Subj : Re: Custom finalization for functions
To   : Brendan Eich
From : Alain Frisch
Date : Mon May 23 2005 10:17 pm

Hello,

Many thanks for your quick answers.

> What is the strong reference into the other GC's heap that is stored in
> a Function object (either JSFunction.u.native or a reserved slot, I am
> guessing)?  

Yes, I use the first of the two reserved slots as an index in an array
of closures of the other system; the array is itself a root for the
other GC.

> What keeps the peer function object that you reference in
> this way alive, if it's GC-allocated?  Don't you have to mark or scan
> this reference, or otherwise root or protect it?

Yes, they are rooted.

> If the other language really uses GC, then you don't want to finalize
> the peer function object, unless you can be 100% certain that no strong
> refs to it exist apart from the one stored in, or associated with, the
> JS function object.  You simply want to stop marking that peer function
> object.

Indeed. Actually, I want to remove the closure from the above mentioned
array.

> XPConnect uses JS_SetGCCallback to run its own mark/sweep GC on top of
> the SpiderMonkey one.  You might do the same.  You need to keep track of
> JS functions that have peers in the other language's runtime.

I need to be able to detect when a JSFunction that I created is
finalized. I don't see immediatly how to do that with JS_SetGCCallback.
Is there a way to retrieve all the objects just before they are finalized?


-- Alain

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