Add threading tutorial and fix a couple rare crashes

7 files changed, 237 insertions, 5 deletions

diff --git a/src/kernel/qapplication.cpp b/src/kernel/qapplication.cpp
index a9c9fb8..f3b0119 100644
--- a/src/kernel/qapplication.cpp
+++ b/src/kernel/qapplication.cpp
@@ -2767,7 +2767,10 @@ bool QApplication::internalNotify( QObject *receiver, QEvent * e)
 
     if (!handled) {
 #if defined(QT_THREAD_SUPPORT)
-	bool locked = QApplication::qt_mutex->locked();
+	bool locked = false;
+	if (QApplication::qt_mutex) {
+	    locked = QApplication::qt_mutex->locked();
+	}
 	if (locked) {
 	    QApplication::qt_mutex->unlock();
 	}
@@ -2775,7 +2778,9 @@ bool QApplication::internalNotify( QObject *receiver, QEvent * e)
 	consumed = receiver->event( e );
 #if defined(QT_THREAD_SUPPORT)
 	if (locked) {
-	    QApplication::qt_mutex->lock();
+	    if (QApplication::qt_mutex) {
+		QApplication::qt_mutex->lock();
+	    }
 	}
 #endif
     }
diff --git a/src/kernel/qeventloop_unix.cpp b/src/kernel/qeventloop_unix.cpp
index 202ef12..80c8f29 100644
--- a/src/kernel/qeventloop_unix.cpp
+++ b/src/kernel/qeventloop_unix.cpp
@@ -562,6 +562,8 @@ int QEventLoop::activateTimers()
 	    n_act++;
 	QTimerEvent e( t->id );
 	QApplication::sendEvent( t->obj, &e );	// send event
+	if ( !timerList )	// sendEvent allows other threads to execute, therefore we must check for list existence when it returns!
+	    return 0;
 	if ( timerList->findRef( begin ) == -1 )
 	    begin = 0;
     }
diff --git a/src/kernel/qeventloop_x11.cpp b/src/kernel/qeventloop_x11.cpp
index cd3e865..5ee41ca 100644
--- a/src/kernel/qeventloop_x11.cpp
+++ b/src/kernel/qeventloop_x11.cpp
@@ -284,7 +284,8 @@ bool QEventLoop::processEvents( ProcessEventsFlags flags )
     // unlock the GUI mutex and select.  when we return from this function, there is
     // something for us to do
 #if defined(QT_THREAD_SUPPORT)
-    locker.mutex()->unlock();
+    if ( locker.mutex() ) locker.mutex()->unlock();
+    else return false;
 #endif
 
     int nsel;
@@ -298,7 +299,8 @@ bool QEventLoop::processEvents( ProcessEventsFlags flags )
 
     // relock the GUI mutex before processing any pending events
 #if defined(QT_THREAD_SUPPORT)
-    locker.mutex()->lock();
+    if ( locker.mutex() ) locker.mutex()->lock();
+    else return false;
 #endif
 
