Re: [Chicken-users] Safely holding on to a <procedure> reference in C

[Peter Bex]

On Sun, Feb 20, 2011 at 08:55:24PM -0800, Naitik Shah wrote:
> Hi,
> 
> I'm experimenting with Chicken and libevent using the bind extension to
> build a event based webserver. I'm trying to figure out if there's a way to
> have C code hold on to a <procedure> in a GC safe manner. The implementation
> I have so far works for a few requests, but eventually fails. Based on what
> I've learned so far it seems like this is because the GC is either throwing
> away or moving the <procedure> making the pointer in C being held by
> libevent invalid. Is it possible to hold on to a <procedure> like this?

I think you can use object-evict for that.  It's from unit lolevel, see
http://wiki.call-cc.org/man/4/Unit%20lolevel#object-evict

Alternatively, you can construct a new GC root with CHICKEN_new_gc_root()
and put the procedure object in it with CHICKEN_gc_root_set():
http://wiki.call-cc.org/man/4/Embedding#chicken_new_gc_root

I don't think there's a Scheme interface for that, though.

Cheers,
Peter
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