Fix shutdown assertions in stasis-core

In r388005, macros were introduced to consistently define message
types. This added an assert if a message type was used either before
it was initialized or after it had been cleaned up. It turns out that
this assertion fires during shutdown.

This actually exposed a hidden shutdown ordering problem. Since
unsubscribing is asynchronous, it's possible that the message types
used by the subscription could be freed before the final message of
the subscription was processed.

This patch adds stasis_subscription_join(), which blocks until the
last message has been processed by the subscription. Since joining was
most commonly done right after an unsubscribe, a
stasis_unsubscribe_and_join() convenience function was also added.

Similar functions were also added to the stasis_caching_topic and
stasis_message_router, since they wrap subscriptions and have similar
problems.

Other code in trunk was refactored to join() where appropriate, or at
least verify that the subscription was complete before being
destroyed.

Review: https://reviewboard.asterisk.org/r/2540


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@389011 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 19 insertions, 0 deletions

diff --git a/main/stasis_cache.c b/main/stasis_cache.c
index 75e6b5f95..154b4f020 100644
--- a/main/stasis_cache.c
+++ b/main/stasis_cache.c
@@ -53,6 +53,8 @@ struct stasis_caching_topic {
 static void stasis_caching_topic_dtor(void *obj) {
 	struct stasis_caching_topic *caching_topic = obj;
 	ast_assert(!stasis_subscription_is_subscribed(caching_topic->sub));
+	ast_assert(stasis_subscription_is_done(caching_topic->sub));
+	ao2_cleanup(caching_topic->sub);
 	caching_topic->sub = NULL;
 	ao2_cleanup(caching_topic->cache);
 	caching_topic->cache = NULL;
@@ -69,6 +71,9 @@ struct stasis_caching_topic *stasis_caching_unsubscribe(struct stasis_caching_to
 {
 	if (caching_topic) {
 		if (stasis_subscription_is_subscribed(caching_topic->sub)) {
+			/* Increment the reference to hold on to it past the
+			 * unsubscribe */
+			ao2_ref(caching_topic->sub, +1);
 			stasis_unsubscribe(caching_topic->sub);
 		} else {
 			ast_log(LOG_ERROR, "stasis_caching_topic unsubscribed multiple times\n");
@@ -77,6 +82,20 @@ struct stasis_caching_topic *stasis_caching_unsubscribe(struct stasis_caching_to
 	return NULL;
 }
 
+struct stasis_caching_topic *stasis_caching_unsubscribe_and_join(struct stasis_caching_topic *caching_topic)
+{
+	if (!caching_topic) {
+		return NULL;
+	}
+
+	/* Hold a ref past the unsubscribe */
+	ao2_ref(caching_topic, +1);
+	stasis_caching_unsubscribe(caching_topic);
+	stasis_subscription_join(caching_topic->sub);
+	ao2_cleanup(caching_topic);
+	return NULL;
+}
+
 struct cache_entry {
 	struct stasis_message_type *type;
 	char *id;