Merge remote-tracking branch 'github/pr/1931'

[collectd.git] / contrib / examples / myplugin.c

diff --git a/contrib/examples/myplugin.c b/contrib/examples/myplugin.c
index cdd537a..71fb5f8 100644 (file)
--- a/contrib/examples/myplugin.c
+++ b/contrib/examples/myplugin.c
@@ -39,6 +39,7 @@
 #endif /* ! HAVE_CONFIG */
 
 #include <collectd/collectd.h>
+
 #include <collectd/common.h>
 #include <collectd/plugin.h>
 
@@ -59,6 +60,12 @@ static data_source_t dsrc[1] =
  * - 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 =
 {
@@ -78,39 +85,57 @@ static int my_init (void)
 } /* static int my_init (void) */
 
 /*
- * This function is called in regular intervalls to collect the data.
+ * 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_read (void)
+static int my_submit (gauge_t value)
 {
-       value_t values[1]; /* the size of this list should equal the number of
-                                                 data sources */
        value_list_t vl = VALUE_LIST_INIT;
 
-       /* do the magic to read the data */
-       values[0].gauge = random ();
-
-       vl.values     = values;
+       /* 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;
-       vl.time       = time (NULL);
-       strcpy (vl.host, hostname_g);
-       strcpy (vl.plugin, "myplugin");
+
+       /* 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.host, hostname_g, sizeof (vl.host));
+       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 - the first argument is used to lookup the data set
-        * definition */
-       plugin_dispatch_values ("myplugin", &vl);
+        * 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;
+       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)
+static int my_write (const data_set_t *ds, const value_list_t *vl,
+               user_data_t *ud)
 {
        char name[1024] = "";
        int i = 0;
@@ -144,7 +169,7 @@ static int my_write (const data_set_t *ds, const value_list_t *vl)
 /*
  * This function is called when plugin_log () has been used.
  */
-static void my_log (int severity, const char *msg)
+static void my_log (int severity, const char *msg, user_data_t *ud)
 {
        printf ("LOG: %i - %s\n", severity, msg);
        return;
@@ -153,7 +178,7 @@ static void my_log (int severity, const char *msg)
 /*
  * This function is called when plugin_dispatch_notification () has been used.
  */
-static int my_notify (const notification_t *notif)
+static int my_notify (const notification_t *notif, user_data_t *ud)
 {
        char time_str[32] = "";
        struct tm *tm = NULL;
@@ -203,12 +228,13 @@ static int my_shutdown (void)
  */
 void module_register (void)
 {
-       plugin_register_log ("myplugin", my_log);
-       plugin_register_notification ("myplugin", my_notify);
+       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);
+       plugin_register_write ("myplugin", my_write, /* user data */ NULL);
        plugin_register_shutdown ("myplugin", my_shutdown);
     return;
 } /* void module_register (void) */