Fix context leak in akka-http instrumentation (DataDog/dd-trace-java#2320)

instrumentation/akka-http-10.0/javaagent/akka-http-10.0-javaagent.gradle

@@ -43,9 +43,9 @@ muzzle {
 dependencies {
   library "com.typesafe.akka:akka-http_2.11:10.0.0"
   library "com.typesafe.akka:akka-stream_2.11:2.4.14"
-}
 
-tasks.withType(Test).configureEach {
-  // https://github.com/open-telemetry/opentelemetry-java-instrumentation/issues/2639
-  jvmArgs "-Dio.opentelemetry.javaagent.shaded.io.opentelemetry.context.enableStrictContext=false"
-}
+  // these instrumentations are not needed for the tests to pass
+  // they are here to test for context leaks
+  testInstrumentation project(':instrumentation:akka-actor-2.5:javaagent')
+  testInstrumentation project(':instrumentation:akka-actor-fork-join-2.5:javaagent')
+}

instrumentation/akka-http-10.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/akkahttp/client/PoolMasterActorInstrumentation.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.javaagent.instrumentation.akkahttp.client;
+
+import static net.bytebuddy.matcher.ElementMatchers.named;
+
+import io.opentelemetry.context.Scope;
+import io.opentelemetry.javaagent.extension.instrumentation.TypeInstrumentation;
+import io.opentelemetry.javaagent.extension.instrumentation.TypeTransformer;
+import io.opentelemetry.javaagent.instrumentation.api.Java8BytecodeBridge;
+import net.bytebuddy.asm.Advice;
+import net.bytebuddy.description.type.TypeDescription;
+import net.bytebuddy.matcher.ElementMatcher;
+
+public class PoolMasterActorInstrumentation implements TypeInstrumentation {
+  @Override
+  public ElementMatcher<TypeDescription> typeMatcher() {
+    return named("akka.http.impl.engine.client.PoolMasterActor");
+  }
+
+  @Override
+  public void transform(TypeTransformer transformer) {
+    // scala compiler mangles method names
+    transformer.applyAdviceToMethod(
+        named("akka$http$impl$engine$client$PoolMasterActor$$startPoolInterface")
+            .or(named("akka$http$impl$engine$client$PoolMasterActor$$startPoolInterfaceActor")),
+        ClearContextAdvice.class.getName());
+  }
+
+  public static class ClearContextAdvice {
+    @Advice.OnMethodEnter(suppress = Throwable.class)
+    public static Scope enter() {
+      return Java8BytecodeBridge.rootContext().makeCurrent();
+    }
+
+    @Advice.OnMethodExit(onThrowable = Throwable.class, suppress = Throwable.class)
+    public static void exit(@Advice.Enter Scope scope) {
+      if (scope != null) {
+        scope.close();
+      }
+    }
+  }
+}

javaagent-api/src/main/java/io/opentelemetry/javaagent/instrumentation/api/Java8BytecodeBridge.java

@@ -22,6 +22,11 @@ public static Context currentContext() {
     return Context.current();
   }
 
+  /** Calls {@link Context#root()}. */
+  public static Context rootContext() {
+    return Context.root();
+  }
+
   /** Calls {@link Span#current()}. */
   public static Span currentSpan() {
     return Span.current();