Transition MWI to Stasis-core

Remove MWI's dependency on the event system by moving it to
Stasis-core. This also introduces forwarding topic pools in Stasis-core
which aggregate many dynamically allocated topics into a single primary
topic.

Review: https://reviewboard.asterisk.org/r/2368/
(closes issue ASTERISK-21097)
Patch-by: Kinsey Moore


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@383284 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/stasis.c

@@ -41,6 +41,9 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 /*! Initial size of the subscribers list. */
 #define INITIAL_SUBSCRIBERS_MAX 4
 
+/*! The number of buckets to use for topic pools */
+#define TOPIC_POOL_BUCKETS 57
+
 /*! Threadpool for dispatching notifications to subscribers */
 static struct ast_threadpool *pool;
 
@@ -470,6 +473,96 @@ static void send_subscription_change_message(struct stasis_topic *topic, char *u
 	stasis_publish(topic, msg);
 }
 
+struct topic_pool_entry {
+	struct stasis_subscription *forward;
+	struct stasis_topic *topic;
+};
+
+static void topic_pool_entry_dtor(void *obj)
+{
+	struct topic_pool_entry *entry = obj;
+	entry->forward = stasis_unsubscribe(entry->forward);
+	ao2_cleanup(entry->topic);
+	entry->topic = NULL;
+}
+
+static struct topic_pool_entry *topic_pool_entry_alloc(void)
+{
+	return ao2_alloc(sizeof(struct topic_pool_entry), topic_pool_entry_dtor);
+}
+
+struct stasis_topic_pool {
+	struct ao2_container *pool_container;
+	struct stasis_topic *pool_topic;
+};
+
+static void topic_pool_dtor(void *obj)
+{
+	struct stasis_topic_pool *pool = obj;
+	ao2_cleanup(pool->pool_container);
+	pool->pool_container = NULL;
+	ao2_cleanup(pool->pool_topic);
+	pool->pool_topic = NULL;
+}
+
+static int topic_pool_entry_hash(const void *obj, const int flags)
+{
+	const char *topic_name= (flags & OBJ_KEY) ? obj : stasis_topic_name(((struct topic_pool_entry*) obj)->topic);
+	return ast_str_case_hash(topic_name);
+}
+
+static int topic_pool_entry_cmp(void *obj, void *arg, int flags)
+{
+	struct topic_pool_entry *opt1 = obj, *opt2 = arg;
+	const char *topic_name = (flags & OBJ_KEY) ? arg : stasis_topic_name(opt2->topic);
+	return strcasecmp(stasis_topic_name(opt1->topic), topic_name) ? 0 : CMP_MATCH | CMP_STOP;
+}
+
+struct stasis_topic_pool *stasis_topic_pool_create(struct stasis_topic *pooled_topic)
+{
+	RAII_VAR(struct stasis_topic_pool *, pool, ao2_alloc(sizeof(*pool), topic_pool_dtor), ao2_cleanup);
+	if (!pool) {
+		return NULL;
+	}
+	pool->pool_container = ao2_container_alloc(TOPIC_POOL_BUCKETS, topic_pool_entry_hash, topic_pool_entry_cmp);
+	ao2_ref(pooled_topic, +1);
+	pool->pool_topic = pooled_topic;
+
+	ao2_ref(pool, +1);
+	return pool;
+}
+
+struct stasis_topic *stasis_topic_pool_get_topic(struct stasis_topic_pool *pool, const char *topic_name)
+{
+	RAII_VAR(struct topic_pool_entry *, topic_pool_entry, NULL, ao2_cleanup);
+	SCOPED_AO2LOCK(topic_container_lock, pool->pool_container);
+	topic_pool_entry = ao2_find(pool->pool_container, topic_name, OBJ_KEY | OBJ_NOLOCK);
+
+	if (topic_pool_entry) {
+		return topic_pool_entry->topic;
+	}
+
+	topic_pool_entry = topic_pool_entry_alloc();
+
+	if (!topic_pool_entry) {
+		return NULL;
+	}
+
+	topic_pool_entry->topic = stasis_topic_create(topic_name);
+	if (!topic_pool_entry->topic) {
+		return NULL;
+	}
+
+	topic_pool_entry->forward = stasis_forward_all(topic_pool_entry->topic, pool->pool_topic);
+	if (!topic_pool_entry->forward) {
+		return NULL;
+	}
+
+	ao2_link_flags(pool->pool_container, topic_pool_entry, OBJ_NOLOCK);
+
+	return topic_pool_entry->topic;
+}
+
 /*! \brief Cleanup function */
 static void stasis_exit(void)
 {