bridges.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2019 Sangoma, Inc.
 *
 * Matt Jordan <[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.
 */

/*!
 * \file
 * \brief Prometheus Bridge Metrics
 *
 * \author Matt Jordan <[email protected]>
 *
 */

#include "asterisk.h"

#include "asterisk/stasis_bridges.h"
#include "asterisk/res_prometheus.h"
#include "prometheus_internal.h"

#define BRIDGES_CHANNELS_COUNT_HELP "Number of channels in the bridge."

/*!
 * \internal
 * \brief Callback function to get the number of channels in a bridge
 *
 * \param metric The metric to populate
 * \snapshot Bridge snapshot
 */
static void get_bridge_channel_count(struct prometheus_metric *metric, struct ast_bridge_snapshot *snapshot)
{
   snprintf(metric->value, sizeof(metric->value), "%d", snapshot->num_channels);
}

/*!
 * \internal
 * \brief Helper struct for generating individual bridge stats
 */
struct bridge_metric_defs {
   /*!
    * \brief Help text to display
    */
   const char *help;
   /*!
    * \brief Name of the metric
    */
   const char *name;
   /*!
    * \brief Callback function to generate a metric value for a given bridge
    */
   void (* const get_value)(struct prometheus_metric *metric, struct ast_bridge_snapshot *snapshot);
} bridge_metric_defs[] = {
   {
      .help = BRIDGES_CHANNELS_COUNT_HELP,
      .name = "asterisk_bridges_channels_count",
      .get_value = get_bridge_channel_count,
   },
};

/*!
 * \internal
 * \brief Callback invoked when Prometheus scrapes the server
 *
 * \param response The response to populate with formatted metrics
 */
static void bridges_scrape_cb(struct ast_str **response)
{
   struct ao2_container *bridge_cache;
   struct ao2_container *bridges;
   struct ao2_iterator it_bridges;
   struct ast_bridge *bridge;
   struct prometheus_metric *bridge_metrics;
   char eid_str[32];
   int i, j, num_bridges;
   struct prometheus_metric bridge_count = PROMETHEUS_METRIC_STATIC_INITIALIZATION(
      PROMETHEUS_METRIC_GAUGE,
      "asterisk_bridges_count",
      "Current bridge count.",
      NULL
   );

   ast_eid_to_str(eid_str, sizeof(eid_str), &ast_eid_default);

   bridge_cache = ast_bridges();
   if (!bridge_cache) {
      return;
   }

   bridges = ao2_container_clone(bridge_cache, 0);
   ao2_ref(bridge_cache, -1);
   if (!bridges) {
      return;
   }

   num_bridges = ao2_container_count(bridges);

   /* Current endpoint count */
   PROMETHEUS_METRIC_SET_LABEL(&bridge_count, 0, "eid", eid_str);
   snprintf(bridge_count.value, sizeof(bridge_count.value), "%d", num_bridges);
   prometheus_metric_to_string(&bridge_count, response);

   if (num_bridges == 0) {
      ao2_ref(bridges, -1);
      return;
   }

   bridge_metrics = ast_calloc(ARRAY_LEN(bridge_metric_defs) * num_bridges, sizeof(*bridge_metrics));
   if (!bridge_metrics) {
      ao2_ref(bridges, -1);
      return;
   }

   /* Bridge dependent values */
   it_bridges = ao2_iterator_init(bridges, 0);
   for (i = 0; (bridge = ao2_iterator_next(&it_bridges)); ao2_ref(bridge, -1), i++) {
      struct ast_bridge_snapshot *snapshot = ast_bridge_get_snapshot(bridge);

      for (j = 0; j < ARRAY_LEN(bridge_metric_defs); j++) {
         int index = i * ARRAY_LEN(bridge_metric_defs) + j;

         bridge_metrics[index].type = PROMETHEUS_METRIC_GAUGE;
         ast_copy_string(bridge_metrics[index].name, bridge_metric_defs[j].name, sizeof(bridge_metrics[index].name));
         bridge_metrics[index].help = bridge_metric_defs[j].help;
         PROMETHEUS_METRIC_SET_LABEL(&bridge_metrics[index], 0, "eid", eid_str);
         PROMETHEUS_METRIC_SET_LABEL(&bridge_metrics[index], 1, "id", (snapshot->uniqueid));
         PROMETHEUS_METRIC_SET_LABEL(&bridge_metrics[index], 2, "tech", (snapshot->technology));
         PROMETHEUS_METRIC_SET_LABEL(&bridge_metrics[index], 3, "subclass", (snapshot->subclass));
         PROMETHEUS_METRIC_SET_LABEL(&bridge_metrics[index], 4, "creator", (snapshot->creator));
         PROMETHEUS_METRIC_SET_LABEL(&bridge_metrics[index], 5, "name", (snapshot->name));
         bridge_metric_defs[j].get_value(&bridge_metrics[index], snapshot);

         if (i > 0) {
            AST_LIST_INSERT_TAIL(&bridge_metrics[j].children, &bridge_metrics[index], entry);
         }
      }
      ao2_ref(snapshot, -1);
   }
   ao2_iterator_destroy(&it_bridges);

   for (j = 0; j < ARRAY_LEN(bridge_metric_defs); j++) {
      prometheus_metric_to_string(&bridge_metrics[j], response);
   }

   ast_free(bridge_metrics);
   ao2_ref(bridges, -1);
}

struct prometheus_callback bridges_callback = {
   .name = "bridges callback",
   .callback_fn = bridges_scrape_cb,
};

/*!
 * \internal
 * \brief Callback invoked when the core module is unloaded
 */
static void bridge_metrics_unload_cb(void)
{
   prometheus_callback_unregister(&bridges_callback);
}

/*!
 * \internal
 * \brief Metrics provider definition
 */
static struct prometheus_metrics_provider provider = {
   .name = "bridges",
   .unload_cb = bridge_metrics_unload_cb,
};

int bridge_metrics_init(void)
{
   prometheus_metrics_provider_register(&provider);
   prometheus_callback_register(&bridges_callback);

   return 0;
}