[SOLVED] Wait for timeout or some signal
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Hi All!
I need send some message by the local net, and than need wait to some answer or exit at the function by timeout,
I try stop by forever loop, and there wait some signals, but no signal is comming (i think thats because i create this loop at the main thread), i want to try create wait loop and timeout timer not at the main threads, but i don't like this idea, some one can tall me easy way to resolve this problem? -
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forever {
doMyLogic();
qApp->processEvents();
}
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WOW so easy? i'll try that :) thnx
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Yeah, it forces the QCoreApplication instance to process events in the event queue, including signals and slots provided by MOC. This way, the loop does not block operation of the app.
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tnx, i note that!
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Or, look into "QxtSignalWaiter":http://libqxt.bitbucket.org/doc/0.6/qxtsignalwaiter.html from the libQxt library.
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tnx a lot!
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Calling processEvents() in a loop like proposed will keep your CPU 100% bussy, because you just keep polling the event queue. Using an eventloop is a smarter solution that doesn't waste CPU cycles like that, so it will not spike your CPU. It is also the solution implemented by the libQxt in QxtSignalWaiter.
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QxtSignalWaiter is implemented with a help of processEvents, not eventLoop. See "here":http://dev.libqxt.org/libqxt/src/21ea5919eabb2a404eafdffcdb8383472ca66bdd/src/core/qxtsignalwaiter.cpp?at=master#cl-143.
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[quote author="RomaHagen" date="1357227120"]QxtSignalWaiter is implemented with a help of processEvents, not eventLoop. See "here":http://dev.libqxt.org/libqxt/src/21ea5919eabb2a404eafdffcdb8383472ca66bdd/src/core/qxtsignalwaiter.cpp?at=master#cl-143. [/quote]
Hmmm... You're right. Surprising. Thanks for the correction.
Does anyone know why Qxt choose this implementation instead?
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See "this":http://dev.libqxt.org/libqxt/src/21ea5919eabb2a404eafdffcdb8383472ca66bdd/src/core/qxtsignalwaiter.cpp?at=master#cl-143 and read the doc about WaitForMoreEvents "here":http://qt-project.org/doc/qt-4.8/qeventloop.html#ProcessEventsFlag-enum.
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Yes, I know where to find the sources and I know the docs, but that was not my question. I sometimes use this idea:
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QEventLoop loop;
connect(myObject, SIGNAL(theSignalToWaitFor()), &loop, SLOT(quit()));
connect(timeoutTimer, SIGNAL(timeout()), &loop, SLOT(quit()));
loop.exec(); //blocks untill either theSignalToWaitFor or timeout was fired
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[quote author="Andre" date="1357286986"]Yes, I know where to find the sources and I know the docs, but that was not my question. I sometimes use this idea:
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QEventLoop loop;
connect(myObject, SIGNAL(theSignalToWaitFor()), &loop, SLOT(quit()));
connect(timeoutTimer, SIGNAL(timeout()), &loop, SLOT(quit()));
loop.exec(); //blocks untill either theSignalToWaitFor or timeout was fired
@[/quote]
thank you. it's very useful.
