Added myplugin.c to contrib/examples/.

This is a sample/template C plugin.

Signed-off-by: Sebastian Harl <sh@tokkee.org>
Signed-off-by: Florian Forster <octo@huhu.verplant.org>

diff --git a/contrib/examples/myplugin.c b/contrib/examples/myplugin.c
new file mode 100644 (file)
index 0000000..fc7856b
--- /dev/null
+++ b/contrib/examples/myplugin.c
@@ -0,0 +1,171 @@
+/*
+ * /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
+ */
+
+#include <stdio.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 <collectd/collectd.h>
+#include <collectd/common.h>
+#include <collectd/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
+ */
+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 function is called in regular intervalls to collect the data.
+ */
+static int my_read (void)
+{
+       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;
+       vl.values_len = 1;
+       vl.time       = time (NULL);
+       strcpy (vl.host, hostname_g);
+       strcpy (vl.plugin, "myplugin");
+       /* 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);
+
+       /* 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)
+{
+       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)
+{
+       printf ("LOG: %i - %s\n", severity, msg);
+       return;
+} /* static void my_log (int, const char *) */
+
+/*
+ * 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);
+       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_shutdown ("myplugin", my_shutdown);
+    return;
+} /* void module_register (void) */
+