C++/Qt/QMutexLocker

Using QMutexLocker

<source lang="cpp">

Foundations of Qt Development\Chapter12\orderedthreads\main.cpp /*

* Copyright (c) 2006-2007, Johan Thelin
* 
* All rights reserved.
* 
* Redistribution and use in source and binary forms, with or without modification, 
* are permitted provided that the following conditions are met:
* 
*     * Redistributions of source code must retain the above copyright notice, 
*       this list of conditions and the following disclaimer.
*     * Redistributions in binary form must reproduce the above copyright notice,  
*       this list of conditions and the following disclaimer in the documentation 
*       and/or other materials provided with the distribution.
*     * Neither the name of APress nor the names of its contributors 
*       may be used to endorse or promote products derived from this software 
*       without specific prior written permission.
* 
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/

1. include <QApplication>
2. include <QThread>
3. include <QMessageBox>
4. include <QMutex>
5. include <QtDebug>

class TextDevice { public:

 TextDevice();
 
 void write( QString );

private:

 int count;
 QMutex mutex;

}; TextDevice::TextDevice() {

 count = 0;

} void TextDevice::write( QString text ) {

 QMutexLocker locker( &mutex );
 qDebug() << QString( "Call %1: %2" ).arg( count++ ).arg( text );

} class TextThread : public QThread { public:

 TextThread( QString text, TextDevice *m_device );
 
 void run();
 

private:

 QString m_text;
 TextDevice *m_device;

}; bool stopThreads = false; TextThread::TextThread( QString text, TextDevice *device ) : QThread() {

 m_text = text;
 m_device = device;

} void TextThread::run() {

 while( !stopThreads )
 {
   m_device->write( m_text );
   sleep( 1 );
 }

} int main( int argc, char **argv ) {

 QApplication app( argc, argv );
 TextDevice device;
 TextThread foo( "Foo", &device ), bar( "Bar", &device );
 
 foo.start();
 bar.start();
 
 QMessageBox::information( 0, "Threading", "Close me to stop!" );
   
 stopThreads = true;
 
 foo.wait();
 bar.wait();
   
 return 0;

}

 </source>