Re: [PATCH v2 3/6] tests/qtest: capture RESUME events during migration

[Daniel P . Berrangé]

On Fri, Apr 21, 2023 at 11:59:25PM +0200, Juan Quintela wrote:
> Daniel P. Berrangé <berrange@redhat.com> wrote:
> > When running migration tests we monitor for a STOP event so we can skip
> > redundant waits. This will be needed for the RESUME event too shortly.
> >
> > Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> 
> Reviewed-by: Juan Quintela <quintela@redhat.com>
> 
> i.e. it is better that what we have now.
> 
> But
> 
> 
> > diff --git a/tests/qtest/migration-helpers.c 
> > b/tests/qtest/migration-helpers.c
> > index f6f3c6680f..61396335cc 100644
> > --- a/tests/qtest/migration-helpers.c
> > +++ b/tests/qtest/migration-helpers.c
> > @@ -24,14 +24,20 @@
> >  #define MIGRATION_STATUS_WAIT_TIMEOUT 120
> >  
> >  bool got_stop;
> > +bool got_resume;
> >  
> > -static void check_stop_event(QTestState *who)
> > +static void check_events(QTestState *who)
> >  {
> >      QDict *event = qtest_qmp_event_ref(who, "STOP");
> >      if (event) {
> >          got_stop = true;
> >          qobject_unref(event);
> >      }
> > +    event = qtest_qmp_event_ref(who, "RESUME");
> > +    if (event) {
> > +        got_resume = true;
> > +        qobject_unref(event);
> > +    }
> >  }
> 
> What happens if we receive the events in the order RESUME/STOP (I mean
> in the big scheme of things, not that it makes sense in this particular
> case).
> 
> QDict *qtest_qmp_event_ref(QTestState *s, const char *event)
> {
>     while (s->pending_events) {
> 
>         GList *first = s->pending_events;
>         QDict *response = (QDict *)first->data;
> 
>         s->pending_events = g_list_delete_link(s->pending_events, first);
> 
>         if (!strcmp(qdict_get_str(response, "event"), event)) {
>             return response;
>         }
>         qobject_unref(response);
>     }
>     return NULL;
> }
> 
> if we don't found the event that we are searching for, we just drop it.
> Does this makes sense if we are searching only for more than one event?

You are right about this code being broken in general for multiple events.

In this particular series though we're looking at STOP on the src host and
RESUME on the dst host, so there's no ordering problem to worry about.


With regards,
Daniel
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