Fix MetricsFilter registration to support async

Update `WebMvcMetricsConfiguration` so that the filter is registered
with the correct settings to support async requests.

See gh-11348

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

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.actuate.autoconfigure.metrics.web.servlet;
 
+import javax.servlet.DispatcherType;
+
 import io.micrometer.core.instrument.MeterRegistry;
 
 import org.springframework.boot.actuate.autoconfigure.metrics.MetricsProperties;
@@ -27,6 +29,7 @@ import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.boot.web.servlet.FilterRegistrationBean;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.web.context.WebApplicationContext;
@@ -51,13 +54,17 @@ public class WebMvcMetricsConfiguration {
 	}
 
 	@Bean
-	public WebMvcMetricsFilter webMetricsFilter(MeterRegistry registry,
-			MetricsProperties properties, WebMvcTagsProvider tagsProvider,
-			WebApplicationContext context) {
+	public FilterRegistrationBean<WebMvcMetricsFilter> webMetricsFilter(
+			MeterRegistry registry, MetricsProperties properties,
+			WebMvcTagsProvider tagsProvider, WebApplicationContext context) {
 		Server serverProperties = properties.getWeb().getServer();
-		return new WebMvcMetricsFilter(context, registry, tagsProvider,
-				serverProperties.getRequestsMetricName(),
+		WebMvcMetricsFilter filter = new WebMvcMetricsFilter(context, registry,
+				tagsProvider, serverProperties.getRequestsMetricName(),
 				serverProperties.isAutoTimeRequests());
+		FilterRegistrationBean<WebMvcMetricsFilter> registration = new FilterRegistrationBean<>(
+				filter);
+		registration.setDispatcherTypes(DispatcherType.REQUEST, DispatcherType.ASYNC);
+		return registration;
 	}
 
 }

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/MetricsAutoConfigurationIntegrationTests.java

@@ -19,6 +19,10 @@ package org.springframework.boot.actuate.autoconfigure.metrics;
 import java.util.Collections;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.BrokenBarrierException;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CyclicBarrier;
+import java.util.concurrent.TimeUnit;
 
 import io.micrometer.core.instrument.MeterRegistry;
 import io.micrometer.core.instrument.MockClock;
@@ -83,6 +87,9 @@ public class MetricsAutoConfigurationIntegrationTests {
 	@Autowired
 	private MeterRegistry registry;
 
+	@Autowired
+	private CyclicBarrier cyclicBarrier;
+
 	@SuppressWarnings("unchecked")
 	@Test
 	public void restTemplateIsInstrumented() {
@@ -111,6 +118,21 @@ public class MetricsAutoConfigurationIntegrationTests {
 				.hasAtLeastOneElementOfType(JvmMemoryMetrics.class);
 	}
 
+	@Test
+	public void asyncRequestMappingIsInstrumented() throws InterruptedException, BrokenBarrierException {
+		Thread backgroundRequest = new Thread(() -> this.loopback.getForObject("/api/async", String.class));
+		backgroundRequest.start();
+		this.cyclicBarrier.await();
+		MockClock.clock(this.registry).addSeconds(2);
+		this.cyclicBarrier.await();
+		backgroundRequest.join();
+
+		assertThat(this.registry.find("http.server.requests")
+				.tags("uri", "/api/async").timer())
+				.matches(t -> t.count() == 1)
+				.matches(t -> t.totalTime(TimeUnit.SECONDS) == 2);
+	}
+
 	@Configuration
 	@ImportAutoConfiguration({ MetricsAutoConfiguration.class,
 			JacksonAutoConfiguration.class, HttpMessageConvertersAutoConfiguration.class,
@@ -130,16 +152,38 @@ public class MetricsAutoConfigurationIntegrationTests {
 			return restTemplateBuilder.build();
 		}
 
+		@Bean
+		public CyclicBarrier cyclicBarrier() {
+			return new CyclicBarrier(2);
+		}
 	}
 
 	@RestController
 	static class PersonController {
+		private final CyclicBarrier cyclicBarrier;
+
+		PersonController(CyclicBarrier cyclicBarrier) {
+			this.cyclicBarrier = cyclicBarrier;
+		}
 
 		@GetMapping("/api/people")
 		Set<String> personName() {
 			return Collections.singleton("Jon");
 		}
 
+		@GetMapping("/api/async")
+		CompletableFuture<String> asyncHello() throws BrokenBarrierException, InterruptedException {
+			this.cyclicBarrier.await();
+			return CompletableFuture.supplyAsync(() -> {
+				try {
+					this.cyclicBarrier.await();
+				}
+				catch (InterruptedException | BrokenBarrierException e) {
+					throw new RuntimeException(e);
+				}
+				return "async-hello";
+			});
+		}
 	}
 
 }