>From 467e1d4c0438d24e310a45bc7370bd19b0e8c659 Mon Sep 17 00:00:00 2001 From: Mark H Weaver Date: Sun, 17 Nov 2013 03:35:09 -0500 Subject: [PATCH 3/6] Make guardians thread-safe. * libguile/guardians.c (t_guardian): Add mutex. (finalize_guarded, scm_i_guard, scm_i_get_one_zombie): Lock mutex and block system asyncs during critical sections. (scm_make_guardian): Initialize mutex. --- libguile/guardians.c | 18 ++++++++++++++++-- 1 files changed, 16 insertions(+), 2 deletions(-) diff --git a/libguile/guardians.c b/libguile/guardians.c index 6ba8c0b..e59e1bb 100644 --- a/libguile/guardians.c +++ b/libguile/guardians.c @@ -40,7 +40,6 @@ * monsters we had... * * Rewritten for the Boehm-Demers-Weiser GC by Ludovic Courtès. - * FIXME: This is currently not thread-safe. */ /* Uncomment the following line to debug guardian finalization. */ @@ -72,6 +71,7 @@ static scm_t_bits tc16_guardian; typedef struct t_guardian { + scm_i_pthread_mutex_t mutex; unsigned long live; SCM zombies; struct t_guardian *next; @@ -144,6 +144,9 @@ finalize_guarded (void *ptr, void *finalizer_data) } g = GUARDIAN_DATA (SCM_CAR (guardian_list)); + + scm_i_pthread_mutex_lock_with_asyncs (&g->mutex); + if (g->live == 0) abort (); @@ -157,7 +160,8 @@ finalize_guarded (void *ptr, void *finalizer_data) g->zombies = zombies; g->live--; - g->zombies = zombies; + + scm_i_pthread_mutex_unlock_with_asyncs (&g->mutex); } if (scm_is_true (proxied_finalizer)) @@ -208,6 +212,8 @@ scm_i_guard (SCM guardian, SCM obj) void *prev_data; SCM guardians_for_obj, finalizer_data; + scm_i_pthread_mutex_lock_with_asyncs (&g->mutex); + g->live++; /* Note: GUARDIANS_FOR_OBJ is a weak list so that a guardian can be @@ -249,6 +255,8 @@ scm_i_guard (SCM guardian, SCM obj) PTR2SCM (prev_data)); SCM_SETCAR (finalizer_data, proxied_finalizer); } + + scm_i_pthread_mutex_unlock_with_asyncs (&g->mutex); } } @@ -258,6 +266,8 @@ scm_i_get_one_zombie (SCM guardian) t_guardian *g = GUARDIAN_DATA (guardian); SCM res = SCM_BOOL_F; + scm_i_pthread_mutex_lock_with_asyncs (&g->mutex); + if (!scm_is_null (g->zombies)) { /* Note: We return zombies in reverse order. */ @@ -265,6 +275,8 @@ scm_i_get_one_zombie (SCM guardian) g->zombies = SCM_CDR (g->zombies); } + scm_i_pthread_mutex_unlock_with_asyncs (&g->mutex); + return res; } @@ -335,6 +347,8 @@ SCM_DEFINE (scm_make_guardian, "make-guardian", 0, 0, 0, t_guardian *g = scm_gc_malloc (sizeof (t_guardian), "guardian"); SCM z; + scm_i_pthread_mutex_init (&g->mutex, NULL); + /* A tconc starts out with one tail pair. */ g->live = 0; g->zombies = SCM_EOL; -- 1.7.5.4