run-at-time and Setting system time

run-at-time and Setting system time

[chandan]

Hi,
    Consider the following code:

(defun mwnn-timer-callback ()
  (message "Hi, inside mwnn-timer-callback"))

(run-at-time "60" nil 'mwnn-timer-callback)

The above code is supposed to cause mwnn-timer-callback to get invoked 
after 60 seconds. But if the system time is changed to a future date 
(say 20 seconds after the timer is started) the timer fires immediately.

Is this is a bug in the emacs code. If yes, can this be rectified?

Regards,
mwnn

Re: run-at-time and Setting system time

[J. David Boyd]

chandan <chandan.babu@globaledgesoft.com> writes:

> Hi,
>    Consider the following code:
>
> (defun mwnn-timer-callback ()
>  (message "Hi, inside mwnn-timer-callback"))
>
> (run-at-time "60" nil 'mwnn-timer-callback)
>
> The above code is supposed to cause mwnn-timer-callback to get invoked
> after 60 seconds. But if the system time is changed to a future date
> (say 20 seconds after the timer is started) the timer fires
> immediately.
>
> Is this is a bug in the emacs code. If yes, can this be rectified?
>
> Regards,
> mwnn


It sounds like a good thing to me.

Say the time is 13:00, and you do what you said.  You told the machine
to give an invocation at 13:01.  

If you move the clock ahead, the code _should_ run, as it is now past
13:01.

Dave

Re: bug#5822: run-at-time and Setting system time

[Eli Zaretskii]

> Date: Fri, 02 Apr 2010 12:29:42 +0530
> From: chandan <chandan.babu@globaledgesoft.com>
> Cc: 
> 
> (defun mwnn-timer-callback ()
>   (message "Hi, inside mwnn-timer-callback"))
> 
> (run-at-time "60" nil 'mwnn-timer-callback)
> 
> The above code is supposed to cause mwnn-timer-callback to get invoked 
> after 60 seconds. But if the system time is changed to a future date 
> (say 20 seconds after the timer is started) the timer fires immediately.
> 
> Is this is a bug in the emacs code. If yes, can this be rectified?

I think this how the timers are supposed to behave.  They are not
interval timers, if that's what you expected.

bug#5822: run-at-time and Setting system time

[chandan]

Eli Zaretskii wrote:
>> Date: Fri, 02 Apr 2010 12:29:42 +0530
>> From: chandan <chandan.babu@globaledgesoft.com>
>> Cc: 
>>
>> (defun mwnn-timer-callback ()
>>   (message "Hi, inside mwnn-timer-callback"))
>>
>> (run-at-time "60" nil 'mwnn-timer-callback)
>>
>> The above code is supposed to cause mwnn-timer-callback to get invoked 
>> after 60 seconds. But if the system time is changed to a future date 
>> (say 20 seconds after the timer is started) the timer fires immediately.
>>
>> Is this is a bug in the emacs code. If yes, can this be rectified?
>>     
>
> I think this how the timers are supposed to behave.  They are not
> interval timers, if that's what you expected.
>
>   
Emacs seems to use setitimer & getitimer (interval timers) for 
implementing the timer module. This may be the cause of the problem. 
Using timer_create, timer_delete, timer_settime, timer_gettime etc.

bug#5822: run-at-time and Setting system time

[Glenn Morris]

Please don't cross-post to the help and bug lists.

Anyone reading this on help-gnu-emacs, please use 5822 at
debbugs.gnu.org in place of bug-gnu-emacs in any replies. (Otherwise
every reply creates a new bug report.)


If you really want to cc another address when filing a new bug report,
please use an X-Debbugs-CC header instead of a Cc header, as explained
here:

http://debbugs.gnu.org/Reporting.html#xcc

Yes, it is a bit confusing at first.

Thanks.