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QDBusConnection: systerm Dbus connection created before QCoreApplication

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  • SGaistS SGaist

    @aha_1980

    AFAIK, QString, QStringList and QList are not concerned as they have no dependencies on Qt's internal state. That said, I agree that all of these should be handled by the proper class.

    aha_1980A Offline
    aha_1980A Offline
    aha_1980
    Lifetime Qt Champion
    wrote on last edited by
    #10

    @SGaist said in QDBusConnection: systerm Dbus connection created before QCoreApplication:

    @aha_1980

    AFAIK, QString, QStringList and QList are not concerned as they have no dependencies on Qt's internal state.

    they don't contribute to the current problem, but may create other problems later.

    That said, I agree that all of these should be handled by the proper class.

    @Anny the reason is, that objects need to be constructed before usage. as a global variable, the time when their constructor runs is undefined. so it is possible, that you access variables before construction, which can even lead to crashes.

    Qt has to stay free or it will die.

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    • A Offline
      A Offline
      Anny
      wrote on last edited by Anny
      #11

      Hi @aha_1980 as you said I just declared objects just before usage ,this error is gone . I also tried defining these objects in the header file of class ,there is no error.
      Edit: now there is no such warning/error but this code is not giving me status of wifi connection.I mean it should update status every 5 sec, but it just shows status of wifi in the very first iteration.
      I have a doubt I don't know If I can ask in the same thread, I have defined various variables,strings,structures in global.h file as external and I call them in different files. will this crash my application ?

      jsulmJ 1 Reply Last reply
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      • A Anny

        Hi @aha_1980 as you said I just declared objects just before usage ,this error is gone . I also tried defining these objects in the header file of class ,there is no error.
        Edit: now there is no such warning/error but this code is not giving me status of wifi connection.I mean it should update status every 5 sec, but it just shows status of wifi in the very first iteration.
        I have a doubt I don't know If I can ask in the same thread, I have defined various variables,strings,structures in global.h file as external and I call them in different files. will this crash my application ?

        jsulmJ Offline
        jsulmJ Offline
        jsulm
        Lifetime Qt Champion
        wrote on last edited by
        #12

        @Anny Your

        while(true)
        

        loop is blocking Qt event loop. Remove it and use the asynchronous nature of Qt (you can use QTimer firing in 5 seconds intervals).

        https://forum.qt.io/topic/113070/qt-code-of-conduct

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        • A Offline
          A Offline
          Anny
          wrote on last edited by
          #13

          @jsulm yeah i tried using timer but it not working i dont know why. I m using Timer in other classes , there it works fine. So i switched to thread::sleep

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          • A Offline
            A Offline
            Anny
            wrote on last edited by
            #14

            @jsulm What I did is, I removed while(true) and sleep command and added timer
            connect(&check_network_timer,QTimer::timeout,this,&server_conneciton::run)
            check_network_timer.start(5000);
            This gives me nothing, app crashes after starting timer

            mrjjM 1 Reply Last reply
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            • A Anny

              @jsulm What I did is, I removed while(true) and sleep command and added timer
              connect(&check_network_timer,QTimer::timeout,this,&server_conneciton::run)
              check_network_timer.start(5000);
              This gives me nothing, app crashes after starting timer

              mrjjM Offline
              mrjjM Offline
              mrjj
              Lifetime Qt Champion
              wrote on last edited by
              #15

              @Anny
              Hi
              Where does it crash ?
              You can use the debugger to see what is going on.
              Using timer normally do not crash so there must be some error in the code.

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              • A Offline
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                Anny
                wrote on last edited by
                #16

                @mrjj I tried debugging it using debugger but it gives error box of segmentation fault saying signal received. what does it mean ?

                mrjjM 1 Reply Last reply
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                • A Anny

                  @mrjj I tried debugging it using debugger but it gives error box of segmentation fault saying signal received. what does it mean ?

                  mrjjM Offline
                  mrjjM Offline
                  mrjj
                  Lifetime Qt Champion
                  wrote on last edited by mrjj
                  #17

                  @Anny
                  Hi
                  It sounds like its crashing. ( segmentation faults = bad pointers, memory issues etc)
                  Place break point at top of function that timer calls etc and see if it stops.

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                  • A Offline
                    A Offline
                    Anny
                    wrote on last edited by Anny
                    #18

                    @mrjj I added break points it does not stop. But when I run this class as QThread, app didnt crash but stuck after starting timer. I used moveToThread method to run it as thread. I also checked debugger and added some breakpoints, still not stopping and giving same segmentation fault. There is something I am missing out,I dont know what

                    mrjjM 1 Reply Last reply
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                    • A Anny

                      @mrjj I added break points it does not stop. But when I run this class as QThread, app didnt crash but stuck after starting timer. I used moveToThread method to run it as thread. I also checked debugger and added some breakpoints, still not stopping and giving same segmentation fault. There is something I am missing out,I dont know what

                      mrjjM Offline
                      mrjjM Offline
                      mrjj
                      Lifetime Qt Champion
                      wrote on last edited by
                      #19

                      @Anny

                      Hi
                      Do you start it with debug and not just normal run ?
                      It should stop.

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                      • A Offline
                        A Offline
                        Anny
                        wrote on last edited by Anny
                        #20

                        @mrjj yeah i did it using debug mode. But I got this working now, there was some QThread related issue. Thank you so much everyone

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