File: myplugin.c

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/*
 * /usr/share/doc/collectd/examples/myplugin.c
 *
 * A plugin template for collectd.
 *
 * Written by Sebastian Harl <sh@tokkee.org>
 *
 * This is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free
 * Software Foundation; only version 2 of the License is applicable.
 */

/*
 * Notes:
 * - plugins are executed in parallel, thus, thread-safe
 *   functions need to be used
 * - each of the functions below (except module_register)
 *   is optional
 */

#if !HAVE_CONFIG_H

#include <stdlib.h>

#include <string.h>

#ifndef __USE_ISOC99 /* required for NAN */
#define DISABLE_ISOC99 1
#define __USE_ISOC99 1
#endif /* !defined(__USE_ISOC99) */
#include <math.h>
#if DISABLE_ISOC99
#undef DISABLE_ISOC99
#undef __USE_ISOC99
#endif /* DISABLE_ISOC99 */

#include <time.h>

#endif /* ! HAVE_CONFIG */

#include <collectd/core/daemon/collectd.h>

#include <collectd/core/daemon/common.h>
#include <collectd/core/daemon/plugin.h>

/*
 * data source definition:
 * - name of the data source
 * - type of the data source (DS_TYPE_GAUGE, DS_TYPE_COUNTER)
 * - minimum allowed value
 * - maximum allowed value
 */
static data_source_t dsrc[1] = {{"my_ds", DS_TYPE_GAUGE, 0, NAN}};

/*
 * data set definition:
 * - name of the data set
 * - number of data sources
 * - list of data sources
 *
 * NOTE: If you're defining a custom data-set, you have to make that known to
 * any servers as well. Else, the server is not able to store values using the
 * type defined by that data-set.
 * It is strongly recommended to use one of the types and data-sets
 * pre-defined in the types.db file.
 */
static data_set_t ds = {"myplugin", STATIC_ARRAY_SIZE(dsrc), dsrc};

/*
 * This function is called once upon startup to initialize the plugin.
 */
static int my_init(void) {
  /* open sockets, initialize data structures, ... */

  /* A return value != 0 indicates an error and causes the plugin to be
     disabled. */
  return 0;
} /* static int my_init (void) */

/*
 * This is a utility function used by the read callback to populate a
 * value_list_t and pass it to plugin_dispatch_values.
 */
static int my_submit(gauge_t value) {
  value_list_t vl = VALUE_LIST_INIT;

  /* Convert the gauge_t to a value_t and add it to the value_list_t. */
  vl.values = &(value_t){.gauge = value};
  vl.values_len = 1;

  /* Only set vl.time yourself if you update multiple metrics (i.e. you
   * have multiple calls to plugin_dispatch_values()) and they need to all
   * have the same timestamp. */
  /* vl.time = cdtime(); */

  sstrncpy(vl.plugin, "myplugin", sizeof(vl.plugin));

  /* it is strongly recommended to use a type defined in the types.db file
   * instead of a custom type */
  sstrncpy(vl.type, "myplugin", sizeof(vl.type));
  /* optionally set vl.plugin_instance and vl.type_instance to reasonable
   * values (default: "") */

  /* dispatch the values to collectd which passes them on to all registered
   * write functions */
  return plugin_dispatch_values(&vl);
}

/*
 * This function is called in regular intervalls to collect the data.
 */
static int my_read(void) {
  /* do the magic to read the data */
  gauge_t value = random();

  if (my_submit(value) != 0)
    WARNING("myplugin plugin: Dispatching a random value failed.");

  /* A return value != 0 indicates an error and the plugin will be skipped
   * for an increasing amount of time. */
  return 0;
} /* static int my_read (void) */

/*
 * This function is called after values have been dispatched to collectd.
 */
static int my_write(const data_set_t *ds, const value_list_t *vl,
                    user_data_t *ud) {
  char name[1024] = "";
  int i = 0;

  if (ds->ds_num != vl->values_len) {
    plugin_log(LOG_WARNING, "DS number does not match values length");
    return -1;
  }

  /* get the default base filename for the output file - depending on the
   * provided values this will be something like
   * <host>/<plugin>[-<plugin_type>]/<instance>[-<instance_type>] */
  if (0 != format_name(name, 1024, vl->host, vl->plugin, vl->plugin_instance,
                       ds->type, vl->type_instance))
    return -1;

  for (i = 0; i < ds->ds_num; ++i) {
    /* do the magic to output the data */
    printf("%s (%s) at %i: ", name,
           (ds->ds->type == DS_TYPE_GAUGE) ? "GAUGE" : "COUNTER",
           (int)vl->time);

    if (ds->ds->type == DS_TYPE_GAUGE)
      printf("%f\n", vl->values[i].gauge);
    else
      printf("%lld\n", vl->values[i].counter);
  }
  return 0;
} /* static int my_write (data_set_t *, value_list_t *) */

/*
 * This function is called when plugin_log () has been used.
 */
static void my_log(int severity, const char *msg, user_data_t *ud) {
  printf("LOG: %i - %s\n", severity, msg);
  return;
} /* static void my_log (int, const char *) */

/*
 * This function is called when plugin_dispatch_notification () has been used.
 */
static int my_notify(const notification_t *notif, user_data_t *ud) {
  char time_str[32] = "";
  struct tm *tm = NULL;

  int n = 0;

  if (NULL == (tm = localtime(&notif->time)))
    time_str[0] = '\0';

  n = strftime(time_str, 32, "%F %T", tm);
  if (n >= 32)
    n = 31;
  time_str[n] = '\0';

  printf("NOTIF (%s): %i - ", time_str, notif->severity);

  if ('\0' != *notif->host)
    printf("%s: ", notif->host);

  if ('\0' != *notif->plugin)
    printf("%s: ", notif->plugin);

  if ('\0' != *notif->plugin_instance)
    printf("%s: ", notif->plugin_instance);

  if ('\0' != *notif->type)
    printf("%s: ", notif->type);

  if ('\0' != *notif->type_instance)
    printf("%s: ", notif->type_instance);

  printf("%s\n", notif->message);
  return 0;
} /* static int my_notify (notification_t *) */

/*
 * This function is called before shutting down collectd.
 */
static int my_shutdown(void) {
  /* close sockets, free data structures, ... */
  return 0;
} /* static int my_shutdown (void) */

/*
 * This function is called after loading the plugin to register it with
 * collectd.
 */
void module_register(void) {
  plugin_register_log("myplugin", my_log, /* user data */ NULL);
  plugin_register_notification("myplugin", my_notify,
                               /* user data */ NULL);
  plugin_register_data_set(&ds);
  plugin_register_read("myplugin", my_read);
  plugin_register_init("myplugin", my_init);
  plugin_register_write("myplugin", my_write, /* user data */ NULL);
  plugin_register_shutdown("myplugin", my_shutdown);
  return;
} /* void module_register (void) */