Add histogram to metrics system

CHANGELOG.md

@@ -42,6 +42,7 @@
 - Add a new metric collector for counters which get their value from suppliers [#7894](https://github.com/hyperledger/besu/pull/7894)
 - Add account and state overrides to `eth_call` [#7801](https://github.com/hyperledger/besu/pull/7801) and `eth_estimateGas` [#7890](https://github.com/hyperledger/besu/pull/7890)
 - Prometheus Java Metrics library upgraded to version 1.3.3 [#7880](https://github.com/hyperledger/besu/pull/7880)
+- Add histogram to Prometheus metrics system [#7944](https://github.com/hyperledger/besu/pull/7944)
 
 ### Bug fixes
 - Fix registering new metric categories from plugins [#7825](https://github.com/hyperledger/besu/pull/7825)

metrics/core/src/main/java/org/hyperledger/besu/metrics/noop/NoOpMetricsSystem.java

@@ -18,6 +18,7 @@
 import org.hyperledger.besu.metrics.Observation;
 import org.hyperledger.besu.plugin.services.metrics.Counter;
 import org.hyperledger.besu.plugin.services.metrics.ExternalSummary;
+import org.hyperledger.besu.plugin.services.metrics.Histogram;
 import org.hyperledger.besu.plugin.services.metrics.LabelledGauge;
 import org.hyperledger.besu.plugin.services.metrics.LabelledMetric;
 import org.hyperledger.besu.plugin.services.metrics.LabelledSuppliedMetric;
@@ -63,6 +64,9 @@ public class NoOpMetricsSystem implements ObservableMetricsSystem {
   public static final LabelledMetric<OperationTimer> NO_OP_LABELLED_1_OPERATION_TIMER =
       new LabelCountingNoOpMetric<>(1, NO_OP_OPERATION_TIMER);
 
+  /** The constant NO_OP_HISTOGRAM. */
+  public static final Histogram NO_OP_HISTOGRAM = d -> {};
+
   /** Default constructor */
   public NoOpMetricsSystem() {}
 
@@ -130,6 +134,26 @@ public void createGauge(
       final String help,
       final DoubleSupplier valueSupplier) {}
 
+  @Override
+  public LabelledMetric<Histogram> createLabelledHistogram(
+      final MetricCategory category,
+      final String name,
+      final String help,
+      final double[] buckets,
+      final String... labelNames) {
+    return getHistogramLabelledMetric(labelNames.length);
+  }
+
+  /**
+   * Gets histogram labelled metric.
+   *
+   * @param labelCount the label count
+   * @return the histogram labelled metric
+   */
+  public static LabelledMetric<Histogram> getHistogramLabelledMetric(final int labelCount) {
+    return new LabelCountingNoOpMetric<>(labelCount, NO_OP_HISTOGRAM);
+  }
+
   @Override
   public void createGuavaCacheCollector(
       final MetricCategory category, final String name, final Cache<?, ?> cache) {}

metrics/core/src/main/java/org/hyperledger/besu/metrics/opentelemetry/OpenTelemetrySystem.java

@@ -20,6 +20,7 @@
 import org.hyperledger.besu.metrics.StandardMetricCategory;
 import org.hyperledger.besu.metrics.noop.NoOpMetricsSystem;
 import org.hyperledger.besu.plugin.services.metrics.Counter;
+import org.hyperledger.besu.plugin.services.metrics.Histogram;
 import org.hyperledger.besu.plugin.services.metrics.LabelledMetric;
 import org.hyperledger.besu.plugin.services.metrics.LabelledSuppliedMetric;
 import org.hyperledger.besu.plugin.services.metrics.LabelledSuppliedSummary;
@@ -289,6 +290,17 @@ public void createGauge(
     }
   }
 
+  @Override
+  public LabelledMetric<Histogram> createLabelledHistogram(
+      final MetricCategory category,
+      final String name,
+      final String help,
+      final double[] buckets,
+      final String... labelNames) {
+    // not yet supported
+    return NoOpMetricsSystem.getHistogramLabelledMetric(labelNames.length);
+  }
+
   @Override
   public void createGuavaCacheCollector(
       final MetricCategory category, final String name, final Cache<?, ?> cache) {}

metrics/core/src/main/java/org/hyperledger/besu/metrics/prometheus/AbstractPrometheusHistogram.java

