Make Scheduler consistent for Spring Integration

Currently Spring Integration creates its own `TaskScheduler` bean if one
does not exist in the context yet. When we add `@EnableScheduling`,
Spring Boot auto-configures one for us, but this one comes with slightly
different options than the default in Spring Integration.

This commit makes sure that Spring Integration reuses the
auto-configured TaskScheduler if possible, regardless of the user
opting-in for `@EnabledScheduling`.

See gh-25109

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/integration/IntegrationAutoConfiguration.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.
@@ -34,7 +34,9 @@ import org.springframework.boot.autoconfigure.condition.SearchStrategy;
 import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
 import org.springframework.boot.autoconfigure.jmx.JmxAutoConfiguration;
 import org.springframework.boot.autoconfigure.rsocket.RSocketMessagingAutoConfiguration;
+import org.springframework.boot.autoconfigure.task.TaskSchedulingAutoConfiguration;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.boot.task.TaskSchedulerBuilder;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
@@ -56,6 +58,8 @@ import org.springframework.integration.rsocket.outbound.RSocketOutboundGateway;
 import org.springframework.messaging.rsocket.RSocketRequester;
 import org.springframework.messaging.rsocket.RSocketStrategies;
 import org.springframework.messaging.rsocket.annotation.support.RSocketMessageHandler;
+import org.springframework.scheduling.TaskScheduler;
+import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
 import org.springframework.util.StringUtils;
 
 /**
@@ -72,9 +76,25 @@ import org.springframework.util.StringUtils;
 @Configuration(proxyBeanMethods = false)
 @ConditionalOnClass(EnableIntegration.class)
 @EnableConfigurationProperties(IntegrationProperties.class)
-@AutoConfigureAfter({ DataSourceAutoConfiguration.class, JmxAutoConfiguration.class })
+@AutoConfigureAfter({ DataSourceAutoConfiguration.class, JmxAutoConfiguration.class,
+		TaskSchedulingAutoConfiguration.class })
 public class IntegrationAutoConfiguration {
 
+	/**
+	 * The {@link TaskScheduler} configuration.
+	 */
+	@Configuration(proxyBeanMethods = false)
+	@ConditionalOnBean(TaskSchedulerBuilder.class)
+	protected static class IntegrationTaskSchedulerConfiguration {
+
+		@Bean
+		@ConditionalOnMissingBean
+		public ThreadPoolTaskScheduler taskScheduler(TaskSchedulerBuilder builder) {
+			return builder.build();
+		}
+
+	}
+
 	/**
 	 * Basic Spring Integration configuration.
 	 */

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/integration/IntegrationAutoConfigurationTests.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.
@@ -34,6 +34,7 @@ import org.springframework.boot.autoconfigure.rsocket.RSocketMessagingAutoConfig
 import org.springframework.boot.autoconfigure.rsocket.RSocketRequesterAutoConfiguration;
 import org.springframework.boot.autoconfigure.rsocket.RSocketServerAutoConfiguration;
 import org.springframework.boot.autoconfigure.rsocket.RSocketStrategiesAutoConfiguration;
+import org.springframework.boot.autoconfigure.task.TaskSchedulingAutoConfiguration;
 import org.springframework.boot.jdbc.DataSourceInitializationMode;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
 import org.springframework.context.annotation.Bean;
@@ -42,6 +43,7 @@ import org.springframework.context.annotation.Primary;
 import org.springframework.integration.annotation.IntegrationComponentScan;
 import org.springframework.integration.annotation.MessagingGateway;
 import org.springframework.integration.config.IntegrationManagementConfigurer;
+import org.springframework.integration.context.IntegrationContextUtils;
 import org.springframework.integration.core.MessageSource;
 import org.springframework.integration.endpoint.MessageProcessorMessageSource;
 import org.springframework.integration.gateway.RequestReplyExchanger;
@@ -56,6 +58,7 @@ import org.springframework.jdbc.core.JdbcOperations;
 import org.springframework.jmx.export.MBeanExporter;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.rsocket.annotation.support.RSocketMessageHandler;
+import org.springframework.scheduling.TaskScheduler;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
@@ -71,7 +74,8 @@ import static org.mockito.Mockito.mock;
 class IntegrationAutoConfigurationTests {
 
 	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
-			.withConfiguration(AutoConfigurations.of(JmxAutoConfiguration.class, IntegrationAutoConfiguration.class));
+			.withConfiguration(AutoConfigurations.of(JmxAutoConfiguration.class, IntegrationAutoConfiguration.class,
+					TaskSchedulingAutoConfiguration.class));
 
 	@Test
 	void integrationIsAvailable() {
@@ -221,6 +225,17 @@ class IntegrationAutoConfigurationTests {
 				});
 	}
 
+	@Test
+	void taskSchedulerAutoConfigured() {
+		this.contextRunner
+				.withPropertyValues("spring.task.scheduling.thread-name-prefix=integration-scheduling-",
+						"spring.task.scheduling.pool.size=3")
+				.run((context) -> assertThat(context)
+						.getBean(IntegrationContextUtils.TASK_SCHEDULER_BEAN_NAME, TaskScheduler.class)
+						.hasFieldOrPropertyWithValue("threadNamePrefix", "integration-scheduling-")
+						.hasFieldOrPropertyWithValue("scheduledExecutor.corePoolSize", 3));
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class CustomMBeanExporter {
 

spring-boot-project/spring-boot-docs/src/docs/asciidoc/spring-boot-features.adoc

@@ -6278,6 +6278,10 @@ Spring Boot offers several conveniences for working with {spring-integration}[Sp
 Spring Integration provides abstractions over messaging and also other transports such as HTTP, TCP, and others.
 If Spring Integration is available on your classpath, it is initialized through the `@EnableIntegration` annotation.
 
+Spring Integration polling logic is based on the `TaskScheduler`.
+So, it relies on the auto-configured one (see the previous section), or exposes a `taskScheduler` bean according provided `spring.task.scheduling` configuration properties.
+If only Spring Integration is used, the `@EnableScheduling` annotation is optional and can be omitted on the target configuration classes.
+
 Spring Boot also configures some features that are triggered by the presence of additional Spring Integration modules.
 If `spring-integration-jmx` is also on the classpath, message processing statistics are published over JMX.
 If `spring-integration-jdbc` is available, the default database schema can be created on startup, as shown in the following line: