[SSSD] [PATCH] Make periodic checks for DNS timeouts

Dmitri Pal dpal at redhat.com
Thu Jan 14 13:32:50 UTC 2010


Stephen Gallagher wrote:
> On 01/13/2010 05:38 PM, Simo Sorce wrote:
> > On Wed, 13 Jan 2010 16:54:54 -0500
> > Stephen Gallagher <sgallagh at redhat.com> wrote:
>
> >> It's bad practice to modify current_time in a tevent_timer handler.
> > I agree with the nack, but I want to explain why it is really bad! :)
>
> > There is no problem in using the tevent_timer current_time in the
> > handler, it is just a copy that will die as soon as you return from the
> > handler.
>
> > The real problem here is that current_time is not the *actual* time, it
> > can easily be (0, 0).
>
> > This means that setting it to tv_sec += 1 means causing a busy loop
> > that spins as fast as it can because tv_sec = 1 is always in the past
> > and causes tevent to fire immediately.
>
> > Simo.
>
>
> Well, I would consider that a bug in the tevent API, then. What's the
> value at all of passing a "current_time" argument to the caller if it is
> not accurate. There are cases where a user may want to use this value to
> examine how long after the timer was set to fire it ACTUALLY fired.
>
> If there are ever cases where current_time == { 0, 0 }, this should be
> logged as a bug in tevent.
>
> But this argument is tangential to this patch review.
>
>
I disagree.
The value of passing { 0, 0 } in current_time is to loop once immediately.
As far as I understand this is a preferred way to do it.
Simo?


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-- 
Thank you,
Dmitri Pal

Engineering Manager IPA project,
Red Hat Inc.


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