GH-2116: Add blocking retries to RT (#2124)

* GH-2116: Add blocking retries to RT

Before we hardcoded a no-ops back off in the DefaultErrorHandler used in the Retryable Topics feature.
Adds a setter to let the user provide their own back off policy and configure blocking retries in conjunction with RT.

* Change DHE in LCFC to defaultFalse

With this we no longer need a no ops back off.
Some minor adjustments were needed to maintain behavior when the logic gets to DLPR.

* Change DHE in LCFC to defaultFalse

With this we no longer need a no ops back off.
Some minor adjustments were needed to maintain behavior when the logic gets to DLPR.

* Improve API and docs

Now retryable exceptions can be set directly in the lcfc class.
Improved the docs on how to combine blocking and non-blocking behaviors.
Added what's new entry for this feature.

* Improve ExceptionClassifier JavaDoc

Also add assertions to the LCFC new methods to warn the user if they already set the blocking configurations.

Author: tomazfernandes

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

@@ -430,6 +430,80 @@ DeadLetterPublishingRecovererFactory factory(DestinationTopicResolver resolver)
 ----
 ====
 
+[[retry-topic-combine-blocking]]
+==== Combining blocking and non-blocking retries
+
+Starting in 2.8.4 you can configure the framework to use both blocking and non-blocking retries in conjunction.
+For example, you can have a set of exceptions that would likely trigger errors on the next records as well, such as `DatabaseAccessException`, so you can retry the same record a few times before sending it to the retry topic, or straight to the DLT.
+
+To configure blocking retries you just need to add the exceptions you want to retry through the `addRetryableExceptions` method in the `ListenerContainerFactoryConfigurer` bean as follows.
+The default policy is `FixedBackOff`, with nine retries and no delay between them.
+Optionally, you can provide your own back off policy.
+
+====
+[source, java]
+----
+@Bean(name = RetryTopicInternalBeanNames.LISTENER_CONTAINER_FACTORY_CONFIGURER_NAME)
+public ListenerContainerFactoryConfigurer lcfc(KafkaConsumerBackoffManager kafkaConsumerBackoffManager,
+                                               DeadLetterPublishingRecovererFactory deadLetterPublishingRecovererFactory,
+                                               @Qualifier(RetryTopicInternalBeanNames
+                                                       .INTERNAL_BACKOFF_CLOCK_BEAN_NAME) Clock clock) {
+    ListenerContainerFactoryConfigurer lcfc = new ListenerContainerFactoryConfigurer(kafkaConsumerBackoffManager, deadLetterPublishingRecovererFactory, clock);
+    lcfc.setBlockingRetryableExceptions(MyBlockingRetryException.class, MyOtherBlockingRetryException.class);
+    lcfc.setBlockingRetriesBackOff(new FixedBackOff(500, 5)); // Optional
+    return lcfc;
+}
+----
+====
+
+If you need to further tune the exception classification, you can set your own `Map` of classifications through the `ListenerContainerFactoryConfigurer.setErrorHandlerCustomizer()` method, such as:
+
+====
+[source, java]
+----
+lcfc.setErrorHandlerCustomizer(ceh -> ((DefaultErrorHandler) ceh).setClassifications(myClassificationsMap, myDefaultValue));
+----
+====
+
+NOTE: In combination with the global retryable topic's fatal exceptions classification, you can configure the framework for any behavior you'd like, such as having some exceptions trigger both blocking and non-blocking retries, trigger only one kind or the other, or go straight to the DLT without retries of any kind.
+
+Here's an example with both configurations working together:
+
+====
+[source, java]
+----
+@Bean(name = RetryTopicInternalBeanNames.LISTENER_CONTAINER_FACTORY_CONFIGURER_NAME)
+public ListenerContainerFactoryConfigurer lcfc(KafkaConsumerBackoffManager kafkaConsumerBackoffManager,
+                                            DeadLetterPublishingRecovererFactory deadLetterPublishingRecovererFactory,
+                                            @Qualifier(RetryTopicInternalBeanNames
+                                                    .INTERNAL_BACKOFF_CLOCK_BEAN_NAME) Clock clock) {
+    ListenerContainerFactoryConfigurer lcfc = new ListenerContainerFactoryConfigurer(kafkaConsumerBackoffManager, deadLetterPublishingRecovererFactory, clock);
+    lcfc.setBlockingRetryableExceptions(ShouldRetryOnlyBlockingException.class, ShouldRetryViaBothException.class);
+    return lcfc;
+}
+
+@Bean(name = RetryTopicInternalBeanNames.DESTINATION_TOPIC_CONTAINER_NAME)
+public DefaultDestinationTopicResolver ddtr(ApplicationContext applicationContext,
+                                            @Qualifier(RetryTopicInternalBeanNames
+                                                    .INTERNAL_BACKOFF_CLOCK_BEAN_NAME) Clock clock) {
+    DefaultDestinationTopicResolver ddtr = new DefaultDestinationTopicResolver(clock, applicationContext);
+    ddtr.addNotRetryableExceptions(ShouldRetryOnlyBlockingException.class, ShouldSkipBothRetriesException.class);
+    return ddtr;
+}
+
+----
+====
+
+In this example:
+
+* `ShouldRetryOnlyBlockingException.class` would retry only via blocking and, if all retries fail, would go straight to the DLT.
+* `ShouldRetryViaBothException.class` would retry via blocking, and if all blocking retries fail would be forwarded to the  next retry topic for another set of attempts.
+* `ShouldSkipBothRetriesException.class` would never be retried in any way and would go straight to the DLT if the first processing attempt failed.
+
+IMPORTANT: Note that the blocking retries behavior is allowlist - you add the exceptions you do want to retry that way; while the non-blocking retries classification is geared towards FATAL exceptions and as such is denylist - you add the exceptions you don't want to do non-blocking retries, but to send directly to the DLT instead.
+
+IMPORTANT: The non-blocking exception classification behavior also depends on the specific topic's configuration.
+
 ==== Topic Naming
 
