Fix finalizer resuscitation causing excessive GC

* libguile/finalizers.c (async_gc_finalizer):
  (scm_i_register_async_gc_callback): Replace "weak gc callback"
  mechanism with "async gc callback" mechanism.  Very similar but the
  new API is designed to be called a bounded number of times, to avoid
  running afoul of libgc heuristics.
* libguile/weak-list.h: New internal header.
* libguile/Makefile.am (noinst_HEADERS): Add weak-list.h.
* libguile/weak-set.c (vacuum_all_weak_sets):
  (scm_c_make_weak_set, scm_init_weak_set):
* libguile/weak-table.c (vacuum_all_weak_tables):
  (scm_c_make_weak_table, scm_init_weak_table): Arrange to vacuum all
  weak sets from a single async GC callback, and likewise for weak
  tables.

Thanks to Ludovic Courtès for tracking this bug down!

1 files changed, 4 insertions, 4 deletions

diff --git a/libguile/finalizers.h b/libguile/finalizers.h
index d01d1b734..27b2cbf82 100644
--- a/libguile/finalizers.h
+++ b/libguile/finalizers.h
@@ -36,10 +36,10 @@ SCM_INTERNAL void scm_i_add_resuscitator (void *obj, scm_t_finalizer_proc,
 
 SCM_INTERNAL void scm_i_finalizer_pre_fork (void);
 
-/* CALLBACK will be called on OBJ after each garbage collection, as long
-   as OBJ is accessible.  It will be called from a finalizer, which may
-   be from an async or from another thread. */
-SCM_INTERNAL void scm_i_register_weak_gc_callback (SCM obj, void (*callback) (SCM));
+/* CALLBACK will be called after each garbage collection.  It will be
+   called from a finalizer, which may be from an async or from another
+   thread. */
+SCM_INTERNAL void scm_i_register_async_gc_callback (void (*callback) (void));
 
 SCM_API int scm_set_automatic_finalization_enabled (int enabled_p);
 SCM_API int scm_run_finalizers (void);