Provide a way to run HealthIndicators concurrently

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/health/HealthEndpointConfiguration.java

@@ -21,6 +21,7 @@
 import org.springframework.boot.actuate.health.HealthAggregator;
 import org.springframework.boot.actuate.health.HealthEndpoint;
 import org.springframework.boot.actuate.health.HealthIndicatorRegistry;
+import org.springframework.boot.actuate.health.HealthIndicatorStrategy;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnSingleCandidate;
 import org.springframework.context.annotation.Bean;
@@ -38,8 +39,9 @@ class HealthEndpointConfiguration {
 
 	@Bean
 	@ConditionalOnMissingBean
-	HealthEndpoint healthEndpoint(HealthAggregator healthAggregator, HealthIndicatorRegistry registry) {
-		return new HealthEndpoint(new CompositeHealthIndicator(healthAggregator, registry));
+	HealthEndpoint healthEndpoint(HealthAggregator healthAggregator, HealthIndicatorRegistry registry,
+			HealthIndicatorStrategy healthIndicatorStrategy) {
+		return new HealthEndpoint(new CompositeHealthIndicator(healthAggregator, registry, healthIndicatorStrategy));
 	}
 
 }

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/health/HealthIndicatorAutoConfiguration.java

@@ -21,9 +21,11 @@
 import reactor.core.publisher.Flux;
 
 import org.springframework.boot.actuate.health.ApplicationHealthIndicator;
+import org.springframework.boot.actuate.health.DefaultHealthIndicatorStrategy;
 import org.springframework.boot.actuate.health.HealthAggregator;
 import org.springframework.boot.actuate.health.HealthIndicator;
 import org.springframework.boot.actuate.health.HealthIndicatorRegistry;
+import org.springframework.boot.actuate.health.HealthIndicatorStrategy;
 import org.springframework.boot.actuate.health.OrderedHealthAggregator;
 import org.springframework.boot.actuate.health.ReactiveHealthIndicator;
 import org.springframework.boot.actuate.health.ReactiveHealthIndicatorRegistry;
@@ -71,6 +73,12 @@ public HealthIndicatorRegistry healthIndicatorRegistry(ApplicationContext applic
 		return HealthIndicatorRegistryBeans.get(applicationContext);
 	}
 
+	@Bean
+	@ConditionalOnMissingBean
+	public HealthIndicatorStrategy healthIndicatorStrategy() {
+		return new DefaultHealthIndicatorStrategy();
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	@ConditionalOnClass(Flux.class)
 	static class ReactiveHealthIndicatorConfiguration {

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/health/HealthIndicatorAutoConfigurationTests.java

@@ -16,15 +16,18 @@
 
 package org.springframework.boot.actuate.autoconfigure.health;
 
+import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.Map;
 
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.actuate.health.ApplicationHealthIndicator;
+import org.springframework.boot.actuate.health.DefaultHealthIndicatorStrategy;
 import org.springframework.boot.actuate.health.Health;
 import org.springframework.boot.actuate.health.HealthAggregator;
 import org.springframework.boot.actuate.health.HealthIndicator;
+import org.springframework.boot.actuate.health.HealthIndicatorStrategy;
 import org.springframework.boot.actuate.health.OrderedHealthAggregator;
 import org.springframework.boot.actuate.health.Status;
 import org.springframework.boot.autoconfigure.AutoConfigurations;
@@ -81,6 +84,18 @@ void runShouldCreateOrderedHealthAggregator() {
 				.isInstanceOf(OrderedHealthAggregator.class));
 	}
 
+	@Test
+	void shouldCreateDefaultHealthIndicatorStrategy() {
+		this.contextRunner.run((context) -> assertThat(context).getBean(HealthIndicatorStrategy.class)
+				.isInstanceOf(DefaultHealthIndicatorStrategy.class));
+	}
+
+	@Test
+	void shouldNotCreateDefaultHealthIndicatorCustomStrategyPresent() {
+		this.contextRunner.withBean(CustomHealthIndicatorStrategy.class).run((context) -> assertThat(context)
+				.getBean(HealthIndicatorStrategy.class).isInstanceOf(CustomHealthIndicatorStrategy.class));
+	}
+
 	@Test
 	void runWhenHasCustomOrderPropertyShouldCreateOrderedHealthAggregator() {
 		this.contextRunner.withPropertyValues("management.health.status.order:UP,DOWN").run((context) -> {
@@ -111,6 +126,15 @@ HealthIndicator customHealthIndicator() {
 
 	}
 
+	static class CustomHealthIndicatorStrategy implements HealthIndicatorStrategy {
+
+		@Override
+		public Map<String, Health> doHealth(Map<String, HealthIndicator> healthIndicators) {
+			return Collections.emptyMap();
+		}
+
+	}
+
 	static class CustomHealthIndicator implements HealthIndicator {
 
 		@Override

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/CompositeHealthIndicator.java

@@ -16,11 +16,12 @@
 
 package org.springframework.boot.actuate.health;
 
-import java.util.LinkedHashMap;
 import java.util.Map;
 
 /**
- * {@link HealthIndicator} that returns health indications from all registered delegates.
+ * {@link HealthIndicator} that returns health indications from all registered delegates
+ * using the {@link HealthIndicatorStrategy} and aggregates the result via
+ * {@link HealthAggregator} into a final one.
  *
  * @author Tyler J. Frederick
  * @author Phillip Webb
@@ -33,6 +34,8 @@ public class CompositeHealthIndicator implements HealthIndicator {
 
 	private final HealthAggregator aggregator;
 
+	private final HealthIndicatorStrategy strategy;
+
 	/**
 	 * Create a new {@link CompositeHealthIndicator} from the specified indicators.
 	 * @param healthAggregator the health aggregator
@@ -50,8 +53,23 @@ public CompositeHealthIndicator(HealthAggregator healthAggregator, Map<String, H
 	 * @param registry the registry of {@link HealthIndicator HealthIndicators}.
 	 */
 	public CompositeHealthIndicator(HealthAggregator healthAggregator, HealthIndicatorRegistry registry) {
+		this(healthAggregator, registry, new DefaultHealthIndicatorStrategy());
+	}
+
+	/**
+	 * Create a new {@link CompositeHealthIndicator} from the indicators in the given
+	 * {@code registry}.
+	 * @param healthAggregator the health aggregator
+	 * @param registry the registry of {@link HealthIndicator HealthIndicators}.
+	 * @param strategy the strategy how {@link HealthIndicator HealthIndicator} instnaces
+	 * should be called.
+	 * @since 2.2.0
+	 */
+	public CompositeHealthIndicator(HealthAggregator healthAggregator, HealthIndicatorRegistry registry,
+			HealthIndicatorStrategy strategy) {
 		this.aggregator = healthAggregator;
 		this.registry = registry;
+		this.strategy = strategy;
 	}
 
 	/**
@@ -65,10 +83,7 @@ public HealthIndicatorRegistry getRegistry() {
 
 	@Override
 	public Health health() {
-		Map<String, Health> healths = new LinkedHashMap<>();
-		for (Map.Entry<String, HealthIndicator> entry : this.registry.getAll().entrySet()) {
-			healths.put(entry.getKey(), entry.getValue().health());
-		}
+		Map<String, Health> healths = this.strategy.doHealth(this.registry.getAll());
 		return this.aggregator.aggregate(healths);
 	}
 

