SOLR-17628: Add query quantiles metrics to prometheus endpoint

solr/core/src/java/org/apache/solr/metrics/prometheus/SolrPrometheusFormatter.java

@@ -18,17 +18,23 @@
 
 import com.codahale.metrics.Meter;
 import com.codahale.metrics.Metric;
+import com.codahale.metrics.Snapshot;
 import com.codahale.metrics.Timer;
 import io.prometheus.metrics.model.snapshots.CounterSnapshot;
 import io.prometheus.metrics.model.snapshots.GaugeSnapshot;
 import io.prometheus.metrics.model.snapshots.Labels;
 import io.prometheus.metrics.model.snapshots.MetricMetadata;
 import io.prometheus.metrics.model.snapshots.MetricSnapshot;
 import io.prometheus.metrics.model.snapshots.MetricSnapshots;
+import io.prometheus.metrics.model.snapshots.Quantile;
+import io.prometheus.metrics.model.snapshots.Quantiles;
+import io.prometheus.metrics.model.snapshots.SummarySnapshot;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import org.apache.solr.util.stats.MetricUtils;
 
 /**
  * Base class for all {@link SolrPrometheusFormatter} holding {@link MetricSnapshot}s. Can export
@@ -38,10 +44,12 @@
 public abstract class SolrPrometheusFormatter {
   protected final Map<String, List<CounterSnapshot.CounterDataPointSnapshot>> metricCounters;
   protected final Map<String, List<GaugeSnapshot.GaugeDataPointSnapshot>> metricGauges;
+  protected final Map<String, List<SummarySnapshot.SummaryDataPointSnapshot>> metricSummaries;
 
   public SolrPrometheusFormatter() {
     this.metricCounters = new HashMap<>();
     this.metricGauges = new HashMap<>();
+    this.metricSummaries = new HashMap<>();
   }
 
   /**
@@ -93,18 +101,36 @@ public void exportCounter(
   }
 
   /**
-   * Export {@link Timer} ands its mean rate to {@link
-   * io.prometheus.metrics.model.snapshots.GaugeSnapshot.GaugeDataPointSnapshot} and collect
+   * Export {@link Timer} ands its quantile data to {@link
+   * io.prometheus.metrics.model.snapshots.SummarySnapshot.SummaryDataPointSnapshot} and collect
    * datapoint
    *
    * @param metricName name of prometheus metric
    * @param dropwizardMetric the {@link Timer} to be exported
    * @param labels label names and values to record
    */
   public void exportTimer(String metricName, Timer dropwizardMetric, Labels labels) {
-    GaugeSnapshot.GaugeDataPointSnapshot dataPoint =
-        createGaugeDatapoint(dropwizardMetric.getSnapshot().getMean(), labels);
-    collectGaugeDatapoint(metricName, dataPoint);
+    Snapshot snapshot = dropwizardMetric.getSnapshot();
+
+    long count = snapshot.size();
+    double sum =
+        Arrays.stream(snapshot.getValues())
+            .asDoubleStream()
+            .map(num -> MetricUtils.nsToMs(num))
+            .sum();
+
+    Quantiles quantiles =
+        Quantiles.of(
+            List.of(
+                new Quantile(0.50, MetricUtils.nsToMs(snapshot.getMedian())),
+                new Quantile(0.75, MetricUtils.nsToMs(snapshot.get75thPercentile())),
+                new Quantile(0.99, MetricUtils.nsToMs(snapshot.get99thPercentile())),
+                new Quantile(0.999, MetricUtils.nsToMs(snapshot.get999thPercentile()))));
+
+    SummarySnapshot.SummaryDataPointSnapshot summary =
+        createSummaryDataPointSnapshot(count, sum, quantiles, labels);
+
+    collectSummaryDatapoint(metricName, summary);
   }
 
   /**
@@ -176,6 +202,25 @@ public GaugeSnapshot.GaugeDataPointSnapshot createGaugeDatapoint(double value, L
     return GaugeSnapshot.GaugeDataPointSnapshot.builder().value(value).labels(labels).build();
   }
 
