Re: PR_WaitCondVar

On May 15, 10:48 pm, Wan-Teh Chang <[email protected]> wrote:
> Wan-Teh Chang wrote:
> > Sabyasachi Ruj wrote:
> >> Hello,
> >> How can I determine that 'PR_WaitCondVar' returned because of timeout or
> >> because it has received the notification?
> >> In both cases that function returns PR_SUCCESS.
>
> >> I've gone through the documentation but do not understand what it meant.
>
> > It is a design decision that PR_WaitCondVar does not report a timeout.
> > If you care about timeout, you must call PR_IntervalNow() before and
> > after the PR_WaitCondVar call and see if the elapsed time is greater
> > than the timeout.
>
> > The rationale for the design decision is that it is hard for the
> > implementation to report a timeout accurately.
>
> I added a sentence at the end of the PR_WaitCondVar page to
> clarify this, with a link to the PR_IntervalNow page:http://developer.mozilla.org/en/docs/PR_WaitCondVar#Description
>
> You can find sample code on the PR_IntervalNow page.
>
> Let me know if the man page or the sample code is still not
> clear.
>
> Wan-Teh- Hide quoted text -
>
> - Show quoted text -

Thanks for the reply.
The documentaion is clear enough now.

I have two doubts. Consider the code below.
Please read that comments in the code.

void start1 (void * arg)
{
    int ret = 1;

     while (1)
     {
          printf("\nHello this is thread: 1\n");

          PR_Lock(mylock);

          PRIntervalTime start = PR_IntervalNow();

          PR_WaitCondVar(mycond, INTERVAL);  /*Let INTERVAL is 1000 */
          /* Suppose the above function returned because of  recieving
signal afrer 999 milli sec*/

           PRIntervalTime elapsed = PR_IntervalNow() - start;
           /* The above function somehow took 1 milli sec to return*/
           /* So now 'elapsed' is 1000*/

          if (elapsed >= INTERVAL)
          {
                /* Then will it enter here? And report 'timed out'
instead of 'signaled' ?*/
               printf("\nTimed Out\n");
          }
          else
          {
               printf("\nSignaled\n");
          }

        PR_Unlock(mylock);
     }
}


Second doubt is - say the conditional variable is signaled just at
INTERVAL.
Then what will happen?

BTW:
I posted this same message half an hour ago with a MSVC project
attached for helping in testing. Till now that message did not appear.
May be the attachment was the problem. So poting this message again
without attachment.

--
Regards,
Sabyasachi.