Review fixes for jetty-11.0:javaagent (#18152)

Co-authored-by: otelbot <197425009+otelbot@users.noreply.github.com>

Author: otelbot[bot]

instrumentation/jetty/jetty-11.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/jetty/v11_0/Jetty11HandlerAdvice.java

@@ -6,13 +6,22 @@
 package io.opentelemetry.javaagent.instrumentation.jetty.v11_0;
 
 import static io.opentelemetry.javaagent.extension.matcher.AgentElementMatchers.hasClassesNamed;
+import static io.opentelemetry.javaagent.instrumentation.jetty.v11_0.Jetty11Singletons.helper;
 import static java.util.Collections.singletonList;
 
 import com.google.auto.service.AutoService;
+import io.opentelemetry.context.Context;
+import io.opentelemetry.context.Scope;
+import io.opentelemetry.instrumentation.servlet.internal.ServletRequestContext;
+import io.opentelemetry.javaagent.bootstrap.http.HttpServerResponseCustomizerHolder;
 import io.opentelemetry.javaagent.extension.instrumentation.InstrumentationModule;
 import io.opentelemetry.javaagent.extension.instrumentation.TypeInstrumentation;
 import io.opentelemetry.javaagent.instrumentation.jetty.common.JettyHandlerInstrumentation;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
 import java.util.List;
+import javax.annotation.Nullable;
+import net.bytebuddy.asm.Advice;
 import net.bytebuddy.matcher.ElementMatcher;
 
 @AutoService(InstrumentationModule.class)
@@ -32,7 +41,69 @@ public ElementMatcher.Junction<ClassLoader> classLoaderMatcher() {
   public List<TypeInstrumentation> typeInstrumentations() {
     return singletonList(
         new JettyHandlerInstrumentation(
-            "jakarta.servlet",
-            Jetty11InstrumentationModule.class.getPackage().getName() + ".Jetty11HandlerAdvice"));
+            "jakarta.servlet", getClass().getName() + "$Jetty11HandlerAdvice"));
+  }
+
+  @SuppressWarnings("unused")
+  public static class Jetty11HandlerAdvice {
+
+    public static class AdviceScope {
+      private final ServletRequestContext<HttpServletRequest> requestContext;
+      private final Context context;
+      private final Scope scope;
+
+      private AdviceScope(
+          ServletRequestContext<HttpServletRequest> requestContext, Context context, Scope scope) {
+        this.requestContext = requestContext;
+        this.context = context;
+        this.scope = scope;
+      }
+
+      @Nullable
+      public static AdviceScope start(HttpServletRequest request, HttpServletResponse response) {
+        Context attachedContext = helper().getServerContext(request);
+        if (attachedContext != null) {
+          // We are inside nested handler, don't create new span
+          return null;
+        }
+        Context parentContext = Context.current();
+        ServletRequestContext<HttpServletRequest> requestContext =
+            new ServletRequestContext<>(request);
+        if (!helper().shouldStart(parentContext, requestContext)) {
+          return null;
+        }
+        Context context = helper().start(parentContext, requestContext);
+        Scope scope = context.makeCurrent();
+        // Must be set here since Jetty handlers can use startAsync outside of servlet scope.
+        helper().setAsyncListenerResponse(context, response);
+        HttpServerResponseCustomizerHolder.getCustomizer()
+            .customize(context, response, new Jetty11ResponseMutator());
+        return new AdviceScope(requestContext, context, scope);
+      }
+
+      public void end(
+          @Nullable Throwable throwable, HttpServletRequest request, HttpServletResponse response) {
+        helper().end(requestContext, request, response, throwable, context, scope);
+      }
+    }
+
+    @Nullable
+    @Advice.OnMethodEnter(suppress = Throwable.class, inline = false)
+    public static AdviceScope onEnter(
+        @Advice.Argument(2) HttpServletRequest request,
+        @Advice.Argument(3) HttpServletResponse response) {
+      return AdviceScope.start(request, response);
+    }
+
+    @Advice.OnMethodExit(onThrowable = Throwable.class, suppress = Throwable.class, inline = false)
+    public static void stopSpan(
+        @Advice.Argument(2) HttpServletRequest request,
+        @Advice.Argument(3) HttpServletResponse response,
+        @Advice.Thrown @Nullable Throwable throwable,
+        @Advice.Enter @Nullable AdviceScope adviceScope) {
+      if (adviceScope != null) {
+        adviceScope.end(throwable, request, response);
+      }
+    }
   }
 }

instrumentation/jetty/jetty-11.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/jetty/v11_0/Jetty11InstrumentationModule.java

@@ -8,7 +8,7 @@
 import io.opentelemetry.javaagent.bootstrap.http.HttpServerResponseMutator;
 import jakarta.servlet.http.HttpServletResponse;
 
-public class Jetty11ResponseMutator implements HttpServerResponseMutator<HttpServletResponse> {
+final class Jetty11ResponseMutator implements HttpServerResponseMutator<HttpServletResponse> {
 
   @Override
   public void appendHeader(HttpServletResponse response, String name, String value) {