@@ -0,0 +1,113 @@
+/*
+ * Copyright contributors to Besu.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package org.hyperledger.besu.metrics.prometheus;
+
+import static org.hyperledger.besu.metrics.prometheus.PrometheusCollector.addLabelValues;
+import static org.hyperledger.besu.metrics.prometheus.PrometheusCollector.getLabelValues;
+
+import org.hyperledger.besu.metrics.Observation;
+import org.hyperledger.besu.plugin.services.metrics.MetricCategory;
+
+import java.util.ArrayList;
+import java.util.stream.Stream;
+
+import io.prometheus.metrics.core.metrics.Histogram;
+import io.prometheus.metrics.model.registry.PrometheusRegistry;
+
+/**
+ * Abstract base class for Prometheus histogram collectors. A histogram samples durations and counts
+ * them in configurable buckets. * It also provides a sum of all observed values.
+ */
+abstract class AbstractPrometheusHistogram extends CategorizedPrometheusCollector {
+  protected Histogram histogram;
+
+  protected AbstractPrometheusHistogram(
+      final MetricCategory category,
+      final String name,
+      final String help,
+      final double[] buckets,
+      final String... labelNames) {
+    super(category, name);
+    this.histogram =
+        Histogram.builder()
+            .name(this.prefixedName)
+            .help(help)
+            .labelNames(labelNames)
+            .classicOnly()
+            .classicUpperBounds(buckets)
+            .build();
+  }
+
+  @Override
+  public String getIdentifier() {
+    return histogram.getPrometheusName();
+  }
+
+  @Override
+  public void register(final PrometheusRegistry registry) {
+    registry.register(histogram);
+  }
+
+  @Override
+  public void unregister(final PrometheusRegistry registry) {
+    registry.unregister(histogram);
+  }
+
+  @Override
+  public Stream<Observation> streamObservations() {
+    final var snapshot = histogram.collect();
+    return snapshot.getDataPoints().stream()
+        .flatMap(
+            dataPoint -> {
+              if (!dataPoint.hasClassicHistogramData()) {
+                throw new IllegalStateException("Only classic histogram are supported");
+              }
+
+              final var labelValues = getLabelValues(dataPoint.getLabels());
+              final var classicBuckets = dataPoint.getClassicBuckets();
+              final var observations = new ArrayList<Observation>(classicBuckets.size() + 2);
+
+              if (dataPoint.hasSum()) {
+                observations.add(
+                    new Observation(
+                        category, name, dataPoint.getSum(), addLabelValues(labelValues, "sum")));
+              }
+
+              if (dataPoint.hasCount()) {
+                observations.add(
+                    new Observation(
+                        category,
+                        name,
+                        dataPoint.getCount(),
+                        addLabelValues(labelValues, "count")));
+              }
+
+              classicBuckets.stream()
+                  .forEach(
+                      bucket ->
+                          observations.add(
+                              new Observation(
+                                  category,
+                                  name,
+                                  bucket.getCount(),
+                                  addLabelValues(
+                                      labelValues,
+                                      "bucket",
+                                      Double.toString(bucket.getUpperBound())))));
+
+              return observations.stream();
+            });
+  }
+}

metrics/core/src/main/java/org/hyperledger/besu/metrics/prometheus/PrometheusHistogram.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright contributors to Besu.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package org.hyperledger.besu.metrics.prometheus;
+
+import org.hyperledger.besu.plugin.services.metrics.Histogram;
+import org.hyperledger.besu.plugin.services.metrics.LabelledMetric;
+import org.hyperledger.besu.plugin.services.metrics.MetricCategory;
+
+/**
+ * A Prometheus histogram. A histogram samples durations and counts them in configurable buckets. It
+ * also provides a sum of all observed values.
+ */
+class PrometheusHistogram extends AbstractPrometheusHistogram implements LabelledMetric<Histogram> {
+
+  public PrometheusHistogram(
+      final MetricCategory category,
+      final String name,
+      final String help,
+      final double[] buckets,
+      final String... labelNames) {
+    super(category, name, help, buckets, labelNames);
+  }
+
+  @Override
+  public Histogram labels(final String... labels) {
+    final var ddp = histogram.labelValues(labels);
+    return ddp::observe;
+  }
+}

metrics/core/src/main/java/org/hyperledger/besu/metrics/prometheus/PrometheusMetricsSystem.java

@@ -21,6 +21,7 @@
 import org.hyperledger.besu.metrics.StandardMetricCategory;
 import org.hyperledger.besu.metrics.noop.NoOpMetricsSystem;
 import org.hyperledger.besu.plugin.services.metrics.Counter;
+import org.hyperledger.besu.plugin.services.metrics.Histogram;
 import org.hyperledger.besu.plugin.services.metrics.LabelledMetric;
 import org.hyperledger.besu.plugin.services.metrics.LabelledSuppliedMetric;
 import org.hyperledger.besu.plugin.services.metrics.LabelledSuppliedSummary;
@@ -67,6 +68,9 @@ public class PrometheusMetricsSystem implements ObservableMetricsSystem {
       new ConcurrentHashMap<>();
   private final Map<CachedMetricKey, LabelledMetric<OperationTimer>> cachedTimers =
       new ConcurrentHashMap<>();
+  private final Map<CachedMetricKey, LabelledMetric<Histogram>> cachedHistograms =
+      new ConcurrentHashMap<>();
+
   private final PrometheusGuavaCache.Context guavaCacheCollectorContext =
       new PrometheusGuavaCache.Context();
 
@@ -164,6 +168,26 @@ public LabelledMetric<OperationTimer> createSimpleLabelledTimer(
         });
   }
 
