From: Joel VanderWerf <vjoel@...>
Date: 2007-11-12T04:06:53+09:00
Subject: Re: JRuby performance questions answered

evanwebb@gmail.com wrote:
> On Nov 11, 6:11 am, Laurent Sansonetti <laurent.sansone...@gmail.com>
...
>> On a completely unrelated note, I was wondering... how did you manage
>> to keep compatibility with existing C extensions without requiring the
>> developer to explicitly set write barriers, in some cases?
>>
> 
> The key is that C extensions don't have direct access to object
> references. A C extension accesses all objects via a handle table. A
> handle is what a C extension sees as an object. This lets the GC
> mutate objects (which are also in the handle table) but keep the
> handles at constant addresses (so they can be stored on the C stack).
> 
> The big problem with this approach is the RARRAY(), RSTRING(), etc
> macros, that access an object directly as C data structure. Thats the
> main reason for trying to move MRI away from using these macros and to
> using something that looks like a function call that we in rubinius
> can implement differently.

The extension code must also lock the handle and unlock in rb_ensure?

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407