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+/****************************************************************************
+**
+** ...
+**
+** Copyright (C) 2005-2008 Trolltech ASA.  All rights reserved.
+**
+** This file is part of the tools module of the Qt GUI Toolkit.
+**
+** This file may be used under the terms of the GNU General
+** Public License versions 2.0 or 3.0 as published by the Free
+** Software Foundation and appearing in the files LICENSE.GPL2
+** and LICENSE.GPL3 included in the packaging of this file.
+** Alternatively you may (at your option) use any later version
+** of the GNU General Public License if such license has been
+** publicly approved by Trolltech ASA (or its successors, if any)
+** and the KDE Free Qt Foundation.
+**
+** Please review the following information to ensure GNU General
+** Public Licensing requirements will be met:
+** http://trolltech.com/products/qt/licenses/licensing/opensource/.
+** If you are unsure which license is appropriate for your use, please
+** review the following information:
+** http://trolltech.com/products/qt/licenses/licensing/licensingoverview
+** or contact the sales department at [email protected].
+**
+** This file may be used under the terms of the Q Public License as
+** defined by Trolltech ASA and appearing in the file LICENSE.QPL
+** included in the packaging of this file.  Licensees holding valid Qt
+** Commercial licenses may use this file in accordance with the Qt
+** Commercial License Agreement provided with the Software.
+**
+** This file is provided "AS IS" with NO WARRANTY OF ANY KIND,
+** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE. Trolltech reserves all rights not granted
+** herein.
+**
+**********************************************************************/
+
+#include "qmutexpool_p.h"
+
+#ifdef QT_THREAD_SUPPORT
+
+#include <qthread.h>
+
+Q_EXPORT QMutexPool *qt_global_mutexpool = 0;
+
+
+/*!
+    \class QMutexPool qmutexpool_p.h
+    \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:
+
+    \code
+    class Number {
+    public:
+	Number( double n ) : num ( n ) { }
+
+	void setNumber( double n ) { num = n; }
+	double number() const { return num; }
+
+    private:
+	double num;
+    };
+    \endcode
+
+    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:
+
+    \code
+    void calcSquare( Number *num )
+    {
+	QMutexLocker locker( mutexpool.get( num ) );
+	num.setNumber( num.number() * num.number() );
+    }
+    \endcode
+
+    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 )
+    : mutex( FALSE ), 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 a QMutex from the pool. QMutexPool uses the value \a
+    address to determine which mutex is retured from the pool.
+*/
+QMutex *QMutexPool::get( void *address )
+{
+    int index = (int) ( (unsigned long) address % 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 as the same index...
+	if ( ! mutexes[index] ) {
+	    mutexes[index] = new QMutex( recurs );
+	}
+    }
+
+    return mutexes[index];
+}
+
+#endif