content: /*
   * Copyright The OpenTelemetry Authors
   * SPDX-License-Identifier: Apache-2.0
   */
  
  package io.opentelemetry.javaagent.instrumentation.netty.v3_8;
  
  import static io.opentelemetry.javaagent.extension.matcher.AgentElementMatchers.hasClassesNamed;
  import static io.opentelemetry.javaagent.extension.matcher.AgentElementMatchers.implementsInterface;
  import static net.bytebuddy.matcher.ElementMatchers.isMethod;
  import static net.bytebuddy.matcher.ElementMatchers.named;
  import static net.bytebuddy.matcher.ElementMatchers.takesArgument;
  
  import io.opentelemetry.context.Context;
  import io.opentelemetry.context.Scope;
  import io.opentelemetry.instrumentation.api.util.VirtualField;
  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;
  import org.jboss.netty.channel.Channel;
  import org.jboss.netty.channel.ChannelFuture;
  
  public class ChannelFutureListenerInstrumentation implements TypeInstrumentation {
  
    @Override
    public ElementMatcher<ClassLoader> classLoaderOptimization() {
      return hasClassesNamed("org.jboss.netty.channel.ChannelFutureListener");
    }
  
    @Override
    public ElementMatcher<TypeDescription> typeMatcher() {
      return implementsInterface(named("org.jboss.netty.channel.ChannelFutureListener"));
    }
  
    @Override
    public void transform(TypeTransformer transformer) {
      transformer.applyAdviceToMethod(
          isMethod()
              .and(named("operationComplete"))
              .and(takesArgument(0, named("org.jboss.netty.channel.ChannelFuture"))),
          ChannelFutureListenerInstrumentation.class.getName() + "$OperationCompleteAdvice");
    }
  
    @SuppressWarnings("unused")
    public static class OperationCompleteAdvice {
  
      @Advice.OnMethodEnter
      public static Scope activateScope(@Advice.Argument(0) ChannelFuture future) {
        /*
        Idea here is:
         - To return scope only if we have captured it.
         - To capture scope only in case of error.
         */
        Throwable cause = future.getCause();
        if (cause == null || future.getChannel() == null) {
          return null;
        }
  
        VirtualField<Channel, NettyConnectionContext> virtualField =
            VirtualField.find(Channel.class, NettyConnectionContext.class);
  
        NettyConnectionContext connectionContext = virtualField.get(future.getChannel());
        if (connectionContext == null) {
          return null;
        }
        Context parentContext = connectionContext.get();
        if (parentContext == null) {
          return null;
        }
        return parentContext.makeCurrent();
      }
  
      @Advice.OnMethodExit(onThrowable = Throwable.class, suppress = Throwable.class)
      public static void deactivateScope(@Advice.Enter Scope scope) {
        if (scope != null) {
          scope.close();
        }
      }
    }
  }
  