Subj : Re: Help with timers/signals
To   : comp.programming.threads
From : vinay
Date : Mon Mar 14 2005 12:54 pm


Sean Burke wrote:
> "vinay" <vinaymathew80@yahoo.com> writes:
>
> > Hi guys,
> > Im new to programming with linux and its timers and signal
handlers.Can
> > any one suggest a possible solution to the problem im having.The
> > problem is described as follows
> > I have an array of queues.Say 10.Now i go thro this array 1 by 1
and
> > dequeue elements from each queue.This is simple.My problem now is
this
> > dequeuing.Every element needs to be dequeued at a particular point
in
> > time.Hence i need to set different timers/signals for the different
> > times that each element will be dequeued.Is there any way of
specifying
> > this functionality using signals/timers.Example:i need to specify
an
> > alarm that goes off at 20ms for the 1 element then at 50ms(after
30ms)
> > for the 2nd element then at 10ms(this timer will go off first
actually)
> > for the 3 element.And the action for the alarm is the dequeue
function
> > that will dequeue the element whose timer expired from the
particular
> > queue. Also Can this queue parameter also be passed to the handler
> > function?? cos as per the documentation for the signal handler it
takes
> > only 1 argument signum. Is it possible to send more arguments to
the
> > handler from the signal call??
> > I dont know if its possible but is there a way of specifying user
> > defined signals in linux.I was thinking of having 10 user defined
> > signals for the 10 queues that i have.And every time a timer
expires in
> > a particular queue i need to send the signal associated with that
> > queue.Is this possible in linux.I have just come across the alarm
and
> > some other standard signals which are generated and hence this does
not
> > suit my need.
> > Thanx in advance for ur suggestions ...... ive been racking my
brains
> > for this one...would indeed be a great help to get some pointers on
> > this.
> > thanx and kind regards
> > vinay
>
> While timers may look like they should be a good solution to this
> problem, I have also found that in practice they aren't very easy
> to use, particularly in view of the issues that attend the use of
> signals in threaded code.
>
> The Nifty library contains thread-based timer package that should
> be a good match to your requirement. The code is free to use, and
> you can download it from
>
>   ftp://ftp.xenadyne.com/pub/Nifty.tgz
>
> -SEan

Hi Sean,
Thanx a million for the library.It is really helpful.But i do have some
questions still though. The stuff that i explained im doin ..im doin
that in a separate thread in my program.Now ur code also uses threads i
think.So will the working of the nft_task_schedule and the
nft_task_cancel be unpredictable when using these function from another
thread in my program.Cos right now the results that im getting are a
little weird.
Thanx for the idea and code ..was really helpful
Regards
Vinay

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