GH-8577: Deprecate ImapIdleCA.sendingTaskExecutor

spring-integration-mail/src/main/java/org/springframework/integration/mail/ImapIdleChannelAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -21,7 +21,6 @@
 import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledFuture;
 
 import jakarta.mail.Folder;
@@ -33,6 +32,7 @@
 import org.springframework.beans.factory.BeanClassLoaderAware;
 import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.context.ApplicationEventPublisherAware;
+import org.springframework.core.task.SyncTaskExecutor;
 import org.springframework.integration.endpoint.MessageProducerSupport;
 import org.springframework.integration.mail.event.MailIntegrationEvent;
 import org.springframework.integration.transaction.IntegrationResourceHolder;
@@ -78,7 +78,7 @@ public class ImapIdleChannelAdapter extends MessageProducerSupport implements Be
 
 	private boolean shouldReconnectAutomatically = true;
 
-	private Executor sendingTaskExecutor = Executors.newFixedThreadPool(1);
+	private Executor sendingTaskExecutor = new SyncTaskExecutor();
 
 	private boolean sendingTaskExecutorSet;
 
@@ -107,7 +107,10 @@ public void setAdviceChain(List<Advice> adviceChain) {
 	 * Specify an {@link Executor} used to send messages received by the
 	 * adapter.
 	 * @param sendingTaskExecutor the sendingTaskExecutor to set
+	 * @deprecated since 6.0.5 in favor of async hands-off downstream in the flow,
+	 * e.g. {@link org.springframework.integration.channel.ExecutorChannel}.
 	 */
+	@Deprecated(since = "6.0.5", forRemoval = true)
 	public void setSendingTaskExecutor(Executor sendingTaskExecutor) {
 		Assert.notNull(sendingTaskExecutor, "'sendingTaskExecutor' must not be null");
 		this.sendingTaskExecutor = sendingTaskExecutor;

spring-integration-mail/src/main/java/org/springframework/integration/mail/dsl/ImapIdleChannelAdapterSpec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2022 the original author or authors.
+ * Copyright 2014-2023 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.
@@ -352,8 +352,11 @@ public ImapIdleChannelAdapterSpec transactional() {
 	 * Specify a task executor to be used to send messages to the downstream flow.
 	 * @param sendingTaskExecutor the sendingTaskExecutor.
 	 * @return the spec.
-	 * @see ImapIdleChannelAdapter#setSendingTaskExecutor(Executor)
+	 * @deprecated since 6.1 in favor of async hands-off downstream in the flow,
+	 * e.g. {@link  org.springframework.integration.channel.ExecutorChannel}.
 	 */
+	@Deprecated(since = "6.0.5", forRemoval = true)
+	@SuppressWarnings("removal")
 	public ImapIdleChannelAdapterSpec sendingTaskExecutor(Executor sendingTaskExecutor) {
 		this.target.setSendingTaskExecutor(sendingTaskExecutor);
 		return this;

spring-integration-mail/src/main/resources/org/springframework/integration/mail/config/spring-integration-mail.xsd

@@ -167,10 +167,11 @@
 					<xsd:attribute name="task-executor" type="xsd:string">
 						<xsd:annotation>
 							<xsd:documentation><![CDATA[
-								Reference to a bean that implements
+								[DEPRECATED] Reference to a bean that implements
 								org.springframework.core.task.TaskExecutor which is used
 								to send Messages received by this adapter.
 								If not provided, the adapter uses a single-threaded executor.
+								Deprecated since 6.0.5 in favor of async hand-off downstream in the flow.
 							]]></xsd:documentation>
 							<xsd:appinfo>
 								<tool:annotation kind="ref">

spring-integration-mail/src/test/java/org/springframework/integration/mail/config/ImapIdleChannelAdapterParserTests-context.xml

@@ -1,15 +1,12 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <beans xmlns="http://www.springframework.org/schema/beans"
 	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	xmlns:task="http://www.springframework.org/schema/task"
 	xmlns:util="http://www.springframework.org/schema/util"
 	xmlns:context="http://www.springframework.org/schema/context"
 	xmlns:mail="http://www.springframework.org/schema/integration/mail"
 	xmlns:integration="http://www.springframework.org/schema/integration"
 	xsi:schemaLocation="http://www.springframework.org/schema/beans
 			https://www.springframework.org/schema/beans/spring-beans.xsd
-			http://www.springframework.org/schema/task
-			https://www.springframework.org/schema/task/spring-task.xsd
 			http://www.springframework.org/schema/context
 			https://www.springframework.org/schema/context/spring-context.xsd
 			http://www.springframework.org/schema/util
@@ -78,8 +75,7 @@
 			store-uri="imap:foo"
 			channel="channel"
 			auto-startup="false"
-			should-delete-messages="true"
-			task-executor="executor">
+			should-delete-messages="true">
 		<mail:transactional synchronization-factory="syncFactory" />
 	</mail:imap-idle-channel-adapter>
 
@@ -95,8 +91,6 @@
 		<prop key="foo">bar</prop>
 	</util:properties>
 
-	<task:executor id="executor" pool-size="5"/>
-
 	<mail:imap-idle-channel-adapter
 			id="autoChannel"
 			store-uri="imap:foo"

spring-integration-mail/src/test/java/org/springframework/integration/mail/config/ImapIdleChannelAdapterParserTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -194,7 +194,6 @@ public void transactionalAdapter() {
 		assertThat(receiverAccessor.getPropertyValue("shouldDeleteMessages")).isEqualTo(Boolean.TRUE);
 		assertThat(receiverAccessor.getPropertyValue("shouldMarkMessagesAsRead")).isEqualTo(Boolean.TRUE);
 		assertThat(adapterAccessor.getPropertyValue("errorChannel")).isNull();
-		assertThat(adapterAccessor.getPropertyValue("sendingTaskExecutor")).isEqualTo(context.getBean("executor"));
 		assertThat(adapterAccessor.getPropertyValue("adviceChain")).isNotNull();
 	}
 

src/reference/asciidoc/mail.adoc

@@ -143,6 +143,8 @@ In this case, the only header populated is the mentioned above `IntegrationMessa
 Starting with version 5.5.11, the folder is closed automatically after `AbstractMailReceiver.receive()` if no messages received or all of them are filtered out independently of the `autoCloseFolder` flag.
 In this case there is nothing to produce downstream for possible logic around `IntegrationMessageHeaderAccessor.CLOSEABLE_RESOURCE` header.
 
+Starting with version 6.0.5, an `ImapIdleChannelAdapter.sendingTaskExecutor` option is deprecated in favor of an asynchronous message handling in downstream flow, e.g. via an `ExecutorChannel` as an output channel of this channel adapter.
+
 [[mail-mapping]]
 === Inbound Mail Message Mapping