 Retry topics and DLT are named by suffixing the main topic with a provided or default value, appended by either the delay or index for that topic.
@@ -746,6 +820,7 @@ public RetryTopicConfigurer retryTopicConfigurer(DestinationTopicProcessor desti
     return retryTopicConfigurer;
 }
 ----
+====
 
 [[change-kboe-logging-level]]
 ==== Changing KafkaBackOffException Logging Level

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

@@ -88,5 +88,8 @@ See <<retry-topic-lcf>> for more information.
 There's now a manageable global list of fatal exceptions that will make the failed record go straight to the DLT.
 Refer to <<retry-topic-ex-classifier>> to see how to manage it.
 
+You can now use blocking and non-blocking retries in conjunction.
+See <<retry-topic-combine-blocking>> for more information.
+
 The KafkaBackOffException thrown when using the retryable topics feature is now logged at DEBUG level.
-See <<change-kboe-logging-level>> if you need to change the logging level back to WARN or set it to any other level.
+See <<change-kboe-logging-level>> if you need to change the logging level back to WARN or set it to any other level.

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

@@ -131,7 +131,7 @@ public void handleRemaining(Exception thrownException, List<ConsumerRecord<?, ?>
 			Consumer<?, ?> consumer, MessageListenerContainer container) {
 
 		SeekUtils.seekOrRecover(thrownException, records, consumer, container, isCommitRecovered(), // NOSONAR
-				getRecoveryStrategy(records, thrownException), this.logger, getLogLevel());
+				getRecoveryStrategy(records, consumer, thrownException), this.logger, getLogLevel());
 	}
 
 	@Override

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

@@ -22,6 +22,7 @@
 import org.springframework.classify.BinaryExceptionClassifier;
 import org.springframework.kafka.support.converter.ConversionException;
 import org.springframework.kafka.support.serializer.DeserializationException;
+import org.springframework.lang.Nullable;
 import org.springframework.messaging.converter.MessageConversionException;
 import org.springframework.messaging.handler.invocation.MethodArgumentResolutionException;
 import org.springframework.util.Assert;
@@ -180,12 +181,14 @@ public boolean removeNotRetryableException(Class<? extends Exception> exceptionT
 	 * </ul>
 	 * All others will be retried, unless {@link #defaultFalse()} has been called.
 	 * @param exceptionType the exception type.
-	 * @return true if the removal was successful.
+	 * @return the classification of the exception if removal was successful;
+	 * null otherwise.
 	 * @since 2.8.4
 	 * @see #addNotRetryableExceptions(Class...)
 	 * @see #setClassifications(Map, boolean)
 	 */
-	public boolean removeClassification(Class<? extends Exception> exceptionType) {
+	@Nullable
+	public Boolean removeClassification(Class<? extends Exception> exceptionType) {
 		return this.classifier.getClassified().remove(exceptionType);
 	}
 

