void QThread::run(){    (void) exec();}int QThread::exec(){    Q_D(QThread);    QMutexLocker locker(&d->mutex);    d->data->quitNow = false;    if (d->exited) {        d->exited = false;        return d->returnCode;    }    locker.unlock();    QEventLoop eventLoop;    int returnCode = eventLoop.exec();    locker.relock();    d->exited = false;    d->returnCode = -1;    return returnCode;}void QThread::exit(int returnCode){    Q_D(QThread);    QMutexLocker locker(&d->mutex);    d->exited = true;    d->returnCode = returnCode;    d->data->quitNow = true;    for (int i = 0; i < d->data->eventLoops.size(); ++i) {        QEventLoop *eventLoop = d->data->eventLoops.at(i);        eventLoop->exit(returnCode);    }}/*!    Tells the thread‘s event loop to exit with return code 0 (success).    Equivalent to calling QThread::exit(0).    This function does nothing if the thread does not have an event    loop.    \sa exit(), QEventLoop*/void QThread::quit(){ exit(); }