     // we are awake, broadcast it
diff --git a/tutorial/t15/main.cpp b/tutorial/t15/main.cpp
new file mode 100644
index 0000000..4c96083
--- /dev/null
+++ b/tutorial/t15/main.cpp
@@ -0,0 +1,173 @@
+/****************************************************************
+**
+** Qt threading tutorial
+** (c) 2012 Timothy Pearson <kb9vqf@pearsoncomputing.net>
+**
+** This tutorial is released into the Public Domain and
+** can therefore be modified and/or used for any purpose
+**
+****************************************************************/
+
+#include "main.h"
+
+#include <unistd.h>
+
+#include <qtimer.h>
+#include <qeventloop.h>
+
+void WorkerObject::run()
+{
+	qDebug( "[%s] thread: %p event loop: %p", threadFriendlyName.ascii(), QThread::currentThreadObject(), QApplication::eventLoop() );
+
+	QEventLoop* eventLoop = QApplication::eventLoop();
+	if (!eventLoop) return;
+
+	QTimer *t = new QTimer(this);
+	connect( t, SIGNAL(timeout()), SLOT(timerHandler()) );
+	t->start( 1000, FALSE );
+
+	for( int count = 0; count < 5; count++ ) {
+		sleep( 1 );
+		qDebug( "[%s] Ping!", threadFriendlyName.ascii() );
+		displayMessage("Hi", "There!");
+		eventLoop->processEvents(QEventLoop::AllEvents);
+	}
+
+	eventLoop->exit(0);
+}
+
+void WorkerObject::timerHandler()
+{
+	qDebug( "[%s] Timer fired!", threadFriendlyName.ascii() );
+}
+
+void MainObject::emitMessage(QString str1, QString str2)
+{
+	qDebug( "%s", ("[MainObject]    emitMessage: " + str1 + " " + str2).ascii() );
+}
+
+void MainObject::buttonClicked()
+{
+	qDebug( "[MainObject]    Button clicked!" );
+
+	QEventLoop* eventLoop = QApplication::eventLoop();
+	if (!eventLoop) return;
+	eventLoop->exit(0);
+}
+
+#define SET_UP_WORKER(x, y, z)															\
+	WorkerObject x;														\
+	x.threadFriendlyName = y;											\
+	x.moveToThread(&z);												\
+	QObject::connect(&x, SIGNAL(displayMessage(QString,QString)), &mainobject, SLOT(emitMessage(QString,QString)));	\
+	QTimer::singleShot(0, &x, SLOT(run()));
+
+int main( int argc, char **argv )
+{
+	QApplication a( argc, argv );
+
+	qDebug( "[MainObject]    thread: %p event loop: %p", QThread::currentThreadObject(), QApplication::eventLoop() );
+
+	QPushButton hello( "Exit", 0 );
+	hello.resize( 100, 30 );
+
+	MainObject mainobject;
+
+	QEventLoopThread workerthread0;
+	QEventLoopThread workerthread1;
+	QEventLoopThread workerthread2;
+	QEventLoopThread workerthread3;
+	QEventLoopThread workerthread4;
+	QEventLoopThread workerthread5;
+	QEventLoopThread workerthread6;
+	QEventLoopThread workerthread7;
+	QEventLoopThread workerthread8;
+	QEventLoopThread workerthread9;
+
+	QEventLoopThread workerthread10;
+	QEventLoopThread workerthread11;
+	QEventLoopThread workerthread12;
+	QEventLoopThread workerthread13;
+	QEventLoopThread workerthread14;
+	QEventLoopThread workerthread15;
+	QEventLoopThread workerthread16;
+	QEventLoopThread workerthread17;
+	QEventLoopThread workerthread18;
+	QEventLoopThread workerthread19;
+
+	SET_UP_WORKER(workerobject0, "WorkerObject0", workerthread0)
+	SET_UP_WORKER(workerobject1, "WorkerObject1", workerthread1)
+	SET_UP_WORKER(workerobject2, "WorkerObject2", workerthread2)
+	SET_UP_WORKER(workerobject3, "WorkerObject3", workerthread3)
+	SET_UP_WORKER(workerobject4, "WorkerObject4", workerthread4)
+	SET_UP_WORKER(workerobject5, "WorkerObject5", workerthread5)
+	SET_UP_WORKER(workerobject6, "WorkerObject6", workerthread6)
+	SET_UP_WORKER(workerobject7, "WorkerObject7", workerthread7)
+	SET_UP_WORKER(workerobject8, "WorkerObject8", workerthread8)
