ENG-9598 Adding distribution summary support (#30)

* ENG-9598 Adding distribution summary support

* Typo in docs

* Increasing test coverage

* Review comments

Co-authored-by: kotharironak <[email protected]>

Co-authored-by: kotharironak <[email protected]>

Author: varsha-abhinandan

platform-metrics/src/main/java/org/hypertrace/core/serviceframework/metrics/PlatformMetricsRegistry.java

@@ -13,6 +13,7 @@
 import io.github.mweirauch.micrometer.jvm.extras.ProcessThreadMetrics;
 import io.micrometer.core.instrument.Clock;
 import io.micrometer.core.instrument.Counter;
+import io.micrometer.core.instrument.DistributionSummary;
 import io.micrometer.core.instrument.Gauge;
 import io.micrometer.core.instrument.ImmutableTag;
 import io.micrometer.core.instrument.MeterRegistry;
@@ -339,6 +340,40 @@ public static <T extends Number> T registerGauge(String name, Map<String, String
     return number;
   }
 
+  /**
+   * Registers a DistributionSummary (with predefined percentiles computed locally) for the given
+   * name with the service's metric registry and reports it periodically to the configured
+   * reporters. Apart from the provided tags, the reporting service's default tags also will be
+   * reported with the metrics.
+   * <p>
+   * See https://micrometer.io/docs/concepts#_distribution_summaries for more details.
+   */
+  public static DistributionSummary registerDistributionSummary(String name,
+      Map<String, String> tags) {
+    return registerDistributionSummary(name, tags, false);
+  }
+
+  /**
+   * Registers a DistributionSummary for the given name with the service's metric registry and
+   * reports it periodically to the configured reporters Apart from the provided tags, the reporting
+   * service's default tags also will be reported with the metrics.
+   * <p>
+   * Param histogram – Determines whether percentile histograms should be published.
+   * <p>
+   * For more details - https://micrometer.io/docs/concepts#_distribution_summaries,
+   * https://micrometer.io/docs/concepts#_histograms_and_percentiles
+   */
+  public static DistributionSummary registerDistributionSummary(String name,
+      Map<String, String> tags, boolean histogram) {
+    DistributionSummary.Builder builder = DistributionSummary.builder(name)
+        .publishPercentiles(0.5, 0.95, 0.99)
+        .tags(addDefaultTags(tags));
+    if (histogram) {
+      builder = builder.publishPercentileHistogram();
+    }
+    return builder.register(METER_REGISTRY);
+  }
+
   /**
    * Registers metrics for the given executor service with the service's metric registry and
    * reports them periodically to the configured reporters. Apart from the given tags, the

platform-metrics/src/test/java/org/hypertrace/core/serviceframework/metrics/PlatformMetricsRegistryTest.java

@@ -1,16 +1,21 @@
 package org.hypertrace.core.serviceframework.metrics;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import com.typesafe.config.Config;
 import com.typesafe.config.ConfigFactory;
 import io.micrometer.core.instrument.Counter;
+import io.micrometer.core.instrument.DistributionSummary;
 import io.micrometer.core.instrument.Timer;
 import io.micrometer.core.instrument.composite.CompositeMeterRegistry;
+import java.util.Arrays;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.stream.Collectors;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
@@ -117,6 +122,40 @@ public void testGauge() {
     assertEquals(11, gauge.get());
   }
 
+  @Test
+  public void testDistributionSummary() {
+    initializeCustomRegistry(List.of("testing"));
+
+    DistributionSummary distribution = PlatformMetricsRegistry
+        .registerDistributionSummary("my.distribution", Map.of("foo", "bar"));
+    distribution.record(100);
+    assertEquals(1, distribution.count());
+    assertEquals(100, distribution.totalAmount());
+
+    // Try to register the same summary again and we should get the same instance.
+    distribution = PlatformMetricsRegistry
+        .registerDistributionSummary("my.distribution", Map.of("foo", "bar"));
+    distribution.record(50);
+    assertEquals(2, distribution.count());
+    assertEquals(150, distribution.totalAmount());
+    assertEquals(75, distribution.mean());
+    assertTrue(
+        Arrays.stream(distribution.takeSnapshot().percentileValues()).map(m -> m.percentile())
+            .collect(
+                Collectors.toList()).containsAll(List.of(0.5, 0.95, 0.99)));
+
+    // Create a new distribution with histogram enabled
+    distribution = PlatformMetricsRegistry
+        .registerDistributionSummary("my.distribution", new HashMap<>(), true);
+    distribution.record(100);
+    assertEquals(1, distribution.count());
+    assertEquals(100, distribution.totalAmount());
+    assertTrue(
+        Arrays.stream(distribution.takeSnapshot().percentileValues()).map(m -> m.percentile())
+            .collect(
+                Collectors.toList()).containsAll(List.of(0.5, 0.95, 0.99)));
+  }
+
   @Test
   public void test_initializePrometheusPushGateway_withNullUrlAddress_throwsException() {
     Assertions.assertThrows(IllegalArgumentException.class,