content: /*
   * Copyright The OpenTelemetry Authors
   * SPDX-License-Identifier: Apache-2.0
   */
  
  package io.opentelemetry.javaagent.instrumentation.spring.webflux.v5_0.server.reactornetty;
  
  import static net.bytebuddy.matcher.ElementMatchers.named;
  import static net.bytebuddy.matcher.ElementMatchers.takesArgument;
  
  import io.netty.channel.Channel;
  import io.opentelemetry.context.Scope;
  import io.opentelemetry.instrumentation.netty.v4_1.internal.ServerContext;
  import io.opentelemetry.instrumentation.netty.v4_1.internal.ServerContexts;
  import io.opentelemetry.javaagent.extension.instrumentation.TypeInstrumentation;
  import io.opentelemetry.javaagent.extension.instrumentation.TypeTransformer;
  import javax.annotation.Nullable;
  import net.bytebuddy.asm.Advice;
  import net.bytebuddy.description.type.TypeDescription;
  import net.bytebuddy.matcher.ElementMatcher;
  
  // used before reactor-netty-0.8
  public class ContextHandlerInstrumentation implements TypeInstrumentation {
    @Override
    public ElementMatcher<TypeDescription> typeMatcher() {
      return named("reactor.ipc.netty.channel.ContextHandler");
    }
  
    @Override
    public void transform(TypeTransformer transformer) {
      transformer.applyAdviceToMethod(
          named("createOperations").and(takesArgument(0, named("io.netty.channel.Channel"))),
          ContextHandlerInstrumentation.class.getName() + "$CreateOperationsAdvice");
    }
  
    @SuppressWarnings("unused")
    public static class CreateOperationsAdvice {
  
      @Nullable
      @Advice.OnMethodEnter(suppress = Throwable.class)
      public static Scope onEnter(@Advice.Argument(0) Channel channel) {
        // set context to the first unprocessed request
        ServerContext serverContext = ServerContexts.peekFirst(channel);
        if (serverContext != null) {
          return serverContext.context().makeCurrent();
        }
        return null;
      }
  
      @Advice.OnMethodExit(onThrowable = Throwable.class, suppress = Throwable.class)
      public static void onExit(@Advice.Enter @Nullable Scope scope) {
        if (scope != null) {
          scope.close();
        }
      }
    }
  }
  