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Remove thread-local weak mutex set

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* libguile/threads.h (scm_i_thread):
* libguile/threads.c (guilify_self_1, do_thread_exit, fat_mutex_lock):
  Remove thread-local weak mutex set.
This commit is contained in:
Andy Wingo 2016-11-05 00:20:39 +01:00
parent c6a8092b3f
commit 857aa581a2
2 changed files with 4 additions and 73 deletions
Download patch file Download diff file Expand all files Collapse all files

76
libguile/threads.c
View file

@ -411,7 +411,6 @@ guilify_self_1 (struct GC_stack_base *base)
t.pthread = scm_i_pthread_self ();
t.handle = SCM_BOOL_F;
t.result = SCM_BOOL_F;
t.mutexes = SCM_EOL;
t.held_mutex = NULL;
t.join_queue = SCM_EOL;
t.freelists = NULL;
@ -543,28 +542,6 @@ do_thread_exit (void *v)
while (scm_is_true (unblock_from_queue (t->join_queue)))
;
while (!scm_is_null (t->mutexes))
{
SCM mutex = scm_c_weak_vector_ref (scm_car (t->mutexes), 0);
if (scm_is_true (mutex))
{
fat_mutex *m = SCM_MUTEX_DATA (mutex);
scm_i_pthread_mutex_lock (&m->lock);
/* Check whether T owns MUTEX. This is usually the case, unless
T abandoned MUTEX; in that case, T is no longer its owner (see
`fat_mutex_lock') but MUTEX is still in `t->mutexes'. */
if (scm_is_eq (m->owner, t->handle))
unblock_from_queue (m->waiting);
scm_i_pthread_mutex_unlock (&m->lock);
}
t->mutexes = scm_cdr (t->mutexes);
}
scm_i_pthread_mutex_unlock (&t->admin_mutex);
return NULL;
@ -1183,26 +1160,6 @@ fat_mutex_lock (SCM mutex, scm_t_timespec *timeout, int *ret)
{
m->owner = new_owner;
m->level++;
if (SCM_I_IS_THREAD (new_owner))
{
scm_i_thread *t = SCM_I_THREAD_DATA (new_owner);
/* FIXME: The order in which `t->admin_mutex' and
`m->lock' are taken differs from that in
`on_thread_exit', potentially leading to deadlocks. */
scm_i_pthread_mutex_lock (&t->admin_mutex);
/* Only keep a weak reference to MUTEX so that it's not
retained when not referenced elsewhere (bug #27450).
The weak pair itself is eventually removed when MUTEX
is unlocked. Note that `t->mutexes' lists mutexes
currently held by T, so it should be small. */
t->mutexes = scm_cons (scm_make_weak_vector (SCM_INUM1, mutex),
t->mutexes);
scm_i_pthread_mutex_unlock (&t->admin_mutex);
}
*ret = 1;
break;
}
@ -1330,25 +1287,6 @@ typedef struct {
#define SCM_CONDVARP(x) SCM_SMOB_PREDICATE (scm_tc16_condvar, x)
#define SCM_CONDVAR_DATA(x) ((fat_cond *) SCM_SMOB_DATA (x))
static void
remove_mutex_from_thread (SCM mutex, scm_i_thread *t)
{
SCM walk, prev;
for (prev = SCM_BOOL_F, walk = t->mutexes; scm_is_pair (walk);
walk = SCM_CDR (walk))
{
if (scm_is_eq (mutex, scm_c_weak_vector_ref (SCM_CAR (walk), 0)))
{
if (scm_is_pair (prev))
SCM_SETCDR (prev, SCM_CDR (walk));
else
t->mutexes = SCM_CDR (walk);
break;
}
}
}
static int
fat_mutex_unlock (SCM mutex, SCM cond,
const scm_t_timespec *waittime, int relock)
@ -1391,11 +1329,8 @@ fat_mutex_unlock (SCM mutex, SCM cond,
if (m->level > 0)
m->level--;
if (m->level == 0)
{
/* Change the owner of MUTEX. */
remove_mutex_from_thread (mutex, t);
m->owner = unblock_from_queue (m->waiting);
}
/* Change the owner of MUTEX. */
m->owner = unblock_from_queue (m->waiting);
t->block_asyncs++;
@ -1439,11 +1374,8 @@ fat_mutex_unlock (SCM mutex, SCM cond,
if (m->level > 0)
m->level--;
if (m->level == 0)
{
/* Change the owner of MUTEX. */
remove_mutex_from_thread (mutex, t);
m->owner = unblock_from_queue (m->waiting);
}
/* Change the owner of MUTEX. */
m->owner = unblock_from_queue (m->waiting);
scm_i_pthread_mutex_unlock (&m->lock);
ret = 1;

1
libguile/threads.h
View file

@ -63,7 +63,6 @@ typedef struct scm_i_thread {
SCM join_queue;
scm_i_pthread_mutex_t admin_mutex;
SCM mutexes;
scm_i_pthread_mutex_t *held_mutex;
SCM result;