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/ConcurrentlyHealthIndicatorStrategy.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.health;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+/**
+ *
+ * {@link HealthIndicatorStrategy} that returns health indications from all
+ * {@link HealthIndicator} instances concurrently.
+ *
+ * @author Dmytro Nosan
+ * @since 2.2.0
+ */
+public class ConcurrentlyHealthIndicatorStrategy implements HealthIndicatorStrategy {
+
+	private static final Health UNKNOWN = Health.unknown().build();
+
+	private final Executor executor;
+
+	private final Long timeout;
+
+	private final Health timeoutHealth;
+
+	/**
+	 * Returns a new {@link ConcurrentlyHealthIndicatorStrategy} with no timeout.
+	 * @param executor the executor to submit {@link HealthIndicator HealthIndicators} on.
+	 */
+	public ConcurrentlyHealthIndicatorStrategy(Executor executor) {
+		this.executor = executor;
+		this.timeout = null;
+		this.timeoutHealth = null;
+	}
+
+	/**
+	 * Returns a new {@link ConcurrentlyHealthIndicatorStrategy} with timeout.
+	 * @param executor the executor to submit {@link HealthIndicator HealthIndicators} on.
+	 * @param timeout number of milliseconds to wait before using the
+	 * {@code timeoutHealth}
+	 * @param timeoutHealth the {@link Health} to use if an health indicator reached the
+	 * {@code timeout}. Defaults to {@code unknown} status.
+	 */
+	public ConcurrentlyHealthIndicatorStrategy(Executor executor, long timeout, Health timeoutHealth) {
+		this.executor = executor;
+		this.timeout = timeout;
+		this.timeoutHealth = (timeoutHealth != null) ? timeoutHealth : UNKNOWN;
+	}
+
+	@Override
+	public Map<String, Health> doHealth(Map<String, HealthIndicator> healthIndicators) {
+		Map<String, Future<Health>> healthsFutures = new LinkedHashMap<>();
+		for (Map.Entry<String, HealthIndicator> entry : healthIndicators.entrySet()) {
+			healthsFutures.put(entry.getKey(), CompletableFuture.supplyAsync(entry.getValue()::health, this.executor));
+		}
+		Map<String, Health> healths = new LinkedHashMap<>();
+		for (Map.Entry<String, Future<Health>> entry : healthsFutures.entrySet()) {
+			healths.put(entry.getKey(), getHealth(entry.getValue(), this.timeout, this.timeoutHealth));
+		}
+		return healths;
+	}
+
+	private static Health getHealth(Future<Health> healthFuture, Long timeout, Health timeoutHealth) {
+		try {
+			return (timeout != null) ? healthFuture.get(timeout, TimeUnit.MILLISECONDS) : healthFuture.get();
+		}
+		catch (InterruptedException ex) {
+			Thread.currentThread().interrupt();
+			return Health.unknown().withException(ex).build();
+		}
+		catch (TimeoutException ex) {
+			return timeoutHealth;
+		}
+		catch (ExecutionException ex) {
+			Throwable cause = ex.getCause();
+			return Health.down((cause instanceof Exception) ? ((Exception) cause) : ex).build();
+		}
+	}
+
+}

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/DefaultHealthIndicatorStrategy.java

@@ -0,0 +1,41 @@
+/*
+ * 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.health;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+/**
+ *
+ * {@link HealthIndicatorStrategy} that returns health indications from all
+ * {@link HealthIndicator} instances sequentially.
+ *
+ * @author Dmytro Nosan
+ * @since 2.2.0
+ */
+public class DefaultHealthIndicatorStrategy implements HealthIndicatorStrategy {
+
+	@Override
+	public Map<String, Health> doHealth(Map<String, HealthIndicator> healthIndicators) {
+		Map<String, Health> healths = new LinkedHashMap<>();
+		for (Map.Entry<String, HealthIndicator> entry : healthIndicators.entrySet()) {
+			healths.put(entry.getKey(), entry.getValue().health());
+		}
+		return healths;
+	}
+
+}

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/HealthIndicatorStrategy.java

@@ -0,0 +1,40 @@
+/*
+ * 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.health;
+
+import java.util.Map;
+
+/**
+ * Strategy interface used to define how {@link HealthIndicator} instances should be
+ * called.
+ *
+ * @author Dmytro Nosan
+ * @since 2.2.0
+ * @see DefaultHealthIndicatorStrategy
+ * @see ConcurrentlyHealthIndicatorStrategy
+ */
+@FunctionalInterface
+public interface HealthIndicatorStrategy {
+
+	/**
+	 * Calls the given {@link HealthIndicator} instances.
+	 * @param healthIndicators the {@link HealthIndicator} instances that should be called
+	 * @return the health indications from all {@link HealthIndicator} instances
+	 */
+	Map<String, Health> doHealth(Map<String, HealthIndicator> healthIndicators);
+
+}