res_chan_stats.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2013, Digium, Inc.
 *
 * David M. Lee, II <dlee@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 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 <dlee@digium.com>
 * \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 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 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 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"
);