From 604a8e8540d2fc27052e1b4383c165c3e156ad70 Mon Sep 17 00:00:00 2001
From: Andy Wingo <wingo@pobox.com>
Date: Fri, 2 May 2025 15:16:26 +0200
Subject: [PATCH] Weak sets and tables no longer vacuum after GC

These tables will be implemented differently after Whippet.

* libguile/weak-set.c (do_vacuum_weak_set, vacuum_all_weak_sets):
Remove.
(scm_c_make_weak_set, scm_init_weak_set): Don't keep a table of all weak
sets.
* libguile/weak-table.c (do_vacuum_weak_table, vacuum_all_weak_tables):
Remove.
(scm_c_make_weak_table, scm_init_weak_table): No table of all tables.
---
 libguile/weak-set.c   | 34 +-------------------------------
 libguile/weak-table.c | 45 +------------------------------------------
 2 files changed, 2 insertions(+), 77 deletions(-)

diff --git a/libguile/weak-set.c b/libguile/weak-set.c
index 93c429346..1a5bc1577 100644
--- a/libguile/weak-set.c
+++ b/libguile/weak-set.c
@@ -1,4 +1,4 @@
-/* Copyright 2011-2013,2018
+/* Copyright 2011-2013,2018,2025
      Free Software Foundation, Inc.
 
    This file is part of Guile.
@@ -689,32 +689,6 @@ scm_i_weak_set_print (SCM exp, SCM port, scm_print_state *pstate)
   scm_puts (">", port);
 }
 
-static void
-do_vacuum_weak_set (SCM set)
-{
-  scm_t_weak_set *s;
-
-  s = SCM_WEAK_SET (set);
-
-  /* We should always be able to grab this lock, because we are run from
-     a finalizer, which runs in another thread (or an async, which is
-     mostly equivalent).  */
-  scm_i_pthread_mutex_lock (&s->lock);
-  vacuum_weak_set (s);
-  scm_i_pthread_mutex_unlock (&s->lock);
-}
-
-static scm_i_pthread_mutex_t all_weak_sets_lock = SCM_I_PTHREAD_MUTEX_INITIALIZER;
-static SCM all_weak_sets = SCM_EOL;
-
-static void
-vacuum_all_weak_sets (void)
-{
-  scm_i_pthread_mutex_lock (&all_weak_sets_lock);
-  scm_i_visit_weak_list (&all_weak_sets, do_vacuum_weak_set);
-  scm_i_pthread_mutex_unlock (&all_weak_sets_lock);
-}
-
 SCM
 scm_c_make_weak_set (unsigned long k)
 {
@@ -722,10 +696,6 @@ scm_c_make_weak_set (unsigned long k)
 
   ret = make_weak_set (k);
 
-  scm_i_pthread_mutex_lock (&all_weak_sets_lock);
-  all_weak_sets = scm_i_weak_cons (ret, all_weak_sets);
-  scm_i_pthread_mutex_unlock (&all_weak_sets_lock);
-
   return ret;
 }
 
@@ -902,6 +872,4 @@ void
 scm_init_weak_set ()
 {
 #include "weak-set.x"
-
-  scm_i_register_async_gc_callback (vacuum_all_weak_sets);
 }
diff --git a/libguile/weak-table.c b/libguile/weak-table.c
index 1e4d8d302..571511256 100644
--- a/libguile/weak-table.c
+++ b/libguile/weak-table.c
@@ -1,4 +1,4 @@
-/* Copyright 2011-2014,2017-2018
+/* Copyright 2011-2014,2017-2018,2025
      Free Software Foundation, Inc.
 
    This file is part of Guile.
@@ -458,43 +458,6 @@ scm_i_weak_table_print (SCM exp, SCM port, scm_print_state *pstate)
   scm_puts (">", port);
 }
 
-static void
-do_vacuum_weak_table (SCM table)
-{
-  scm_t_weak_table *t;
-
-  t = SCM_WEAK_TABLE (table);
-
-  /* Unlike weak sets, the weak table interface allows custom predicates
-     to call out to arbitrary Scheme.  There are two ways that this code
-     can be re-entrant, then: calling weak hash procedures while in a
-     custom predicate, or via finalizers run explicitly by (gc) or in an
-     async (for non-threaded Guile).  We add a restriction that
-     prohibits the first case, by convention.  But since we can't
-     prohibit the second case, here we trylock instead of lock.  In any
-     case, if the mutex is held by another thread, then the table is in
-     active use, so the next user of the table will handle the vacuum
-     for us.  */
-  if (scm_i_pthread_mutex_trylock (&t->lock) == 0)
-    {
-      vacuum_weak_table (t);
-      scm_i_pthread_mutex_unlock (&t->lock);
-    }
-
-  return;
-}
-
-static scm_i_pthread_mutex_t all_weak_tables_lock = SCM_I_PTHREAD_MUTEX_INITIALIZER;
-static SCM all_weak_tables = SCM_EOL;
-
-static void
-vacuum_all_weak_tables (void)
-{
-  scm_i_pthread_mutex_lock (&all_weak_tables_lock);
-  scm_i_visit_weak_list (&all_weak_tables, do_vacuum_weak_table);
-  scm_i_pthread_mutex_unlock (&all_weak_tables_lock);
-}
-
 SCM
 scm_c_make_weak_table (unsigned long k, scm_t_weak_table_kind kind)
 {
@@ -502,10 +465,6 @@ scm_c_make_weak_table (unsigned long k, scm_t_weak_table_kind kind)
 
   ret = make_weak_table (k, kind);
 
-  scm_i_pthread_mutex_lock (&all_weak_tables_lock);
-  all_weak_tables = scm_i_weak_cons (ret, all_weak_tables);
-  scm_i_pthread_mutex_unlock (&all_weak_tables_lock);
-
   return ret;
 }
 
@@ -840,6 +799,4 @@ void
 scm_init_weak_table ()
 {
 #include "weak-table.x"
-
-  scm_i_register_async_gc_callback (vacuum_all_weak_tables);
 }