[collectd] [PATCH] Added myplugin.c to contrib/examples/.

[Sebastian Harl]

This is a sample/template C plugin.

Signed-off-by: Sebastian Harl <sh at tokkee.org>
---
 contrib/examples/myplugin.c |  171 +++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 171 insertions(+), 0 deletions(-)
 create mode 100644 contrib/examples/myplugin.c

diff --git a/contrib/examples/myplugin.c b/contrib/examples/myplugin.c
new file mode 100644
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 at 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) */
+
-- 
1.5.2.1

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