+	SET_UP_WORKER(workerobject9, "WorkerObject9", workerthread9)
+
+	SET_UP_WORKER(workerobject10, "WorkerObjec10", workerthread10)
+	SET_UP_WORKER(workerobject11, "WorkerObjec11", workerthread11)
+	SET_UP_WORKER(workerobject12, "WorkerObjec12", workerthread12)
+	SET_UP_WORKER(workerobject13, "WorkerObjec13", workerthread13)
+	SET_UP_WORKER(workerobject14, "WorkerObjec14", workerthread14)
+	SET_UP_WORKER(workerobject15, "WorkerObjec15", workerthread15)
+	SET_UP_WORKER(workerobject16, "WorkerObjec16", workerthread16)
+	SET_UP_WORKER(workerobject17, "WorkerObjec17", workerthread17)
+	SET_UP_WORKER(workerobject18, "WorkerObjec18", workerthread18)
+	SET_UP_WORKER(workerobject19, "WorkerObjec19", workerthread19)
+
+	workerthread0.start();
+	workerthread1.start();
+	workerthread2.start();
+	workerthread3.start();
+	workerthread4.start();
+	workerthread5.start();
+	workerthread6.start();
+	workerthread7.start();
+	workerthread8.start();
+	workerthread9.start();
+
+	workerthread10.start();
+	workerthread11.start();
+	workerthread12.start();
+	workerthread13.start();
+	workerthread14.start();
+	workerthread15.start();
+	workerthread16.start();
+	workerthread17.start();
+	workerthread18.start();
+	workerthread19.start();
+
+	a.setMainWidget( &hello );
+	QObject::connect(&hello, SIGNAL(clicked()), &mainobject, SLOT(buttonClicked()));
+	hello.show();
+	a.exec();
+	hello.hide();
+
+	qDebug( "[MainObject]    Waiting for thread completion..." );
+
+	workerthread0.wait();
+	workerthread1.wait();
+	workerthread2.wait();
+	workerthread3.wait();
+	workerthread4.wait();
+	workerthread5.wait();
+	workerthread6.wait();
+	workerthread7.wait();
+	workerthread8.wait();
+	workerthread9.wait();
+
+	workerthread10.wait();
+	workerthread11.wait();
+	workerthread12.wait();
+	workerthread13.wait();
+	workerthread14.wait();
+	workerthread15.wait();
+	workerthread16.wait();
+	workerthread17.wait();
+	workerthread18.wait();
+	workerthread19.wait();
+
+	qDebug( "[MainObject]    Finished!" );
+}
diff --git a/tutorial/t15/main.h b/tutorial/t15/main.h
new file mode 100644
index 0000000..13ac5df
--- /dev/null
+++ b/tutorial/t15/main.h
@@ -0,0 +1,45 @@
+/****************************************************************
+**
+** Qt threading tutorial
+** (c) 2012 Timothy Pearson <kb9vqf@pearsoncomputing.net>
+**
+** This tutorial is released into the Public Domain and
+** can therefore be modified and/or used for any purpose
+**
+****************************************************************/
+
+#ifndef _MAIN_H_
+#define _MAIN_H_
+
+#include <qapplication.h>
+#include <qobject.h>
+#include <qpushbutton.h>
+#include <qthread.h>
+
+class MainObject;
+
+class WorkerObject : public QObject
+{
+	Q_OBJECT
+
+	public slots:
+		void run();
+		void timerHandler();
+
+	signals:
+		void displayMessage(QString, QString);
+
+	public:
+		QString threadFriendlyName;
+};
+
+class MainObject : public QObject
+{
+	Q_OBJECT
+
+	public slots:
+		void emitMessage(QString, QString);
+		void buttonClicked();
+};
+
+#endif // _MAIN_H_
diff --git a/tutorial/t15/t15.pro b/tutorial/t15/t15.pro
new file mode 100644
index 0000000..ff0f08d
--- /dev/null
+++ b/tutorial/t15/t15.pro
@@ -0,0 +1,5 @@
+TEMPLATE	= app
+CONFIG		+= qt warn_on release
+HEADERS		= main.h
+SOURCES		= main.cpp
+TARGET		= t15
diff --git a/tutorial/tutorial.pro b/tutorial/tutorial.pro
index 32b31d7..90e37f7 100644
--- a/tutorial/tutorial.pro
+++ b/tutorial/tutorial.pro
@@ -1,2 +1,2 @@
 TEMPLATE = subdirs
-SUBDIRS  = t1 t2 t3 t4 t5 t6 t7 t8 t9 t10 t11 t12 t13 t14
+SUBDIRS  = t1 t2 t3 t4 t5 t6 t7 t8 t9 t10 t11 t12 t13 t14 t15