1 files changed, 274 insertions, 0 deletions
diff --git a/examples/thread/semaphores/main.cpp b/examples/thread/semaphores/main.cpp
new file mode 100644
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+++ b/examples/thread/semaphores/main.cpp
@@ -0,0 +1,274 @@
+/****************************************************************************
+**
+** Copyright (C) 1992-2008 Trolltech ASA.  All rights reserved.
+**
+** This file is part of an example program for Qt.  This example
+** program may be used, distributed and modified without limitation.
+**
+*****************************************************************************/
+#include <qapplication.h>
+#include <qwidget.h>
+#include <qpushbutton.h>
+#include <qmultilineedit.h>
+#include <qthread.h>
+#include <qsemaphore.h>
+#include <qmutex.h>
+#include <qlayout.h>
+#include <qmessagebox.h>
+#include <qlabel.h>
+
+#if defined(QT_NO_THREAD)
+#  error Thread support not enabled.
+#endif
+
+// Use pointers to create semaphores after QApplication object!
+QSemaphore* yellowSem, *greenSem;
+
+
+class YellowThread : public QThread
+{
+public:
+    YellowThread(QWidget *o)
+	: receiver(o), stopped(FALSE)
+    { ; }
+
+    void run();
+    void stop();
+
+
+private:
+    QWidget *receiver;
+    QMutex mutex;
+    bool stopped;
+};
+
+
+void YellowThread::run()
+{
+    for (int i = 0; i < 20; i++) {
+	(*yellowSem)++;
+
+	QCustomEvent *event = new QCustomEvent(12345);
+     	event->setData(new QString("Yellow!"));
+	QApplication::postEvent(receiver, event);
+	msleep(200);
+
+	(*greenSem)--;
+
+	mutex.lock();
+	if (stopped) {
+	    stopped = FALSE;
+	    mutex.unlock();
+	    break;
+	}
+	mutex.unlock();
+    }
+
+    (*yellowSem)++;
+
+    QCustomEvent *event = new QCustomEvent(12346);
+    event->setData(new QString("Yellow!"));
+    QApplication::postEvent(receiver, event);
+
+    (*greenSem)--;
+}
+
+void YellowThread::stop()
+{
+    mutex.lock();
+    stopped = TRUE;
+    mutex.unlock();
+}
+
+
+class GreenThread: public QThread
+{
+public:
+   GreenThread(QWidget *o)
+	: receiver(o), stopped( FALSE )
+    { ; }
+
+    void run();
+    void stop();
+
+
+private:
+    QWidget *receiver;
+    QMutex mutex;
+    bool stopped;
+};
+
+
+void GreenThread::run()
+{
+    for (int i = 0; i < 20; i++) {
+	(*greenSem)++;
+
+	QCustomEvent *event = new QCustomEvent(12345);
+     	event->setData(new QString("Green!"));
+	QApplication::postEvent(receiver, event);
+	msleep(200);
+
+	(*yellowSem)--;
+
+	mutex.lock();
+	if (stopped) {
+	    stopped = FALSE;
+	    mutex.unlock();
+	    break;
+	}
+	mutex.unlock();
+    }
+
+    (*greenSem)++;
+
+    QCustomEvent *event = new QCustomEvent(12346);
+    event->setData(new QString("Green!"));
+    QApplication::postEvent(receiver, event);
+    msleep(10);
+
+    (*yellowSem)--;
+}
+
+void GreenThread::stop()
+{
+    mutex.lock();
+    stopped = TRUE;
+    mutex.unlock();
+}
+
+
+
+class SemaphoreExample : public QWidget
+{
+    Q_OBJECT
+public:
+    SemaphoreExample();
+    ~SemaphoreExample();
+
+    void customEvent(QCustomEvent *);
+
+
+public slots:
+    void startExample();
+
+
+protected:
+
+
+private:
+    QMultiLineEdit *mlineedit;
+    QPushButton *button;
+    QLabel *label;
+
+    YellowThread yellowThread;
+    GreenThread greenThread;
+};
+
+
+SemaphoreExample::SemaphoreExample()
+    : QWidget(), yellowThread(this), greenThread(this)
+{
+    yellowSem = new QSemaphore(1);
+    greenSem = new QSemaphore(1);
+
+    button = new QPushButton("&Ignition!", this);
+    connect(button, SIGNAL(clicked()), SLOT(startExample()));
+
+    mlineedit = new QMultiLineEdit(this);
+    label = new QLabel(this);
+
+    QVBoxLayout *vbox = new QVBoxLayout(this, 5);
+    vbox->addWidget(button);
+    vbox->addWidget(mlineedit);
+    vbox->addWidget(label);
+}
+
+
+SemaphoreExample::~SemaphoreExample()
+{
+    bool stopYellow = yellowThread.running(),
+	  stopGreen = greenThread.running();
+    if (stopYellow)
+	yellowThread.stop();
+    if (greenThread.running())
+	greenThread.stop();
+    if (stopYellow)
+	yellowThread.wait();
+    if (stopGreen)
+	greenThread.wait();
+    delete yellowSem;
+    delete greenSem;
+}
+
+
+void SemaphoreExample::startExample()
+{
+    if (yellowThread.running() || greenThread.running()) {
+	QMessageBox::information(this, "Sorry",
+				 "The threads have not completed yet, and must finish before "
+				 "they can be started again.");
+
+	return;
+    }
+
+    mlineedit->clear();
+
+    while (yellowSem->available() < yellowSem->total()) (*yellowSem)--;
+    (*yellowSem)++;
+
+    yellowThread.start();
+    greenThread.start();
+}
+
+
+void SemaphoreExample::customEvent(QCustomEvent *event) {
+    switch (event->type()) {
+    case 12345:
+	{
+	    QString *s = (QString *) event->data();
+
+	    mlineedit->append(*s);
+
+	    if (*s == "Green!")
+		label->setBackgroundColor(green);
+	    else
+		label->setBackgroundColor(yellow);
+	    label->setText(*s);
+
+	    delete s;
+
+	    break;
+	}
+
+    case 12346:
+	{
+	    QString *s = (QString *) event->data();
+
+	    QMessageBox::information(this, (*s) + " - Finished",
+				     "The thread creating the \"" + *s +
+				     "\" events has finished.");
+	    delete s;
+
+	    break;
+	}
+
+    default:
+	{
+	    qWarning("Unknown custom event type: %d", event->type());
+	}
+    }
+}
+
+
+int main(int argc, char **argv)
+{
+    QApplication app(argc, argv);
+    SemaphoreExample se;
+    app.setMainWidget(&se);
+    se.show();
+    return app.exec();
+}
+
+
+#include "main.moc"