Mega Code Archive
Producer and consumer by Qt thread
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Foundations of Qt Development\Chapter12\competingsemaphore\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.
*
*/
#include <QApplication>
#include <QThread>
#include <QSemaphore>
#include <QMutex>
#include <QtDebug>
const int bufferSize = 20;
QChar buffer[ bufferSize ];
QSemaphore freeSpace( bufferSize );
QSemaphore availableData( 0 );
QSemaphore atEnd( 0 );
class TextProducer : public QThread
{
public:
TextProducer( QString text );
void run();
private:
QString m_text;
};
TextProducer::TextProducer( QString text ) : QThread()
{
atEnd.release();
m_text = text;
}
void TextProducer::run()
{
static int index = 0;
static QMutex indexMutex;
for( int i=0; i<m_text.length(); ++i )
{
freeSpace.acquire();
indexMutex.lock();
buffer[ index++ % bufferSize ] = m_text.data()[ i ];
indexMutex.unlock();
if( i == m_text.length()-1 )
atEnd.acquire();
availableData.release();
}
}
class TextConsumer : public QThread
{
public:
void run();
};
void TextConsumer::run()
{
int i = 0;
while( atEnd.available() || availableData.available() )
{
availableData.acquire();
qDebug() << buffer[ i ];
i = (i+1) % bufferSize;
freeSpace.release();
}
}
int main( int argc, char **argv )
{
QApplication app( argc, argv );
TextProducer p1( "this text is written using lower case characters."
"it will compete with a text written using upper case characters." );
TextProducer p2( "THIS TEXT IS WRITTEN USING UPPER CASE CHARACTERS!"
"IT WILL COMPETE WITH A TEXT WRITTEN USING LOWER CASE CHARACTERS!" );
TextConsumer consumer;
p1.start();
p2.start();
consumer.start();
p1.wait();
p2.wait();
consumer.wait();
return 0;
}
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