GH-9524: Expose SourcePollingChannelAdapterSpec.taskScheduler

Fixes: #9524
Issue link: #9524

It is useful in some use-cases to be able to inject a custom `TaskScheduler`
(e.g. with a `TaskDecorator`) into a source polling channel adapter.

* Add `SourcePollingChannelAdapterFactoryBean.setTaskScheduler()`
 and call it from the `SourcePollingChannelAdapterSpec.taskScheduler()`
* Fix JavaDocs typos in the `ConsumerEndpointSpec`
* Test custom `TaskScheduler` usage and mention new option in the `whats-new.adoc`

spring-integration-core/src/main/java/org/springframework/integration/config/SourcePollingChannelAdapterFactoryBean.java

@@ -34,6 +34,7 @@
 import org.springframework.messaging.MessageChannel;
 import org.springframework.messaging.core.BeanFactoryMessageChannelDestinationResolver;
 import org.springframework.messaging.core.DestinationResolver;
+import org.springframework.scheduling.TaskScheduler;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -75,6 +76,8 @@ public class SourcePollingChannelAdapterFactoryBean implements FactoryBean<Sourc
 
 	private String role;
 
+	private TaskScheduler taskScheduler;
+
 	private volatile SourcePollingChannelAdapter adapter;
 
 	private volatile boolean initialized;
@@ -111,6 +114,15 @@ public void setRole(String role) {
 		this.role = role;
 	}
 
+	/**
+	 * Set a {@link TaskScheduler} for polling tasks.
+	 * @param taskScheduler the {@link TaskScheduler} for polling tasks.
+	 * @since 6.4
+	 */
+	public void setTaskScheduler(TaskScheduler taskScheduler) {
+		this.taskScheduler = taskScheduler;
+	}
+
 	/**
 	 * Specify the {@link DestinationResolver} strategy to use.
 	 * The default is a BeanFactoryChannelResolver.
@@ -208,6 +220,9 @@ private void initializeAdapter() {
 			spca.setBeanName(this.beanName);
 			spca.setBeanFactory(this.beanFactory);
 			spca.setTransactionSynchronizationFactory(this.pollerMetadata.getTransactionSynchronizationFactory());
+			if (this.taskScheduler != null) {
+				spca.setTaskScheduler(this.taskScheduler);
+			}
 			spca.afterPropertiesSet();
 			this.adapter = spca;
 			this.initialized = true;

spring-integration-core/src/main/java/org/springframework/integration/dsl/ConsumerEndpointSpec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2023 the original author or authors.
+ * Copyright 2016-2024 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.
@@ -128,7 +128,7 @@ public S role(String role) {
 
 	/**
 	 * Configure a {@link TaskScheduler} for scheduling tasks, for example in the
-	 * Polling Consumer. By default the global {@code ThreadPoolTaskScheduler} bean is used.
+	 * Polling Consumer. By default, the global {@code ThreadPoolTaskScheduler} bean is used.
 	 * This configuration is useful when there are requirements to dedicate particular threads
 	 * for polling task, for example.
 	 * @param taskScheduler the {@link TaskScheduler} to use.
@@ -144,7 +144,7 @@ public S taskScheduler(TaskScheduler taskScheduler) {
 	/**
 	 * Configure a list of {@link MethodInterceptor} objects to be applied, in nested order, to the
 	 * endpoint's handler. The advice objects are applied to the {@code handleMessage()} method
-	 * and therefore to the whole sub-flow afterwards.
+	 * and therefore to the whole sub-flow afterward.
 	 * @param interceptors the advice chain.
 	 * @return the endpoint spec.
 	 * @since 5.3

spring-integration-core/src/main/java/org/springframework/integration/dsl/SourcePollingChannelAdapterSpec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2023 the original author or authors.
+ * Copyright 2016-2024 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.
@@ -20,6 +20,7 @@
 import org.springframework.integration.core.MessageSource;
 import org.springframework.integration.scheduling.PollerMetadata;
 import org.springframework.lang.Nullable;
+import org.springframework.scheduling.TaskScheduler;
 
 /**
  * @author Artem Bilan
@@ -60,4 +61,15 @@ public SourcePollingChannelAdapterSpec role(String role) {
 		return this;
 	}
 
+	/**
+	 * Set a {@link TaskScheduler} for polling tasks.
+	 * @param taskScheduler the {@link TaskScheduler} for polling tasks.
+	 * @return the spec
+	 * @since 6.4
+	 */
+	public SourcePollingChannelAdapterSpec taskScheduler(TaskScheduler taskScheduler) {
+		this.endpointFactoryBean.setTaskScheduler(taskScheduler);
+		return this;
+	}
+
 }

spring-integration-core/src/test/java/org/springframework/integration/dsl/flows/IntegrationFlowTests.java

@@ -81,6 +81,7 @@
 import org.springframework.integration.store.SimpleMessageStore;
 import org.springframework.integration.support.MessageBuilder;
 import org.springframework.integration.support.MutableMessageBuilder;
+import org.springframework.integration.test.util.TestUtils;
 import org.springframework.integration.transformer.PayloadSerializingTransformer;
 import org.springframework.integration.util.NoBeansOverrideAnnotationConfigContextLoader;
 import org.springframework.messaging.Message;
@@ -94,6 +95,7 @@
 import org.springframework.messaging.support.ChannelInterceptor;
 import org.springframework.messaging.support.GenericMessage;
 import org.springframework.scheduling.TaskScheduler;
+import org.springframework.scheduling.concurrent.SimpleAsyncTaskScheduler;
 import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
 import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
 import org.springframework.stereotype.Component;
@@ -187,10 +189,15 @@ public class IntegrationFlowTests {
 	@Autowired
 	AbstractEndpoint stringSupplierEndpoint;
 
+	@Autowired
+	TaskScheduler customScheduler;
+
 	@Test
 	public void testWithSupplierMessageSourceImpliedPoller() {
 		assertThat(this.stringSupplierEndpoint.isAutoStartup()).isFalse();
 		assertThat(this.stringSupplierEndpoint.isRunning()).isFalse();
+		assertThat(TestUtils.getPropertyValue(this.stringSupplierEndpoint, "taskScheduler"))
+				.isSameAs(this.customScheduler);
 		this.stringSupplierEndpoint.start();
 		assertThat(this.suppliedChannel.receive(10000).getPayload()).isEqualTo("FOO");
 	}
@@ -569,8 +576,14 @@ public Supplier<String> stringSupplier() {
 		}
 
 		@Bean
-		public IntegrationFlow supplierFlow() {
-			return IntegrationFlow.fromSupplier(stringSupplier(), c -> c.id("stringSupplierEndpoint"))
+		public TaskScheduler customScheduler() {
+			return new SimpleAsyncTaskScheduler();
+		}
+
+		@Bean
+		public IntegrationFlow supplierFlow(TaskScheduler customScheduler) {
+			return IntegrationFlow.fromSupplier(stringSupplier(),
+							c -> c.id("stringSupplierEndpoint").taskScheduler(customScheduler))
 					.transform(toUpperCaseFunction())
 					.channel("suppliedChannel")
 					.get();

src/reference/antora/modules/ROOT/pages/whats-new.adoc

@@ -30,6 +30,8 @@ See xref:spel.adoc[SpEL Support] for more information.
 [[x6.4-general]]
 === General Changes
 
+The Java DSL `SourcePollingChannelAdapterSpec` can now be configured with a custom `TaskScheduler`
+
 [[x6.4-remote-files-changes]]
 === Remote File Adapters Changes