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Fake

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Posts: 7

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1

Wednesday, July 27th 2011, 7:13pm

Wait For All Threads to Be Finished

Heyho,
I'm currently working on a very small GUI program. There is one window and a few http and ftp connections are handled in the background.
When the mainwindow is closed the program will quit and I suspect it not to wait for all it's threads to finish (since I'm using QCoreApplication::exit(0) in my mainwindow's destructor).
Classes using e.g. an ftp connection close them by calling QFtp::close() on destruction. Same goes for a class using QNetworkReply and calling QNetworkReply::deleteLater() upon destruction.

Is there a way to wait in my mainwindow's destructor till all threads are done?
I found a way to wait/join (for) specific threads but non of them are manually created by me.

tomschuring

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2

Thursday, July 28th 2011, 4:38am

could you add a loop in your threads where it checks if it is shutting down instead. something like:

Source code

 
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void myThreadFunction()
{
    while ( !nowShuttingDown )
    {
        //handle your ftp upload or so 
        .....

        sleep(1);
    }
     QFtp::close()
}

and then when you want to quit, instead of calling QCoreApplication::exit(0) in your main thread right away

do a:

Source code

 
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nowShuttingDown = true;
sleep(2);
QCoreApplication::exit(0);


?

Fake

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3

Thursday, July 28th 2011, 1:13pm

But I can't access the threads used by classes like QFtp/QNetworkReply (without subclassing).

Junior

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4

Thursday, July 28th 2011, 3:11pm

Fake,

The QThread class provides several signals that help provide the status of the thread; started() and finished(). You could monitor the status of your thread by connecting these signals to a local slot that would maintain some sort of variable in tracking the status that could be used to trap in the closeEvent() of your mainwindow.

psuedo:

bool ftpActive;

connect( ftpThread, SIGNAL( started() ), mainwindow, SLOT( ftpStarted() ));
connect( ftpThread, SIGNAL( finished() ), mainwindow, SLOT (ftpFinished() ));

void MainWindow::ftpStarted(){ ftpActive = true; }
void MainWindow::ftpFinished(){ ftpActive = false; }

In the closeEvent you could trap for the ftpActive flag;
void MainWindow::closeEvent()
{
while( ftpActive ){ // do something: sleep or maybe show progress dialog in pulsate state while waiting for process to finish // };
}

Just a thought...

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