Просмотр исходного текста страницы C++/Qt/QSemaphore

==Producer and consumer and QSemaphore==


   
<source lang="cpp">  
Foundations of Qt Development\Chapter12\semaphorethreads\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 <QtDebug>
const int bufferSize = 20;
QChar buffer[ bufferSize ];
QSemaphore freeSpace( bufferSize );
QSemaphore availableData( 0 );
bool atEnd = false;
class TextProducer : public QThread
{
public:
  TextProducer( QString text );
  
  void run();
  
private:
  QString m_text;
};
TextProducer::TextProducer( QString text ) : QThread()
{
  m_text = text;
}
void TextProducer::run()
{
  for( int i=0; i<m_text.length(); ++i )
  {
    freeSpace.acquire();
    buffer[ i % bufferSize ] = m_text.data()[ i ];
    if( i == m_text.length()-1 )
      atEnd = true;
    availableData.release();
  }
}
class TextConsumer : public QThread
{
public:
  void run();
};
void TextConsumer::run()
{
  int i = 0;
  
  while( !atEnd || availableData.available() )
  {
    availableData.acquire();
    qDebug() << buffer[ i ];
    i = (i+1) % bufferSize;
    freeSpace.release();
  }
}
int main( int argc, char **argv )
{
  QApplication app( argc, argv );
  
  TextProducer producer( "Lorem ipsum dolor sit amet, "
                         "consectetuer adipiscing elit. "
                         "Praesent tortor." );
  TextConsumer consumer;
  
  producer.start();
  consumer.start();
  
  producer.wait();
  consumer.wait();
    
  return 0;
}
   
    
  </source>


==QSemaphore demo==


   
<source lang="cpp">  
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QtCore>
#include <stdio.h>
#include <stdlib.h>

const int DataSize = 100000;
const int BufferSize = 8192;
char buffer[BufferSize];
QSemaphore freeBytes(BufferSize);
QSemaphore usedBytes;
 

class Producer : public QThread
 
{
public:
    void run();
};
void Producer::run()
{
    qsrand(QTime(0,0,0).secsTo(QTime::currentTime()));
    for (int i = 0; i < DataSize; ++i) {
        freeBytes.acquire();
        buffer[i % BufferSize] = "ACGT"[(int)qrand() % 4];
        usedBytes.release();
    }
}

class Consumer : public QThread
 
{
public:
    void run();
};
void Consumer::run()
{
    for (int i = 0; i < DataSize; ++i) {
        usedBytes.acquire();
        fprintf(stderr, "%c", buffer[i % BufferSize]);
        freeBytes.release();
    }
    fprintf(stderr, "\n");
}

int main(int argc, char *argv[])
 
{
    QCoreApplication app(argc, argv);
    Producer producer;
    Consumer consumer;
    producer.start();
    consumer.start();
    producer.wait();
    consumer.wait();
    return 0;
}
   
    
  </source>


==Using QSemaphore==


   
<source lang="cpp">  
Foundations of Qt Development\Chapter12\basicsemaphore\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 <QSemaphore>
int main( int argc, char *argv )
{
  QSemaphore s( 10 );
  
  s.acquire();      // s.available() = 9
  s.acquire(5);     // s.available() = 4 
  s.release(2);     // s.available() = 6
  s.release();      // s.available() = 7
  s.release(5);     // s.available() = 12
  s.tryAcquire(15); // s.available() = 12
  return 0;
}
   
    
  </source>