Alternative to scm_protects?

Alternative to scm_protects?

[Devon Schudy]

scm_protects is no longer public in Guile 2.1. AFAICT there's no other
way to find out what objects are protected. Should there be?

Lilypond uses scm_protects as a tool for debugging memory leaks
(especially ones due to forgetting to unprotect). This isn't an
important feature, so it can just be disabled when not available. But
other users of the C interface are likely to have leaks and want a way
to debug them, so it might be worth supporting.

Re: Alternative to scm_protects?

[Ludovic Courtès]

Since Guile 2.0, which switched to BDW-GC, scm_protects has been mostly
irrelevant because BDW-GC scans all the C global variables.

Actually, libguile/gc.c in 2.0 reads this:

--8<---------------cut here---------------start------------->8---
#if SCM_ENABLE_DEPRECATED == 1
/* Hash table that keeps a reference to objects the user wants to protect from
   garbage collection.  It could arguably be private but applications have come
   to rely on it (e.g., Lilypond 2.13.9).  */
SCM scm_protects;
#else
static SCM scm_protects;
#endif
--8<---------------cut here---------------end--------------->8---

So the alternative to scm_protects should be just something like this:

  static SCM my_protects;

    ...
    my_protects = scm_cons (obj, my_protects); /* or a hash table */

Would it work for LilyPond?

Ludo’.

Re: Alternative to scm_protects?

[Devon Schudy]

Ludovic Courtès wrote:
> Since Guile 2.0, which switched to BDW-GC, scm_protects has been mostly
> irrelevant because BDW-GC scans all the C global variables.

Oh, it's irrelevant because users can easily implement it themselves —
it's just a convenience now.

So at worst, Lilypond can simply reimplement protects, which is <1 page. Thanks.