
102 m_killed = true;
103 m_condition.notifyAll();
104}
105
106template<typename DataType>
107bool CrossThreadQueue<DataType>::isKilled() const
108{
109 LockHolder lock(m_lock);
110 return m_killed;
111}
112
113template<typename DataType>
114bool CrossThreadQueue<DataType>::isEmpty() const
115{
116 LockHolder lock(m_lock);
117 return m_queue.isEmpty();
118}
119
120} // namespace WTF
121
122using WTF::CrossThreadQueue;
123