content: /*
   * Copyright The OpenTelemetry Authors
   * SPDX-License-Identifier: Apache-2.0
   */
  
  package io.opentelemetry.javaagent.instrumentation.finaglehttp.v23_11;
  
  import static io.opentelemetry.javaagent.extension.matcher.AgentElementMatchers.hasClassesNamed;
  import static io.opentelemetry.javaagent.extension.matcher.AgentElementMatchers.hasSuperType;
  import static net.bytebuddy.matcher.ElementMatchers.isMethod;
  import static net.bytebuddy.matcher.ElementMatchers.named;
  
  import io.opentelemetry.context.Context;
  import io.opentelemetry.javaagent.extension.instrumentation.TypeInstrumentation;
  import io.opentelemetry.javaagent.extension.instrumentation.TypeTransformer;
  import net.bytebuddy.asm.Advice;
  import net.bytebuddy.description.type.TypeDescription;
  import net.bytebuddy.matcher.ElementMatcher;
  
  public class GenStreamingServerDispatcherInstrumentation implements TypeInstrumentation {
    @Override
    public ElementMatcher<TypeDescription> typeMatcher() {
      return hasSuperType(named("com.twitter.finagle.http.GenStreamingSerialServerDispatcher"));
    }
  
    @Override
    public ElementMatcher<ClassLoader> classLoaderOptimization() {
      return hasClassesNamed("com.twitter.finagle.http.GenStreamingSerialServerDispatcher");
    }
  
    @Override
    public void transform(TypeTransformer transformer) {
      transformer.applyAdviceToMethod(
          isMethod().and(named("loop")),
          GenStreamingServerDispatcherInstrumentation.class.getName() + "$LoopAdvice");
    }
  
    @SuppressWarnings("unused")
    public static class LoopAdvice {
  
      @Advice.OnMethodEnter(suppress = Throwable.class)
      public static void methodEnter() {
        // this works bc at this point in the server evaluation, the netty
        // instrumentation has already gone to work and assigned the context to the
        // local thread;
        //
        // this works specifically in finagle's netty stack bc at this point the loop()
        // method is running on a netty thread with the necessary access to the
        // java-native ThreadLocal where the Context is stored
        Helpers.CONTEXT_LOCAL.update(Context.current());
      }
  
      @Advice.OnMethodExit(suppress = Throwable.class, onThrowable = Throwable.class)
      public static void methodExit(@Advice.Thrown Throwable thrown) {
        // always clear this
        Helpers.CONTEXT_LOCAL.clear();
      }
    }
  }
  