content: /*
   * Copyright The OpenTelemetry Authors
   * SPDX-License-Identifier: Apache-2.0
   */
  
  package io.opentelemetry.javaagent.instrumentation.undertow;
  
  import static io.opentelemetry.javaagent.extension.matcher.AgentElementMatchers.hasClassesNamed;
  import static io.opentelemetry.javaagent.extension.matcher.AgentElementMatchers.implementsInterface;
  import static io.opentelemetry.javaagent.instrumentation.undertow.UndertowSingletons.helper;
  import static net.bytebuddy.matcher.ElementMatchers.isPublic;
  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.javaagent.bootstrap.Java8BytecodeBridge;
  import io.opentelemetry.javaagent.extension.instrumentation.TypeInstrumentation;
  import io.opentelemetry.javaagent.extension.instrumentation.TypeTransformer;
  import io.undertow.server.HttpServerExchange;
  import net.bytebuddy.asm.Advice;
  import net.bytebuddy.description.type.TypeDescription;
  import net.bytebuddy.matcher.ElementMatcher;
  
  public class HandlerInstrumentation implements TypeInstrumentation {
  
    @Override
    public ElementMatcher.Junction<ClassLoader> classLoaderOptimization() {
      return hasClassesNamed("io.undertow.server.HttpHandler");
    }
  
    @Override
    public ElementMatcher<TypeDescription> typeMatcher() {
      return implementsInterface(named("io.undertow.server.HttpHandler"));
    }
  
    @Override
    public void transform(TypeTransformer transformer) {
      transformer.applyAdviceToMethod(
          named("handleRequest")
              .and(takesArgument(0, named("io.undertow.server.HttpServerExchange")))
              .and(isPublic()),
          this.getClass().getName() + "$HandleRequestAdvice");
    }
  
    @SuppressWarnings("unused")
    public static class HandleRequestAdvice {
  
      @Advice.OnMethodEnter(suppress = Throwable.class)
      public static void onEnter(
          @Advice.Argument(0) HttpServerExchange exchange,
          @Advice.Local("otelContext") Context context,
          @Advice.Local("otelScope") Scope scope) {
        Context attachedContext = helper().getServerContext(exchange);
        if (attachedContext != null) {
          if (!helper().sameTrace(Java8BytecodeBridge.currentContext(), attachedContext)) {
            // request processing is dispatched to another thread
            scope = attachedContext.makeCurrent();
            context = attachedContext;
            helper().handlerStarted(attachedContext);
          }
          return;
        }
  
        Context parentContext = Java8BytecodeBridge.currentContext();
        if (!helper().shouldStart(parentContext, exchange)) {
          return;
        }
  
        context = helper().start(parentContext, exchange);
        scope = context.makeCurrent();
  
        exchange.addExchangeCompleteListener(new EndSpanListener(context));
      }
  
      @Advice.OnMethodExit(onThrowable = Throwable.class, suppress = Throwable.class)
      public static void onExit(
          @Advice.Argument(0) HttpServerExchange exchange,
          @Advice.Thrown Throwable throwable,
          @Advice.Local("otelContext") Context context,
          @Advice.Local("otelScope") Scope scope) {
        if (scope == null) {
          return;
        }
        scope.close();
  
        helper().handlerCompleted(context, throwable, exchange);
      }
    }
  }
  