Re: (guix git) and guile-git finalizers.

[Mathieu Othacehe]

Hi Andy,

> Nice sleuthing!

Thanks :)

>
> If you want to manually handle finalization at 'safe' points from
> Scheme, guardians are the things to use.  Add your "finalizable" object
> to a guardian, and periodically "pump" the guardian to see if anything
> is finalizable; you can run the finalizer there.

So, the idea would be to create a global guardian with :

--8<---------------cut here---------------start------------->8---
(define pointer-guardian (make-guardian))
--8<---------------cut here---------------end--------------->8---

and replace those kind of functions :

--8<---------------cut here---------------start------------->8---
(define (pointer->commit! pointer)
  (set-pointer-finalizer! pointer %commit-free)
  (pointer->commit pointer))
--8<---------------cut here---------------end--------------->8---

by,

--8<---------------cut here---------------start------------->8---
(define (pointer->commit! pointer)
  (pointer-guardian pointer)
  (pointer->commit pointer))
--8<---------------cut here---------------end--------------->8---

But then, at shutdown, when I'll call (pointer-guardian) to get the list
of free-able pointers, how can I know that %commit-free has to be called
on commit pointers, %reference-free on reference pointers, ... ?

Thanks,

Mathieu