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-rw-r--r--libguile/hashtab.c52
1 files changed, 37 insertions, 15 deletions
diff --git a/libguile/hashtab.c b/libguile/hashtab.c
index a76c03812..48660d75c 100644
--- a/libguile/hashtab.c
+++ b/libguile/hashtab.c
@@ -418,32 +418,54 @@ SCM_DEFINE (scm_make_hash_table, "make-hash-table", 0, 1, 0,
}
#undef FUNC_NAME
-static void
-weak_gc_callback (void *ptr, void *data)
+/* The before-gc C hook only runs if GC_set_start_callback is available,
+ so if not, fall back on a finalizer-based implementation. */
+static int
+weak_gc_callback (void **weak)
{
- void **weak = ptr;
- void *val = *weak;
+ void *val = weak[0];
+ void (*callback) (SCM) = weak[1];
- if (val)
- {
- void (*callback) (SCM) = data;
+ if (!val)
+ return 0;
+
+ callback (PTR2SCM (val));
- GC_REGISTER_FINALIZER_NO_ORDER (ptr, weak_gc_callback, data, NULL, NULL);
-
- callback (PTR2SCM (val));
- }
+ return 1;
}
+#ifdef HAVE_GC_SET_START_CALLBACK
+static void*
+weak_gc_hook (void *hook_data, void *fn_data, void *data)
+{
+ if (!weak_gc_callback (fn_data))
+ scm_c_hook_remove (&scm_before_gc_c_hook, weak_gc_hook, fn_data);
+
+ return NULL;
+}
+#else
+static void
+weak_gc_finalizer (void *ptr, void *data)
+{
+ if (weak_gc_callback (ptr))
+ GC_REGISTER_FINALIZER_NO_ORDER (ptr, weak_gc_finalizer, data, NULL, NULL);
+}
+#endif
+
static void
scm_c_register_weak_gc_callback (SCM obj, void (*callback) (SCM))
{
- void **weak = GC_MALLOC_ATOMIC (sizeof (void**));
+ void **weak = GC_MALLOC_ATOMIC (sizeof (void*) * 2);
- *weak = SCM2PTR (obj);
+ weak[0] = SCM2PTR (obj);
+ weak[1] = (void*)callback;
GC_GENERAL_REGISTER_DISAPPEARING_LINK (weak, SCM2PTR (obj));
- GC_REGISTER_FINALIZER_NO_ORDER (weak, weak_gc_callback, (void*)callback,
- NULL, NULL);
+#ifdef HAVE_GC_SET_START_CALLBACK
+ scm_c_hook_add (&scm_before_gc_c_hook, weak_gc_hook, weak, 0);
+#else
+ GC_REGISTER_FINALIZER_NO_ORDER (weak, weak_gc_finalizer, NULL, NULL, NULL);
+#endif
}
SCM_DEFINE (scm_make_weak_key_hash_table, "make-weak-key-hash-table", 0, 1, 0,