From: "Iñaki Baz Castillo" <ibc@...>
Date: 2011-02-09T08:18:36+09:00
Subject: Re: C extension: How to check if a VALUE is still alive (not being GC'ed)?

2011/2/8 Eric Hodel <drbrain@segment7.net>:
>> Yes, that's work: the resolver object contains a hash attribute in
>> which queries are stored until completed.
>
> Use a ruby hash and supply mark and GC callbacks to Data_Wrap_Struct so the GC will keep track of it.

Thanks, but I don't understand why I must use mark callback:

- My class uses Data_Wrap_Struct containing a xxx_free function to
free the C structure when the object is GC'ed.

- An instance of my class contains an @hash attribute (which is set
empty in initialize method).

- Such @hash is populted with some normal Ruby objects during runtime.
Nothing special here.

- So when my instance is GC'ed, at some point Ruby will GC the @hash
attribute and also the objects it contains.

Then... why do I need a mark callback? Maybe I miss something, however
Itested my code under high load and doesn't seem to leak.
Thanks a lot.
-- 
Iñaki Baz Castillo
<ibc@aliax.net>