res_chan_stats.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2013, Digium, Inc.
 *
 * David M. Lee, II <[email protected]>
 *
 * 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 channel stats. Exmaple of how to subscribe to Stasis events.
 *
 * This module subscribes to the channel caching topic and issues statsd stats
 * based on the received messages.
 *
 * \author David M. Lee, II <[email protected]>
 * \since 12
 */

/*** MODULEINFO
 <depend>res_statsd</depend>
 <defaultenabled>no</defaultenabled>
 <support_level>extended</support_level>
 ***/

#include "asterisk.h"

#include "asterisk/module.h"
#include "asterisk/stasis_channels.h"
#include "asterisk/stasis_message_router.h"
#include "asterisk/statsd.h"
#include "asterisk/time.h"

/*! Regular Stasis subscription */
static struct stasis_subscription *sub;
/*! Stasis message router */
static struct stasis_message_router *router;

/*!
 * \brief Subscription callback for all channel messages.
 * \param data Data pointer given when creating the subscription.
 * \param sub This subscription.
 * \param topic The topic the message was posted to. This is not necessarily the
 * topic you subscribed to, since messages may be forwarded between
 * topics.
 * \param message The message itself.
 */
static void statsmaker(void *data, struct stasis_subscription *sub,
 struct stasis_message *message)
{
 RAII_VAR(struct ast_str *, metric, NULL, ast_free);

 if (stasis_subscription_final_message(sub, message)) {
 /* Normally, data points to an object that must be cleaned up.
 * The final message is an unsubscribe notification that's
 * guaranteed to be the last message this subscription receives.
 * This would be a safe place to kick off any needed cleanup.
 */
 return;
 }

 /* For no good reason, count message types */
 metric = ast_str_create(80);
 if (metric) {
 ast_str_set(&metric, 0, "stasis.message.%s",
 stasis_message_type_name(stasis_message_type(message)));
 ast_statsd_log(ast_str_buffer(metric), AST_STATSD_METER, 1);
 }
}

/*!
 * \brief Router callback for \ref ast_channel_snapshot_update messages.
 * \param data Data pointer given when added to router.
 * \param sub This subscription.
 * \param topic The topic the message was posted to. This is not necessarily the
 * topic you subscribed to, since messages may be forwarded between
 * topics.
 * \param message The message itself.
 */
static void updates(void *data, struct stasis_subscription *sub,
 struct stasis_message *message)
{
 /* Since this came from a message router, we know the type of the
 * message. We can cast the data without checking its type.
 */
 struct ast_channel_snapshot_update *update = stasis_message_data(message);

 /* There are three types of channel snapshot updates.
 * !old && new -> Initial channel creation
 * old && new -> Updated channel snapshot
 * old && dead -> Final channel snapshot
 */

 if (!update->old_snapshot && update->new_snapshot) {
 /* Initial channel snapshot; count a channel creation */
 ast_statsd_log_string("channels.count", AST_STATSD_GAUGE, "+1", 1.0);
 } else if (update->old_snapshot && ast_test_flag(&update->new_snapshot->flags, AST_FLAG_DEAD)) {
 /* Channel is gone. Compute the age of the channel and post
 * that, as well as decrementing the channel count.
 */
 int64_t age;

 age = ast_tvdiff_ms(*stasis_message_timestamp(message),
 update->new_snapshot->base->creationtime);
 ast_statsd_log("channels.calltime", AST_STATSD_TIMER, age);

 /* And decrement the channel count */
 ast_statsd_log_string("channels.count", AST_STATSD_GAUGE, "-1", 1.0);
 }
}

/*!
 * \brief Router callback for any message that doesn't otherwise have a route.
 * \param data Data pointer given when added to router.
 * \param sub This subscription.
 * \param topic The topic the message was posted to. This is not necessarily the
 * topic you subscribed to, since messages may be forwarded between
 * topics.
 * \param message The message itself.
 */
static void default_route(void *data, struct stasis_subscription *sub,
 struct stasis_message *message)
{
 if (stasis_subscription_final_message(sub, message)) {
 /* Much like with the regular subscription, you may need to
 * perform some cleanup when done with a message router. You
 * can look for the final message in the default route.
 */
 return;
 }
}

static int unload_module(void)
{
 stasis_unsubscribe_and_join(sub);
 sub = NULL;
 stasis_message_router_unsubscribe_and_join(router);
 router = NULL;
 return 0;
}

static int load_module(void)
{
 /* You can create a message router to route messages by type */
 router = stasis_message_router_create(
 ast_channel_topic_all());
 if (!router) {
 return AST_MODULE_LOAD_DECLINE;
 }
 stasis_message_router_add(router, ast_channel_snapshot_type(),
 updates, NULL);
 stasis_message_router_set_default(router, default_route, NULL);

 /* Or a subscription to receive all of the messages from a topic */
 sub = stasis_subscribe(ast_channel_topic_all(), statsmaker, NULL);
 if (!sub) {
 unload_module();
 return AST_MODULE_LOAD_DECLINE;
 }
 return AST_MODULE_LOAD_SUCCESS;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "Example of how to use Stasis",
 .support_level = AST_MODULE_SUPPORT_EXTENDED,
 .load = load_module,
 .unload = unload_module,
 .requires = "res_statsd"
);