Support @Timed annotation for WebFlux

Update `MetricsWebFilter` to support `@Timed` annotations on the WebFlux
handler methods or beans.

See gh-23112

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

@@ -16,18 +16,27 @@
 
 package org.springframework.boot.actuate.metrics.web.reactive.server;
 
+import java.lang.reflect.AnnotatedElement;
+import java.util.Collections;
+import java.util.Set;
 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 org.reactivestreams.Publisher;
 import reactor.core.publisher.Mono;
 
 import org.springframework.boot.actuate.metrics.AutoTimer;
 import org.springframework.boot.web.reactive.error.ErrorAttributes;
 import org.springframework.core.Ordered;
+import org.springframework.core.annotation.MergedAnnotationCollectors;
+import org.springframework.core.annotation.MergedAnnotations;
 import org.springframework.core.annotation.Order;
 import org.springframework.http.server.reactive.ServerHttpResponse;
+import org.springframework.web.method.HandlerMethod;
+import org.springframework.web.reactive.HandlerMapping;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.WebFilter;
 import org.springframework.web.server.WebFilterChain;
@@ -68,9 +77,6 @@ public class MetricsWebFilter implements WebFilter {
 
 	@Override
 	public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
-		if (!this.autoTimer.isEnabled()) {
-			return chain.filter(exchange);
-		}
 		return chain.filter(exchange).transformDeferred((call) -> filter(exchange, call));
 	}
 
@@ -97,9 +103,45 @@ public class MetricsWebFilter implements WebFilter {
 		if (cause == null) {
 			cause = exchange.getAttribute(ErrorAttributes.ERROR_ATTRIBUTE);
 		}
+		Object handler = exchange.getAttribute(HandlerMapping.BEST_MATCHING_HANDLER_ATTRIBUTE);
+		Set<Timed> annotations = getTimedAnnotations(handler);
 		Iterable<Tag> tags = this.tagsProvider.httpRequestTags(exchange, cause);
-		this.autoTimer.builder(this.metricName).tags(tags).register(this.registry).record(System.nanoTime() - start,
-				TimeUnit.NANOSECONDS);
+		long duration = System.nanoTime() - start;
+		if (annotations.isEmpty()) {
+			if (this.autoTimer.isEnabled()) {
+				this.autoTimer.builder(this.metricName).tags(tags).register(this.registry).record(duration,
+						TimeUnit.NANOSECONDS);
+			}
+		}
+		else {
+			for (Timed annotation : annotations) {
+				Timer.builder(annotation, this.metricName).tags(tags).register(this.registry).record(duration,
+						TimeUnit.NANOSECONDS);
+			}
+		}
+	}
+
+	private Set<Timed> getTimedAnnotations(Object handler) {
+		if (!(handler instanceof HandlerMethod)) {
+			return Collections.emptySet();
+		}
+		return getTimedAnnotations((HandlerMethod) handler);
+	}
+
+	private Set<Timed> getTimedAnnotations(HandlerMethod handler) {
+		Set<Timed> methodAnnotations = findTimedAnnotations(handler.getMethod());
+		if (!methodAnnotations.isEmpty()) {
+			return methodAnnotations;
+		}
+		return findTimedAnnotations(handler.getBeanType());
+	}
+
+	private Set<Timed> findTimedAnnotations(AnnotatedElement element) {
+		MergedAnnotations annotations = MergedAnnotations.from(element);
+		if (!annotations.isPresent(Timed.class)) {
+			return Collections.emptySet();
+		}
+		return annotations.stream(Timed.class).collect(MergedAnnotationCollectors.toAnnotationSet());
 	}
 
