Qt 5.9 | Qt Core | Wait Conditions Example | waitconditions.cpp Example File

Qt 5.9.9 Reference Documentation

# waitconditions.cpp Example File

threads/waitconditions/waitconditions.cpp

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      #include <QtCore>

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

      const int DataSize = 100000;

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

                  fprintf(stderr, "%c", buffer[i % BufferSize]);

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

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

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

      #include "waitconditions.moc"