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/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef QSEMAPHORE_H
#define QSEMAPHORE_H
#include <QtCore/qglobal.h>
#include <QtCore/qmutex.h> // for convertToMilliseconds()
#include <chrono>
QT_REQUIRE_CONFIG(thread);
QT_BEGIN_NAMESPACE
class QSemaphorePrivate;
class Q_CORE_EXPORT QSemaphore
{
public:
explicit QSemaphore(int n = 0);
~QSemaphore();
void acquire(int n = 1);
bool tryAcquire(int n = 1);
bool tryAcquire(int n, int timeout);
template <typename Rep, typename Period>
bool tryAcquire(int n, std::chrono::duration<Rep, Period> timeout)
{ return tryAcquire(n, QtPrivate::convertToMilliseconds(timeout)); }
void release(int n = 1);
int available() const;
// std::counting_semaphore compatibility:
bool try_acquire() noexcept { return tryAcquire(); }
template <typename Rep, typename Period>
bool try_acquire_for(const std::chrono::duration<Rep, Period> &timeout)
{ return tryAcquire(1, timeout); }
template <typename Clock, typename Duration>
bool try_acquire_until(const std::chrono::time_point<Clock, Duration> &tp)
{
return try_acquire_for(tp - Clock::now());
}
private:
Q_DISABLE_COPY(QSemaphore)
union {
QSemaphorePrivate *d;
QBasicAtomicInteger<quintptr> u;
QBasicAtomicInteger<quint32> u32[2];
QBasicAtomicInteger<quint64> u64;
};
};
class QSemaphoreReleaser
{
public:
QSemaphoreReleaser() = default;
explicit QSemaphoreReleaser(QSemaphore &sem, int n = 1) noexcept
: m_sem(&sem), m_n(n) {}
explicit QSemaphoreReleaser(QSemaphore *sem, int n = 1) noexcept
: m_sem(sem), m_n(n) {}
QSemaphoreReleaser(QSemaphoreReleaser &&other) noexcept
: m_sem(other.cancel()), m_n(other.m_n) {}
QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_MOVE_AND_SWAP(QSemaphoreReleaser)
~QSemaphoreReleaser()
{
if (m_sem)
m_sem->release(m_n);
}
void swap(QSemaphoreReleaser &other) noexcept
{
qt_ptr_swap(m_sem, other.m_sem);
std::swap(m_n, other.m_n);
}
QSemaphore *semaphore() const noexcept
{ return m_sem; }
QSemaphore *cancel() noexcept
{
return qExchange(m_sem, nullptr);
}
private:
QSemaphore *m_sem = nullptr;
int m_n;
};
QT_END_NAMESPACE
#endif // QSEMAPHORE_H
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