Adopted a predictable scheduling behavior when broadcasting threads.

1 files changed, 60 insertions, 0 deletions

diff --git a/src/glibext/delayed.c b/src/glibext/delayed.c
index d05b67a..9d67a7c 100644
--- a/src/glibext/delayed.c
+++ b/src/glibext/delayed.c
@@ -442,8 +442,17 @@ static void g_work_group_dispose(GWorkGroup *group)
 
     group->force_exit = true;
 
+    /**
+     * Concernant la pose du verrou, se référer aux commentaires de la
+     * fonction g_work_group_process().
+     */
+
+    g_mutex_lock(&group->mutex);
+
     g_cond_broadcast(&group->cond);
 
+    g_mutex_unlock(&group->mutex);
+
     for (i = 0; i < group->threads_count; i++)
         g_thread_join(group->threads[i]);
 
@@ -599,9 +608,51 @@ static void *g_work_group_process(GWorkGroup *group)
 
         g_object_unref(G_OBJECT(work));
 
+        /**
+         * Verrou ou pas verrou ?
+         *
+         * La documentation de la GLib indique que ce n'est pas nécessaire :
+         *
+         *    '''
+         *    It is good practice to lock the same mutex as the waiting threads
+         *    while calling this function, though not required.
+         *    '''
+         *
+         * Ce conseil se trouve verbatim à l'adresse :
+         *
+         *    https://developer.gnome.org/glib/stable/glib-Threads.html#g-cond-broadcast
+         *
+         * Dans la pratique, il peut arriver que l'attente de la fonction
+         * g_work_group_wait_for_completion() ne soit jamais interrompue.
+         *
+         * La documentation POSIX est un peu plus orientée :
+         *
+         *    '''
+         *    The pthread_cond_broadcast() functions may be called by a thread
+         *    whether or not it currently owns the mutex that threads calling
+         *    pthread_cond_wait() have associated with the condition variable
+         *    during their waits; however, if predictable scheduling behavior is
+         *    required, then that mutex shall be locked by the thread calling
+         *    pthread_cond_broadcast().
+         *    '''
+         *
+         * Ce passage complet est consultable à l'adresse :
+         *
+         *    http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_broadcast.html
+         *
+         * La page de manuel pthread_cond_broadcast(3) est quant à elle plus
+         * directrice : aucun complément d'information sur le sujet n'est fourni
+         * et les exemples associés utilisent implicement un verrou pendant
+         * sont appel.
+         */
+
+        g_mutex_lock(&group->mutex);
+
         if (g_atomic_int_dec_and_test(&group->pending))
             g_cond_broadcast(&group->wait_cond);
 
+        g_mutex_unlock(&group->mutex);
+
     }
 
     return NULL;
@@ -730,8 +781,17 @@ static void g_work_group_set_extra_wait_callback(GWorkGroup *group, wait_for_inc
 
 static void g_work_group_wake_up_waiters(GWorkGroup *group)
 {
+    /**
+     * Concernant la pose du verrou, se référer aux commentaires de la
+     * fonction g_work_group_process().
+     */
+
+    g_mutex_lock(&group->mutex);
+
     g_cond_broadcast(&group->wait_cond);
 
+    g_mutex_unlock(&group->mutex);
+
 }