Rework @Timer annotation support

Rework existing `@Timer` annotation support to remove duplicate code
and offer general purpose utilities that can be used in future metrics
support.

See gh-23112
See gh-22217

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/AutoTimer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,12 +16,16 @@
 
 package org.springframework.boot.actuate.metrics;
 
+import java.util.Set;
+import java.util.function.Consumer;
 import java.util.function.Supplier;
 
 import io.micrometer.core.annotation.Timed;
 import io.micrometer.core.instrument.Timer;
 import io.micrometer.core.instrument.Timer.Builder;
 
+import org.springframework.util.CollectionUtils;
+
 /**
  * Strategy that can be used to apply {@link Timer Timers} automatically instead of using
  * {@link Timed @Timed}.
@@ -94,4 +98,17 @@ public interface AutoTimer {
 	 */
 	void apply(Timer.Builder builder);
 
+	static void apply(AutoTimer autoTimer, String metricName, Set<Timed> annotations, Consumer<Timer.Builder> action) {
+		if (!CollectionUtils.isEmpty(annotations)) {
+			for (Timed annotation : annotations) {
+				action.accept(Timer.builder(annotation, metricName));
+			}
+		}
+		else {
+			if (autoTimer != null && autoTimer.isEnabled()) {
+				action.accept(autoTimer.builder(metricName));
+			}
+		}
+	}
+
 }

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/annotation/TimedAnnotations.java

@@ -14,9 +14,10 @@
  * limitations under the License.
  */
 
-package org.springframework.boot.actuate.metrics.web.method;
+package org.springframework.boot.actuate.metrics.annotation;
 
 import java.lang.reflect.AnnotatedElement;
+import java.lang.reflect.Method;
 import java.util.Collections;
 import java.util.Map;
 import java.util.Set;
@@ -26,30 +27,39 @@ import io.micrometer.core.annotation.Timed;
 import org.springframework.core.annotation.MergedAnnotationCollectors;
 import org.springframework.core.annotation.MergedAnnotations;
 import org.springframework.util.ConcurrentReferenceHashMap;
-import org.springframework.web.method.HandlerMethod;
 
 /**
- * Utility used to obtain {@link Timed @Timed} annotations from a {@link HandlerMethod}.
+ * Utility used to obtain {@link Timed @Timed} annotations from bean methods.
  *
  * @author Phillip Webb
  * @since 2.5.0
  */
-public final class HandlerMethodTimedAnnotations {
+public final class TimedAnnotations {
 
 	private static Map<AnnotatedElement, Set<Timed>> cache = new ConcurrentReferenceHashMap<>();
 
-	private HandlerMethodTimedAnnotations() {
+	private TimedAnnotations() {
 	}
 
-	public static Set<Timed> get(HandlerMethod handler) {
-		Set<Timed> methodAnnotations = findTimedAnnotations(handler.getMethod());
+	/**
+	 * Return {@link Timed} annotation that should be used for the given {@code method}
+	 * and {@code type}.
+	 * @param method the source method
+	 * @param type the source type
+	 * @return the {@link Timed} annotations to use or an empty set
+	 */
+	public static Set<Timed> get(Method method, Class<?> type) {
+		Set<Timed> methodAnnotations = findTimedAnnotations(method);
 		if (!methodAnnotations.isEmpty()) {
 			return methodAnnotations;
 		}
-		return findTimedAnnotations(handler.getBeanType());
+		return findTimedAnnotations(type);
 	}
 
 	private static Set<Timed> findTimedAnnotations(AnnotatedElement element) {
+		if (element == null) {
+			return Collections.emptySet();
+		}
 		Set<Timed> result = cache.get(element);
 		if (result != null) {
 			return result;

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/annotation/package-info.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2012-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Support classes for handler method metrics.
+ */
+package org.springframework.boot.actuate.metrics.annotation;

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/reactive/server/MetricsWebFilter.java

@@ -23,13 +23,11 @@ import java.util.concurrent.TimeUnit;
 import io.micrometer.core.annotation.Timed;
 import io.micrometer.core.instrument.MeterRegistry;
 import io.micrometer.core.instrument.Tag;
-import io.micrometer.core.instrument.Timer;
-import io.micrometer.core.instrument.Timer.Builder;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Mono;
 
 import org.springframework.boot.actuate.metrics.AutoTimer;
-import org.springframework.boot.actuate.metrics.web.method.HandlerMethodTimedAnnotations;
+import org.springframework.boot.actuate.metrics.annotation.TimedAnnotations;
 import org.springframework.boot.web.reactive.error.ErrorAttributes;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.Order;
@@ -102,22 +100,19 @@ public class MetricsWebFilter implements WebFilter {
 	private void record(ServerWebExchange exchange, Throwable cause, long start) {
 		cause = (cause != null) ? cause : exchange.getAttribute(ErrorAttributes.ERROR_ATTRIBUTE);
 		Object handler = exchange.getAttribute(HandlerMapping.BEST_MATCHING_HANDLER_ATTRIBUTE);
-		Set<Timed> annotations = (handler instanceof HandlerMethod)
-				? HandlerMethodTimedAnnotations.get((HandlerMethod) handler) : Collections.emptySet();
+		Set<Timed> annotations = getTimedAnnotations(handler);
 		Iterable<Tag> tags = this.tagsProvider.httpRequestTags(exchange, cause);
 		long duration = System.nanoTime() - start;
-		if (annotations.isEmpty()) {
-			if (this.autoTimer.isEnabled()) {
-				Builder builder = this.autoTimer.builder(this.metricName);
-				builder.tags(tags).register(this.registry).record(duration, TimeUnit.NANOSECONDS);
-			}
-		}
-		else {
-			for (Timed annotation : annotations) {
-				Builder builder = Timer.builder(annotation, this.metricName);
-				builder.tags(tags).register(this.registry).record(duration, TimeUnit.NANOSECONDS);
-			}
+		AutoTimer.apply(this.autoTimer, this.metricName, annotations,
+				(builder) -> builder.tags(tags).register(this.registry).record(duration, TimeUnit.NANOSECONDS));
+	}
+
+	private Set<Timed> getTimedAnnotations(Object handler) {
+		if (handler instanceof HandlerMethod) {
+			HandlerMethod handlerMethod = (HandlerMethod) handler;
+			return TimedAnnotations.get(handlerMethod.getMethod(), handlerMethod.getBeanType());
 		}
+		return Collections.emptySet();
 	}
 
 }

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/servlet/WebMvcMetricsFilter.java

@@ -32,7 +32,7 @@ import io.micrometer.core.instrument.Timer.Builder;
 import io.micrometer.core.instrument.Timer.Sample;
 
 import org.springframework.boot.actuate.metrics.AutoTimer;
-import org.springframework.boot.actuate.metrics.web.method.HandlerMethodTimedAnnotations;
+import org.springframework.boot.actuate.metrics.annotation.TimedAnnotations;
 import org.springframework.boot.web.servlet.error.ErrorAttributes;
 import org.springframework.http.HttpStatus;
 import org.springframework.web.filter.OncePerRequestFilter;
@@ -42,8 +42,8 @@ import org.springframework.web.servlet.HandlerMapping;
 import org.springframework.web.util.NestedServletException;
 
 /**
- * Intercepts incoming HTTP requests and records metrics about Spring MVC execution time
- * and results.
+ * Intercepts incoming HTTP requests handled by Spring MVC handlers and records metrics
+ * about execution time and results.
  *
  * @author Jon Schneider
  * @author Phillip Webb
@@ -128,27 +128,24 @@ public class WebMvcMetricsFilter extends OncePerRequestFilter {
 	private void record(TimingContext timingContext, HttpServletRequest request, HttpServletResponse response,
 			Throwable exception) {
 		Object handler = getHandler(request);
-		Set<Timed> annotations = (handler instanceof HandlerMethod)
-				? HandlerMethodTimedAnnotations.get((HandlerMethod) handler) : Collections.emptySet();
+		Set<Timed> annotations = getTimedAnnotations(handler);
 		Timer.Sample timerSample = timingContext.getTimerSample();
-		if (annotations.isEmpty()) {
-			if (this.autoTimer.isEnabled()) {
-				Builder builder = this.autoTimer.builder(this.metricName);
-				timerSample.stop(getTimer(builder, handler, request, response, exception));
-			}
-		}
-		else {
-			for (Timed annotation : annotations) {
-				Builder builder = Timer.builder(annotation, this.metricName);
-				timerSample.stop(getTimer(builder, handler, request, response, exception));
-			}
-		}
+		AutoTimer.apply(this.autoTimer, this.metricName, annotations,
+				(builder) -> timerSample.stop(getTimer(builder, handler, request, response, exception)));
 	}
 
 	private Object getHandler(HttpServletRequest request) {
 		return request.getAttribute(HandlerMapping.BEST_MATCHING_HANDLER_ATTRIBUTE);
 	}
 
+	private Set<Timed> getTimedAnnotations(Object handler) {
+		if (handler instanceof HandlerMethod) {
+			HandlerMethod handlerMethod = (HandlerMethod) handler;
+			return TimedAnnotations.get(handlerMethod.getMethod(), handlerMethod.getBeanType());
+		}
+		return Collections.emptySet();
+	}
+
 	private Timer getTimer(Builder builder, Object handler, HttpServletRequest request, HttpServletResponse response,
 			Throwable exception) {
 		return builder.tags(this.tagsProvider.getTags(request, response, handler, exception)).register(this.registry);

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/metrics/annotation/TimedAnnotationsTests.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package org.springframework.boot.actuate.metrics.web.method;
+package org.springframework.boot.actuate.metrics.annotation;
 
 import java.lang.reflect.Method;
 import java.util.Set;
@@ -23,22 +23,21 @@ import io.micrometer.core.annotation.Timed;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.util.ReflectionUtils;
-import org.springframework.web.method.HandlerMethod;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
- * Tests for {@link HandlerMethodTimedAnnotations}.
+ * Tests for {@link TimedAnnotations}.
  *
  * @author Phillip Webb
  */
-class HandlerMethodTimedAnnotationsTests {
+class TimedAnnotationsTests {
 
 	@Test
 	void getWhenNoneReturnsEmptySet() {
 		Object bean = new None();
 		Method method = ReflectionUtils.findMethod(bean.getClass(), "handle");
-		Set<Timed> annotations = HandlerMethodTimedAnnotations.get(new HandlerMethod(bean, method));
+		Set<Timed> annotations = TimedAnnotations.get(method, bean.getClass());
 		assertThat(annotations).isEmpty();
 	}
 
@@ -46,7 +45,7 @@ class HandlerMethodTimedAnnotationsTests {
 	void getWhenOnMethodReturnsMethodAnnotations() {
 		Object bean = new OnMethod();
 		Method method = ReflectionUtils.findMethod(bean.getClass(), "handle");
-		Set<Timed> annotations = HandlerMethodTimedAnnotations.get(new HandlerMethod(bean, method));
+		Set<Timed> annotations = TimedAnnotations.get(method, bean.getClass());
 		assertThat(annotations).extracting(Timed::value).containsOnly("y", "z");
 	}
 
@@ -54,7 +53,7 @@ class HandlerMethodTimedAnnotationsTests {
 	void getWhenNonOnMethodReturnsBeanAnnotations() {
 		Object bean = new OnBean();
 		Method method = ReflectionUtils.findMethod(bean.getClass(), "handle");
-		Set<Timed> annotations = HandlerMethodTimedAnnotations.get(new HandlerMethod(bean, method));
+		Set<Timed> annotations = TimedAnnotations.get(method, bean.getClass());
 		assertThat(annotations).extracting(Timed::value).containsOnly("y", "z");
 	}