stasis_cache_pattern: Backport to 13

Somehow stasis_cache_pattern got out of sync between 13 and master
and it was causing duplicate channel message issues in 13 when
related to a specific endpoint. I.E. from statsd,
'endpoints.PJSIP.1174.channels 0|g' was being emitted twice.

Backporting stasis_cache_pattern from master to 13 solved
the issue and running the unit and testsuite tests confirmed
that no new ones were created.

ASTERISK-25317 #close

Change-Id: Ia8707462f62d15eed14541c37f332a7bbbceb548

include/asterisk/stasis_cache_pattern.h

@@ -121,9 +121,12 @@ struct stasis_cp_single *stasis_cp_single_create(struct stasis_cp_all *all,
 	const char *name);
 
 /*!
- * \brief Create the 'one' side of the cache pattern.
+ * \brief Create a sink in the cache pattern
  *
- * Create the 'one' but do not automatically forward.
+ * Create the 'one' but do not automatically forward to the all's topic.
+ * This is useful when aggregating other topic's messages created with
+ * \c stasis_cp_single_create in another caching topic without replicating
+ * those messages in the all's topics.
  *
  * Dispose of using stasis_cp_single_unsubscribe().
  *
@@ -131,21 +134,9 @@ struct stasis_cp_single *stasis_cp_single_create(struct stasis_cp_all *all,
  * \param name Base name for the topics.
  * \return One side instance
  */
-struct stasis_cp_single *stasis_cp_single_create_only(struct stasis_cp_all *all,
+struct stasis_cp_single *stasis_cp_sink_create(struct stasis_cp_all *all,
 	const char *name);
 
-/*!
- * \brief Set up a topic and topic cache forward.
- *
- * Forward 'from' to 'to'.
- *
- * \param from Source 'one' side instance.
- * \param to Destination 'one' side instance.
- * \retval 0 Success
- * \retval -1 Failure
- */
-int stasis_cp_single_forward(struct stasis_cp_single *from, struct stasis_cp_single *to);
-
 /*!
  * \brief Stops caching and forwarding messages.
  *

main/endpoints.c

@@ -74,6 +74,8 @@ struct ast_endpoint {
 	struct stasis_message_router *router;
 	/*! ast_str_container of channels associated with this endpoint */
 	struct ao2_container *channel_ids;
+	/*! Forwarding subscription from an endpoint to its tech endpoint */
+	struct stasis_forward *tech_forward;
 };
 
 static int endpoint_hash(const void *obj, int flags)
@@ -303,7 +305,7 @@ static struct ast_endpoint *endpoint_internal_create(const char *tech, const cha
 
 	if (!ast_strlen_zero(resource)) {
 
-		endpoint->topics = stasis_cp_single_create_only(ast_endpoint_cache_all(),
+		endpoint->topics = stasis_cp_single_create(ast_endpoint_cache_all(),
 			endpoint->id);
 		if (!endpoint->topics) {
 			return NULL;
@@ -322,14 +324,13 @@ static struct ast_endpoint *endpoint_internal_create(const char *tech, const cha
 			return NULL;
 		}
 
-		if (stasis_cp_single_forward(endpoint->topics, tech_endpoint->topics)) {
-			return NULL;
-		}
+		endpoint->tech_forward = stasis_forward_all(stasis_cp_single_topic(endpoint->topics),
+			stasis_cp_single_topic(tech_endpoint->topics));
 
 		endpoint_publish_snapshot(endpoint);
 		ao2_link(endpoints, endpoint);
 	} else {
-		endpoint->topics = stasis_cp_single_create(ast_endpoint_cache_all(),
+		endpoint->topics = stasis_cp_sink_create(ast_endpoint_cache_all(),
 			endpoint->id);
 		if (!endpoint->topics) {
 			return NULL;
@@ -382,6 +383,7 @@ void ast_endpoint_shutdown(struct ast_endpoint *endpoint)
 	}
 
 	ao2_unlink(endpoints, endpoint);
+	endpoint->tech_forward = stasis_forward_cancel(endpoint->tech_forward);
 
 	clear_msg = create_endpoint_snapshot_message(endpoint);
 	if (clear_msg) {

main/stasis_cache_pattern.c

@@ -138,7 +138,7 @@ struct stasis_cp_single *stasis_cp_single_create(struct stasis_cp_all *all,
 {
 	RAII_VAR(struct stasis_cp_single *, one, NULL, ao2_cleanup);
 
-	one = stasis_cp_single_create_only(all, name);
+	one = stasis_cp_sink_create(all, name);
 	if (!one) {
 		return NULL;
 	}
@@ -157,7 +157,7 @@ struct stasis_cp_single *stasis_cp_single_create(struct stasis_cp_all *all,
 	return one;
 }
 
-struct stasis_cp_single *stasis_cp_single_create_only(struct stasis_cp_all *all,
+struct stasis_cp_single *stasis_cp_sink_create(struct stasis_cp_all *all,
 	const char *name)
 {
 	RAII_VAR(struct stasis_cp_single *, one, NULL, ao2_cleanup);
@@ -180,23 +180,6 @@ struct stasis_cp_single *stasis_cp_single_create_only(struct stasis_cp_all *all,
 	return one;
 }
 
-int stasis_cp_single_forward(struct stasis_cp_single *from, struct stasis_cp_single *to)
-{
-	from->forward_topic_to_all = stasis_forward_all(from->topic, to->topic);
-	if (!from->forward_topic_to_all) {
-		return -1;;
-	}
-
-	from->forward_cached_to_all = stasis_forward_all(
-		stasis_caching_get_topic(from->topic_cached),
-		stasis_caching_get_topic(to->topic_cached));
-	if (!from->forward_cached_to_all) {
-		return -1;
-	}
-
-	return 0;
-}
-
 void stasis_cp_single_unsubscribe(struct stasis_cp_single *one)
 {
 	if (!one) {