[Kde-bindings] QtRuby memleak continued

[Ashley Winters]

--- Caleb Tennis <caleb at aei-tech.com> wrote:

> Ok, I've updated to the latest changes in the 3.5 branch of the
> qtruby/korundum and ran my program through valgrind for about 24
> hours to
> accumulate where the leaks are still coming from.  Here are the two
> big
> offenders:
> 
> 

[charP marshaller leaks]

> I can definitely see HOW the memory is being leaked, but it's not
> entirely
> clear where the responsibility lies for cleaning up the heap objects
> after
> they are created.  I may just stab at it for a while unless you have
> any
> thoughts, Richard?

In the latest Qt4 version, the m->cleanup() logic has been commented
out. Is there a reason?

Smoke has delete-responsibility information built in, for
argument/return-values. Here's the charP marshaller from PerlQt, for
comparison:

    switch(m->action()) {
      case Marshall::FromSV:
	{
	    SV *sv = m->var();
	    if(!SvOK(sv)) {
		m->item().s_voidp = 0;
		break;
	    }
	    if(m->cleanup())
		m->item().s_voidp = SvPV_nolen(sv);
	    else {
		STRLEN len;
		char *svstr = SvPV(sv, len);
		char *str = new char [len + 1];
		strncpy(str, svstr, len);
		str[len] = 0;
		m->item().s_voidp = str;
	    }
	}
	break;
      case Marshall::ToSV:
	{
	    char *p = (char*)m->item().s_voidp;
	    if(p)
		sv_setpv_mg(m->var(), p);
	    else
		sv_setsv_mg(m->var(), &PL_sv_undef);
	    if(m->cleanup())
		delete[] p;
	}
	break;
      default:
	m->unsupported();
	break;
    }

If you'll notice, it's checking m->cleanup() on both the To and From
marshallers. In the From marshaller, m->cleanup() indicates that the
CALLEE will destroy the passed-in value -- in that case, I make a copy
of my string before passing it through.

In the To marshaller, m->cleanup() indicates that the contents were
copied automatically *inside the Smoke library* before being passed to
the marshaller. As soon as you copy the string into a language
variable, it's your responsibility to delete it. This happens most
often with objects (such as a function returning 'const QSize&') which
are copied via new inside Smoke, where it's your responsibility to
destroy the object.

That's my knowledge in the matter. I don't know how much it applies to
QtRuby these days. :)

Good luck,
- Ashley Winters


__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com