add CounterGauge option in statsd (#3914)

diff --git a/src/collectd.conf.in b/src/collectd.conf.in
index f5b4fdcdceb1645bf192b31d67fd88cb1f54851e..6f06184cd31bfb3da581636b1e7845af8fd4255b 100644 (file)
--- a/src/collectd.conf.in
+++ b/src/collectd.conf.in
@@ -1719,6 +1719,7 @@
 #  DeleteGauges   false
 #  DeleteSets     false
 #  CounterSum     false
+#  CounterGauge   false
 #  TimerPercentile 90.0
 #  TimerPercentile 95.0
 #  TimerPercentile 99.0

diff --git a/src/collectd.conf.pod b/src/collectd.conf.pod
index 43855bdb4cfa37bbcbe517379fa29c396e4e3c6b..80e0d04921d7784afcb8b698d532129a61e1bd2c 100644 (file)
--- a/src/collectd.conf.pod
+++ b/src/collectd.conf.pod
@@ -9130,6 +9130,13 @@ When enabled, creates a C<count> metric which reports the change since the last
 read. This option primarily exists for compatibility with the I<statsd>
 implementation by Etsy.
 
+=item B<CounterSum> B<false>|B<true>
+
+When enabled, creates a C<gauge> metric which reports counters as a "gauge"
+of the differential, resetting the counter between flush intervals.  This
+option primarily exists for compatibility with the I<statsd> implementation
+in GitHub Enterprise Server.
+
 =item B<TimerPercentile> I<Percent>
 
 Calculate and dispatch the configured percentile, i.e. compute the latency, so

diff --git a/src/statsd.c b/src/statsd.c
index 9050596f9d3f1894830d479a4d8d09bed27c4c22..3d852ccdeac68dcf4211fb5ec5f1b317b563f565 100644 (file)
--- a/src/statsd.c
+++ b/src/statsd.c
@@ -80,6 +80,7 @@ static double *conf_timer_percentile;
 static size_t conf_timer_percentile_num;
 
 static bool conf_counter_sum;
+static bool conf_counter_gauge;
 static bool conf_timer_lower;
 static bool conf_timer_upper;
 static bool conf_timer_sum;
@@ -636,6 +637,8 @@ static int statsd_config(oconfig_item_t *ci) /* {{{ */
       cf_util_get_boolean(child, &conf_delete_gauges);
     else if (strcasecmp("DeleteSets", child->key) == 0)
       cf_util_get_boolean(child, &conf_delete_sets);
+    else if (strcasecmp("CounterGauge", child->key) == 0)
+      cf_util_get_boolean(child, &conf_counter_gauge);
     else if (strcasecmp("CounterSum", child->key) == 0)
       cf_util_get_boolean(child, &conf_counter_sum);
     else if (strcasecmp("TimerLower", child->key) == 0)
@@ -806,6 +809,43 @@ static int statsd_metric_submit_unsafe(char const *name,
       sstrncpy(vl.type, "derive", sizeof(vl.type));
     }
 
+    /*
+     * From: Vicent Marti <tanoku@gmail.com>
+     * Date: Mon, 15 Dec 2014 17:07:28 +0100
+     * Subject: [PATCH] Report Counters using the same behavior as StatsD
+     *
+     * The current implementation is not really compatible with what the
+     * reference StatsD implementation does. StatsD aggregates the increase in
+     * the counter during the flushing interval, and at flush, reports the
+     * current value as a differential and resets the counter.
+     *
+     * The implementation in Collectd instead never resets the counter, and
+     * always reports the *absolute* value to RRD as a DERIVE, assuming it will
+     * perform the differential itself. This behavior is rather surprising,
+     * particularly when graphing with tools that expect to be
+     * Graphite-compatible.
+     *
+     * This patch implements the right behavior by reporting counters as a
+     * "gauge" of the differential (i.e. resetting the counter between flush
+     * intervals). This mimics StatsD's behavior, and even the same behavior
+     * that Collectd performs when reporting the "count" row in a histogram --
+     * after all, the count row in the histogram should have the same semantics
+     * as a counter metric. This was previously inconsistent in this
+     * implementation. */
+    if (conf_counter_gauge) {
+      gauge_t previous_gauge = vl.values[0].gauge;
+
+      sstrncpy(vl.type, "gauge", sizeof(vl.type));
+      vl.values[0].gauge = (gauge_t)metric->value;
+      metric->value = 0.0;
+      plugin_dispatch_values(&vl);
+
+      /* restore vl.type and values[0].gauge */
+      sstrncpy(vl.type, "derive", sizeof(vl.type));
+      metric->value = vl.values[0].gauge;
+      vl.values[0].gauge = previous_gauge;
+    }
+
     /* Rather than resetting value to zero, subtract delta so we correctly keep
      * track of residuals. */
     metric->value -= delta;