QThread

[TheKedge]

Hello everybody,
I'm using threads ... and I've got a question. I've subclassed QThread and when I call start() the function below is called. Great. Now I thought there's be two ways of doing things: the first way with a forever loop - it works fine; and the second way, with a timer. My question: How do I connect the timer properly?

update() is a func in 'this' i.e. MyClass where I do the work.

void MyClass::run()
{
	//can do this .... 
 
	forever{
		update();
		sleep(3);//seconds
	}
	return;
 
	//or could do this...
 
	QTimer* timer = new QTimer();
	timer->setInterval(3000);
	connect(timer, SIGNAL(timeout()), this, SLOT(update()), Qt::QueuedConnection);
 
	exec();
 
	delete timer;
 
	return;
}

void MyClass::run()
{
	//can do this .... 

	forever{
		update();
		sleep(3);//seconds
	}
	return;

	//or could do this...

	QTimer* timer = new QTimer();
	timer->setInterval(3000);
	connect(timer, SIGNAL(timeout()), this, SLOT(update()), Qt::QueuedConnection);

	exec();

	delete timer;

	return;
}

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[jacek]

In this case you should use a direct connection, otherwise timeout events will be queued in... the main event loop, since MyClass instance belongs to the GUI thread.

[ball]

Jacek, do you mean when he want to use the QTimer and exec() method, he need to connect using Qt:irectConnection in order to let the timer event to be triggered and run in a the same thread as the thread using in run()?

[jacek]

do you mean when he want to use the QTimer and exec() method, he need to connect using Qt:irectConnection in order to let the timer event to be triggered and run in a the same thread as the thread using in run()?

Yes, that's what I meant.

[TheKedge]

Sorry guys,
I don't got it. (using DirectConnection)
The stange thing is that the first variant works fine.
I thought that getting a timer to trigger the work instead of a wait would be a little more elegant. But the timer way doesn't work. I don't get any messages that the connect() doesn't work.

note also (although perhaps beside the point): I have emits in the update() func and they work fine into the gui thread.

any ideas?

thanks
K

[jacek]

But the timer way doesn't work.

How did you start it?

[TheKedge]

I call
start()
from the constructor of my class. Or more precisely, I have an init() func called a single shot timer in the constructor. Thus:
QTimer::singleShot(0, this, SLOT(init()));

start() is called from the init() func.

As said, the thread is running -> the loop/sleep method works. But I have the feeling somethings not right with the connect() (although I don't get any error messages)
K

[jacek]

Does it work with queued connection?

[TheKedge]

Khryst!
ok ... I'm sorry ... how about using timer->start() ?
It works with both Direct and Queued connections.
thank you, thank you ...
K