Re: [boost] Re: RC + GC

From: Larry Evans (jcampbell3_at_[hidden])
Date: 2002-09-10 22:03:56

On Tue, 2002-09-10 at 20:27, Philippe A. Bouchard wrote:
> Larry Evans wrote:
> 
> > On Tue, 2002-09-10 at 17:11, Philippe A. Bouchard wrote:
> >> I've cleaned up operator new()s and reference counts can now be mixed
> >> with garbage collectors:
> >> http://groups.yahoo.com/group/boost/files/ptr/
> >> 
> >> Any comments are welcome.
> >> 
> > I don't see any cycles in the pointer graph in placed_ptr_test.cpp.
> 
> It's the following:
>         {
>                 placed_ptr<node> pN = new (gc) node();
> 
>                 pN->p = pN;
> 
>                 pN.clear();
>         }
> 
> remove pN.clear() and the node will never be destructed (cout of ~node()).
> 
OOPS.  So obvious I missed it.

However, pN.clear() should NOT collect anything at the point it's
called above because pN.get() and pN->p.get() are both still "live".

In addition, clear should be a static method since it deals with
with all placed_ptr's, not just one.  After exit from the {}, the static
collect() should be called to collect the "dead" objects.

A good definition of "live" and "dead" are at:
  http://www.memorymanagement.org/glossary/