+  /**
+   * Create a {@link io.prometheus.metrics.model.snapshots.SummarySnapshot.SummaryDataPointSnapshot}
+   * with labels
+   *
+   * @param count number of observations
+   * @param sum sum of all values
+   * @param quantiles quantile information
+   * @param labels set of name/values labels
+   */
+  public SummarySnapshot.SummaryDataPointSnapshot createSummaryDataPointSnapshot(
+      long count, double sum, Quantiles quantiles, Labels labels) {
+    return SummarySnapshot.SummaryDataPointSnapshot.builder()
+        .count(count)
+        .sum(sum)
+        .labels(labels)
+        .quantiles(quantiles)
+        .build();
+  }
+
   /**
    * Collects {@link io.prometheus.metrics.model.snapshots.CounterSnapshot.CounterDataPointSnapshot}
    * and appends to existing metric or create new metric if name does not exist
@@ -206,6 +251,22 @@ public void collectGaugeDatapoint(
     metricGauges.get(metricName).add(dataPoint);
   }
 
+  /**
+   * Collects {@link io.prometheus.metrics.model.snapshots.SummarySnapshot.SummaryDataPointSnapshot}
+   * and appends to existing metric or create new metric if name does not exist
+   *
+   * @param metricName Name of metric
+   * @param dataPoint Gauge datapoint to be collected
+   */
+  public void collectSummaryDatapoint(
+      String metricName, SummarySnapshot.SummaryDataPointSnapshot dataPoint) {
+    if (!metricSummaries.containsKey(metricName)) {
+      metricSummaries.put(metricName, new ArrayList<>());
+    }
+
+    metricSummaries.get(metricName).add(dataPoint);
+  }
+
   /**
    * Returns an immutable {@link MetricSnapshots} from the {@link
    * io.prometheus.metrics.model.snapshots.DataPointSnapshot}s collected from the registry
@@ -220,6 +281,11 @@ public MetricSnapshots collect() {
       snapshots.add(
           new GaugeSnapshot(new MetricMetadata(metricName), metricGauges.get(metricName)));
     }
+    for (String metricName : metricSummaries.keySet()) {
+      snapshots.add(
+          new SummarySnapshot(new MetricMetadata(metricName), metricSummaries.get(metricName)));
+    }
+
     return new MetricSnapshots(snapshots);
   }
 }

solr/core/src/java/org/apache/solr/metrics/prometheus/core/SolrCoreHandlerMetric.java

@@ -28,7 +28,7 @@ public class SolrCoreHandlerMetric extends SolrCoreMetric {
   public static final String CORE_REQUESTS_TOTAL = "solr_metrics_core_requests";
   public static final String CORE_REQUESTS_UPDATE_HANDLER = "solr_metrics_core_update_handler";
   public static final String CORE_REQUESTS_TOTAL_TIME = "solr_metrics_core_requests_time";
-  public static final String CORE_REQUEST_TIMES = "solr_metrics_core_average_request_time";
+  public static final String CORE_REQUEST_TIMES = "solr_metrics_core_request_time";
 
   public SolrCoreHandlerMetric(Metric dropwizardMetric, String metricName) {
     super(dropwizardMetric, metricName);

solr/core/src/java/org/apache/solr/metrics/prometheus/core/SolrCoreSearcherMetric.java

@@ -27,7 +27,7 @@
 /** Dropwizard metrics of name SEARCHER.* */
 public class SolrCoreSearcherMetric extends SolrCoreMetric {
   public static final String CORE_SEARCHER_METRICS = "solr_metrics_core_searcher_documents";
-  public static final String CORE_SEARCHER_TIMES = "solr_metrics_core_average_searcher_warmup_time";
+  public static final String CORE_SEARCHER_TIMES = "solr_metrics_core_searcher_warmup_time";
 
   public SolrCoreSearcherMetric(Metric dropwizardMetric, String metricName) {
     super(dropwizardMetric, metricName);

solr/core/src/test/org/apache/solr/handler/admin/MetricsHandlerTest.java

@@ -25,6 +25,7 @@
 import io.prometheus.metrics.model.snapshots.Labels;
 import io.prometheus.metrics.model.snapshots.MetricSnapshot;
 import io.prometheus.metrics.model.snapshots.MetricSnapshots;
+import io.prometheus.metrics.model.snapshots.SummarySnapshot;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Map;
@@ -731,12 +732,12 @@ public void testPrometheusMetricsCore() throws Exception {
     assertNotNull(actualSnapshots);
 
