CTL_ERROR_NO_TASKS_TO_RUN

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Casper Hedegaard

• October 24, 2011 13:49

Hi,

 

I have started a simple ctl_task sample where I have added a LED_task to toggle a LED. When I have toggled the LED, I have used the code "ctl_timeout_wait(ctl_get_current_time()+100);" to wait before toggling again. When the wait function is called, the code ends up in the ctl_handle_error function with e = CTL_ERROR_NO_TASKS_TO_RUN. Is the main_task created with ctl_task_init not surposed to be some sort of idle_task to run when others aren't? Or have i missed a detail in the ctl_task system?

 

Best regards

Casper

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  Casper Hedegaard

  • October 25, 2011 10:17

  Problem solved. My main_task (the task with the lowest priority) may not contain any wait calls.

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  Michael Johnson

  • October 25, 2011 12:28

  There must always be a task ready to run CTL doesn't have a built-in idle task.

  Regards

  Michael

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  Casper Hedegaard

  • October 25, 2011 12:40

  Okay, that explains it. Thanks.

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  Paul Corr

  • November 05, 2019 01:35

  Follow-up question: if I get a CTL_ERROR_NO_TASKS_TO_RUN error, can I simply return from the ctl_handle_error() handler so it'll run a task as soon as there is one available? That seems to be working for me, but not sure if that's the proper way to handle it?

  Thanks,
  Paul

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  Paul Corr

  • November 05, 2019 18:14

  As a follow-up, the CTL_ERROR_NO_TASKS_TO_RUN error was being caused by my delay function (WaitMS) being called before threads are started. I added code to detect that and do a "manual" wait in that case:

  void WaitMS(int nMS)
  {
    if(ctl_task_list[0].next == NULL)
    {
        // If no other tasks are running, need to do a manual wait
        DWORD dwTicksEnd;
        dwTicksEnd = GetTickCount() + nMS; // Timer ISR must be running for this to work.
        while(!IsTimeoutExpired(dwTicksEnd))
        ResetCPUWatchDog();
    }
    else
    {
        // Otherwise, use the CTL wait to allow other tasks to immediately run
        ctl_timeout_wait(ctl_get_current_time()+nMS);
    }
  }

  That's resolved the issue, but question still stands: can I simple return ctl_handle_error() if this error occurs? Assuming, of course, the code that caused it can handle the immediate resumption of execution.

  Thanks,
  Paul

   

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  Michael Johnson

  • November 06, 2019 07:43

  Hi Paul,

  You'll need to add the CTL sources to your project and step through to see if it's okay. I would always make the main task the lowest priority idle task.

  Regards

  Michael

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  Paul Corr

  • November 06, 2019 16:12

  Hi Michael,

  Thanks for the quick reply. Based on my testing, appears the answer is yes, but I'll take a look at the sources and see. The modification of my wait function above solves the immediate issue and prevents the error from happening, so at this point it's more of an intellectual question than a practical one.

  Thanks for your help!

  Paul

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