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These rights are described in The Qt Company LGPL Exception ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. ** ** $QT_END_LICENSE$ ** ****************************************************************************/ #include "qeventloop.h" #include "qabstracteventdispatcher.h" #include "qcoreapplication.h" #include "qcoreapplication_p.h" #include "qelapsedtimer.h" #include "qobject_p.h" #include "qeventloop_p.h" #include <private/qthread_p.h> QT_BEGIN_NAMESPACE /*! class QEventLoop inmodule QtCore rief The QEventLoop class provides a means of entering and leaving an event loop. At any time, you can create a QEventLoop object and call exec() on it to start a local event loop. From within the event loop, calling exit() will force exec() to return. sa QAbstractEventDispatcher */ /*! enum QEventLoop::ProcessEventsFlag This enum controls the types of events processed by the processEvents() functions. value AllEvents All events. Note that l{QEvent::DeferredDelete}{DeferredDelete} events are processed specially. See QObject::deleteLater() for more details. value ExcludeUserInputEvents Do not process user input events, such as ButtonPress and KeyPress. Note that the events are not discarded; they will be delivered the next time processEvents() is called without the ExcludeUserInputEvents flag. value ExcludeSocketNotifiers Do not process socket notifier events. Note that the events are not discarded; they will be delivered the next time processEvents() is called without the ExcludeSocketNotifiers flag. value WaitForMoreEvents Wait for events if no pending events are available. omitvalue X11ExcludeTimers omitvalue EventLoopExec omitvalue DialogExec sa processEvents() */ /*! Constructs an event loop object with the given a parent. */ QEventLoop::QEventLoop(QObject *parent) : QObject(*new QEventLoopPrivate, parent) { Q_D(QEventLoop); if (!QCoreApplication::instance() && QCoreApplicationPrivate::threadRequiresCoreApplication()) { qWarning("QEventLoop: Cannot be used without QApplication"); } else if (!d->threadData->eventDispatcher.load()) { QThreadPrivate::createEventDispatcher(d->threadData); } } /*! Destroys the event loop object. */ QEventLoop::~QEventLoop() { } /*! Processes pending events that match a flags until there are no more events to process. Returns c true if pending events were handled; otherwise returns c false. This function is especially useful if you have a long running operation and want to show its progress without allowing user input; i.e. by using the l ExcludeUserInputEvents flag. This function is simply a wrapper for QAbstractEventDispatcher::processEvents(). See the documentation for that function for details. */ bool QEventLoop::processEvents(ProcessEventsFlags flags) { Q_D(QEventLoop); if (!d->threadData->eventDispatcher.load()) return false; return d->threadData->eventDispatcher.load()->processEvents(flags); } /*! Enters the main event loop and waits until exit() is called. Returns the value that was passed to exit(). If a flags are specified, only events of the types allowed by the a flags will be processed. It is necessary to call this function to start event handling. The main event loop receives events from the window system and dispatches these to the application widgets. Generally speaking, no user interaction can take place before calling exec(). As a special case, modal widgets like QMessageBox can be used before calling exec(), because modal widgets use their own local event loop. To make your application perform idle processing (i.e. executing a special function whenever there are no pending events), use a QTimer with 0 timeout. More sophisticated idle processing schemes can be achieved using processEvents(). sa QCoreApplication::quit(), exit(), processEvents() */ int QEventLoop::exec(ProcessEventsFlags flags) { Q_D(QEventLoop); //we need to protect from race condition with QThread::exit QMutexLocker locker(&static_cast<QThreadPrivate *>(QObjectPrivate::get(d->threadData->thread))->mutex); if (d->threadData->quitNow) return -1; if (d->inExec) { qWarning("QEventLoop::exec: instance %p has already called exec()", this); return -1; } struct LoopReference { QEventLoopPrivate *d; QMutexLocker &locker; bool exceptionCaught; LoopReference(QEventLoopPrivate *d, QMutexLocker &locker) : d(d), locker(locker), exceptionCaught(true) { d->inExec = true; d->exit.storeRelease(false); ++d->threadData->loopLevel; d->threadData->eventLoops.push(d->q_func()); locker.unlock(); } ~LoopReference() { if (exceptionCaught) { qWarning("Qt has caught an exception thrown from an event handler. Throwing " "exceptions from an event handler is not supported in Qt. " "You must not let any exception whatsoever propagate through Qt code. " "If that is not possible, in Qt 5 you must at least reimplement " "QCoreApplication::notify() and catch all exceptions there. "); } locker.relock(); QEventLoop *eventLoop = d->threadData->eventLoops.pop(); Q_ASSERT_X(eventLoop == d->q_func(), "QEventLoop::exec()", "internal error"); Q_UNUSED(eventLoop); // --release warning d->inExec = false; --d->threadData->loopLevel; } }; LoopReference ref(d, locker); // remove posted quit events