153 lines
4.6 KiB
C++
153 lines
4.6 KiB
C++
/****************************************************************************
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**
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** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
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** Contact: http://www.qt-project.org/
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**
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** This file is part of the QtCore module of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** GNU Lesser General Public License Usage
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** This file may be used under the terms of the GNU Lesser General Public
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** License version 2.1 as published by the Free Software Foundation and
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** appearing in the file LICENSE.LGPL included in the packaging of this
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** file. Please review the following information to ensure the GNU Lesser
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** General Public License version 2.1 requirements will be met:
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** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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**
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** In addition, as a special exception, Nokia gives you certain additional
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** rights. These rights are described in the Nokia Qt LGPL Exception
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU General
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** Public License version 3.0 as published by the Free Software Foundation
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** and appearing in the file LICENSE.GPL included in the packaging of this
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** file. Please review the following information to ensure the GNU General
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** Public License version 3.0 requirements will be met:
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** http://www.gnu.org/copyleft/gpl.html.
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**
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** Other Usage
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** Alternatively, this file may be used in accordance with the terms and
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** conditions contained in a signed written agreement between you and Nokia.
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**
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**
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**
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**
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**
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#include "qatomic.h"
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#include "qmutexpool_p.h"
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#ifndef QT_NO_THREAD
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QT_BEGIN_NAMESPACE
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Q_GLOBAL_STATIC_WITH_ARGS(QMutexPool, globalMutexPool, (QMutex::Recursive))
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/*!
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\class QMutexPool
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\brief The QMutexPool class provides a pool of QMutex objects.
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\internal
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\ingroup thread
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QMutexPool is a convenience class that provides access to a fixed
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number of QMutex objects.
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Typical use of a QMutexPool is in situations where it is not
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possible or feasible to use one QMutex for every protected object.
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The mutex pool will return a mutex based on the address of the
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object that needs protection.
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For example, consider this simple class:
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\snippet code/src_corelib_thread_qmutexpool.cpp 0
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Adding a QMutex member to the Number class does not make sense,
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because it is so small. However, in order to ensure that access to
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each Number is protected, you need to use a mutex. In this case, a
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QMutexPool would be ideal.
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Code to calculate the square of a number would then look something
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like this:
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\snippet code/src_corelib_thread_qmutexpool.cpp 1
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This function will safely calculate the square of a number, since
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it uses a mutex from a QMutexPool. The mutex is locked and
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unlocked automatically by the QMutexLocker class. See the
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QMutexLocker documentation for more details.
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*/
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/*!
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Constructs a QMutexPool, reserving space for \a size QMutexes. All
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mutexes in the pool are created with \a recursionMode. By default,
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all mutexes are non-recursive.
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The QMutexes are created when needed, and deleted when the
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QMutexPool is destructed.
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*/
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QMutexPool::QMutexPool(QMutex::RecursionMode recursionMode, int size)
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: mutexes(size), recursionMode(recursionMode)
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{
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for (int index = 0; index < mutexes.count(); ++index) {
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mutexes[index].store(0);
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}
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}
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/*!
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Destructs a QMutexPool. All QMutexes that were created by the pool
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are deleted.
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*/
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QMutexPool::~QMutexPool()
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{
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for (int index = 0; index < mutexes.count(); ++index)
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delete mutexes[index].load();
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}
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/*!
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Returns the global QMutexPool instance.
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*/
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QMutexPool *QMutexPool::instance()
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{
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return globalMutexPool();
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}
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/*!
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\fn QMutexPool::get(const void *address)
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Returns a QMutex from the pool. QMutexPool uses the value \a address
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to determine which mutex is returned from the pool.
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*/
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/*! \internal
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create the mutex for the given index
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*/
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QMutex *QMutexPool::createMutex(int index)
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{
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// mutex not created, create one
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QMutex *newMutex = new QMutex(recursionMode);
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if (!mutexes[index].testAndSetRelease(0, newMutex))
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delete newMutex;
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return mutexes[index].load();
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}
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/*!
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Returns a QMutex from the global mutex pool.
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*/
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QMutex *QMutexPool::globalInstanceGet(const void *address)
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{
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QMutexPool * const globalInstance = globalMutexPool();
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if (globalInstance == 0)
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return 0;
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return globalInstance->get(address);
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}
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QT_END_NAMESPACE
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#endif // QT_NO_THREAD
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