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fix thread cleanup

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* libguile/threads.h: Always declare a scm_i_thread_key, for cleanup
  purposes, in the BUILDING_LIBGUILE case.

* libguile/threads.c (scm_i_thread_key): Init with a cleanup handler, so
  any guile-specific info for a thread can be cleaned up reliably.
  (guilify_self_1): Always set the thread key.
  (do_thread_exit_trampoline, on_thread_exit): Enter guile-mode for the
  guile-mode cleanup handler, and trampoline through a
  gc_call_with_stack_base for reasons explained in the code.
  (init_thread_key, scm_i_init_thread_for_guile): Always init the key.
  (scm_i_with_guile_and_parent): No need for pthread_cancel cleanup
  handlers, as the pthread key destructor will take care of that for
  us.
  (really_launch): Remove needless pthread_exit call with incorrect
  comment.
This commit is contained in:
Andy Wingo 2011-03-18 13:18:47 +01:00
parent 60582b7c2a
commit f60a7648d5
2 changed files with 43 additions and 33 deletions
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71
libguile/threads.c
View file

@ -343,6 +343,12 @@ unblock_from_queue (SCM queue)
/* Getting into and out of guile mode.
*/
/* Key used to attach a cleanup handler to a given thread. Also, if
thread-local storage is unavailable, this key is used to retrieve the
current thread with `pthread_getspecific ()'. */
scm_i_pthread_key_t scm_i_thread_key;
#ifdef SCM_HAVE_THREAD_STORAGE_CLASS
/* When thread-local storage (TLS) is available, a pointer to the
@ -352,17 +358,7 @@ unblock_from_queue (SCM queue)
represent. */
SCM_THREAD_LOCAL scm_i_thread *scm_i_current_thread = NULL;
# define SET_CURRENT_THREAD(_t) scm_i_current_thread = (_t)
#else /* !SCM_HAVE_THREAD_STORAGE_CLASS */
/* Key used to retrieve the current thread with `pthread_getspecific ()'. */
scm_i_pthread_key_t scm_i_thread_key;
# define SET_CURRENT_THREAD(_t) \
scm_i_pthread_setspecific (scm_i_thread_key, (_t))
#endif /* !SCM_HAVE_THREAD_STORAGE_CLASS */
#endif /* SCM_HAVE_THREAD_STORAGE_CLASS */
static scm_i_pthread_mutex_t thread_admin_mutex = SCM_I_PTHREAD_MUTEX_INITIALIZER;
@ -428,7 +424,12 @@ guilify_self_1 (SCM_STACKITEM *base)
t->exited = 0;
t->guile_mode = 0;
SET_CURRENT_THREAD (t);
scm_i_pthread_setspecific (scm_i_thread_key, t);
#ifdef SCM_HAVE_THREAD_STORAGE_CLASS
/* Cache the current thread in TLS for faster lookup. */
scm_i_current_thread = t;
#endif
scm_i_pthread_mutex_lock (&thread_admin_mutex);
t->next_thread = all_threads;
@ -537,6 +538,22 @@ do_thread_exit (void *v)
return NULL;
}
static void *
do_thread_exit_trampoline (struct GC_stack_base *sb, void *v)
{
void *ret;
int registered;
registered = GC_register_my_thread (sb);
ret = scm_with_guile (do_thread_exit, v);
if (registered == GC_SUCCESS)
GC_unregister_my_thread ();
return ret;
}
static void
on_thread_exit (void *v)
{
@ -551,19 +568,20 @@ on_thread_exit (void *v)
t->held_mutex = NULL;
}
SET_CURRENT_THREAD (v);
/* Reinstate the current thread for purposes of scm_with_guile
guile-mode cleanup handlers. Only really needed in the non-TLS
case but it doesn't hurt to be consistent. */
scm_i_pthread_setspecific (scm_i_thread_key, t);
/* Ensure the signal handling thread has been launched, because we might be
shutting it down. */
scm_i_ensure_signal_delivery_thread ();
/* Unblocking the joining threads needs to happen in guile mode
since the queue is a SCM data structure. */
/* Note: Since `do_thread_exit ()' uses allocates memory via `libgc', we
assume the GC is usable at this point, and notably that thread-local
storage (TLS) hasn't been deallocated yet. */
do_thread_exit (v);
since the queue is a SCM data structure. Trampoline through
GC_call_with_stack_base so that the GC works even if it already
cleaned up for this thread. */
GC_call_with_stack_base (do_thread_exit_trampoline, v);
/* Removing ourself from the list of all threads needs to happen in
non-guile mode since all SCM values on our stack become
@ -590,21 +608,17 @@ on_thread_exit (void *v)
scm_i_pthread_mutex_unlock (&thread_admin_mutex);
SET_CURRENT_THREAD (NULL);
scm_i_pthread_setspecific (scm_i_thread_key, NULL);
}
#ifndef SCM_HAVE_THREAD_STORAGE_CLASS
static scm_i_pthread_once_t init_thread_key_once = SCM_I_PTHREAD_ONCE_INIT;
static void
init_thread_key (void)
{
scm_i_pthread_key_create (&scm_i_thread_key, NULL);
scm_i_pthread_key_create (&scm_i_thread_key, on_thread_exit);
}
#endif
/* Perform any initializations necessary to make the current thread
known to Guile (via SCM_I_CURRENT_THREAD), initializing Guile itself,
if necessary.
@ -625,9 +639,7 @@ init_thread_key (void)
static int
scm_i_init_thread_for_guile (SCM_STACKITEM *base, SCM parent)
{
#ifndef SCM_HAVE_THREAD_STORAGE_CLASS
scm_i_pthread_once (&init_thread_key_once, init_thread_key);
#endif
if (SCM_I_CURRENT_THREAD)
{
@ -790,9 +802,7 @@ scm_i_with_guile_and_parent (void *(*func)(void *), void *data, SCM parent)
/* We are in Guile mode. */
assert (t->guile_mode);
scm_i_pthread_cleanup_push (scm_leave_guile_cleanup, NULL);
res = scm_c_with_continuation_barrier (func, data);
scm_i_pthread_cleanup_pop (0);
/* Leave Guile mode. */
t->guile_mode = 0;
@ -880,9 +890,6 @@ really_launch (void *d)
else
t->result = scm_catch (SCM_BOOL_T, thunk, handler);
/* Trigger a call to `on_thread_exit ()'. */
pthread_exit (NULL);
return 0;
}

5
libguile/threads.h
View file

@ -192,6 +192,10 @@ SCM_API void scm_dynwind_critical_section (SCM mutex);
#ifdef BUILDING_LIBGUILE
/* Though we don't need the key for SCM_I_CURRENT_THREAD if we have TLS,
we do use it for cleanup purposes. */
SCM_INTERNAL scm_i_pthread_key_t scm_i_thread_key;
# ifdef SCM_HAVE_THREAD_STORAGE_CLASS
SCM_INTERNAL SCM_THREAD_LOCAL scm_i_thread *scm_i_current_thread;
@ -199,7 +203,6 @@ SCM_INTERNAL SCM_THREAD_LOCAL scm_i_thread *scm_i_current_thread;
# else /* !SCM_HAVE_THREAD_STORAGE_CLASS */
SCM_INTERNAL scm_i_pthread_key_t scm_i_thread_key;
# define SCM_I_CURRENT_THREAD \
((scm_i_thread *) scm_i_pthread_getspecific (scm_i_thread_key))