#14768 | draft for: measure pending time in executors

Author: mateusz-nalepa

instrumentation/executors/bootstrap/src/main/java/io/opentelemetry/javaagent/bootstrap/executors/ContextPropagatingRunnable.java

@@ -5,9 +5,14 @@
 
 package io.opentelemetry.javaagent.bootstrap.executors;
 
+import io.opentelemetry.api.GlobalOpenTelemetry;
+import io.opentelemetry.api.common.AttributeKey;
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.api.metrics.DoubleHistogram;
 import io.opentelemetry.context.Context;
 import io.opentelemetry.context.Scope;
 import io.opentelemetry.instrumentation.api.internal.ContextPropagationDebug;
+import java.util.concurrent.TimeUnit;
 
 public final class ContextPropagatingRunnable implements Runnable {
 
@@ -22,18 +27,36 @@ public static boolean shouldDecorateRunnable(Runnable task) {
   public static Runnable propagateContext(Runnable task, Context context) {
     return new ContextPropagatingRunnable(task, context);
   }
-
+  private static final double NANOS_PER_S = TimeUnit.SECONDS.toNanos(1);
   private final Runnable delegate;
   private final Context context;
+  private final Long startObservation;
+  private final DoubleHistogram pendingTimeHistogram;
 
   private ContextPropagatingRunnable(Runnable delegate, Context context) {
     this.delegate = delegate;
     this.context = ContextPropagationDebug.addDebugInfo(context, delegate);
+    this.startObservation = System.nanoTime();
+
+    this.pendingTimeHistogram =
+        GlobalOpenTelemetry
+            .getMeter("thread.pending.duration")
+            .histogramBuilder("thread.pending.duration")
+            .setUnit("s")
+            .setDescription("Duration of HTTP client requests.")
+            .build();
   }
 
   @Override
   public void run() {
     try (Scope ignored = context.makeCurrent()) {
+      pendingTimeHistogram
+          .record(System.nanoTime() - startObservation / NANOS_PER_S,
+              Attributes.of(
+                  AttributeKey.stringKey("thread"),
+                  Thread.currentThread().getName()
+              )
+          );
       delegate.run();
     }
   }