On Sun, May 12, 2002 at 01:10:03AM -0400, Allen Smith wrote:
> On May 11, 11:28pm, Joshua N Pritikin wrote:
> > That means that Event probably has a reference counting bug.
>
> Sigh... yes. I am wondering myself about a couple things in ev.c:
> A. pe_event_invoke. Callbacks only return values via calling
> "unloop('value')", not returning something, right? Thus the
> G_VOID? Then why not also G_DISCARD?
Look at the source code for call_sv in perl.c. The only things that
G_DISCARD does is turn on the ENTER/SAVETMPS FREETMPS/LEAVE pair.
This is already done in _loop() so we don't need to do it again.
i tried adding G_DISCARD and it doesn't make any difference.
> B. pe_event_release decreases the refcount for ev->mysv; the same
> happens in event_2sv thanks to the "sv_2mortal", which
> compensates for the SvREFCNT_inc. But ev->mysv is a
> reference. What decreases the refcount to the thing it's
> referring to?
When the rv is destroyed then it does a SvREFCNT_dec on the SV to which
it is pointing. See the doc for newSVrv -- the sv is created with
a refcnt=1, so this should work. You can verify it with $Event::DebugLevel=3;
which turns on a warning "Event=0x%x '%s' destroyed (SV=0x%x)".
Oops, this warning isn't getting triggered. Well, here is one memory leak.
i don't know why this stopped working.
> That sv gets created _again_ anytime ev->mysv is 0,
> which it will be if the event has gone through pe_event_release
> (whether or not ev->mysv is freed...).
Correct.
> SV *event_2sv(pe_event *ev) { /**MAKE FAST**/
> if (!ev->mysv) {
> SV *rv = newSV(0);
> SV *sv = newSVrv(rv,0);
> sv_bless(rv, ev->vtbl->stash);
> sv_setiv(sv, (IV)ev);
> ev->mysv = rv;
>
> if (WaDEBUGx(ev->up) >= 4) {
> STRLEN n_a;
> warn("Event=0x%x '%s' wrapped with SV=0x%x",
> ev, SvPV(ev->up->desc, n_a), SvRV(ev->mysv));
> }
> }
> return SvREFCNT_inc(sv_2mortal(ev->mysv));
> }
But if the SvREFCNT_inc is removed then we get:
"Attempt to free unreferenced scalar ..."
i don't have much time but i'll try to look at this today.
--
Victory to the Divine Mother!! after all,
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