Allow Exemplars on histogram _count (#930)

Signed-off-by: Fabian Stäber <[email protected]>
prometheus · Mar 21, 2024 · 40c3599 · 40c3599
1 parent fc447f8
commit 40c3599
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Showing 6 changed files with 184 additions and 37 deletions.
diff --git a/prometheus-metrics-config/src/main/java/io/prometheus/metrics/config/ExporterProperties.java b/prometheus-metrics-config/src/main/java/io/prometheus/metrics/config/ExporterProperties.java
@@ -27,7 +27,7 @@ public boolean getIncludeCreatedTimestamps() {
 
     /**
      * Allow Exemplars on all metric types in OpenMetrics format?
-     * Default is {@code false}, which means Exemplars will only be added for Counters and Histograms.
+     * Default is {@code false}, which means Exemplars will only be added for Counters and Histogram buckets.
      */
     public boolean getExemplarsOnAllMetricTypes() {
         return exemplarsOnAllMetricTypes != null && exemplarsOnAllMetricTypes;

diff --git a/...ts/src/main/java/io/prometheus/metrics/expositionformats/OpenMetricsTextFormatWriter.java b/...ts/src/main/java/io/prometheus/metrics/expositionformats/OpenMetricsTextFormatWriter.java
@@ -138,11 +138,9 @@ private void writeClassicHistogramBuckets(OutputStreamWriter writer, MetricMetad
                 }
                 writeScrapeTimestampAndExemplar(writer, data, exemplar);
             }
+            // In OpenMetrics format, histogram _count and _sum are either both present or both absent.
             if (data.hasCount() && data.hasSum()) {
-                // In OpenMetrics format, histogram _count and _sum are either both present or both absent.
-                // While Prometheus allows Exemplars for histogram's _count and _sum now, we don't
-                // use Exemplars here to be backwards compatible with previous behavior.
-                writeCountAndSum(writer, metadata, data, countSuffix, sumSuffix, Exemplars.EMPTY);
+                writeCountAndSum(writer, metadata, data, countSuffix, sumSuffix, exemplars);
             }
             writeCreated(writer, metadata, data);
         }
@@ -241,33 +239,27 @@ private void writeUnknown(OutputStreamWriter writer, UnknownSnapshot snapshot) t
             writeNameAndLabels(writer, metadata.getPrometheusName(), null, data.getLabels());
             writeDouble(writer, data.getValue());
             if (exemplarsOnAllMetricTypesEnabled) {
-            writeScrapeTimestampAndExemplar(writer, data, data.getExemplar());
+                writeScrapeTimestampAndExemplar(writer, data, data.getExemplar());
             } else {
                 writeScrapeTimestampAndExemplar(writer, data, null);
             }
         }
     }
 
     private void writeCountAndSum(OutputStreamWriter writer, MetricMetadata metadata, DistributionDataPointSnapshot data, String countSuffix, String sumSuffix, Exemplars exemplars) throws IOException {
-        int exemplarIndex = 0;
         if (data.hasCount()) {
             writeNameAndLabels(writer, metadata.getPrometheusName(), countSuffix, data.getLabels());
             writeLong(writer, data.getCount());
-            if (exemplars.size() > 0) {
-                writeScrapeTimestampAndExemplar(writer, data, exemplars.get(exemplarIndex));
-                exemplarIndex = exemplarIndex + 1 % exemplars.size();
+            if (exemplarsOnAllMetricTypesEnabled) {
+                writeScrapeTimestampAndExemplar(writer, data, exemplars.getLatest());
             } else {
                 writeScrapeTimestampAndExemplar(writer, data, null);
             }
         }
         if (data.hasSum()) {
             writeNameAndLabels(writer, metadata.getPrometheusName(), sumSuffix, data.getLabels());
             writeDouble(writer, data.getSum());
-            if (exemplars.size() > 0) {
-                writeScrapeTimestampAndExemplar(writer, data, exemplars.get(exemplarIndex));
-            } else {
-                writeScrapeTimestampAndExemplar(writer, data, null);
-            }
+            writeScrapeTimestampAndExemplar(writer, data, null);
         }
     }