waitconditions.cpp Example File

threads/waitconditions/waitconditions.cpp
/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
** "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 The Qt Company Ltd 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."
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include <QtGui>

#include <stdio.h>
#include <stdlib.h>

#ifdef Q_WS_S60
const int DataSize = 300;
#else
const int DataSize = 100000;
#endif

const int BufferSize = 8192;
char buffer[BufferSize];

QWaitCondition bufferNotEmpty;
QWaitCondition bufferNotFull;
QMutex mutex;
int numUsedBytes = 0;

class Producer : public QThread
{
public:
    Producer(QObject *parent = NULL) : QThread(parent)
    {
    }

    void run()
    {
        qsrand(QTime(0,0,0).secsTo(QTime::currentTime()));

        for (int i = 0; i < DataSize; ++i) {
            mutex.lock();
            if (numUsedBytes == BufferSize)
                bufferNotFull.wait(&mutex);
            mutex.unlock();

            buffer[i % BufferSize] = "ACGT"[(int)qrand() % 4];

            mutex.lock();
            ++numUsedBytes;
            bufferNotEmpty.wakeAll();
            mutex.unlock();
        }
    }
};

class Consumer : public QThread
{
    Q_OBJECT
public:
    Consumer(QObject *parent = NULL) : QThread(parent)
    {
    }

    void run()
    {
        for (int i = 0; i < DataSize; ++i) {
            mutex.lock();
            if (numUsedBytes == 0)
                bufferNotEmpty.wait(&mutex);
            mutex.unlock();

    #ifdef Q_WS_S60
            emit stringConsumed(QString(buffer[i % BufferSize]));
    #else
            fprintf(stderr, "%c", buffer[i % BufferSize]);
    #endif

            mutex.lock();
            --numUsedBytes;
            bufferNotFull.wakeAll();
            mutex.unlock();
        }
        fprintf(stderr, "\n");
    }

signals:
    void stringConsumed(const QString &text);
};

#ifdef Q_WS_S60
class PlainTextEdit : public QPlainTextEdit
{
    Q_OBJECT
public:
    PlainTextEdit(QWidget *parent = NULL) : QPlainTextEdit(parent), producer(NULL), consumer(NULL)
    {
        setTextInteractionFlags(Qt::NoTextInteraction);

        producer = new Producer(this);
        consumer = new Consumer(this);

        QObject::connect(consumer, SIGNAL(stringConsumed(const QString &)), SLOT(insertPlainText(const QString &)), Qt::BlockingQueuedConnection);

        QTimer::singleShot(0, this, SLOT(startThreads()));
    }

protected:
    Producer *producer;
    Consumer *consumer;

protected slots:
    void startThreads()
    {
        producer->start();
        consumer->start();
    }
};
#endif

int main(int argc, char *argv[])
{
#ifdef Q_WS_S60
    QApplication app(argc, argv);

    PlainTextEdit console;
    console.showMaximized();

    return app.exec();
#else
    QCoreApplication app(argc, argv);
    Producer producer;
    Consumer consumer;
    producer.start();
    consumer.start();
    producer.wait();
    consumer.wait();
    return 0;
#endif
}

#include "waitconditions.moc"

© 2016 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners.