Add instrumentation showing the rendering time

dd-java-agent/instrumentation/spring-web/src/main/java/datadog/trace/instrumentation/springweb/DispatcherServletInstrumentation.java

@@ -1,18 +1,17 @@
 package datadog.trace.instrumentation.springweb;
 
 import static io.opentracing.log.Fields.ERROR_OBJECT;
-import static net.bytebuddy.matcher.ElementMatchers.isInterface;
 import static net.bytebuddy.matcher.ElementMatchers.isMethod;
 import static net.bytebuddy.matcher.ElementMatchers.isProtected;
 import static net.bytebuddy.matcher.ElementMatchers.nameStartsWith;
 import static net.bytebuddy.matcher.ElementMatchers.named;
-import static net.bytebuddy.matcher.ElementMatchers.not;
 import static net.bytebuddy.matcher.ElementMatchers.takesArgument;
 
 import com.google.auto.service.AutoService;
 import datadog.trace.agent.tooling.Instrumenter;
 import io.opentracing.Scope;
 import io.opentracing.Span;
+import io.opentracing.Tracer;
 import io.opentracing.tag.Tags;
 import io.opentracing.util.GlobalTracer;
 import java.util.Collections;
@@ -21,32 +20,70 @@ import java.util.Map;
 import net.bytebuddy.asm.Advice;
 import net.bytebuddy.description.type.TypeDescription;
 import net.bytebuddy.matcher.ElementMatcher;
+import org.springframework.web.servlet.ModelAndView;
 
 @AutoService(Instrumenter.class)
-public final class SpringWebErrorInstrumentation extends Instrumenter.Default {
+public final class DispatcherServletInstrumentation extends Instrumenter.Default {
 
-  public SpringWebErrorInstrumentation() {
+  public DispatcherServletInstrumentation() {
     super("spring-web");
   }
 
   @Override
   public ElementMatcher<TypeDescription> typeMatcher() {
-    return not(isInterface()).and(named("org.springframework.web.servlet.DispatcherServlet"));
+    return named("org.springframework.web.servlet.DispatcherServlet");
   }
 
   @Override
   public Map<ElementMatcher, String> transformers() {
     final Map<ElementMatcher, String> transformers = new HashMap<>();
+    transformers.put(
+        isMethod()
+            .and(isProtected())
+            .and(named("render"))
+            .and(takesArgument(0, named("org.springframework.web.servlet.ModelAndView"))),
+        DispatcherAdvice.class.getName());
     transformers.put(
         isMethod()
             .and(isProtected())
             .and(nameStartsWith("processHandlerException"))
             .and(takesArgument(3, Exception.class)),
-        SpringWebErrorHandlerAdvice.class.getName());
+        ErrorHandlerAdvice.class.getName());
     return transformers;
   }
 
-  public static class SpringWebErrorHandlerAdvice {
+  public static class DispatcherAdvice {
+
+    @Advice.OnMethodEnter(suppress = Throwable.class)
+    public static Scope startSpan(@Advice.Argument(0) final ModelAndView mv) {
+
+      final Tracer.SpanBuilder builder =
+          GlobalTracer.get()
+              .buildSpan("response.render")
+              .withTag(Tags.COMPONENT.getKey(), "spring-webmvc");
+      if (mv.getViewName() != null) {
+        builder.withTag("view.name", mv.getViewName());
+      }
+      if (mv.getView() != null) {
+        builder.withTag("view.type", mv.getView().getClass().getName());
+      }
+      return builder.startActive(true);
+    }
+
+    @Advice.OnMethodExit(onThrowable = Throwable.class, suppress = Throwable.class)
+    public static void stopSpan(
+        @Advice.Enter final Scope scope, @Advice.Thrown final Throwable throwable) {
+
+      if (throwable != null) {
+        final Span span = scope.span();
+        Tags.ERROR.set(span, true);
+        span.log(Collections.singletonMap(ERROR_OBJECT, throwable));
+      }
+      scope.close();
+    }
+  }
+
+  public static class ErrorHandlerAdvice {
     @Advice.OnMethodEnter(suppress = Throwable.class)
     public static void nameResource(@Advice.Argument(3) final Exception exception) {
       final Scope scope = GlobalTracer.get().scopeManager().active();

dd-java-agent/instrumentation/spring-web/src/main/java/datadog/trace/instrumentation/springweb/HandlerAdapterInstrumentation.java

@@ -22,7 +22,6 @@ import io.opentracing.tag.Tags;
 import io.opentracing.util.GlobalTracer;
 import java.lang.reflect.Method;
 import java.util.Collections;
-import java.util.HashMap;
 import java.util.Map;
 import javax.servlet.Servlet;
 import javax.servlet.http.HttpServletRequest;
@@ -35,9 +34,9 @@ import org.springframework.web.servlet.HandlerMapping;
 import org.springframework.web.servlet.mvc.Controller;
 
 @AutoService(Instrumenter.class)
-public final class SpringWebInstrumentation extends Instrumenter.Default {
+public final class HandlerAdapterInstrumentation extends Instrumenter.Default {
 
-  public SpringWebInstrumentation() {
+  public HandlerAdapterInstrumentation() {
     super("spring-web");
   }
 
@@ -55,15 +54,13 @@ public final class SpringWebInstrumentation extends Instrumenter.Default {
 
   @Override
   public Map<ElementMatcher, String> transformers() {
-    final Map<ElementMatcher, String> transformers = new HashMap<>();
+    return Collections.<ElementMatcher, String>singletonMap(
-    transformers.put(
         isMethod()
             .and(isPublic())
             .and(nameStartsWith("handle"))
             .and(takesArgument(0, named("javax.servlet.http.HttpServletRequest")))
             .and(takesArguments(3)),
         ControllerAdvice.class.getName());
-    return transformers;
   }
 
   public static class ControllerAdvice {