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semaphores.cpp Example File
threads/semaphores/semaphores.cpp

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 ** Copyright (C) 2005-2008 Trolltech ASA. All rights reserved.
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 ** This file is part of the example classes of the Qt Toolkit.
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 ** contained therein.  Please consult your licensing agreement or
 ** contact sales@trolltech.com if any conditions of this licensing
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 ** contacting info@trolltech.com.
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 ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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 #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;
 }


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Qt 4.3.5