[racket-dev] [plt] Push #25886: master branch updated

Thanks for the fix and the stress test!

Also, I want to make sure I understand this:

On 12/11/2012 09:32 AM, mflatt at racket-lang.org wrote:
> collects/math/private/bigfloat/mpfr.rkt
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> --- OLD/collects/math/private/bigfloat/mpfr.rkt
> +++ NEW/collects/math/private/bigfloat/mpfr.rkt
> @@ -76,9 +76,14 @@
>       [(_ name type fail-thunk) (get-ffi-obj name mpfr-lib type fail-thunk)]))
>
>   (define mpfr-free-cache (get-mpfr-fun 'mpfr_free_cache (_fun -> _void)))
> -#;
> +
>   (define mpfr-shutdown
> -  (register-custodian-shutdown mpfr-free-cache (λ (free) (free))))
> +  (register-custodian-shutdown
> +   mpfr-free-cache ; acts as a "random" object for a shutdown handle
> +   (λ (free)
> +      ;; The direct reference here is important, since custodian holds only
> +      ;; a weak reference to shutdown handle:
> +      (mpfr-free-cache))))

Is the problem here that `free' may point to an object that has been 
collected, or may be #f because the object has been collected?

If so, then the callback procedure can't rely on the value of `free' 
unless it contains its own reference to `free'. So why pass it? Also, 
why doesn't the module's reference to `mpfr-free-cache' count? Because 
the module may have been collected already?

Neil ⊥