+  @Override
+  public LabelledMetric<Histogram> createLabelledHistogram(
+      final MetricCategory category,
+      final String name,
+      final String help,
+      final double[] buckets,
+      final String... labelNames) {
+    return cachedHistograms.computeIfAbsent(
+        CachedMetricKey.of(category, name),
+        k -> {
+          if (isCategoryEnabled(category)) {
+            final var histogram =
+                new PrometheusHistogram(category, name, help, buckets, labelNames);
+            registerCollector(category, histogram);
+            return histogram;
+          }
+          return NoOpMetricsSystem.getHistogramLabelledMetric(labelNames.length);
+        });
+  }
+
   @Override
   public LabelledSuppliedSummary createLabelledSuppliedSummary(
       final MetricCategory category,

metrics/core/src/main/java/org/hyperledger/besu/metrics/prometheus/PrometheusSimpleTimer.java

@@ -14,86 +14,29 @@
  */
 package org.hyperledger.besu.metrics.prometheus;
 
-import static org.hyperledger.besu.metrics.prometheus.PrometheusCollector.addLabelValues;
-import static org.hyperledger.besu.metrics.prometheus.PrometheusCollector.getLabelValues;
-
-import org.hyperledger.besu.metrics.Observation;
 import org.hyperledger.besu.plugin.services.metrics.LabelledMetric;
 import org.hyperledger.besu.plugin.services.metrics.MetricCategory;
 import org.hyperledger.besu.plugin.services.metrics.OperationTimer;
 
-import java.util.stream.Stream;
-
-import io.prometheus.metrics.core.metrics.Histogram;
-import io.prometheus.metrics.model.registry.PrometheusRegistry;
-
 /**
  * An implementation of Besu simple timer backed by a Prometheus histogram. The histogram samples
  * durations and counts them in configurable buckets. It also provides a sum of all observed values.
  */
-class PrometheusSimpleTimer extends CategorizedPrometheusCollector
+class PrometheusSimpleTimer extends AbstractPrometheusHistogram
     implements LabelledMetric<OperationTimer> {
 
-  private final Histogram histogram;
-
   public PrometheusSimpleTimer(
       final MetricCategory category,
       final String name,
       final String help,
       final double[] buckets,
       final String... labelNames) {
-    super(category, name);
-    this.histogram =
-        Histogram.builder()
-            .name(this.prefixedName)
-            .help(help)
-            .labelNames(labelNames)
-            .classicOnly()
-            .classicUpperBounds(buckets)
-            .build();
+    super(category, name, help, buckets, labelNames);
   }
 
   @Override
   public OperationTimer labels(final String... labels) {
     final var ddp = histogram.labelValues(labels);
     return () -> ddp.startTimer()::observeDuration;
   }
-
-  @Override
-  public String getIdentifier() {
-    return histogram.getPrometheusName();
-  }
-
-  @Override
-  public void register(final PrometheusRegistry registry) {
-    registry.register(histogram);
-  }
-
-  @Override
-  public void unregister(final PrometheusRegistry registry) {
-    registry.unregister(histogram);
-  }
-
-  @Override
-  public Stream<Observation> streamObservations() {
-    final var snapshot = histogram.collect();
-    return snapshot.getDataPoints().stream()
-        .flatMap(
-            dataPoint -> {
-              final var labelValues = getLabelValues(dataPoint.getLabels());
-              if (!dataPoint.hasClassicHistogramData()) {
-                throw new IllegalStateException("Only classic histogram are supported");
-              }
-
-              return dataPoint.getClassicBuckets().stream()
-                  .map(
-                      bucket ->
-                          new Observation(
-                              category,
-                              name,
-                              bucket.getCount(),
-                              addLabelValues(
-                                  labelValues, Double.toString(bucket.getUpperBound()))));
-            });
-  }
 }

metrics/core/src/test-support/java/org/hyperledger/besu/metrics/StubMetricsSystem.java

@@ -18,6 +18,7 @@
 
 import org.hyperledger.besu.metrics.noop.NoOpMetricsSystem;
 import org.hyperledger.besu.plugin.services.metrics.Counter;
+import org.hyperledger.besu.plugin.services.metrics.Histogram;
 import org.hyperledger.besu.plugin.services.metrics.LabelledMetric;
 import org.hyperledger.besu.plugin.services.metrics.LabelledSuppliedMetric;
 import org.hyperledger.besu.plugin.services.metrics.LabelledSuppliedSummary;
@@ -114,6 +115,16 @@ public void createGauge(
     gauges.put(name, valueSupplier);
   }
 
+  @Override
+  public LabelledMetric<Histogram> createLabelledHistogram(
+      final MetricCategory category,
+      final String name,
+      final String help,
+      final double[] buckets,
+      final String... labelNames) {
+    return NoOpMetricsSystem.getHistogramLabelledMetric(labelNames.length);
+  }
+
   @Override
   public void createGuavaCacheCollector(
       final MetricCategory category, final String name, final Cache<?, ?> cache) {}