when entering a new event loop QCoreApplication *app = QCoreApplication::instance(); if (app && app->thread() == thread()) QCoreApplication::removePostedEvents(app, QEvent::Quit); while (!d->exit.loadAcquire()) processEvents(flags | WaitForMoreEvents | EventLoopExec); ref.exceptionCaught = false; return d->returnCode.load(); } /*! Process pending events that match a flags for a maximum of a maxTime milliseconds, or until there are no more events to process, whichever is shorter. This function is especially useful if you have a long running operation and want to show its progress without allowing user input, i.e. by using the l ExcludeUserInputEvents flag. {Notes:} list li This function does not process events continuously; it returns after all available events are processed. li Specifying the l WaitForMoreEvents flag makes no sense and will be ignored. endlist */ void QEventLoop::processEvents(ProcessEventsFlags flags, int maxTime) { Q_D(QEventLoop); if (!d->threadData->eventDispatcher.load()) return; QElapsedTimer start; start.start(); while (processEvents(flags & ~WaitForMoreEvents)) { if (start.elapsed() > maxTime) break; } } /*! Tells the event loop to exit with a return code. After this function has been called, the event loop returns from the call to exec(). The exec() function returns a returnCode. By convention, a a returnCode of 0 means success, and any non-zero value indicates an error. Note that unlike the C library function of the same name, this function e does return to the caller -- it is event processing that stops. sa QCoreApplication::quit(), quit(), exec() */ void QEventLoop::exit(int returnCode) { Q_D(QEventLoop); if (!d->threadData->eventDispatcher.load()) return; d->returnCode.store(returnCode); d->exit.storeRelease(true); d->threadData->eventDispatcher.load()->interrupt(); } /*! Returns c true if the event loop is running; otherwise returns false. The event loop is considered running from the time when exec() is called until exit() is called. sa exec(), exit() */ bool QEventLoop::isRunning() const { Q_D(const QEventLoop); return !d->exit.loadAcquire(); } /*! Wakes up the event loop. sa QAbstractEventDispatcher::wakeUp() */ void QEventLoop::wakeUp() { Q_D(QEventLoop); if (!d->threadData->eventDispatcher.load()) return; d->threadData->eventDispatcher.load()->wakeUp(); } /*! eimp */ bool QEventLoop::event(QEvent *event) { if (event->type() == QEvent::Quit) { quit(); return true; } else { return QObject::event(event); } } /*! Tells the event loop to exit normally. Same as exit(0). sa QCoreApplication::quit(), exit() */ void QEventLoop::quit() { exit(0); } class QEventLoopLockerPrivate { public: explicit QEventLoopLockerPrivate(QEventLoopPrivate *loop) : loop(loop), type(EventLoop) { loop->ref(); } explicit QEventLoopLockerPrivate(QThreadPrivate *thread) : thread(thread), type(Thread) { thread->ref(); } explicit QEventLoopLockerPrivate(QCoreApplicationPrivate *app) : app(app), type(Application) { app->ref(); } ~QEventLoopLockerPrivate() { switch (type) { case EventLoop: loop->deref(); break; case Thread: thread->deref(); break; default: app->deref(); break; } } private: union { QEventLoopPrivate * loop; QThreadPrivate * thread; QCoreApplicationPrivate * app; }; enum Type { EventLoop, Thread, Application }; const Type type; }; /*! class QEventLoopLocker inmodule QtCore rief The QEventLoopLocker class provides a means to quit an event loop when it is no longer needed. since 5.0 The QEventLoopLocker operates on particular objects - either a QCoreApplication instance, a QEventLoop instance or a QThread instance. This makes it possible to, for example, run a batch of jobs with an event loop and exit that event loop after the last job is finished. That is accomplished by keeping a QEventLoopLocker with each job instance. The variant which operates on QCoreApplication makes it possible to finish asynchronously running jobs after the last gui window has been closed. This can be useful for example for running a job which uploads data to a network. sa QEventLoop, QCoreApplication */ /*! Creates an event locker operating on the QCoreApplication. The application will quit when there are no more QEventLoopLockers operating on it. sa QCoreApplication::quit(), QCoreApplication::isQuitLockEnabled() */ QEventLoopLocker::QEventLoopLocker() : d_ptr(new QEventLoopLockerPrivate(static_cast<QCoreApplicationPrivate*>(QObjectPrivate::get(QCoreApplication::instance())))) { } /*! Creates an event locker operating on the a loop. This particular QEventLoop will quit when there are no more QEventLoopLockers operating on it. sa QEventLoop::quit() */ QEventLoopLocker::QEventLoopLocker(QEventLoop *loop) : d_ptr(new QEventLoopLockerPrivate(static_cast<QEventLoopPrivate*>(QObjectPrivate::get(loop)))) { } /*! Creates an event locker operating on the a thread. This particular QThread will quit when there are no more QEventLoopLockers operating on it. sa QThread::quit() */ QEventLoopLocker::QEventLoopLocker(QThread *thread) : d_ptr(new QEventLoopLockerPrivate(static_cast<QThreadPrivate*>(QObjectPrivate::get(thread)))) { } /*! Destroys this event loop locker object */ QEventLoopLocker::~QEventLoopLocker() { delete d_ptr; } QT_END_NAMESPACE