res/res_endpoint_stats: Add module to emit endpoint StatsD statistics

This patch adds a module that emits StatsD statistics about Asterisk
endpoints. This includes:
 * A GUAGE statistic for endpoint states, tracking how many endpoints are in
   a particular state.
 * A GUAGE statistic for each endpoint, counting the number of channels
   currently associated with an endpoint.

ASTERISK-25572

Change-Id: If7e1333c5aeda8d136850b30c2101c0ee1c97305

CHANGES

@@ -73,6 +73,18 @@ func_callerid
    The same applies to CONNECTEDLINE(pres), REDIRECTING(orig-pres),
    REDIRECTING(to-pres) and REDIRECTING(from-pres).
 
+res_endpoint_stats
+-------------------
+ * A new module that emits StatsD statistics regarding Asterisk endpoints.
+   This includes a total count of the number of endpoints, the count of the
+   number of endpoints in the technology agnosti state of the endpoint -
+   online or offline - as well as the number of channels associated with each
+   endpoint. These are recorded as three differeng GUAGE statistics:
+    - endpoints.count
+    - endpoints.state.{unknown|offline|online}
+    - endpoints.{tech}.{resource}.channels
+
+
 ------------------------------------------------------------------------------
 --- Functionality changes from Asterisk 13.5.0 to Asterisk 13.6.0 ------------
 ------------------------------------------------------------------------------

res/res_endpoint_stats.c

+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2015, Digium, Inc.
+ *
+ * Matthew Jordan <mjordan@digium.com>
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+/*!
+ * \brief Statsd Endpoint stats.
+ *
+ * This module subscribes to Stasis endpoints and send statistics
+ * based on their state.
+ *
+ * \author Matthew Jordan <mjordan@digium.com>
+ * \since 13.7.0
+ */
+
+/*** MODULEINFO
+	<depend>res_statsd</depend>
+	<defaultenabled>no</defaultenabled>
+	<support_level>extended</support_level>
+ ***/
+
+#include "asterisk.h"
+
+ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
+
+#include "asterisk/module.h"
+#include "asterisk/stasis_endpoints.h"
+#include "asterisk/stasis_message_router.h"
+#include "asterisk/statsd.h"
+
+/*! Stasis message router */
+static struct stasis_message_router *router;
+
+static void update_endpoint_state(struct ast_endpoint_snapshot *snapshot, const char *delta)
+{
+	switch (snapshot->state) {
+	case AST_ENDPOINT_UNKNOWN:
+		ast_statsd_log_string("endpoints.state.unknown", AST_STATSD_GUAGE, delta, 1.0);
+		break;
+	case AST_ENDPOINT_OFFLINE:
+		ast_statsd_log_string("endpoints.state.offline", AST_STATSD_GUAGE, delta, 1.0);
+		break;
+	case AST_ENDPOINT_ONLINE:
+		ast_statsd_log_string("endpoints.state.online", AST_STATSD_GUAGE, delta, 1.0);
+		break;
+	}
+}
+
+static void handle_endpoint_update(struct ast_endpoint_snapshot *old_snapshot, struct ast_endpoint_snapshot *new_snapshot)
+{
+	if (!old_snapshot && new_snapshot) {
+		ast_statsd_log_string("endpoints.count", AST_STATSD_GUAGE, "+1", 1.0);
+		update_endpoint_state(new_snapshot, "+1");
+	} else if (old_snapshot && !new_snapshot) {
+		ast_statsd_log_string("endpoints.count", AST_STATSD_GUAGE, "-1", 1.0);
+		update_endpoint_state(old_snapshot, "-1");
+	} else {
+		if (old_snapshot->state != new_snapshot->state) {
+			update_endpoint_state(old_snapshot, "-1");
+			update_endpoint_state(new_snapshot, "+1");
+		}
+		ast_statsd_log_full_va("endpoints.%s.%s.channels", AST_STATSD_GUAGE, new_snapshot->num_channels, 1.0,
+			new_snapshot->tech, new_snapshot->resource);
+	}
+}
+
+static void cache_update_cb(void *data, struct stasis_subscription *sub,
+	struct stasis_message *message)
+{
+	struct stasis_cache_update *update = stasis_message_data(message);
+	struct ast_endpoint_snapshot *old_snapshot;
+	struct ast_endpoint_snapshot *new_snapshot;
+
+	if (ast_endpoint_snapshot_type() != update->type) {
+		return;
+	}
+
+	old_snapshot = stasis_message_data(update->old_snapshot);
+	new_snapshot = stasis_message_data(update->new_snapshot);
+
+	handle_endpoint_update(old_snapshot, new_snapshot);
+}
+
+static int dump_cache_load(void *obj, void *arg, int flags)
+{
+	struct stasis_message *msg = obj;
+	struct ast_endpoint_snapshot *snapshot = stasis_message_data(msg);
+
+	handle_endpoint_update(NULL, snapshot);
+
+	return 0;
+}
+
+static int dump_cache_unload(void *obj, void *arg, int flags)
+{
+	struct stasis_message *msg = obj;
+	struct ast_endpoint_snapshot *snapshot = stasis_message_data(msg);
+
+	handle_endpoint_update(snapshot, NULL);
+
+	return 0;
+}
+
+static int load_module(void)
+{
+	struct ao2_container *endpoints;
+
+	router = stasis_message_router_create(ast_endpoint_topic_all_cached());
+	if (!router) {
+		return AST_MODULE_LOAD_FAILURE;
+	}
+	stasis_message_router_add(router, stasis_cache_update_type(), cache_update_cb, NULL);
+
+	endpoints = stasis_cache_dump(ast_endpoint_cache(), ast_endpoint_snapshot_type());
+	if (endpoints) {
+		ao2_callback(endpoints, OBJ_MULTIPLE | OBJ_NODATA | OBJ_NOLOCK, dump_cache_load, NULL);
+		ao2_ref(endpoints, -1);
+	}
+
+	return AST_MODULE_LOAD_SUCCESS;
+}
+
+static int unload_module(void)
+{
+	struct ao2_container *endpoints;
+
+	endpoints = stasis_cache_dump(ast_endpoint_cache(), ast_endpoint_snapshot_type());
+	if (endpoints) {
+		ao2_callback(endpoints, OBJ_MULTIPLE | OBJ_NODATA | OBJ_NOLOCK, dump_cache_unload, NULL);
+		ao2_ref(endpoints, -1);
+	}
+
+	stasis_message_router_unsubscribe_and_join(router);
+	router = NULL;
+
+	return 0;
+}
+
+AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "Endpoint statistics",
+	.support_level = AST_MODULE_SUPPORT_EXTENDED,
+	.load = load_module,
+	.unload = unload_module,
+	.nonoptreq = "res_statsd"
+	);