GH-2318: ReplyingKT - Wait for Assignment

Resolves #2318

Add an option to wait for assignment to the `ReplyingKafkaTemplate`; useful
when using `auto.offset.reset=latest` to avoid sending a request with the reply
sent before the container is initialized.

**cherry-pick to 2.9.x, 2.8.x**

Author: garyrussell

spring-kafka-docs/src/main/asciidoc/kafka.adoc

@@ -555,6 +555,11 @@ You can use this future to determine the result of the send operation.
 
 If the first method is used, or the `replyTimeout` argument is `null`, the template's `defaultReplyTimeout` property is used (5 seconds by default).
 
+Starting with version 2.8.8, the template has a new method `waitForAssignment`.
+This is useful if the reply container is configured with `auto.offset.reset=latest` to avoid sending a request and a reply sent before the container is initialized.
+
+IMPORTANT: When using manual partition assignment (no group management), the duration for the wait must be greater than the container's `pollTimeout` property because the notification will not be sent until after the first poll is completed.
+
 The following Spring Boot application shows an example of how to use the feature:
 
 ====
@@ -570,6 +575,9 @@ public class KRequestingApplication {
     @Bean
     public ApplicationRunner runner(ReplyingKafkaTemplate<String, String, String> template) {
         return args -> {
+            if (!template.waitForAssignment(Duration.ofSeconds(10))) {
+                throw new IllegalStateException("Reply container did not initialize");
+            }
             ProducerRecord<String, String> record = new ProducerRecord<>("kRequests", "foo");
             RequestReplyFuture<String, String, String> replyFuture = template.sendAndReceive(record);
             SendResult<String, String> sendResult = replyFuture.getSendFuture().get(10, TimeUnit.SECONDS);

spring-kafka/src/main/java/org/springframework/kafka/listener/ConsumerSeekAware.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2019 the original author or authors.
+ * Copyright 2016-2022 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.
@@ -39,7 +39,6 @@ public interface ConsumerSeekAware {
 	 * @param callback the callback.
 	 */
 	default void registerSeekCallback(ConsumerSeekCallback callback) {
-		// do nothing
 	}
 
 	/**
@@ -48,7 +47,6 @@ default void registerSeekCallback(ConsumerSeekCallback callback) {
 	 * @param callback the callback to perform an initial seek after assignment.
 	 */
 	default void onPartitionsAssigned(Map<TopicPartition, Long> assignments, ConsumerSeekCallback callback) {
-		// do nothing
 	}
 
 	/**
@@ -59,7 +57,6 @@ default void onPartitionsAssigned(Map<TopicPartition, Long> assignments, Consume
 	 * @since 2.3
 	 */
 	default void onPartitionsRevoked(Collection<TopicPartition> partitions) {
-		// do nothing
 	}
 
 	/**
@@ -69,7 +66,15 @@ default void onPartitionsRevoked(Collection<TopicPartition> partitions) {
 	 * @param callback the callback to perform a seek.
 	 */
 	default void onIdleContainer(Map<TopicPartition, Long> assignments, ConsumerSeekCallback callback) {
-		// do nothing
+	}
+
+	/**
+	 * When using manual partition assignment, called when the first poll has completed;
+	 * useful when using {@code auto.offset.reset=latest} and you need to wait until the
+	 * initial position has been established.
+	 * @since 2.8.8
+	 */
+	default void onFirstPoll() {
 	}
 
 	/**
@@ -78,7 +83,6 @@ default void onIdleContainer(Map<TopicPartition, Long> assignments, ConsumerSeek
 	 * @since 2.4
 	 */
 	default void unregisterSeekCallback() {
-		// do nothing
 	}
 
 	/**

spring-kafka/src/main/java/org/springframework/kafka/listener/KafkaMessageListenerContainer.java

@@ -767,6 +767,8 @@ private final class ListenerConsumer implements SchedulingAwareRunnable, Consume
 
 		private volatile long lastPoll = System.currentTimeMillis();
 
+		private boolean firstPoll;
+
 		@SuppressWarnings(UNCHECKED)
 		ListenerConsumer(GenericMessageListener<?> listener, ListenerType listenerType) {
 			Properties consumerProperties = propertiesFromProperties();
@@ -1349,6 +1351,10 @@ protected void pollAndInvoke() {
 				}
 				return;
 			}
+			if (!this.firstPoll && this.definedPartitions != null && this.consumerSeekAwareListener != null) {
+				this.firstPoll = true;
+				this.consumerSeekAwareListener.onFirstPoll();
+			}
 			debugRecords(records);
 
 			invokeIfHaveRecords(records);
@@ -3443,6 +3449,12 @@ public void onPartitionsAssigned(Collection<TopicPartition> partitions) {
 				else {
 					this.userListener.onPartitionsAssigned(partitions);
 				}
+				if (!ListenerConsumer.this.firstPoll && ListenerConsumer.this.definedPartitions == null
+						&& ListenerConsumer.this.consumerSeekAwareListener != null) {
+
+					ListenerConsumer.this.firstPoll = true;
+					ListenerConsumer.this.consumerSeekAwareListener.onFirstPoll();
+				}
 			}
 
 			private void repauseIfNeeded(Collection<TopicPartition> partitions) {

spring-kafka/src/main/java/org/springframework/kafka/requestreply/ReplyingKafkaOperations.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2021 the original author or authors.
+ * Copyright 2018-2022 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.
@@ -37,6 +37,19 @@
  */
 public interface ReplyingKafkaOperations<K, V, R> {
 
