Question about Threads

RolBri

Hi,

I have a question about using threads.

Until know I derived my classes form QObject and then I made a thread and moved my instances to a thread like this:

QThread* thread = new QThread;
Worker* worker = new Worker();
worker->moveToThread(thread);
connect(thread, SIGNAL(started()), worker, SLOT(process()));
connect(worker, SIGNAL(finished()), thread, SLOT(quit()));
connect(worker, SIGNAL(finished()), worker, SLOT(deleteLater()));
connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));
thread->start();

I always emitted finished and used the thread only for the function which was connected with the start signal of the thread.

Now I would like to start a thread which is running all the time while the GUI thread is running.
The worker has several methods I would like to call from the GUI thread using signal slots.

So would it work just to do it like this:

QThread* thread = new QThread;
Worker* worker = new Worker();
worker->moveToThread(thread);
thread->start();*/

//Are the following methods executed in the thread of the worker object or in the GUI thread?
worker->method1(); 
worker->method2();
worker->method3();

If I would connect methods with the Signal-Slot-Mechanism without specifying a connection type QT would automatically use a Queued Connection, right?

Thank you very much :-)

jsulm

//Are the following methods executed in the thread of the worker object or in the GUI thread?
worker->method1(); 
worker->method2();
worker->method3();

All these calls will be executed in the thread calling them.

I would suggest to provide the connection type explicitly, so you do not do any assumption about the type Qt selects by default.

RolBri

Thanks,

this means if I use always signals and slots and specify the connection type to "QueuedConnection" the members would be executed in the worker thread which always runs in the example I provided?

jsulm

Yes, it should be like this

t3685

@RolBri

As an alternative, you can use QMetaObject::invokeMethod instead of signals and slots. FYI

RolBri

Thank you all very much :-)

I tested both and both works fine.
The QMetaObject::invokeMethod is really convenient :-)