Long live Qt 4.5!

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diff --git a/src/corelib/thread/qmutexpool.cpp b/src/corelib/thread/qmutexpool.cpp
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+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Qt Software Information (qt-info@nokia.com)
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the either Technology Preview License Agreement or the
+** Beta Release License Agreement.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain
+** additional rights. These rights are described in the Nokia Qt LGPL
+** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
+** package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at qt-sales@nokia.com.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qatomic.h"
+#include "qmutexpool_p.h"
+
+#ifndef QT_NO_THREAD
+
+QT_BEGIN_NAMESPACE
+
+// qt_global_mutexpool is here for backwards compatability only,
+// use QMutexpool::instance() in new clode.
+Q_CORE_EXPORT QMutexPool *qt_global_mutexpool = 0;
+Q_GLOBAL_STATIC_WITH_ARGS(QMutexPool, globalMutexPool, (true))
+
+/*!
+    \class QMutexPool
+    \brief The QMutexPool class provides a pool of QMutex objects.
+
+    \internal
+
+    \ingroup thread
+
+    QMutexPool is a convenience class that provides access to a fixed
+    number of QMutex objects.
+
+    Typical use of a QMutexPool is in situations where it is not
+    possible or feasible to use one QMutex for every protected object.
+    The mutex pool will return a mutex based on the address of the
+    object that needs protection.
+
+    For example, consider this simple class:
+
+    \snippet doc/src/snippets/code/src_corelib_thread_qmutexpool.cpp 0
+
+    Adding a QMutex member to the Number class does not make sense,
+    because it is so small. However, in order to ensure that access to
+    each Number is protected, you need to use a mutex. In this case, a
+    QMutexPool would be ideal.
+
+    Code to calculate the square of a number would then look something
+    like this:
+
+    \snippet doc/src/snippets/code/src_corelib_thread_qmutexpool.cpp 1
+
+    This function will safely calculate the square of a number, since
+    it uses a mutex from a QMutexPool. The mutex is locked and
+    unlocked automatically by the QMutexLocker class. See the
+    QMutexLocker documentation for more details.
+*/
+
+/*!
+    Constructs  a QMutexPool, reserving space for \a size QMutexes. If
+    \a recursive is true, all QMutexes in the pool will be recursive
+    mutexes; otherwise they will all be non-recursive (the default).
+
+    The QMutexes are created when needed, and deleted when the
+    QMutexPool is destructed.
+*/
+QMutexPool::QMutexPool(bool recursive, int size)
+    : count(size), recurs(recursive)
+{
+    mutexes = new QMutex*[count];
+    for (int index = 0; index < count; ++index) {
+        mutexes[index] = 0;
+    }
+}
+
+/*!
+    Destructs a QMutexPool. All QMutexes that were created by the pool
+    are deleted.
+*/
+QMutexPool::~QMutexPool()
+{
+    QMutexLocker locker(&mutex);
+    for (int index = 0; index < count; ++index) {
+        delete mutexes[index];
+        mutexes[index] = 0;
+    }
+    delete [] mutexes;
+    mutexes = 0;
+}
+
+/*!
+    Returns the global QMutexPool instance.
+*/
+QMutexPool *QMutexPool::instance()
+{
+    return globalMutexPool();
+}
+
+/*!
+    Returns a QMutex from the pool. QMutexPool uses the value \a address
+    to determine which mutex is returned from the pool.
+*/
+QMutex *QMutexPool::get(const void *address)
+{
+    Q_ASSERT_X(address != 0, "QMutexPool::get()", "'address' argument cannot be zero");
+    int index = int((quintptr(address) >> (sizeof(address) >> 1)) % count);
+
+    if (!mutexes[index]) {
+        // mutex not created, create one
+
+        QMutexLocker locker(&mutex);
+        // we need to check once again that the mutex hasn't been created, since
+        // 2 threads could be trying to create a mutex at the same index...
+        if (!mutexes[index])
+            mutexes[index] = new QMutex(recurs ? QMutex::Recursive : QMutex::NonRecursive);
+    }
+
+    return mutexes[index];
+}
+
+/*!
+    Returns a QMutex from the global mutex pool.
+*/
+QMutex *QMutexPool::globalInstanceGet(const void *address)
+{
+    QMutexPool * const globalInstance = globalMutexPool();
+    if (globalInstance == 0)
+        return 0;
+    return globalInstance->get(address);
+}
+
+QT_END_NAMESPACE
+
+#endif // QT_NO_THREAD