How to know if all pending tevent_req requests have completed?

[Amitay Isaacs]

On Fri, Feb 24, 2017 at 5:55 AM, Stefan Metzmacher <metze at samba.org> wrote:

> Am 23.02.2017 um 18:25 schrieb Jeremy Allison:
> > On Thu, Feb 23, 2017 at 03:58:36PM +1100, Amitay Isaacs wrote:
> >> On Thu, Feb 23, 2017 at 11:39 AM, Jeremy Allison <jra at samba.org> wrote:
> >>
> >>> On Thu, Feb 23, 2017 at 11:18:41AM +1100, Amitay Isaacs wrote:
> >>>> Hi tevent experts,
> >>>>
> >>>> tevent_req_poll() allows to wait for a specific request.
> >>>>
> >>>> If I want to create n requests and wait for all of them to finish, is
> >>> there
> >>>> an easy way to do it?
> >>>>
> >>>> Here is an example computation:
> >>>>
> >>>> run_event_send()
> >>>>    ... run scripts one after the other ...
> >>>>
> >>>>    if (timer expires) {
> >>>>       run_debug_send()
> >>>>       tevent_req_done()
> >>>>    }
> >>>>
> >>>> In this case, run_debug_send() computation is *not* hanging off the
> >>>> run_event_send() request.
> >>>> The calling code needs to know that run_event computation has timed
> out,
> >>>> but doesn't really care whether debugging computation is over or not.
> >>> The
> >>>> debug program can run in the background and log useful debug
> information
> >>>> without affecting the caller.
> >>>
> >>> Can't you use tevent_wakeup_send() to set a timeout on the
> >>> tevent context, and then check the state of each req you've
> >>> saved off in a list somewhere by using tevent_req_is_in_progress() ?
> >>>
> >>
> >> Well, the requests could created any at level, so keeping track of them
> >> might not be feasible without layering violations.
> >>
> >> I was really hoping that event context keeps track of active requests
> and I
> >> can query the event context if the requests list (or queue) is empty or
> not.
> >
> > The event context does keep track, but different backends
> > may do so in different ways - so there's no generic 'are
> > any events pending' call (well, there's tevent_common_have_events(),
> > but that's an internal tevent call meant for simple backends
> > to use, so you can't use that :-).
> >
> > The layering violation is your real problem here.
>
> tevent_common_have_events() is used to break out of
>
> tevent_loop_wait(ev);
> so you may just want to use that and wait for it to return.
>

Thank you.  That's what I wanted.  I missed that one.

Amitay.