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

@@ -22,6 +22,7 @@
 import java.util.function.BiPredicate;
 
 import org.apache.commons.logging.LogFactory;
+import org.apache.kafka.clients.consumer.Consumer;
 import org.apache.kafka.clients.consumer.ConsumerRecord;
 
 import org.springframework.core.log.LogAccessor;
@@ -126,12 +127,26 @@ public int deliveryAttempt(TopicPartitionOffset topicPartitionOffset) {
 	 * @since 2.7
 	 */
 	protected RecoveryStrategy getRecoveryStrategy(List<ConsumerRecord<?, ?>> records, Exception thrownException) {
+		return getRecoveryStrategy(records, null, thrownException);
+	}
+
+	/**
+	 * Return a {@link RecoveryStrategy} to call to determine whether the first record in the
+	 * list should be skipped.
+	 * @param records the records.
+	 * @param recoveryConsumer the consumer.
+	 * @param thrownException the exception.
+	 * @return the {@link RecoveryStrategy}.
+	 * @since 2.8.4
+	 */
+	protected RecoveryStrategy getRecoveryStrategy(List<ConsumerRecord<?, ?>> records,
+												@Nullable Consumer<?, ?> recoveryConsumer, Exception thrownException) {
 		if (getClassifier().classify(thrownException)) {
 			return this.failureTracker::recovered;
 		}
 		else {
 			try {
-				this.failureTracker.getRecoverer().accept(records.get(0), thrownException);
+				this.failureTracker.getRecoverer().accept(records.get(0), recoveryConsumer, thrownException);
 				this.failureTracker.getRetryListeners().forEach(rl -> rl.recovered(records.get(0), thrownException));
 			}
 			catch (Exception ex) {

spring-kafka/src/main/java/org/springframework/kafka/listener/FailedRecordTracker.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.
@@ -240,7 +240,7 @@ void clearThreadState() {
 		this.failures.remove();
 	}
 
-	BiConsumer<ConsumerRecord<?, ?>, Exception> getRecoverer() {
+	ConsumerAwareRecordRecoverer getRecoverer() {
 		return this.recoverer;
 	}
 

spring-kafka/src/main/java/org/springframework/kafka/retrytopic/ListenerContainerFactoryConfigurer.java

@@ -17,6 +17,7 @@
 package org.springframework.kafka.retrytopic;
 
 import java.time.Clock;
+import java.util.Arrays;
 import java.util.Comparator;
 import java.util.HashSet;
 import java.util.List;
@@ -42,7 +43,7 @@
 import org.springframework.kafka.listener.adapter.KafkaBackoffAwareMessageListenerAdapter;
 import org.springframework.kafka.support.TopicPartitionOffset;
 import org.springframework.util.Assert;
-import org.springframework.util.backoff.FixedBackOff;
+import org.springframework.util.backoff.BackOff;
 
 /**
  *
@@ -81,6 +82,10 @@ public class ListenerContainerFactoryConfigurer {
 
 	private static final long LOWEST_BACKOFF_THRESHOLD = 1500L;
 
+	private BackOff providedBlockingBackOff = null;
+
+	private Class<? extends Exception>[] blockingExceptionTypes = null;
+
 	private Consumer<ConcurrentMessageListenerContainer<?, ?>> containerCustomizer = container -> {
 	};
 
@@ -158,6 +163,42 @@ public KafkaListenerContainerFactory<?> decorateFactoryWithoutSettingContainerPr
 		return new RetryTopicListenerContainerFactoryDecorator(factory, configuration, false);
 	}
 