 }

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

@@ -0,0 +1,138 @@
+/*
+ * Copyright 2012-2020 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.
+ */
+
+package org.springframework.boot.actuate.metrics.web.reactive.server;
+
+import java.time.Duration;
+
+import io.micrometer.core.annotation.Timed;
+import io.micrometer.core.instrument.MockClock;
+import io.micrometer.core.instrument.simple.SimpleConfig;
+import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import reactor.core.publisher.Mono;
+
+import org.springframework.boot.actuate.metrics.AutoTimer;
+import org.springframework.mock.http.server.reactive.MockServerHttpRequest;
+import org.springframework.mock.web.server.MockServerWebExchange;
+import org.springframework.util.ReflectionUtils;
+import org.springframework.web.method.HandlerMethod;
+import org.springframework.web.reactive.HandlerMapping;
+import org.springframework.web.util.pattern.PathPatternParser;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Unit tests for {@link MetricsWebFilter} for handlers with {@link Timed} annotation.
+ *
+ * @author Andrey Shlykov
+ */
+class MetricsWebFilterTimedAnnotationTests {
+
+	private static final String REQUEST_METRICS_NAME = "http.server.requests";
+
+	private static final String REQUEST_METRICS_NAME_PERCENTILE = REQUEST_METRICS_NAME + ".percentile";
+
+	private SimpleMeterRegistry registry;
+
+	private MetricsWebFilter webFilter;
+
+	@BeforeEach
+	void setup() {
+		MockClock clock = new MockClock();
+		this.registry = new SimpleMeterRegistry(SimpleConfig.DEFAULT, clock);
+		this.webFilter = new MetricsWebFilter(this.registry, new DefaultWebFluxTagsProvider(true), REQUEST_METRICS_NAME,
+				AutoTimer.ENABLED);
+	}
+
+	@Test
+	void filterAddsStandardTags() {
+		MockServerWebExchange exchange = createExchange("timedHandler");
+		this.webFilter.filter(exchange, (serverWebExchange) -> exchange.getResponse().setComplete())
+				.block(Duration.ofSeconds(30));
+		assertMetricsContainsTag("uri", "/projects/{project}");
+		assertMetricsContainsTag("status", "200");
+	}
+
+	@Test
+	void filterAddsExtraTags() {
+		MockServerWebExchange exchange = createExchange("timedExtraTagsHandler");
+		this.webFilter.filter(exchange, (serverWebExchange) -> exchange.getResponse().setComplete())
+				.block(Duration.ofSeconds(30));
+		assertMetricsContainsTag("uri", "/projects/{project}");
+		assertMetricsContainsTag("status", "200");
+		assertMetricsContainsTag("tag1", "value1");
+		assertMetricsContainsTag("tag2", "value2");
+	}
+
+	@Test
+	void filterAddsExtraTagsAndException() {
+		MockServerWebExchange exchange = createExchange("timedExtraTagsHandler");
+		this.webFilter.filter(exchange, (serverWebExchange) -> Mono.error(new IllegalStateException("test error")))
+				.onErrorResume((t) -> {
+					exchange.getResponse().setRawStatusCode(500);
+					return exchange.getResponse().setComplete();
+				}).block(Duration.ofSeconds(30));
+		assertMetricsContainsTag("uri", "/projects/{project}");
+		assertMetricsContainsTag("status", "500");
+		assertMetricsContainsTag("exception", "IllegalStateException");
+		assertMetricsContainsTag("tag1", "value1");
+		assertMetricsContainsTag("tag2", "value2");
+	}
+
+	@Test
+	void filterAddsPercentileMeters() {
+		MockServerWebExchange exchange = createExchange("timedPercentilesHandler");
+		this.webFilter.filter(exchange, (serverWebExchange) -> exchange.getResponse().setComplete())
+				.block(Duration.ofSeconds(30));
+		assertMetricsContainsTag("uri", "/projects/{project}");
+		assertMetricsContainsTag("status", "200");
+		assertThat(this.registry.get(REQUEST_METRICS_NAME_PERCENTILE).tag("phi", "0.95").gauge().value()).isNotZero();
+		assertThat(this.registry.get(REQUEST_METRICS_NAME_PERCENTILE).tag("phi", "0.5").gauge().value()).isNotZero();
+	}
+
+	private MockServerWebExchange createExchange(String handlerName) {
+		PathPatternParser parser = new PathPatternParser();
+		HandlerMethod handlerMethod = new HandlerMethod(this, ReflectionUtils.findMethod(this.getClass(), handlerName));
+		MockServerWebExchange exchange = MockServerWebExchange
+				.from(MockServerHttpRequest.get("/projects/spring-boot").build());
+		exchange.getAttributes().put(HandlerMapping.BEST_MATCHING_PATTERN_ATTRIBUTE,
+				parser.parse("/projects/{project}"));
+		exchange.getAttributes().put(HandlerMapping.BEST_MATCHING_HANDLER_ATTRIBUTE, handlerMethod);
+		return exchange;
+	}
+
+	private void assertMetricsContainsTag(String tagKey, String tagValue) {
+		assertThat(this.registry.get(REQUEST_METRICS_NAME).tag(tagKey, tagValue).timer().count()).isEqualTo(1);
+	}
+
+	@Timed
+	Mono<String> timedHandler() {
+		return Mono.just("test");
+	}
+
+	@Timed(extraTags = { "tag1", "value1", "tag2", "value2" })
+	Mono<String> timedExtraTagsHandler() {
+		return Mono.just("test");
+	}
+
+	@Timed(percentiles = { 0.5, 0.95 })
+	Mono<String> timedPercentilesHandler() {
+		return Mono.just("test");
+	}
+
+}