stats: openmetrics: Do not duplicate counter and duration metrics for histograms

Histograms generate "_count" and "_sum" metrics either for each quantile or
for the whole distribution. This patch prevents creating a duplicate metric
with type counter which results in metric name collision.

diff --git a/src/stats/stats-service-openmetrics.c b/src/stats/stats-service-openmetrics.c
index f64abf7a81337bcc2d451bfca8634b51d9c561c0..f195bdb389b64ec267b51027aa9fac61e1bd18f1 100644 (file)
--- a/src/stats/stats-service-openmetrics.c
+++ b/src/stats/stats-service-openmetrics.c
@@ -123,10 +123,16 @@ openmetrics_export_metric_value(struct openmetrics_request *req, string_t *out,
        str_append(out, req->metric->name);
        switch (req->metric_type) {
        case OPENMETRICS_METRIC_TYPE_COUNT:
-               str_append(out, "_total");
+               if (req->metric->group_by != NULL && str_len(req->labels) == 0)
+                       str_append(out, "_count");
+               else
+                       str_append(out, "_total");
                break;
        case OPENMETRICS_METRIC_TYPE_DURATION:
-               str_append(out, "_duration_seconds_total");
+               if (req->metric->group_by != NULL && str_len(req->labels) == 0)
+                       str_append(out, "_duration_seconds_sum");
+               else
+                       str_append(out, "_duration_seconds_total");
                break;
        case OPENMETRICS_METRIC_TYPE_HISTOGRAM:
                i_unreached();
@@ -221,6 +227,13 @@ openmetrics_export_histogram(struct openmetrics_request *req, string_t *out,
                                                    group_by->ranges[i].max,
                                                    count);
        }
+
+       /* There is either no data in histogram, which adding the optional
+          sum and count metrics doesn't add any new information or
+          these have already been exported for submetrics. */
+       if (count == 0)
+               return;
+
        /* Sum */
        str_append(out, "dovecot_");
        str_append(out, metric->name);
@@ -565,8 +578,13 @@ openmetrics_export_continue(struct openmetrics_request *req, string_t *out)
                        str_truncate(req->labels, 0);
                req->labels_pos = 0;
 
-               /* Start with count output for this metric. */
-               req->metric_type = OPENMETRICS_METRIC_TYPE_COUNT;
+               /* Start with count output for this metric if the type
+                  is not histogram. If the metric is of type histogram,
+                  start with quantiles. */
+               if (openmetrics_export_has_histogram(req))
+                       req->metric_type = OPENMETRICS_METRIC_TYPE_HISTOGRAM;
+               else
+                       req->metric_type = OPENMETRICS_METRIC_TYPE_COUNT;
                req->state = OPENMETRICS_REQUEST_STATE_METRIC_HEADER;
                /* Fall through */
        case OPENMETRICS_REQUEST_STATE_METRIC_HEADER:
@@ -583,25 +601,15 @@ openmetrics_export_continue(struct openmetrics_request *req, string_t *out)
                if (!openmetrics_export_sub_metrics(req, out))
                        break;
                /* All sub-metrics written. */
-               if (req->metric_type == OPENMETRICS_METRIC_TYPE_HISTOGRAM ||
-                   req->has_submetric) {
-                       /* If either:
-
-                          - we're writing a histogram metric, or
-                          - sub-metrics are present,
-
-                          then skip the top-level metric body.
-                        */
-                       openmetrics_export_next(req);
-               } else {
-                       /* Export values for top-level metric */
-                       req->state = OPENMETRICS_REQUEST_STATE_METRIC_BODY;
-               }
+               req->state = OPENMETRICS_REQUEST_STATE_METRIC_BODY;
                break;
        case OPENMETRICS_REQUEST_STATE_METRIC_BODY:
                /* Export the body of the current metric. */
                str_truncate(req->labels, req->labels_pos);
-               openmetrics_export_metric_body(req, out);
+               if (req->metric_type == OPENMETRICS_METRIC_TYPE_HISTOGRAM)
+                       openmetrics_export_histogram(req, out, req->metric);
+               else
+                       openmetrics_export_metric_body(req, out);
                openmetrics_export_next(req);
                break;
        case OPENMETRICS_REQUEST_STATE_FINISHED: