1/****************************************************************************
2**
3** Copyright (C) 2016 The Qt Company Ltd.
4** Contact: https://www.qt.io/licensing/
5**
6** This file is part of the QtCore module of the Qt Toolkit.
7**
8** $QT_BEGIN_LICENSE:LGPL$
9** Commercial License Usage
10** Licensees holding valid commercial Qt licenses may use this file in
11** accordance with the commercial license agreement provided with the
12** Software or, alternatively, in accordance with the terms contained in
13** a written agreement between you and The Qt Company. For licensing terms
14** and conditions see https://www.qt.io/terms-conditions. For further
15** information use the contact form at https://www.qt.io/contact-us.
16**
17** GNU Lesser General Public License Usage
18** Alternatively, this file may be used under the terms of the GNU Lesser
19** General Public License version 3 as published by the Free Software
20** Foundation and appearing in the file LICENSE.LGPL3 included in the
21** packaging of this file. Please review the following information to
22** ensure the GNU Lesser General Public License version 3 requirements
23** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
24**
25** GNU General Public License Usage
26** Alternatively, this file may be used under the terms of the GNU
27** General Public License version 2.0 or (at your option) the GNU General
28** Public license version 3 or any later version approved by the KDE Free
29** Qt Foundation. The licenses are as published by the Free Software
30** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
31** included in the packaging of this file. Please review the following
32** information to ensure the GNU General Public License requirements will
33** be met: https://www.gnu.org/licenses/gpl-2.0.html and
34** https://www.gnu.org/licenses/gpl-3.0.html.
35**
36** $QT_END_LICENSE$
37**
38****************************************************************************/
39
40#ifndef QSEMAPHORE_H
41#define QSEMAPHORE_H
42
43#include <QtCore/qglobal.h>
44
45QT_REQUIRE_CONFIG(thread);
46
47QT_BEGIN_NAMESPACE
48
49class QSemaphorePrivate;
50
51class Q_CORE_EXPORT QSemaphore
52{
53public:
54 explicit QSemaphore(int n = 0);
55 ~QSemaphore();
56
57 void acquire(int n = 1);
58 bool tryAcquire(int n = 1);
59 bool tryAcquire(int n, int timeout);
60
61 void release(int n = 1);
62
63 int available() const;
64
65private:
66 Q_DISABLE_COPY(QSemaphore)
67
68 union {
69 QSemaphorePrivate *d;
70 QBasicAtomicInteger<quintptr> u;
71 QBasicAtomicInteger<quint32> u32[2];
72 QBasicAtomicInteger<quint64> u64;
73 };
74};
75
76class QSemaphoreReleaser
77{
78public:
79 QSemaphoreReleaser() = default;
80 explicit QSemaphoreReleaser(QSemaphore &sem, int n = 1) noexcept
81 : m_sem(&sem), m_n(n) {}
82 explicit QSemaphoreReleaser(QSemaphore *sem, int n = 1) noexcept
83 : m_sem(sem), m_n(n) {}
84 QSemaphoreReleaser(QSemaphoreReleaser &&other) noexcept
85 : m_sem(other.cancel()), m_n(other.m_n) {}
86 QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_MOVE_AND_SWAP(QSemaphoreReleaser)
87
88 ~QSemaphoreReleaser()
89 {
90 if (m_sem)
91 m_sem->release(m_n);
92 }
93
94 void swap(QSemaphoreReleaser &other) noexcept
95 {
96 qSwap(m_sem, other.m_sem);
97 qSwap(m_n, other.m_n);
98 }
99
100 QSemaphore *semaphore() const noexcept
101 { return m_sem; }
102
103 QSemaphore *cancel() noexcept
104 {
105 return qExchange(m_sem, nullptr);
106 }
107
108private:
109 QSemaphore *m_sem = nullptr;
110 int m_n;
111};
112
113QT_END_NAMESPACE
114
115#endif // QSEMAPHORE_H
116