From bcaab02b7d79d7312d8ef7a3c3b5446a1d3041cd Mon Sep 17 00:00:00 2001
From: Felix Barnsteiner <felix.barnsteiner@elastic.co>
Date: Mon, 22 Mar 2021 16:04:22 +0100
Subject: [PATCH] Add runtime.jvm.gc.collection.count metric

---
 .../runtimemetrics/RuntimeMetricsTest.groovy        |  1 +
 .../runtimemetrics/GarbageCollector.java            | 13 +++++++++++++
 .../smoketest/SpringBootSmokeTest.groovy            |  1 +
 3 files changed, 15 insertions(+)

diff --git a/instrumentation/runtime-metrics/javaagent/src/test/groovy/io/opentelemetry/instrumentation/javaagent/runtimemetrics/RuntimeMetricsTest.groovy b/instrumentation/runtime-metrics/javaagent/src/test/groovy/io/opentelemetry/instrumentation/javaagent/runtimemetrics/RuntimeMetricsTest.groovy
index a7a823471ba0..8a7277b5ebb1 100644
--- a/instrumentation/runtime-metrics/javaagent/src/test/groovy/io/opentelemetry/instrumentation/javaagent/runtimemetrics/RuntimeMetricsTest.groovy
+++ b/instrumentation/runtime-metrics/javaagent/src/test/groovy/io/opentelemetry/instrumentation/javaagent/runtimemetrics/RuntimeMetricsTest.groovy
@@ -17,6 +17,7 @@ class RuntimeMetricsTest extends AgentInstrumentationSpecification {
     then:
     conditions.eventually {
       assert getMetrics().any { it.name == "runtime.jvm.gc.collection" }
+      assert getMetrics().any { it.name == "runtime.jvm.gc.collection.count" }
       assert getMetrics().any { it.name == "runtime.jvm.memory.area" }
       assert getMetrics().any { it.name == "runtime.jvm.memory.pool" }
     }
diff --git a/instrumentation/runtime-metrics/library/src/main/java/io/opentelemetry/instrumentation/runtimemetrics/GarbageCollector.java b/instrumentation/runtime-metrics/library/src/main/java/io/opentelemetry/instrumentation/runtimemetrics/GarbageCollector.java
index 7c2029ce459d..42ec73452801 100644
--- a/instrumentation/runtime-metrics/library/src/main/java/io/opentelemetry/instrumentation/runtimemetrics/GarbageCollector.java
+++ b/instrumentation/runtime-metrics/library/src/main/java/io/opentelemetry/instrumentation/runtimemetrics/GarbageCollector.java
@@ -26,6 +26,7 @@
  *
  * <pre>
  *   runtime.jvm.gc.collection{gc="PS1"} 6.7
+ *   runtime.jvm.gc.collection.count{gc="PS1"} 1
  * </pre>
  */
 public final class GarbageCollector {
@@ -51,6 +52,18 @@ public static void registerObservers() {
               }
             })
         .build();
+    meter
+        .longSumObserverBuilder("runtime.jvm.gc.collection.count")
+        .setDescription("The number of collections that have occurred for a given JVM garbage collector.")
+        .setUnit("collections")
+        .setUpdater(
+            resultLongObserver -> {
+              for (int i = 0; i < garbageCollectors.size(); i++) {
+                resultLongObserver.observe(
+                    garbageCollectors.get(i).getCollectionCount(), labelSets.get(i));
+              }
+            })
+        .build();
   }
 
   private GarbageCollector() {}
diff --git a/smoke-tests/src/test/groovy/io/opentelemetry/smoketest/SpringBootSmokeTest.groovy b/smoke-tests/src/test/groovy/io/opentelemetry/smoketest/SpringBootSmokeTest.groovy
index 4f1b981d805f..fa948384ed25 100644
--- a/smoke-tests/src/test/groovy/io/opentelemetry/smoketest/SpringBootSmokeTest.groovy
+++ b/smoke-tests/src/test/groovy/io/opentelemetry/smoketest/SpringBootSmokeTest.groovy
@@ -63,6 +63,7 @@ class SpringBootSmokeTest extends SmokeTest {
     then: "JVM metrics are exported"
     def metrics = new MetricsInspector(waitForMetrics())
     metrics.hasMetricsNamed("runtime.jvm.gc.collection")
+    metrics.hasMetricsNamed("runtime.jvm.gc.collection.count")
     metrics.hasMetricsNamed("runtime.jvm.memory.area")
     metrics.hasMetricsNamed("runtime.jvm.memory.pool")