     MetricSnapshot actualSnapshot =
-        getMetricSnapshot(actualSnapshots, "solr_metrics_core_average_request_time");
-    GaugeSnapshot.GaugeDataPointSnapshot actualGaugeDataPoint =
-        getGaugeDatapointSnapshot(
+        getMetricSnapshot(actualSnapshots, "solr_metrics_core_request_time");
+    SummarySnapshot.SummaryDataPointSnapshot actualSummaryDataPoint =
+        getSummaryDataPointSnapshot(
             actualSnapshot,
             Labels.of("category", "QUERY", "core", "collection1", "handler", "/select[shard]"));
-    assertEquals(0, actualGaugeDataPoint.getValue(), 0);
+    assertEquals(0, actualSummaryDataPoint.getCount(), 0);
 
     actualSnapshot = getMetricSnapshot(actualSnapshots, "solr_metrics_core_requests");
     CounterSnapshot.CounterDataPointSnapshot actualCounterDataPoint =
@@ -754,7 +755,7 @@ public void testPrometheusMetricsCore() throws Exception {
     assertEquals(0, actualCounterDataPoint.getValue(), 0);
 
     actualSnapshot = getMetricSnapshot(actualSnapshots, "solr_metrics_core_cache");
-    actualGaugeDataPoint =
+    GaugeSnapshot.GaugeDataPointSnapshot actualGaugeDataPoint =
         getGaugeDatapointSnapshot(
             actualSnapshot,
             Labels.of("cacheType", "fieldValueCache", "core", "collection1", "item", "hits"));
@@ -795,12 +796,11 @@ public void testPrometheusMetricsCore() throws Exception {
                 "updateHandler"));
     assertEquals(0, actualGaugeDataPoint.getValue(), 0);
 
-    actualSnapshot =
-        getMetricSnapshot(actualSnapshots, "solr_metrics_core_average_searcher_warmup_time");
-    actualGaugeDataPoint =
-        getGaugeDatapointSnapshot(
+    actualSnapshot = getMetricSnapshot(actualSnapshots, "solr_metrics_core_searcher_warmup_time");
+    actualSummaryDataPoint =
+        getSummaryDataPointSnapshot(
             actualSnapshot, Labels.of("core", "collection1", "type", "warmup"));
-    assertEquals(0, actualGaugeDataPoint.getValue(), 0);
+    assertEquals(0, actualSummaryDataPoint.getCount(), 0);
 
     handler.close();
   }
@@ -1184,6 +1184,15 @@ private CounterSnapshot.CounterDataPointSnapshot getCounterDatapointSnapshot(
             .get();
   }
 
+  private SummarySnapshot.SummaryDataPointSnapshot getSummaryDataPointSnapshot(
+      MetricSnapshot snapshot, Labels labels) {
+    return (SummarySnapshot.SummaryDataPointSnapshot)
+        snapshot.getDataPoints().stream()
+            .filter(ss -> ss.getLabels().hasSameValues(labels))
+            .findAny()
+            .get();
+  }
+
   static class RefreshablePluginHolder extends PluginBag.PluginHolder<SolrRequestHandler> {
 
     private DumpRequestHandler rh;

solr/core/src/test/org/apache/solr/metrics/SolrPrometheusFormatterTest.java

@@ -28,6 +28,7 @@
 import io.prometheus.metrics.model.snapshots.CounterSnapshot;
 import io.prometheus.metrics.model.snapshots.GaugeSnapshot;
 import io.prometheus.metrics.model.snapshots.Labels;
+import io.prometheus.metrics.model.snapshots.SummarySnapshot;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -84,11 +85,11 @@ public void testExportTimer() throws InterruptedException {
 
     Labels expectedLabels = Labels.of("test", "test-value");
     testFormatter.exportTimer(expectedMetricName, metric, expectedLabels);
-    assertTrue(testFormatter.getMetricGauges().containsKey(expectedMetricName));
+    assertTrue(testFormatter.getMetricSummaries().containsKey(expectedMetricName));
 
-    GaugeSnapshot.GaugeDataPointSnapshot actual =
-        testFormatter.getMetricGauges().get("test_metric").get(0);
-    assertEquals(5000000000L, actual.getValue(), 500000000L);
+    SummarySnapshot.SummaryDataPointSnapshot actual =
+        testFormatter.getMetricSummaries().get("test_metric").get(0);
+    assertEquals(5000L, actual.getSum(), 500L);
     assertEquals(expectedLabels, actual.getLabels());
   }
 
@@ -199,5 +200,9 @@ public Map<String, List<CounterSnapshot.CounterDataPointSnapshot>> getMetricCoun
     public Map<String, List<GaugeSnapshot.GaugeDataPointSnapshot>> getMetricGauges() {
       return metricGauges;
     }
+
+    public Map<String, List<SummarySnapshot.SummaryDataPointSnapshot>> getMetricSummaries() {
+      return metricSummaries;
+    }
   }
 }