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Thread: qt4 daemon

  1. #1
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    Default qt4 daemon

    hello,
    i need an application running background which will continously check current time to some predefine time, and emit a signal whenever match.

    any help regarding this is a great favour.

  2. #2
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    Default Re: qt4 daemon

    Ok, but what exactly is the problem?
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

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  3. #3
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    Default Re: qt4 daemon

    i made a dbus interface, run a method where in a forever loop i tried ..


    Qt Code:
    1. QDateTime aTime_=getTime(); //gives the same format as current
    2. while(1){
    3. QDateTime currTime=QDateTime::currentDateTime ();
    4. qDebug()<<currTime << aTime_;
    5. if(aTime_.date()==currTime.date()){
    6. qDebug()<<"date checked"
    7. emit signalTime();
    8. }
    9.  
    10. //this part never calls
    11. if(aTime_.time()==currTime.time()){
    12. qDebug()<<"time checked";
    13. emit signalTime();
    14. }
    15. }
    To copy to clipboard, switch view to plain text mode 

    aTime_.time()==currTime.time() ....this compare never calls, ???
    another question is Is that the right way to make a daemon, or there is any other alternatives..
    Last edited by wysota; 10th March 2009 at 22:04. Reason: missing [code] tags

  4. #4
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    Default Re: qt4 daemon

    If you run a while(1) loop, you are starving the event loop and it's not possible for your application to do anything. You should use QTimer instead. And your comparison never works because you'd have to trigger it in the exact time the other object points to (up to miliseconds).

    And have a look at this article:
    http://doc.trolltech.com/qq/qq27-responsive-guis.html
    Although it deals with GUI issues, it all applies to a non-gui application as well.
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

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  5. The following user says thank you to wysota for this useful post:

    akon (10th March 2009)

  6. #5
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    Default Re: qt4 daemon

    thanks, much helpfull
    i will check it out.

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    Default Re: qt4 daemon

    hello wysota,
    know its a FAQ...
    may be I am doing some stupid mistake. it will be very helpful if u give a sample code snip, for this daemon running.

  8. #7
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    Default Re: qt4 daemon

    What exactly do you want? A snippet to use QTimer? Have you seen the docs of QTimer?
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

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  9. #8
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    Default Re: qt4 daemon

    i got the problem....but still not getting the solution...


    QDateTime aTime_=getTime(); //gives the same format as current
    QDateTime currTime;
    currTime.setTimeSpec(Qt::UTC);
    currTime=QDateTime::currentDateTime();

    QTimer::singleShot(currTime.secsTo(aTime_)*1000, this, SLOT(slot_a_Mode()));

    qDebug()<<currTime<<aTime_<< "seconds to call..."<<currTime.secsTo(aTime_);

    ____________

    currTime.secsTo(aTime_); ----giving some unknown value, and I cant figure out why

  10. #9
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    Default Re: qt4 daemon

    Why are you compilating things so much?

    Qt Code:
    1. QTimer *timer = new QTimer(this);
    2. connect(timer, SIGNAL(timeout()), this, SLOT(checkTime()));
    3. timer->start(1000); // will fire every second
    4.  
    5. void ...::checkTime(){
    6. QDateTime ct = QDateTime::currentDateTime();
    7. if(qAbs(ct.toTime_t()-definedTime.toTime_t())<2){
    8. emit alarm();
    9. }
    10. }
    To copy to clipboard, switch view to plain text mode 

    There is also another possibility, that you check the time before setting the timer and then set the timer to the exact number of miliseconds you need to reach the time you want.
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

    Please ask Qt related questions on the forum and not using private messages or visitor messages.


  11. The following user says thank you to wysota for this useful post:

    akon (11th March 2009)

  12. #10
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    Default Re: qt4 daemon

    one thing , how u came to know I m trying something with alarm,

  13. #11
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    Default Re: qt4 daemon

    You said you wanted to signal the approach of a predefined moment in time. That's what we call raising an alarm
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

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