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POHow to listen for a "finished" indication after moving the execution to another thread in Qt
 

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  1. POHow to listen for a "finished" indication after moving the execution to another thread in Qt
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    <p>I have a non-GUI operation which I intend to perform in a worker thread. After some googling, I figured out a simple way to achieve this <a href="http://qt-project.org/wiki/Threads_Events_QObjects" rel="nofollow">here</a></p> <p>In particular, the <code>QMetaObject::invokeMethod()</code> suits me fine. I have also taken care of not sub-classing QThread and instead subclassing QObject to create my worker object and then moving the thread affinity of this object to a newly created thread. (decribed in some detail <a href="http://mayaposch.wordpress.com/2011/11/01/how-to-really-truly-use-qthreads-the-full-explanation/" rel="nofollow">here</a></p> <p>Now my question:</p> <p>I will begin queuing methods from my main thread (I imagine this happens under the hood using a QEventLoop, even though I have not set one up and even though I have not re-implemented <code>QThread::run()</code> or called <code>QThread::exec()</code>) I need to find out when my worker has finished processing. In other words, I need to know when the QEventLoop is empty. I thought I could use the signal finished() for this. But it does not appear to work. Can someone throw some light on how to find out when a worker thread has finished execution? If you need more info/code, just let me know. </p> <p>Class Plugin is a subclass of QObject</p> <pre><code>Plugin::Plugin() { m_workerThread = new QThread(this); m_workerThread-&gt;start(QThread::IdlePriority); m_worker = new DataWorker(this); connect(m_workerThread, SIGNAL(finished()), m_worker, SLOT(deleteLater())); m_worker-&gt;moveToThread(m_workerThread); } </code></pre> <p>...</p> <pre><code>Plugin::updateData() { .... if( true == QMetaObject::invokeMethod(m_worker, "RunFProcToGetData", Qt::QueuedConnection, Q_ARG(QString, foo))) { qDebug() &lt;&lt; "successfully invoked RunFProcToGetData"; } if( true == QMetaObject::invokeMethod(m_worker, "updateDataIntoDB", Qt::QueuedConnection, Q_ARG(QSqlDatabase, db), Q_ARG(QString, foo))) { qDebug() &lt;&lt; "successfully invoked updateDataIntoDB"; } .... } </code></pre> <p>In Dataworker class</p> <pre><code>Dataworker::RunProcToGetData(const QString &amp;foo) { // invoke a program to get the Data } Dataworker::updateDataIntoDB(const QSqlDatabase&amp; db, const QString &amp;foo) { // Update database } </code></pre> <p>So when there are no more updateDataIntoDB and RunFProcToGetData left to process, I need a trigger</p>
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    1. COpost some code i have no idea what you are saying
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    2. COUpdated some code
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    3. CODoes simply calling `quit()` in the thread cause the `terminated()` signal to be emitted? Unless of course you want to keep the worker alive all the time, in which case you will have to create your own signal.
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