+	/**
+	 * Set a {@link BackOff} to be used with blocking retries.
+	 * If the BackOff execution returns STOP, the record will be forwarded
+	 * to the next retry topic or to the DLT, depending on how the non-blocking retries
+	 * are configured.
+	 * @param blockingBackOff the BackOff policy to be used by blocking retries.
+	 * @since 2.8.4
+	 * @see DefaultErrorHandler
+	 */
+	public void setBlockingRetriesBackOff(BackOff blockingBackOff) {
+		Assert.notNull(blockingBackOff, "The provided BackOff cannot be null");
+		Assert.state(this.providedBlockingBackOff == null, () ->
+				"Blocking retries back off has already been set. Current: "
+						+ this.providedBlockingBackOff
+						+ " You provided: " + blockingBackOff);
+		this.providedBlockingBackOff = blockingBackOff;
+	}
+
+	/**
+	 * Specify the exceptions to be retried via blocking.
+	 * @param exceptionTypes the exceptions that should be retried.
+	 * @since 2.8.4
+	 * @see DefaultErrorHandler
+	 */
+	@SafeVarargs
+	@SuppressWarnings("varargs")
+	public final void setBlockingRetryableExceptions(Class<? extends Exception>... exceptionTypes) {
+		Assert.notNull(exceptionTypes, "The exception types cannot be null");
+		Assert.noNullElements(exceptionTypes, "The exception types cannot have null elements");
+		Assert.state(this.blockingExceptionTypes == null,
+				() -> "Blocking retryable exceptions have already been set."
+						+  "Current ones: " + Arrays.toString(this.blockingExceptionTypes)
+						+ " You provided: " + Arrays.toString(exceptionTypes));
+		this.blockingExceptionTypes = exceptionTypes;
+	}
+
 	private ConcurrentKafkaListenerContainerFactory<?, ?> doConfigure(
 			ConcurrentKafkaListenerContainerFactory<?, ?> containerFactory, Configuration configuration,
 			boolean isSetContainerProperties) {
@@ -193,14 +234,23 @@ public void setErrorHandlerCustomizer(Consumer<CommonErrorHandler> errorHandlerC
 
 	protected CommonErrorHandler createErrorHandler(DeadLetterPublishingRecoverer deadLetterPublishingRecoverer,
 												Configuration configuration) {
-		DefaultErrorHandler errorHandler = new DefaultErrorHandler(deadLetterPublishingRecoverer,
-				new FixedBackOff(0, 0));
+		DefaultErrorHandler errorHandler = createDefaultErrorHandlerInstance(deadLetterPublishingRecoverer);
+		errorHandler.defaultFalse();
 		errorHandler.setCommitRecovered(true);
 		errorHandler.setLogLevel(KafkaException.Level.DEBUG);
+		if (this.blockingExceptionTypes != null) {
+			errorHandler.addRetryableExceptions(this.blockingExceptionTypes);
+		}
 		this.errorHandlerCustomizer.accept(errorHandler);
 		return errorHandler;
 	}
 
+	protected DefaultErrorHandler createDefaultErrorHandlerInstance(DeadLetterPublishingRecoverer deadLetterPublishingRecoverer) {
+		return this.providedBlockingBackOff != null
+				? new DefaultErrorHandler(deadLetterPublishingRecoverer, this.providedBlockingBackOff)
+				: new DefaultErrorHandler(deadLetterPublishingRecoverer);
+	}
+
 	protected void setupBackoffAwareMessageListenerAdapter(ConcurrentMessageListenerContainer<?, ?> container,
 														Configuration configuration, boolean isSetContainerProperties) {
 		AcknowledgingConsumerAwareMessageListener<?, ?> listener = checkAndCast(container.getContainerProperties()

spring-kafka/src/test/java/org/springframework/kafka/retrytopic/ListenerContainerFactoryConfigurerTests.java

@@ -17,12 +17,14 @@
 package org.springframework.kafka.retrytopic;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyLong;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.BDDMockito.given;
 import static org.mockito.BDDMockito.then;
 import static org.mockito.BDDMockito.willReturn;
+import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.times;
 
