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Diffstat (limited to 'src/tools/qmutexpool.cpp')
| -rw-r--r-- | src/tools/qmutexpool.cpp | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/src/tools/qmutexpool.cpp b/src/tools/qmutexpool.cpp new file mode 100644 index 000000000..bcf20edab --- /dev/null +++ b/src/tools/qmutexpool.cpp @@ -0,0 +1,155 @@ +/**************************************************************************** +** +** ... +** +** Copyright (C) 2005-2008 Trolltech ASA. All rights reserved. +** +** This file is part of the tools module of the TQt 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 TQt Foundation. +** +** Please review the following information to ensure GNU General +** Public Licensing retquirements 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 sales@trolltech.com. +** +** This file may be used under the terms of the Q Public License as +** defined by Trolltech ASA and appearing in the file LICENSE.TQPL +** included in the packaging of this file. Licensees holding valid TQt +** Commercial licenses may use this file in accordance with the TQt +** 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 TQMutexPool *qt_global_mutexpool = 0; + + +/*! + \class TQMutexPool qmutexpool_p.h + \brief The TQMutexPool class provides a pool of TQMutex objects. + + \internal + + \ingroup thread + + TQMutexPool is a convenience class that provides access to a fixed + number of TQMutex objects. + + Typical use of a TQMutexPool is in situations where it is not + possible or feasible to use one TQMutex 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 TQMutex 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 + TQMutexPool would be ideal. + + Code to calculate the square of a number would then look something + like this: + + \code + void calcSquare( Number *num ) + { + TQMutexLocker 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 TQMutexPool. The mutex is locked and + unlocked automatically by the TQMutexLocker class. See the + TQMutexLocker documentation for more details. +*/ + +/*! + Constructs a TQMutexPool, reserving space for \a size TQMutexes. If + \a recursive is TRUE, all TQMutexes in the pool will be recursive + mutexes; otherwise they will all be non-recursive (the default). + + The TQMutexes are created when needed, and deleted when the + TQMutexPool is destructed. +*/ +TQMutexPool::TQMutexPool( bool recursive, int size ) + : mutex( FALSE ), count( size ), recurs( recursive ) +{ + mutexes = new TQMutex*[count]; + for ( int index = 0; index < count; ++index ) { + mutexes[index] = 0; + } +} + +/*! + Destructs a TQMutexPool. All TQMutexes that were created by the pool + are deleted. +*/ +TQMutexPool::~TQMutexPool() +{ + TQMutexLocker locker( &mutex ); + for ( int index = 0; index < count; ++index ) { + delete mutexes[index]; + mutexes[index] = 0; + } + delete [] mutexes; + mutexes = 0; +} + +/*! + Returns a TQMutex from the pool. TQMutexPool uses the value \a + address to determine which mutex is retured from the pool. +*/ +TQMutex *TQMutexPool::get( void *address ) +{ + int index = (int) ( (unsigned long) address % count ); + + if ( ! mutexes[index] ) { + // mutex not created, create one + + TQMutexLocker 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 TQMutex( recurs ); + } + } + + return mutexes[index]; +} + +#endif |