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156 lines
4.7 KiB
156 lines
4.7 KiB
/****************************************************************************
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**
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** ...
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**
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** Copyright (C) 2005-2008 Trolltech ASA. All rights reserved.
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**
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** This file is part of the tools module of the TQt GUI Toolkit.
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**
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** This file may be used under the terms of the GNU General
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** Public License versions 2.0 or 3.0 as published by the Free
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** Software Foundation and appearing in the files LICENSE.GPL2
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** and LICENSE.GPL3 included in the packaging of this file.
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** Alternatively you may (at your option) use any later version
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** of the GNU General Public License if such license has been
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** publicly approved by Trolltech ASA (or its successors, if any)
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** and the KDE Free TQt Foundation.
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**
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** Please review the following information to ensure GNU General
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** Public Licensing requirements will be met:
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** http://trolltech.com/products/qt/licenses/licensing/opensource/.
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** If you are unsure which license is appropriate for your use, please
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** review the following information:
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** http://trolltech.com/products/qt/licenses/licensing/licensingoverview
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** or contact the sales department at sales@trolltech.com.
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**
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** This file may be used under the terms of the Q Public License as
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** defined by Trolltech ASA and appearing in the file LICENSE.TQPL
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** included in the packaging of this file. Licensees holding valid TQt
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** Commercial licenses may use this file in accordance with the TQt
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** Commercial License Agreement provided with the Software.
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**
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** This file is provided "AS IS" with NO WARRANTY OF ANY KIND,
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** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR
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** A PARTICULAR PURPOSE. Trolltech reserves all rights not granted
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** herein.
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**
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**********************************************************************/
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#include "qmutexpool_p.h"
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#ifdef TQT_THREAD_SUPPORT
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#include <ntqthread.h>
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TQ_EXPORT TQMutexPool *tqt_global_mutexpool = 0;
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/*!
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\class TQMutexPool qmutexpool_p.h
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\brief The TQMutexPool class provides a pool of TQMutex objects.
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\internal
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\ingroup thread
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TQMutexPool is a convenience class that provides access to a fixed
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number of TQMutex objects.
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Typical use of a TQMutexPool is in situations where it is not
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possible or feasible to use one TQMutex 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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\code
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class Number {
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public:
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Number( double n ) : num ( n ) { }
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void setNumber( double n ) { num = n; }
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double number() const { return num; }
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private:
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double num;
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};
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\endcode
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Adding a TQMutex 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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TQMutexPool 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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\code
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void calcSquare( Number *num )
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{
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TQMutexLocker locker( mutexpool.get( num ) );
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num.setNumber( num.number() * num.number() );
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}
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\endcode
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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 TQMutexPool. The mutex is locked and
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unlocked automatically by the TQMutexLocker class. See the
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TQMutexLocker documentation for more details.
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*/
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/*!
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Constructs a TQMutexPool, reserving space for \a size TQMutexes. If
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\a recursive is TRUE, all TQMutexes in the pool will be recursive
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mutexes; otherwise they will all be non-recursive (the default).
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The TQMutexes are created when needed, and deleted when the
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TQMutexPool is destructed.
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*/
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TQMutexPool::TQMutexPool( bool recursive, int size )
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: mutex( FALSE ), count( size ), recurs( recursive )
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{
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mutexes = new TQMutex*[count];
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for ( int index = 0; index < count; ++index ) {
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mutexes[index] = 0;
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}
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}
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/*!
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Destructs a TQMutexPool. All TQMutexes that were created by the pool
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are deleted.
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*/
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TQMutexPool::~TQMutexPool()
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{
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TQMutexLocker locker( &mutex );
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for ( int index = 0; index < count; ++index ) {
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delete mutexes[index];
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mutexes[index] = 0;
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}
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delete [] mutexes;
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mutexes = 0;
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}
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/*!
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Returns a TQMutex from the pool. TQMutexPool uses the value \a
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address to determine which mutex is retured from the pool.
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*/
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TQMutex *TQMutexPool::get( void *address )
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{
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int index = (int) ( (unsigned long) address % count );
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if ( ! mutexes[index] ) {
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// mutex not created, create one
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TQMutexLocker locker( &mutex );
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// we need to check once again that the mutex hasn't been created, since
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// 2 threads could be trying to create a mutex as the same index...
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if ( ! mutexes[index] ) {
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mutexes[index] = new TQMutex( recurs );
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}
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}
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return mutexes[index];
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}
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#endif
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