@@ -59,13 +61,18 @@
 import org.springframework.kafka.listener.adapter.AbstractDelegatingMessageListenerAdapter;
 import org.springframework.kafka.listener.adapter.KafkaBackoffAwareMessageListenerAdapter;
 import org.springframework.kafka.support.Acknowledgment;
+import org.springframework.kafka.support.converter.ConversionException;
+import org.springframework.kafka.support.serializer.DeserializationException;
+import org.springframework.util.backoff.BackOff;
+import org.springframework.util.backoff.BackOffExecution;
+import org.springframework.util.backoff.FixedBackOff;
 
 /**
  * @author Tomaz Fernandes
  * @since 2.7
  */
 @ExtendWith(MockitoExtension.class)
-@SuppressWarnings({"unchecked", "rawtypes"})
+@SuppressWarnings({"unchecked", "rawtypes", "deprecation"})
 class ListenerContainerFactoryConfigurerTests {
 
 	@Mock
@@ -404,10 +411,63 @@ void shouldDecorateFactory() {
 				.createContext(anyLong(), listenerIdCaptor.capture(), any(TopicPartition.class), eq(consumer));
 		assertThat(listenerIdCaptor.getValue()).isEqualTo(testListenerId);
 		then(listener).should(times(1)).onMessage(data, ack, consumer);
-
 		then(this.configurerContainerCustomizer).should(times(1)).accept(container);
 	}
 
+	@Test
+	void shouldUseGivenBackOffAndExceptions() {
+
+		// given
+		given(container.getContainerProperties()).willReturn(containerProperties);
+		given(deadLetterPublishingRecovererFactory.create()).willReturn(recoverer);
+		given(containerProperties.getMessageListener()).willReturn(listener);
+		given(configuration.forContainerFactoryConfigurer()).willReturn(lcfcConfiguration);
+		willReturn(container).given(containerFactory).createListenerContainer(endpoint);
+		BackOff backOffMock = mock(BackOff.class);
+		BackOffExecution backOffExecutionMock = mock(BackOffExecution.class);
+		given(backOffMock.start()).willReturn(backOffExecutionMock);
+
+		ListenerContainerFactoryConfigurer configurer =
+				new ListenerContainerFactoryConfigurer(kafkaConsumerBackoffManager,
+						deadLetterPublishingRecovererFactory, clock);
+		configurer.setBlockingRetriesBackOff(backOffMock);
+		configurer.setBlockingRetryableExceptions(IllegalArgumentException.class, IllegalStateException.class);
+
+		// when
+		KafkaListenerContainerFactory<?> decoratedFactory =
+				configurer.decorateFactory(this.containerFactory, configuration.forContainerFactoryConfigurer());
+		decoratedFactory.createListenerContainer(endpoint);
+
+		// then
+		then(backOffMock).should().start();
+		then(container).should().setCommonErrorHandler(errorHandlerCaptor.capture());
+		CommonErrorHandler errorHandler = errorHandlerCaptor.getValue();
+		assertThat(DefaultErrorHandler.class.isAssignableFrom(errorHandler.getClass())).isTrue();
+		DefaultErrorHandler defaultErrorHandler = (DefaultErrorHandler) errorHandler;
+		assertThat(defaultErrorHandler.removeClassification(IllegalArgumentException.class)).isTrue();
+		assertThat(defaultErrorHandler.removeClassification(IllegalStateException.class)).isTrue();
+		assertThat(defaultErrorHandler.removeClassification(ConversionException.class)).isNull();
+
+	}
+
+
+	@Test
+	void shouldThrowIfBackOffOrRetryablesAlreadySet() {
+		// given
+		BackOff backOff = new FixedBackOff();
+		ListenerContainerFactoryConfigurer configurer =
+				new ListenerContainerFactoryConfigurer(kafkaConsumerBackoffManager,
+						deadLetterPublishingRecovererFactory, clock);
+		configurer.setBlockingRetriesBackOff(backOff);
+		configurer.setBlockingRetryableExceptions(IllegalArgumentException.class, IllegalStateException.class);
+
+		// when / then
+		assertThatThrownBy(() -> configurer.setBlockingRetriesBackOff(backOff)).isInstanceOf(IllegalStateException.class);
+		assertThatThrownBy(() -> configurer.setBlockingRetryableExceptions(ConversionException.class, DeserializationException.class))
+				.isInstanceOf(IllegalStateException.class);
+	}
+
+
 	@Test
 	void shouldCacheFactoryInstances() {