Qt Reference Documentation

# semaphores.cpp Example File

threads/semaphores/semaphores.cpp

     /****************************************************************************
     **
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     ** All rights reserved.
     ** Contact: Nokia Corporation (qt-info@nokia.com)
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     ** This file is part of the examples of the Qt Toolkit.
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     **
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     **     the names of its contributors may be used to endorse or promote
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     #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];

     QSemaphore freeBytes(BufferSize);
     QSemaphore usedBytes;

     class Producer : public QThread
     {
     public:
         void 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
     {
         Q_OBJECT
     public:
         void run()
         {
             for (int i = 0; i < DataSize; ++i) {
                 usedBytes.acquire();
         #ifdef Q_WS_S60
                 QString text(buffer[i % BufferSize]);
                 freeBytes.release();
                 emit stringConsumed(text);
         #else
                 fprintf(stderr, "%c", buffer[i % BufferSize]);
                 freeBytes.release();
         #endif
             }
             fprintf(stderr, "\n");
         }

     signals:
         void stringConsumed(const QString &text);

     protected:
         bool finish;
     };

     int main(int argc, char *argv[])
     {
     #ifdef Q_WS_S60
         // Self made console for Symbian
         QApplication app(argc, argv);
         QPlainTextEdit console;
         console.setReadOnly(true);
         console.setTextInteractionFlags(Qt::NoTextInteraction);
         console.showMaximized();

         Producer producer;
         Consumer consumer;

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

         producer.start();
         consumer.start();

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

     #include "semaphores.moc"