Extract AutoTimer interface for metrics

Refactor `Autotime` from a properties object to an interface and
change the existing metric recording implementations. The `AutoTimer`
interface is a general purpose callback that can be applied to a
`Timer.Builder` to configure it. Autotime properties are now located
in `spring-boot-actuator-autoconfigure` and have become an
implementation of the interface.

Closes gh-17026

Author: philwebb

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/Autotime.java renamed to spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/AutoTimeProperties.java

@@ -14,18 +14,21 @@
  * limitations under the License.
  */
 
-package org.springframework.boot.actuate.metrics;
+package org.springframework.boot.actuate.autoconfigure.metrics;
 
-import java.util.List;
+import io.micrometer.core.instrument.Timer.Builder;
+
+import org.springframework.boot.actuate.metrics.AutoTimer;
 
 /**
- * Settings for requests that are automatically timed.
+ * Nested configuration properties for items that are automatically timed.
  *
  * @author Tadaya Tsuyukubo
  * @author Stephane Nicoll
+ * @author Phillip Webb
  * @since 2.2.0
  */
-public final class Autotime {
+public final class AutoTimeProperties implements AutoTimer {
 
 	private boolean enabled = true;
 
@@ -36,24 +39,10 @@ public final class Autotime {
 	/**
 	 * Create an instance that automatically time requests with no percentiles.
 	 */
-	public Autotime() {
-	}
-
-	/**
-	 * Create an instance with the specified settings.
-	 * @param enabled whether requests should be automatically timed
-	 * @param percentilesHistogram whether percentile histograms should be published
-	 * @param percentiles computed non-aggregable percentiles to publish (can be
-	 * {@code null})
-	 */
-	public Autotime(boolean enabled, boolean percentilesHistogram,
-			List<Double> percentiles) {
-		this.enabled = enabled;
-		this.percentilesHistogram = percentilesHistogram;
-		this.percentiles = (percentiles != null)
-				? percentiles.stream().mapToDouble(Double::doubleValue).toArray() : null;
+	public AutoTimeProperties() {
 	}
 
+	@Override
 	public boolean isEnabled() {
 		return this.enabled;
 	}
@@ -78,12 +67,10 @@ public void setPercentiles(double[] percentiles) {
 		this.percentiles = percentiles;
 	}
 
-	/**
-	 * Create an instance that disable auto-timed requests.
-	 * @return an instance that disable auto-timed requests
-	 */
-	public static Autotime disabled() {
-		return new Autotime(false, false, null);
+	@Override
+	public void apply(Builder builder) {
+		builder.publishPercentileHistogram(this.percentilesHistogram)
+				.publishPercentiles(this.percentiles);
 	}
 
 }

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

@@ -19,7 +19,6 @@
 import java.util.LinkedHashMap;
 import java.util.Map;
 
-import org.springframework.boot.actuate.metrics.Autotime;
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.boot.context.properties.DeprecatedConfigurationProperty;
 import org.springframework.boot.context.properties.NestedConfigurationProperty;
@@ -116,6 +115,7 @@ public ClientRequest getRequest() {
 			 * @return request metric name
 			 * @deprecated since 2.2.0 in favor of {@link ClientRequest#getMetricName()}
 			 */
+			@Deprecated
 			@DeprecatedConfigurationProperty(
 					replacement = "management.metrics.web.client.request.metric-name")
 			public String getRequestsMetricName() {
@@ -128,6 +128,7 @@ public String getRequestsMetricName() {
 			 * @deprecated since 2.2.0 in favor of
 			 * {@link ClientRequest#setMetricName(String)}
 			 */
+			@Deprecated
 			public void setRequestsMetricName(String requestsMetricName) {
 				this.request.setMetricName(requestsMetricName);
 			}
@@ -151,10 +152,10 @@ public static class ClientRequest {
 				 * Auto-timed request settings.
 				 */
 				@NestedConfigurationProperty
-				private final Autotime autoTime = new Autotime();
+				private final AutoTimeProperties autotime = new AutoTimeProperties();
 
-				public Autotime getAutotime() {
-					return this.autoTime;
+				public AutoTimeProperties getAutotime() {
+					return this.autotime;
 				}
 
 				public String getMetricName() {
@@ -187,7 +188,7 @@ public ServerRequest getRequest() {
 			/**
 			 * Return whether server requests should be automatically timed.
 			 * @return {@code true} if server request should be automatically timed
-			 * @deprecated since 2.2.0 in favor of {@link Autotime#isEnabled()}
+			 * @deprecated since 2.2.0 in favor of {@link AutoTimeProperties#isEnabled()}
 			 */
 			@DeprecatedConfigurationProperty(
 					replacement = "management.metrics.web.server.request.autotime.enabled")
@@ -200,7 +201,7 @@ public boolean isAutoTimeRequests() {
 			 * Set whether server requests should be automatically timed.
 			 * @param autoTimeRequests whether server requests should be automatically
 			 * timed
-			 * @deprecated since 2.2.0 in favor of {@link Autotime#isEnabled()}
+			 * @deprecated since 2.2.0 in favor of {@link AutoTimeProperties#isEnabled()}
 			 */
 			@Deprecated
 			public void setAutoTimeRequests(boolean autoTimeRequests) {
@@ -249,9 +250,9 @@ public static class ServerRequest {
 				 * Auto-timed request settings.
 				 */
 				@NestedConfigurationProperty
-				private final Autotime autotime = new Autotime();
+				private final AutoTimeProperties autotime = new AutoTimeProperties();
 
-				public Autotime getAutotime() {
+				public AutoTimeProperties getAutotime() {
 					return this.autotime;
 				}
 

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

@@ -0,0 +1,100 @@
+/*
+ * Copyright 2012-2019 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;
+/**
+ * @author pwebb
+ */
+
+import java.util.function.Supplier;
+
+import io.micrometer.core.annotation.Timed;
+import io.micrometer.core.instrument.Timer;
+import io.micrometer.core.instrument.Timer.Builder;
+
+/**
+ * Strategy that can be used to apply {@link Timer Timers} automatically instead of using
+ * {@link Timed @Timed}.
+ *
+ * @author Tadaya Tsuyukubo
+ * @author Stephane Nicoll
+ * @author Phillip Webb
+ * @since 2.2.0
+ */
+@FunctionalInterface
+public interface AutoTimer {
+
+	/**
+	 * An {@link AutoTimer} implementation that is enabled but applies no additional
+	 * customizations.
+	 */
+	AutoTimer ENABLED = (builder) -> {
+	};
+
+	/**
+	 * An {@link AutoTimer} implementation that is disabled and will not record metrics.
+	 */
+	AutoTimer DISABLED = new AutoTimer() {
+
+		@Override
+		public boolean isEnabled() {
+			return false;
+		}
+
+		@Override
+		public void apply(Builder builder) {
+			throw new IllegalStateException("AutoTimer is disabled");
+		}
+
+	};
+
+	/**
+	 * Return if the auto-timer is enabled and metrics should be recorded.
+	 * @return if the auto-timer is enabled
+	 */
+	default boolean isEnabled() {
+		return true;
+	}
+
+	/**
+	 * Factory method to create a new {@link Builder Timer.Builder} with auto-timer
+	 * settings {@link #apply(Builder) applied}.
+	 * @param name the name of the timer
+	 * @return a new builder instance with auto-settings applied
+	 */
+	default Timer.Builder builder(String name) {
+		return builder(() -> Timer.builder(name));
+	}
+
+	/**
+	 * Factory method to create a new {@link Builder Timer.Builder} with auto-timer
+	 * settings {@link #apply(Builder) applied}.
+	 * @param supplier the builder supplier
+	 * @return a new builder instance with auto-settings applied
+	 */
+	default Timer.Builder builder(Supplier<Timer.Builder> supplier) {
+		Timer.Builder builder = supplier.get();
+		apply(builder);
+		return builder;
+	}
+
+	/**
+	 * Called to apply any auto-timer settings to the given {@link Builder Timer.Builder}.
+	 * @param builder the builder to apply settings to
+	 */
+	void apply(Timer.Builder builder);
+
+}

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/client/MetricsClientHttpRequestInterceptor.java

@@ -24,7 +24,7 @@
 import io.micrometer.core.instrument.MeterRegistry;
 import io.micrometer.core.instrument.Timer;
 
-import org.springframework.boot.actuate.metrics.Autotime;
+import org.springframework.boot.actuate.metrics.AutoTimer;
 import org.springframework.core.NamedThreadLocal;
 import org.springframework.http.HttpRequest;
 import org.springframework.http.client.ClientHttpRequestExecution;
@@ -51,52 +51,54 @@ class MetricsClientHttpRequestInterceptor implements ClientHttpRequestIntercepto
 
 	private final String metricName;
 
-	private final Autotime autotime;
+	private final AutoTimer autoTimer;
 
 	/**
 	 * Create a new {@code MetricsClientHttpRequestInterceptor}.
 	 * @param meterRegistry the registry to which metrics are recorded
 	 * @param tagProvider provider for metrics tags
 	 * @param metricName name of the metric to record
 	 * @deprecated since 2.2.0 in favor of
-	 * {@link #MetricsClientHttpRequestInterceptor(MeterRegistry, RestTemplateExchangeTagsProvider, String, Autotime)}
+	 * {@link #MetricsClientHttpRequestInterceptor(MeterRegistry, RestTemplateExchangeTagsProvider, String, AutoTimer)}
 	 */
+	@Deprecated
 	MetricsClientHttpRequestInterceptor(MeterRegistry meterRegistry,
 			RestTemplateExchangeTagsProvider tagProvider, String metricName) {
-		this(meterRegistry, tagProvider, metricName, new Autotime());
+		this(meterRegistry, tagProvider, metricName, AutoTimer.ENABLED);
 	}
 
 	/**
 	 * Create a new {@code MetricsClientHttpRequestInterceptor}.
 	 * @param meterRegistry the registry to which metrics are recorded
 	 * @param tagProvider provider for metrics tags
 	 * @param metricName name of the metric to record
-	 * @param autotime auto timed request settings
+	 * @param autoTimer the auto-timers to apply or {@code null} to disable auto-timing
 	 * @since 2.2.0
 	 */
 	MetricsClientHttpRequestInterceptor(MeterRegistry meterRegistry,
 			RestTemplateExchangeTagsProvider tagProvider, String metricName,
-			Autotime autotime) {
+			AutoTimer autoTimer) {
 		this.tagProvider = tagProvider;
 		this.meterRegistry = meterRegistry;
 		this.metricName = metricName;
-		this.autotime = (autotime != null) ? autotime : Autotime.disabled();
+		this.autoTimer = (autoTimer != null) ? autoTimer : AutoTimer.DISABLED;
 	}
 
 	@Override
 	public ClientHttpResponse intercept(HttpRequest request, byte[] body,
 			ClientHttpRequestExecution execution) throws IOException {
+		if (!this.autoTimer.isEnabled()) {
+			return execution.execute(request, body);
+		}
 		long startTime = System.nanoTime();
 		ClientHttpResponse response = null;
 		try {
 			response = execution.execute(request, body);
 			return response;
 		}
 		finally {
-			if (this.autotime.isEnabled()) {
-				getTimeBuilder(request, response).register(this.meterRegistry)
-						.record(System.nanoTime() - startTime, TimeUnit.NANOSECONDS);
-			}
+			getTimeBuilder(request, response).register(this.meterRegistry)
+					.record(System.nanoTime() - startTime, TimeUnit.NANOSECONDS);
 			urlTemplate.remove();
 		}
 	}
@@ -121,9 +123,7 @@ public URI expand(String url, Object... arguments) {
 
 	private Timer.Builder getTimeBuilder(HttpRequest request,
 			ClientHttpResponse response) {
-		return Timer.builder(this.metricName)
-				.publishPercentiles(this.autotime.getPercentiles())
-				.publishPercentileHistogram(this.autotime.isPercentilesHistogram())
+		return this.autoTimer.builder(this.metricName)
 				.tags(this.tagProvider.getTags(urlTemplate.get(), request, response))
 				.description("Timer of RestTemplate operation");
 	}

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/client/MetricsRestTemplateCustomizer.java

@@ -21,7 +21,7 @@
 
 import io.micrometer.core.instrument.MeterRegistry;
 
-import org.springframework.boot.actuate.metrics.Autotime;
+import org.springframework.boot.actuate.metrics.AutoTimer;
 import org.springframework.boot.web.client.RestTemplateCustomizer;
 import org.springframework.http.client.ClientHttpRequestInterceptor;
 import org.springframework.web.client.RestTemplate;
@@ -47,29 +47,30 @@ public class MetricsRestTemplateCustomizer implements RestTemplateCustomizer {
 	 * @param tagProvider the tag provider
 	 * @param metricName the name of the recorded metric
 	 * @deprecated since 2.2.0 in favor of
-	 * {@link #MetricsRestTemplateCustomizer(MeterRegistry, RestTemplateExchangeTagsProvider, String, Autotime)}
+	 * {@link #MetricsRestTemplateCustomizer(MeterRegistry, RestTemplateExchangeTagsProvider, String, AutoTimer)}
 	 */
+	@Deprecated
 	public MetricsRestTemplateCustomizer(MeterRegistry meterRegistry,
 			RestTemplateExchangeTagsProvider tagProvider, String metricName) {
-		this(meterRegistry, tagProvider, metricName, new Autotime());
+		this(meterRegistry, tagProvider, metricName, AutoTimer.ENABLED);
 	}
 
 	/**
 	 * Creates a new {@code MetricsRestTemplateInterceptor}. When {@code autoTimeRequests}
 	 * is set to {@code true}, the interceptor records metrics using the given
 	 * {@code meterRegistry} with tags provided by the given {@code tagProvider} and with
-	 * {@link Autotime auto-timed request configuration}.
+	 * {@link AutoTimer auto-timed configuration}.
 	 * @param meterRegistry the meter registry
 	 * @param tagProvider the tag provider
 	 * @param metricName the name of the recorded metric
-	 * @param autotime auto-timed request settings
+	 * @param autoTimer the auto-timers to apply or {@code null} to disable auto-timing
 	 * @since 2.2.0
 	 */
 	public MetricsRestTemplateCustomizer(MeterRegistry meterRegistry,
 			RestTemplateExchangeTagsProvider tagProvider, String metricName,
-			Autotime autotime) {
+			AutoTimer autoTimer) {
 		this.interceptor = new MetricsClientHttpRequestInterceptor(meterRegistry,
-				tagProvider, metricName, autotime);
+				tagProvider, metricName, autoTimer);
 	}
 
 	@Override