+	/**
+	 * Wait until partitions are assigned, e.g. when {@code auto.offset.reset=latest}.
+	 * When using manual assignment, the duration must be greater than the container's
+	 * {@code pollTimeout} property.
+	 * @param duration how long to wait.
+	 * @return true if the partitions have been assigned.
+	 * @throws InterruptedException if the thread is interrupted while waiting.
+	 * @since 2.8.8
+	 */
+	default boolean waitForAssignment(Duration duration) throws InterruptedException {
+		throw new UnsupportedOperationException();
+	}
+
 	/**
 	 * Send a request message and receive a reply message with the default timeout.
 	 * @param message the message to send.

spring-kafka/src/main/java/org/springframework/kafka/requestreply/ReplyingKafkaTemplate.java

@@ -25,6 +25,8 @@
 import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
 import java.util.function.Function;
 
 import org.apache.kafka.clients.consumer.ConsumerRecord;
@@ -43,6 +45,7 @@
 import org.springframework.kafka.core.KafkaTemplate;
 import org.springframework.kafka.core.ProducerFactory;
 import org.springframework.kafka.listener.BatchMessageListener;
+import org.springframework.kafka.listener.ConsumerSeekAware;
 import org.springframework.kafka.listener.ContainerProperties;
 import org.springframework.kafka.listener.GenericMessageListenerContainer;
 import org.springframework.kafka.listener.ListenerUtils;
@@ -71,7 +74,7 @@
  *
  */
 public class ReplyingKafkaTemplate<K, V, R> extends KafkaTemplate<K, V> implements BatchMessageListener<K, R>,
-		InitializingBean, SmartLifecycle, DisposableBean, ReplyingKafkaOperations<K, V, R> {
+		InitializingBean, SmartLifecycle, DisposableBean, ReplyingKafkaOperations<K, V, R>, ConsumerSeekAware {
 
 	private static final String WITH_CORRELATION_ID = " with correlationId: ";
 
@@ -109,6 +112,8 @@ public class ReplyingKafkaTemplate<K, V, R> extends KafkaTemplate<K, V> implemen
 
 	private Function<ConsumerRecord<?, ?>, Exception> replyErrorChecker = rec -> null;
 
+	private CountDownLatch assignLatch = new CountDownLatch(1);
+
 	private volatile boolean running;
 
 	private volatile boolean schedulerInitialized;
@@ -295,6 +300,7 @@ public synchronized void start() {
 			catch (Exception e) {
 				throw new KafkaException("Failed to initialize", e);
 			}
+			this.assignLatch = new CountDownLatch(1);
 			this.replyContainer.start();
 			this.running = true;
 		}
@@ -315,6 +321,16 @@ public void stop(Runnable callback) {
 		callback.run();
 	}
 
+	@Override
+	public void onFirstPoll() {
+		this.assignLatch.countDown();
+	}
+
+	@Override
+	public boolean waitForAssignment(Duration duration) throws InterruptedException {
+		return this.assignLatch.await(duration.toMillis(), TimeUnit.MILLISECONDS);
+	}
+
 	@Override
 	public RequestReplyMessageFuture<K, V> sendAndReceive(Message<?> message) {
 		return sendAndReceive(message, this.defaultReplyTimeout, null);

spring-kafka/src/test/java/org/springframework/kafka/requestreply/ReplyingKafkaTemplateTests.java

@@ -611,13 +611,16 @@ public void onPartitionsAssigned(Collection<TopicPartition> partitions) {
 				new ReplyingKafkaTemplate<>(this.config.pf(), container);
 		template.setSharedReplyTopic(true);
 		template.start();
+		assertThat(template.waitForAssignment(Duration.ofSeconds(10))).isTrue();
 		assertThat(latch.await(30, TimeUnit.SECONDS)).isTrue();
 		assertThat(template.getAssignedReplyTopicPartitions()).hasSize(5);
 		assertThat(template.getAssignedReplyTopicPartitions().iterator().next().topic()).isEqualTo(topic);
 		return template;
 	}
 
-	public ReplyingKafkaTemplate<Integer, String, String> createTemplate(TopicPartitionOffset topic) {
+	public ReplyingKafkaTemplate<Integer, String, String> createTemplate(TopicPartitionOffset topic)
+			throws InterruptedException {
+
 		ContainerProperties containerProperties = new ContainerProperties(topic);
 		Map<String, Object> consumerProps = KafkaTestUtils.consumerProps(this.testName, "false", embeddedKafka);
 		DefaultKafkaConsumerFactory<Integer, String> cf = new DefaultKafkaConsumerFactory<>(consumerProps);
@@ -628,6 +631,7 @@ public ReplyingKafkaTemplate<Integer, String, String> createTemplate(TopicPartit
 				container);
 		template.setSharedReplyTopic(true);
 		template.start();
+		assertThat(template.waitForAssignment(Duration.ofSeconds(10))).isTrue();
 		assertThat(template.getAssignedReplyTopicPartitions()).hasSize(1);
 		assertThat(template.getAssignedReplyTopicPartitions().iterator().next().topic()).isEqualTo(topic.getTopic());
 		return template;