Merge pull request #10 from ychunxue/ltr_base_ShardEnd

ShardEnd shard sync with Child Shards

amazon-kinesis-client/src/main/java/software/amazon/kinesis/leases/HierarchicalShardSyncer.java

@@ -39,6 +39,7 @@ import org.apache.commons.lang3.StringUtils;
 import lombok.NonNull;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
+import software.amazon.awssdk.services.kinesis.model.ChildShard;
 import software.amazon.awssdk.services.kinesis.model.Shard;
 import software.amazon.awssdk.services.kinesis.model.ShardFilter;
 import software.amazon.awssdk.services.kinesis.model.ShardFilterType;
@@ -763,6 +764,41 @@ public class HierarchicalShardSyncer {
         }
     }
 
+    public synchronized Lease createLeaseForChildShard(final ChildShard childShard, final StreamIdentifier streamIdentifier) throws InvalidStateException {
+        final MultiStreamArgs multiStreamArgs = new MultiStreamArgs(isMultiStreamMode, streamIdentifier);
+
+        return multiStreamArgs.isMultiStreamMode() ? newKCLMultiStreamLeaseForChildShard(childShard, streamIdentifier)
+                                                   : newKCLLeaseForChildShard(childShard);
+    }
+
+    private static Lease newKCLLeaseForChildShard(final ChildShard childShard) throws InvalidStateException {
+        Lease newLease = new Lease();
+        newLease.leaseKey(childShard.shardId());
+        if (!CollectionUtils.isNullOrEmpty(childShard.parentShards())) {
+            newLease.parentShardIds(childShard.parentShards());
+        } else {
+            throw new InvalidStateException("Unable to populate new lease for child shard " + childShard.shardId() + "because parent shards cannot be found.");
+        }
+        newLease.checkpoint(ExtendedSequenceNumber.TRIM_HORIZON);
+        newLease.ownerSwitchesSinceCheckpoint(0L);
+        return newLease;
+    }
+
+    private static Lease newKCLMultiStreamLeaseForChildShard(final ChildShard childShard, final StreamIdentifier streamIdentifier) throws InvalidStateException {
+        MultiStreamLease newLease = new MultiStreamLease();
+        newLease.leaseKey(MultiStreamLease.getLeaseKey(streamIdentifier.serialize(), childShard.shardId()));
+        if (!CollectionUtils.isNullOrEmpty(childShard.parentShards())) {
+            newLease.parentShardIds(childShard.parentShards());
+        } else {
+            throw new InvalidStateException("Unable to populate new lease for child shard " + childShard.shardId() + "because parent shards cannot be found.");
+        }
+        newLease.checkpoint(ExtendedSequenceNumber.TRIM_HORIZON);
+        newLease.ownerSwitchesSinceCheckpoint(0L);
+        newLease.streamIdentifier(streamIdentifier.serialize());
+        newLease.shardId(childShard.shardId());
+        return newLease;
+    }
+
     /**
      * Helper method to create a new Lease POJO for a shard.
      * Note: Package level access only for testing purposes

amazon-kinesis-client/src/main/java/software/amazon/kinesis/leases/exceptions/CustomerApplicationException.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2019 Amazon.com, Inc. or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package software.amazon.kinesis.leases.exceptions;
+
+/**
+ * Exception type for all exceptions thrown by the customer implemented code.
+ */
+public class CustomerApplicationException extends Exception {
+
+    public CustomerApplicationException(Throwable e) { super(e);}
+
+    public CustomerApplicationException(String message, Throwable e) { super(message, e);}
+
+    public CustomerApplicationException(String message) { super(message);}
+}

amazon-kinesis-client/src/main/java/software/amazon/kinesis/lifecycle/ConsumerStates.java

@@ -496,7 +496,8 @@ class ConsumerStates {
                     argument.taskBackoffTimeMillis(),
                     argument.recordsPublisher(),
                     argument.hierarchicalShardSyncer(),
-                    argument.metricsFactory());
+                    argument.metricsFactory(),
+                    input == null ? null : input.childShards());
         }
 
         @Override

amazon-kinesis-client/src/main/java/software/amazon/kinesis/lifecycle/ShardConsumer.java

@@ -16,6 +16,7 @@ package software.amazon.kinesis.lifecycle;
 
 import java.time.Duration;
 import java.time.Instant;
+import java.util.List;
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
@@ -32,6 +33,7 @@ import lombok.Getter;
 import lombok.NonNull;
 import lombok.experimental.Accessors;
 import lombok.extern.slf4j.Slf4j;
+import software.amazon.awssdk.services.kinesis.model.ChildShard;
 import software.amazon.kinesis.annotations.KinesisClientInternalApi;
 import software.amazon.kinesis.exceptions.internal.BlockedOnParentShardException;
 import software.amazon.kinesis.leases.ShardInfo;
@@ -86,6 +88,8 @@ public class ShardConsumer {
 
     private final ShardConsumerSubscriber subscriber;
 
+    private ProcessRecordsInput shardEndProcessRecordsInput;
+
     @Deprecated
     public ShardConsumer(RecordsPublisher recordsPublisher, ExecutorService executorService, ShardInfo shardInfo,
             Optional<Long> logWarningForTaskAfterMillis, ShardConsumerArgument shardConsumerArgument,
@@ -148,6 +152,7 @@ public class ShardConsumer {
         processData(input);
         if (taskOutcome == TaskOutcome.END_OF_SHARD) {
             markForShutdown(ShutdownReason.SHARD_END);
+            shardEndProcessRecordsInput = input;
             subscription.cancel();
             return;
         }
@@ -305,7 +310,7 @@ public class ShardConsumer {
                     return true;
                 }
 
-                executeTask(null);
+                executeTask(shardEndProcessRecordsInput);
                 return false;
             }
         }, executorService);

amazon-kinesis-client/src/main/java/software/amazon/kinesis/lifecycle/ShutdownTask.java

@@ -20,6 +20,7 @@ import lombok.NonNull;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.commons.lang3.StringUtils;
+import software.amazon.awssdk.services.kinesis.model.ChildShard;
 import software.amazon.awssdk.services.kinesis.model.Shard;
 import software.amazon.awssdk.utils.CollectionUtils;
 import software.amazon.kinesis.annotations.KinesisClientInternalApi;
@@ -30,6 +31,10 @@ import software.amazon.kinesis.leases.LeaseCoordinator;
 import software.amazon.kinesis.leases.ShardDetector;
 import software.amazon.kinesis.leases.ShardInfo;
 import software.amazon.kinesis.leases.HierarchicalShardSyncer;
+import software.amazon.kinesis.leases.exceptions.CustomerApplicationException;
+import software.amazon.kinesis.leases.exceptions.DependencyException;
+import software.amazon.kinesis.leases.exceptions.InvalidStateException;
+import software.amazon.kinesis.leases.exceptions.ProvisionedThroughputException;
 import software.amazon.kinesis.lifecycle.events.LeaseLostInput;
 import software.amazon.kinesis.lifecycle.events.ShardEndedInput;
 import software.amazon.kinesis.metrics.MetricsFactory;
@@ -66,8 +71,6 @@ public class ShutdownTask implements ConsumerTask {
     @NonNull
     private final InitialPositionInStreamExtended initialPositionInStream;
     private final boolean cleanupLeasesOfCompletedShards;
-    private final boolean garbageCollectLeases = false;
-    private final boolean isLeaseTableEmpty = false;
     private final boolean ignoreUnexpectedChildShards;
     @NonNull
     private final LeaseCoordinator leaseCoordinator;
@@ -81,6 +84,8 @@ public class ShutdownTask implements ConsumerTask {
 
     private final TaskType taskType = TaskType.SHUTDOWN;
 
+    private final List<ChildShard> childShards;
+
     private static final Function<ShardInfo, String> shardInfoIdProvider = shardInfo -> shardInfo
             .streamIdentifierSerOpt().map(s -> s + ":" + shardInfo.shardId()).orElse(shardInfo.shardId());
     /*
@@ -95,85 +100,48 @@ public class ShutdownTask implements ConsumerTask {
         final MetricsScope scope = MetricsUtil.createMetricsWithOperation(metricsFactory, SHUTDOWN_TASK_OPERATION);
 
         Exception exception;
-        boolean applicationException = false;
 
         try {
             try {
-                ShutdownReason localReason = reason;
+                log.debug("Invoking shutdown() for shard {}, concurrencyToken {}. Shutdown reason: {}",
-                List<Shard> latestShards = null;
+                          shardInfoIdProvider.apply(shardInfo), shardInfo.concurrencyToken(), reason);
-                /*
-                 * Revalidate if the current shard is closed before shutting down the shard consumer with reason SHARD_END
-                 * If current shard is not closed, shut down the shard consumer with reason LEASE_LOST that allows
-                 * active workers to contend for the lease of this shard.
-                 */
-                if (localReason == ShutdownReason.SHARD_END) {
-                    latestShards = shardDetector.listShards();
 
-                    //If latestShards is empty, should also shutdown the ShardConsumer without checkpoint with SHARD_END
+                final long startTime = System.currentTimeMillis();
-                    if (CollectionUtils.isNullOrEmpty(latestShards) || !isShardInContextParentOfAny(latestShards)) {
+                if (reason == ShutdownReason.SHARD_END) {
-                        localReason = ShutdownReason.LEASE_LOST;
+                    // Create new lease for the child shards if they don't exist.
-                        dropLease();
+                    if (!CollectionUtils.isNullOrEmpty(childShards)) {
-                        log.info("Forcing the lease to be lost before shutting down the consumer for Shard: " + shardInfoIdProvider.apply(shardInfo));
+                        createLeasesForChildShardsIfNotExist();
-                    }
+                    } else {
+                        log.warn("Shard {} no longer exists. Shutting down consumer with SHARD_END reason without creating leases for child shards.", shardInfoIdProvider.apply(shardInfo));
                     }
 
-                // If we reached end of the shard, set sequence number to SHARD_END.
-                if (localReason == ShutdownReason.SHARD_END) {
                     recordProcessorCheckpointer
                             .sequenceNumberAtShardEnd(recordProcessorCheckpointer.largestPermittedCheckpointValue());
                     recordProcessorCheckpointer.largestPermittedCheckpointValue(ExtendedSequenceNumber.SHARD_END);
+                    // Call the shardRecordsProcessor to checkpoint with SHARD_END sequence number.
+                    // The shardEnded is implemented by customer. We should validate if the SHARD_END checkpointing is successful after calling shardEnded.
+                    throwOnApplicationException(() -> applicationCheckpointAndVerification(), scope, startTime);
+                } else {
+                    throwOnApplicationException(() -> shardRecordProcessor.leaseLost(LeaseLostInput.builder().build()), scope, startTime);
                 }
 
-                log.debug("Invoking shutdown() for shard {}, concurrencyToken {}. Shutdown reason: {}",
+                log.debug("Shutting down retrieval strategy for shard {}.", shardInfoIdProvider.apply(shardInfo));
-                        shardInfoIdProvider.apply(shardInfo), shardInfo.concurrencyToken(), localReason);
-                final ShutdownInput shutdownInput = ShutdownInput.builder().shutdownReason(localReason)
-                        .checkpointer(recordProcessorCheckpointer).build();
-                final long startTime = System.currentTimeMillis();
-                try {
-                    if (localReason == ShutdownReason.SHARD_END) {
-                        shardRecordProcessor.shardEnded(ShardEndedInput.builder().checkpointer(recordProcessorCheckpointer).build());
-                        ExtendedSequenceNumber lastCheckpointValue = recordProcessorCheckpointer.lastCheckpointValue();
-                        if (lastCheckpointValue == null
-                                || !lastCheckpointValue.equals(ExtendedSequenceNumber.SHARD_END)) {
-                            throw new IllegalArgumentException("Application didn't checkpoint at end of shard "
-                                    + shardInfoIdProvider.apply(shardInfo) + ". Application must checkpoint upon shard end. " +
-                                    "See ShardRecordProcessor.shardEnded javadocs for more information.");
-                        }
-                    } else {
-                        shardRecordProcessor.leaseLost(LeaseLostInput.builder().build());
-                    }
-                    log.debug("Shutting down retrieval strategy.");
                 recordsPublisher.shutdown();
                 log.debug("Record processor completed shutdown() for shard {}", shardInfoIdProvider.apply(shardInfo));
-                } catch (Exception e) {
-                    applicationException = true;
-                    throw e;
-                } finally {
-                    MetricsUtil.addLatency(scope, RECORD_PROCESSOR_SHUTDOWN_METRIC, startTime, MetricsLevel.SUMMARY);
-                }
-
-                if (localReason == ShutdownReason.SHARD_END) {
-                    log.debug("Looking for child shards of shard {}", shardInfoIdProvider.apply(shardInfo));
-                    // create leases for the child shards
-                    hierarchicalShardSyncer.checkAndCreateLeaseForNewShards(shardDetector, leaseCoordinator.leaseRefresher(),
-                            initialPositionInStream, latestShards, cleanupLeasesOfCompletedShards, ignoreUnexpectedChildShards, scope, garbageCollectLeases,
-                            isLeaseTableEmpty);
-                    log.debug("Finished checking for child shards of shard {}", shardInfoIdProvider.apply(shardInfo));
-                }
 
                 return new TaskResult(null);
             } catch (Exception e) {
-                if (applicationException) {
+                if (e instanceof CustomerApplicationException) {
-                    log.error("Application exception. ", e);
+                    log.error("Shard {}: Application exception. ", shardInfoIdProvider.apply(shardInfo), e);
                 } else {
-                    log.error("Caught exception: ", e);
+                    log.error("Shard {}: Caught exception: ", shardInfoIdProvider.apply(shardInfo), e);
                 }
                 exception = e;
                 // backoff if we encounter an exception.
                 try {
                     Thread.sleep(this.backoffTimeMillis);
                 } catch (InterruptedException ie) {
-                    log.debug("Interrupted sleep", ie);
+                    log.debug("Shard {}: Interrupted sleep", shardInfoIdProvider.apply(shardInfo), ie);
                 }
             }
         } finally {
@@ -181,7 +149,37 @@ public class ShutdownTask implements ConsumerTask {
         }
 
         return new TaskResult(exception);
+    }
 
+    private void applicationCheckpointAndVerification() {
+        shardRecordProcessor.shardEnded(ShardEndedInput.builder().checkpointer(recordProcessorCheckpointer).build());
+        final ExtendedSequenceNumber lastCheckpointValue = recordProcessorCheckpointer.lastCheckpointValue();
+        if (lastCheckpointValue == null
+                || !lastCheckpointValue.equals(ExtendedSequenceNumber.SHARD_END)) {
+            throw new IllegalArgumentException("Application didn't checkpoint at end of shard "
+                                                       + shardInfoIdProvider.apply(shardInfo) + ". Application must checkpoint upon shard end. " +
+                                                       "See ShardRecordProcessor.shardEnded javadocs for more information.");
+        }
+    }
+
+    private void throwOnApplicationException(Runnable action, MetricsScope metricsScope, final long startTime) throws CustomerApplicationException {
+        try {
+            action.run();
+        } catch (Exception e) {
+            throw new CustomerApplicationException("Customer application throws exception for shard " + shardInfoIdProvider.apply(shardInfo) +": ", e);
+        } finally {
+            MetricsUtil.addLatency(metricsScope, RECORD_PROCESSOR_SHUTDOWN_METRIC, startTime, MetricsLevel.SUMMARY);
+        }
+    }
+
+    private void createLeasesForChildShardsIfNotExist()
+            throws DependencyException, InvalidStateException, ProvisionedThroughputException {
+        for(ChildShard childShard : childShards) {
+            if(leaseCoordinator.getCurrentlyHeldLease(childShard.shardId()) == null) {
+                final Lease leaseToCreate = hierarchicalShardSyncer.createLeaseForChildShard(childShard, shardDetector.streamIdentifier());
+                leaseCoordinator.leaseRefresher().createLeaseIfNotExists(leaseToCreate);
+            }
+        }
     }
 
     /*

amazon-kinesis-client/src/main/java/software/amazon/kinesis/lifecycle/events/ProcessRecordsInput.java

@@ -23,6 +23,7 @@ import lombok.EqualsAndHashCode;
 import lombok.Getter;
 import lombok.ToString;
 import lombok.experimental.Accessors;
+import software.amazon.awssdk.services.kinesis.model.ChildShard;
 import software.amazon.kinesis.processor.ShardRecordProcessor;
 import software.amazon.kinesis.processor.RecordProcessorCheckpointer;
 import software.amazon.kinesis.retrieval.KinesisClientRecord;
@@ -66,6 +67,11 @@ public class ProcessRecordsInput {
      * This value does not include the {@link #timeSpentInCache()}.
      */
     private Long millisBehindLatest;
+    /**
+     * A list of child shards if the current GetRecords request reached the shard end.
+     * If not at the shard end, this should be an empty list.
+     */
+    private List<ChildShard> childShards;
 
     /**
      * How long the records spent waiting to be dispatched to the {@link ShardRecordProcessor}

amazon-kinesis-client/src/main/java/software/amazon/kinesis/retrieval/fanout/FanOutRecordsPublisher.java

@@ -33,11 +33,13 @@ import software.amazon.awssdk.services.kinesis.model.SubscribeToShardEventStream
 import software.amazon.awssdk.services.kinesis.model.SubscribeToShardRequest;
 import software.amazon.awssdk.services.kinesis.model.SubscribeToShardResponse;
 import software.amazon.awssdk.services.kinesis.model.SubscribeToShardResponseHandler;
+import software.amazon.awssdk.utils.CollectionUtils;
 import software.amazon.awssdk.utils.Either;
 import software.amazon.kinesis.annotations.KinesisClientInternalApi;
 import software.amazon.kinesis.common.InitialPositionInStreamExtended;
 import software.amazon.kinesis.common.KinesisRequestsBuilder;
 import software.amazon.kinesis.common.RequestDetails;
+import software.amazon.kinesis.leases.exceptions.InvalidStateException;
 import software.amazon.kinesis.lifecycle.events.ProcessRecordsInput;
 import software.amazon.kinesis.retrieval.BatchUniqueIdentifier;
 import software.amazon.kinesis.retrieval.IteratorBuilder;
@@ -398,7 +400,7 @@ public class FanOutRecordsPublisher implements RecordsPublisher {
             // The ack received for this onNext event will be ignored by the publisher as the global flow object should
             // be either null or renewed when the ack's flow identifier is evaluated.
             FanoutRecordsRetrieved response = new FanoutRecordsRetrieved(
-                    ProcessRecordsInput.builder().records(Collections.emptyList()).isAtShardEnd(true).build(), null,
+                    ProcessRecordsInput.builder().records(Collections.emptyList()).isAtShardEnd(true).childShards(Collections.emptyList()).build(), null,
                     triggeringFlow != null ? triggeringFlow.getSubscribeToShardId() : shardId + "-no-flow-found");
             subscriber.onNext(response);
             subscriber.onComplete();
@@ -477,15 +479,28 @@ public class FanOutRecordsPublisher implements RecordsPublisher {
                 return;
             }
 
+            try {
+                // If recordBatchEvent is not valid event, RuntimeException will be thrown here and trigger the errorOccurred call.
+                // Since the triggeringFlow is active flow, it will then trigger the handleFlowError call.
+                // Since the exception is not ResourceNotFoundException, it will trigger onError in the ShardConsumerSubscriber.
+                // The ShardConsumerSubscriber will finally cancel the subscription.
+                if (!isValidEvent(recordBatchEvent)) {
+                    throw new InvalidStateException("RecordBatchEvent for flow " + triggeringFlow.toString() + " is invalid."
+                                               + " event.continuationSequenceNumber: " + recordBatchEvent.continuationSequenceNumber()
+                                               + ". event.childShards: " + recordBatchEvent.childShards());
+                }
+
                 List<KinesisClientRecord> records = recordBatchEvent.records().stream().map(KinesisClientRecord::fromRecord)
                                                                     .collect(Collectors.toList());
-            ProcessRecordsInput input = ProcessRecordsInput.builder().cacheEntryTime(Instant.now())
+                ProcessRecordsInput input = ProcessRecordsInput.builder()
+                                                               .cacheEntryTime(Instant.now())
                                                                .millisBehindLatest(recordBatchEvent.millisBehindLatest())
-                    .isAtShardEnd(recordBatchEvent.continuationSequenceNumber() == null).records(records).build();
+                                                               .isAtShardEnd(recordBatchEvent.continuationSequenceNumber() == null)
+                                                               .records(records)
+                                                               .childShards(recordBatchEvent.childShards())
+                                                               .build();
                 FanoutRecordsRetrieved recordsRetrieved = new FanoutRecordsRetrieved(input,
                         recordBatchEvent.continuationSequenceNumber(), triggeringFlow.subscribeToShardId);
-
-            try {
                 bufferCurrentEventAndScheduleIfRequired(recordsRetrieved, triggeringFlow);
             } catch (Throwable t) {
                 log.warn("{}: Unable to buffer or schedule onNext for subscriber.  Failing publisher." +
@@ -495,6 +510,11 @@ public class FanOutRecordsPublisher implements RecordsPublisher {
         }
     }
 
+    private boolean isValidEvent(SubscribeToShardEvent event) {
+        return event.continuationSequenceNumber() == null ? !CollectionUtils.isNullOrEmpty(event.childShards())
+                                                          : event.childShards() != null && event.childShards().isEmpty();
+    }
+
     private void updateAvailableQueueSpaceAndRequestUpstream(RecordFlow triggeringFlow) {
         if (availableQueueSpace <= 0) {
             log.debug(

amazon-kinesis-client/src/main/java/software/amazon/kinesis/retrieval/polling/BlockingRecordsPublisher.java

@@ -67,6 +67,7 @@ public class BlockingRecordsPublisher implements RecordsPublisher {
         return ProcessRecordsInput.builder()
                 .records(records)
                 .millisBehindLatest(getRecordsResult.millisBehindLatest())
+                .childShards(getRecordsResult.childShards())
                 .build();
     }
 

amazon-kinesis-client/src/main/java/software/amazon/kinesis/retrieval/polling/KinesisDataFetcher.java

@@ -36,6 +36,7 @@ import software.amazon.awssdk.services.kinesis.model.GetShardIteratorRequest;
 import software.amazon.awssdk.services.kinesis.model.GetShardIteratorResponse;
 import software.amazon.awssdk.services.kinesis.model.KinesisException;
 import software.amazon.awssdk.services.kinesis.model.ResourceNotFoundException;
+import software.amazon.awssdk.utils.CollectionUtils;
 import software.amazon.kinesis.annotations.KinesisClientInternalApi;
 import software.amazon.kinesis.common.FutureUtils;
 import software.amazon.kinesis.common.InitialPositionInStreamExtended;
@@ -133,8 +134,12 @@ public class KinesisDataFetcher {
     final DataFetcherResult TERMINAL_RESULT = new DataFetcherResult() {
         @Override
         public GetRecordsResponse getResult() {
-            return GetRecordsResponse.builder().millisBehindLatest(null).records(Collections.emptyList())
+            return GetRecordsResponse.builder()
-                    .nextShardIterator(null).build();
+                                     .millisBehindLatest(null)
+                                     .records(Collections.emptyList())
+                                     .nextShardIterator(null)
+                                     .childShards(Collections.emptyList())
+                                     .build();
         }
 
         @Override
@@ -281,6 +286,11 @@ public class KinesisDataFetcher {
         try {
             final GetRecordsResponse response = FutureUtils.resolveOrCancelFuture(kinesisClient.getRecords(request),
                     maxFutureWait);
+            if (!isValidResponse(response)) {
+                throw new RetryableRetrievalException("GetRecords response is not valid for shard: " + streamAndShardId
+                        + ". nextShardIterator: " + response.nextShardIterator()
+                        + ". childShards: " + response.childShards() + ". Will retry GetRecords with the same nextIterator.");
+            }
             success = true;
             return response;
         } catch (ExecutionException e) {
@@ -298,6 +308,11 @@ public class KinesisDataFetcher {
         }
     }
 
+    private boolean isValidResponse(GetRecordsResponse response) {
+        return response.nextShardIterator() == null ? !CollectionUtils.isNullOrEmpty(response.childShards())
+                                                    : response.childShards() != null && response.childShards().isEmpty();
+    }
+
     private AWSExceptionManager createExceptionManager() {
         final AWSExceptionManager exceptionManager = new AWSExceptionManager();
         exceptionManager.add(ResourceNotFoundException.class, t -> t);

amazon-kinesis-client/src/main/java/software/amazon/kinesis/retrieval/polling/PrefetchRecordsPublisher.java

@@ -162,7 +162,7 @@ public class PrefetchRecordsPublisher implements RecordsPublisher {
             } else {
                 log.info(
                         "{}: No record batch found while evicting from the prefetch queue. This indicates the prefetch buffer"
-                                + "was reset.", streamAndShardId);
+                                + " was reset.", streamAndShardId);
             }
             return result;
         }
@@ -437,6 +437,7 @@ public class PrefetchRecordsPublisher implements RecordsPublisher {
                             .millisBehindLatest(getRecordsResult.millisBehindLatest())
                             .cacheEntryTime(lastSuccessfulCall)
                             .isAtShardEnd(getRecordsRetrievalStrategy.getDataFetcher().isShardEndReached())
+                            .childShards(getRecordsResult.childShards())
                             .build();
 
                     PrefetchRecordsRetrieved recordsRetrieved = new PrefetchRecordsRetrieved(processRecordsInput,

amazon-kinesis-client/src/test/java/software/amazon/kinesis/lifecycle/ConsumerStatesTest.java

@@ -25,6 +25,8 @@ import static org.mockito.Mockito.when;
 import static software.amazon.kinesis.lifecycle.ConsumerStates.ShardConsumerState;
 
 import java.lang.reflect.Field;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Optional;
 import java.util.concurrent.ExecutorService;
 
@@ -33,13 +35,13 @@ import org.hamcrest.Description;
 import org.hamcrest.Matcher;
 import org.hamcrest.TypeSafeDiagnosingMatcher;
 import org.junit.Before;
-import org.junit.Ignore;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.Mock;
 import org.mockito.runners.MockitoJUnitRunner;
 
 import software.amazon.awssdk.services.kinesis.KinesisAsyncClient;
+import software.amazon.awssdk.services.kinesis.model.ChildShard;
 import software.amazon.kinesis.checkpoint.ShardRecordProcessorCheckpointer;
 import software.amazon.kinesis.common.InitialPositionInStream;
 import software.amazon.kinesis.common.InitialPositionInStreamExtended;
@@ -49,6 +51,7 @@ import software.amazon.kinesis.leases.LeaseRefresher;
 import software.amazon.kinesis.leases.ShardDetector;
 import software.amazon.kinesis.leases.ShardInfo;
 import software.amazon.kinesis.leases.HierarchicalShardSyncer;
+import software.amazon.kinesis.leases.ShardObjectHelper;
 import software.amazon.kinesis.lifecycle.events.ProcessRecordsInput;
 import software.amazon.kinesis.metrics.MetricsFactory;
 import software.amazon.kinesis.processor.Checkpointer;
@@ -57,6 +60,7 @@ import software.amazon.kinesis.processor.ShardRecordProcessor;
 import software.amazon.kinesis.retrieval.AggregatorUtil;
 import software.amazon.kinesis.retrieval.RecordsPublisher;
 
+
 @RunWith(MockitoJUnitRunner.class)
 public class ConsumerStatesTest {
     private static final String STREAM_NAME = "TestStream";
@@ -300,13 +304,27 @@ public class ConsumerStatesTest {
 
     }
 
-    // TODO: Fix this test
-    @Ignore
     @Test
     public void shuttingDownStateTest() {
         consumer.markForShutdown(ShutdownReason.SHARD_END);
         ConsumerState state = ShardConsumerState.SHUTTING_DOWN.consumerState();
-        ConsumerTask task = state.createTask(argument, consumer, null);
+        List<ChildShard> childShards = new ArrayList<>();
+        List<String> parentShards = new ArrayList<>();
+        parentShards.add("shardId-000000000000");
+        ChildShard leftChild = ChildShard.builder()
+                                         .shardId("shardId-000000000001")
+                                         .parentShards(parentShards)
+                                         .hashKeyRange(ShardObjectHelper.newHashKeyRange("0", "49"))
+                                         .build();
+        ChildShard rightChild = ChildShard.builder()
+                                          .shardId("shardId-000000000002")
+                                          .parentShards(parentShards)
+                                          .hashKeyRange(ShardObjectHelper.newHashKeyRange("50", "99"))
+                                          .build();
+        childShards.add(leftChild);
+        childShards.add(rightChild);
+        when(processRecordsInput.childShards()).thenReturn(childShards);
+        ConsumerTask task = state.createTask(argument, consumer, processRecordsInput);
 
         assertThat(task, shutdownTask(ShardInfo.class, "shardInfo", equalTo(shardInfo)));
         assertThat(task,
@@ -315,8 +333,6 @@ public class ConsumerStatesTest {
                 equalTo(recordProcessorCheckpointer)));
         assertThat(task, shutdownTask(ShutdownReason.class, "reason", equalTo(reason)));
         assertThat(task, shutdownTask(LeaseCoordinator.class, "leaseCoordinator", equalTo(leaseCoordinator)));
-        assertThat(task, shutdownTask(InitialPositionInStreamExtended.class, "initialPositionInStream",
-                equalTo(initialPositionInStream)));
         assertThat(task,
                 shutdownTask(Boolean.class, "cleanupLeasesOfCompletedShards", equalTo(cleanupLeasesOfCompletedShards)));
         assertThat(task, shutdownTask(Long.class, "backoffTimeMillis", equalTo(taskBackoffTimeMillis)));

amazon-kinesis-client/src/test/java/software/amazon/kinesis/lifecycle/ShutdownTaskTest.java

@@ -26,6 +26,7 @@ import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
@@ -33,9 +34,11 @@ import java.util.List;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.mockito.Matchers;
 import org.mockito.Mock;
 import org.mockito.runners.MockitoJUnitRunner;
 
+import software.amazon.awssdk.services.kinesis.model.ChildShard;
 import software.amazon.awssdk.services.kinesis.model.SequenceNumberRange;
 import software.amazon.awssdk.services.kinesis.model.Shard;
 import software.amazon.kinesis.checkpoint.ShardRecordProcessorCheckpointer;
@@ -43,11 +46,16 @@ import software.amazon.kinesis.common.InitialPositionInStream;
 import software.amazon.kinesis.common.InitialPositionInStreamExtended;
 import software.amazon.kinesis.exceptions.internal.KinesisClientLibIOException;
 import software.amazon.kinesis.leases.HierarchicalShardSyncer;
+import software.amazon.kinesis.leases.Lease;
 import software.amazon.kinesis.leases.LeaseCoordinator;
 import software.amazon.kinesis.leases.LeaseRefresher;
 import software.amazon.kinesis.leases.ShardDetector;
 import software.amazon.kinesis.leases.ShardInfo;
 import software.amazon.kinesis.leases.ShardObjectHelper;
+import software.amazon.kinesis.leases.exceptions.CustomerApplicationException;
+import software.amazon.kinesis.leases.exceptions.DependencyException;
+import software.amazon.kinesis.leases.exceptions.InvalidStateException;
+import software.amazon.kinesis.leases.exceptions.ProvisionedThroughputException;
 import software.amazon.kinesis.lifecycle.events.LeaseLostInput;
 import software.amazon.kinesis.lifecycle.events.ShardEndedInput;
 import software.amazon.kinesis.metrics.MetricsFactory;
@@ -104,7 +112,7 @@ public class ShutdownTaskTest {
         task = new ShutdownTask(shardInfo, shardDetector, shardRecordProcessor, recordProcessorCheckpointer,
                 SHARD_END_SHUTDOWN_REASON, INITIAL_POSITION_TRIM_HORIZON, cleanupLeasesOfCompletedShards,
                 ignoreUnexpectedChildShards, leaseCoordinator, TASK_BACKOFF_TIME_MILLIS, recordsPublisher,
-                hierarchicalShardSyncer, NULL_METRICS_FACTORY);
+                hierarchicalShardSyncer, NULL_METRICS_FACTORY, constructChildShards());
     }
 
     /**
@@ -113,12 +121,12 @@ public class ShutdownTaskTest {
      */
     @Test
     public final void testCallWhenApplicationDoesNotCheckpoint() {
-        when(shardDetector.listShards()).thenReturn(constructShardListGraphA());
         when(recordProcessorCheckpointer.lastCheckpointValue()).thenReturn(new ExtendedSequenceNumber("3298"));
+        when(leaseCoordinator.leaseRefresher()).thenReturn(leaseRefresher);
 
         final TaskResult result = task.call();
         assertNotNull(result.getException());
-        assertTrue(result.getException() instanceof IllegalArgumentException);
+        assertTrue(result.getException() instanceof CustomerApplicationException);
     }
 
     /**
@@ -126,28 +134,18 @@ public class ShutdownTaskTest {
      * This test is for the scenario that checkAndCreateLeaseForNewShards throws an exception.
      */
     @Test
-    public final void testCallWhenSyncingShardsThrows() throws Exception {
+    public final void testCallWhenCreatingNewLeasesThrows() throws Exception {
-        final boolean garbageCollectLeases = false;
-        final boolean isLeaseTableEmpty = false;
-
-        List<Shard> latestShards = constructShardListGraphA();
-        when(shardDetector.listShards()).thenReturn(latestShards);
         when(recordProcessorCheckpointer.lastCheckpointValue()).thenReturn(ExtendedSequenceNumber.SHARD_END);
         when(leaseCoordinator.leaseRefresher()).thenReturn(leaseRefresher);
-
+        when(leaseRefresher.createLeaseIfNotExists(Matchers.any(Lease.class))).thenThrow(new KinesisClientLibIOException("KinesisClientLibIOException"));
-        doAnswer((invocation) -> {
-            throw new KinesisClientLibIOException("KinesisClientLibIOException");
-        }).when(hierarchicalShardSyncer)
-                .checkAndCreateLeaseForNewShards(shardDetector, leaseRefresher, INITIAL_POSITION_TRIM_HORIZON,
-                        latestShards, cleanupLeasesOfCompletedShards, ignoreUnexpectedChildShards,
-                        NULL_METRICS_FACTORY.createMetrics(), garbageCollectLeases, isLeaseTableEmpty);
 
         final TaskResult result = task.call();
         assertNotNull(result.getException());
         assertTrue(result.getException() instanceof KinesisClientLibIOException);
-        verify(recordsPublisher).shutdown();
+        verify(recordsPublisher, never()).shutdown();
-        verify(shardRecordProcessor).shardEnded(ShardEndedInput.builder().checkpointer(recordProcessorCheckpointer).build());
+        verify(shardRecordProcessor, never()).shardEnded(ShardEndedInput.builder().checkpointer(recordProcessorCheckpointer).build());
         verify(shardRecordProcessor, never()).leaseLost(LeaseLostInput.builder().build());
+        verify(leaseCoordinator, never()).dropLease(Matchers.any(Lease.class));
     }
 
     /**
@@ -155,24 +153,24 @@ public class ShutdownTaskTest {
      * This test is for the scenario that ShutdownTask is created for ShardConsumer reaching the Shard End.
      */
     @Test
-    public final void testCallWhenTrueShardEnd() {
+    public final void testCallWhenTrueShardEnd() throws DependencyException, InvalidStateException, ProvisionedThroughputException {
         shardInfo = new ShardInfo("shardId-0", concurrencyToken, Collections.emptySet(),
                                   ExtendedSequenceNumber.LATEST);
         task = new ShutdownTask(shardInfo, shardDetector, shardRecordProcessor, recordProcessorCheckpointer,
                                 SHARD_END_SHUTDOWN_REASON, INITIAL_POSITION_TRIM_HORIZON, cleanupLeasesOfCompletedShards,
                                 ignoreUnexpectedChildShards, leaseCoordinator, TASK_BACKOFF_TIME_MILLIS, recordsPublisher,
-                                hierarchicalShardSyncer, NULL_METRICS_FACTORY);
+                                hierarchicalShardSyncer, NULL_METRICS_FACTORY, constructChildShards());
 
-        when(shardDetector.listShards()).thenReturn(constructShardListGraphA());
         when(recordProcessorCheckpointer.lastCheckpointValue()).thenReturn(ExtendedSequenceNumber.SHARD_END);
+        when(leaseCoordinator.leaseRefresher()).thenReturn(leaseRefresher);
 
         final TaskResult result = task.call();
         assertNull(result.getException());
         verify(recordsPublisher).shutdown();
         verify(shardRecordProcessor).shardEnded(ShardEndedInput.builder().checkpointer(recordProcessorCheckpointer).build());
         verify(shardRecordProcessor, never()).leaseLost(LeaseLostInput.builder().build());
-        verify(shardDetector, times(1)).listShards();
+        verify(leaseRefresher, times(2)).createLeaseIfNotExists(Matchers.any(Lease.class));
-        verify(leaseCoordinator, never()).getAssignments();
+        verify(leaseCoordinator, never()).dropLease(Matchers.any(Lease.class));
     }
 
     /**
@@ -180,23 +178,25 @@ public class ShutdownTaskTest {
      * This test is for the scenario that a ShutdownTask is created for detecting a false Shard End.
      */
     @Test
-    public final void testCallWhenFalseShardEnd() {
+    public final void testCallWhenShardNotFound() throws DependencyException, InvalidStateException, ProvisionedThroughputException {
         shardInfo = new ShardInfo("shardId-4", concurrencyToken, Collections.emptySet(),
                                   ExtendedSequenceNumber.LATEST);
         task = new ShutdownTask(shardInfo, shardDetector, shardRecordProcessor, recordProcessorCheckpointer,
                                 SHARD_END_SHUTDOWN_REASON, INITIAL_POSITION_TRIM_HORIZON, cleanupLeasesOfCompletedShards,
                                 ignoreUnexpectedChildShards, leaseCoordinator, TASK_BACKOFF_TIME_MILLIS, recordsPublisher,
-                                hierarchicalShardSyncer, NULL_METRICS_FACTORY);
+                                hierarchicalShardSyncer, NULL_METRICS_FACTORY, new ArrayList<>());
 
-        when(shardDetector.listShards()).thenReturn(constructShardListGraphA());
+        when(recordProcessorCheckpointer.lastCheckpointValue()).thenReturn(ExtendedSequenceNumber.SHARD_END);
+        when(leaseCoordinator.leaseRefresher()).thenReturn(leaseRefresher);
 
         final TaskResult result = task.call();
         assertNull(result.getException());
         verify(recordsPublisher).shutdown();
-        verify(shardRecordProcessor, never()).shardEnded(ShardEndedInput.builder().checkpointer(recordProcessorCheckpointer).build());
+        verify(shardRecordProcessor).shardEnded(ShardEndedInput.builder().checkpointer(recordProcessorCheckpointer).build());
-        verify(shardRecordProcessor).leaseLost(LeaseLostInput.builder().build());
+        verify(shardRecordProcessor, never()).leaseLost(LeaseLostInput.builder().build());
-        verify(shardDetector, times(1)).listShards();
+        verify(leaseCoordinator, never()).getCurrentlyHeldLease(shardInfo.shardId());
-        verify(leaseCoordinator).getCurrentlyHeldLease(shardInfo.shardId());
+        verify(leaseRefresher, never()).createLeaseIfNotExists(Matchers.any(Lease.class));
+        verify(leaseCoordinator, never()).dropLease(Matchers.any(Lease.class));
     }
 
     /**
@@ -204,23 +204,22 @@ public class ShutdownTaskTest {
      * This test is for the scenario that a ShutdownTask is created for the ShardConsumer losing the lease.
      */
     @Test
-    public final void testCallWhenLeaseLost() {
+    public final void testCallWhenLeaseLost() throws DependencyException, InvalidStateException, ProvisionedThroughputException {
         shardInfo = new ShardInfo("shardId-4", concurrencyToken, Collections.emptySet(),
                                   ExtendedSequenceNumber.LATEST);
         task = new ShutdownTask(shardInfo, shardDetector, shardRecordProcessor, recordProcessorCheckpointer,
                                 LEASE_LOST_SHUTDOWN_REASON, INITIAL_POSITION_TRIM_HORIZON, cleanupLeasesOfCompletedShards,
                                 ignoreUnexpectedChildShards, leaseCoordinator, TASK_BACKOFF_TIME_MILLIS, recordsPublisher,
-                                hierarchicalShardSyncer, NULL_METRICS_FACTORY);
+                                hierarchicalShardSyncer, NULL_METRICS_FACTORY, new ArrayList<>());
-
-        when(shardDetector.listShards()).thenReturn(constructShardListGraphA());
 
         final TaskResult result = task.call();
         assertNull(result.getException());
         verify(recordsPublisher).shutdown();
         verify(shardRecordProcessor, never()).shardEnded(ShardEndedInput.builder().checkpointer(recordProcessorCheckpointer).build());
         verify(shardRecordProcessor).leaseLost(LeaseLostInput.builder().build());
-        verify(shardDetector, never()).listShards();
         verify(leaseCoordinator, never()).getAssignments();
+        verify(leaseRefresher, never()).createLeaseIfNotExists(Matchers.any(Lease.class));
+        verify(leaseCoordinator, never()).dropLease(Matchers.any(Lease.class));
     }
 
     /**
@@ -231,45 +230,23 @@ public class ShutdownTaskTest {
         assertEquals(TaskType.SHUTDOWN, task.taskType());
     }
 
-
+    private List<ChildShard> constructChildShards() {
-    /*
+        List<ChildShard> childShards = new ArrayList<>();
-     * Helper method to construct a shard list for graph A. Graph A is defined below. Shard structure (y-axis is
+        List<String> parentShards = new ArrayList<>();
-     * epochs): 0 1 2 3 4   5  - shards till
+        parentShards.add(shardId);
-     *          \ / \ / |   |
+        ChildShard leftChild = ChildShard.builder()
-     *           6   7  4   5  - shards from epoch 103 - 205
+                                         .shardId("ShardId-1")
-     *            \ /   |  /\
+                                         .parentShards(parentShards)
-     *             8    4 9 10 - shards from epoch 206 (open - no ending sequenceNumber)
+                                         .hashKeyRange(ShardObjectHelper.newHashKeyRange("0", "49"))
-     */
+                                         .build();
-    private List<Shard> constructShardListGraphA() {
+        ChildShard rightChild = ChildShard.builder()
-        final SequenceNumberRange range0 = ShardObjectHelper.newSequenceNumberRange("11", "102");
+                                         .shardId("ShardId-2")
-        final SequenceNumberRange range1 = ShardObjectHelper.newSequenceNumberRange("11", null);
+                                         .parentShards(parentShards)
-        final SequenceNumberRange range2 = ShardObjectHelper.newSequenceNumberRange("11", "205");
+                                         .hashKeyRange(ShardObjectHelper.newHashKeyRange("50", "99"))
-        final SequenceNumberRange range3 = ShardObjectHelper.newSequenceNumberRange("103", "205");
+                                         .build();
-        final SequenceNumberRange range4 = ShardObjectHelper.newSequenceNumberRange("206", null);
+        childShards.add(leftChild);
-
+        childShards.add(rightChild);
-        return Arrays.asList(
+        return  childShards;
-                ShardObjectHelper.newShard("shardId-0", null, null, range0,
-                                           ShardObjectHelper.newHashKeyRange("0", "99")),
-                ShardObjectHelper.newShard("shardId-1", null, null, range0,
-                                           ShardObjectHelper.newHashKeyRange("100", "199")),
-                ShardObjectHelper.newShard("shardId-2", null, null, range0,
-                                           ShardObjectHelper.newHashKeyRange("200", "299")),
-                ShardObjectHelper.newShard("shardId-3", null, null, range0,
-                                           ShardObjectHelper.newHashKeyRange("300", "399")),
-                ShardObjectHelper.newShard("shardId-4", null, null, range1,
-                                           ShardObjectHelper.newHashKeyRange("400", "499")),
-                ShardObjectHelper.newShard("shardId-5", null, null, range2,
-                                           ShardObjectHelper.newHashKeyRange("500", ShardObjectHelper.MAX_HASH_KEY)),
-                ShardObjectHelper.newShard("shardId-6", "shardId-0", "shardId-1", range3,
-                                           ShardObjectHelper.newHashKeyRange("0", "199")),
-                ShardObjectHelper.newShard("shardId-7", "shardId-2", "shardId-3", range3,
-                                           ShardObjectHelper.newHashKeyRange("200", "399")),
-                ShardObjectHelper.newShard("shardId-8", "shardId-6", "shardId-7", range4,
-                                           ShardObjectHelper.newHashKeyRange("0", "399")),
-                ShardObjectHelper.newShard("shardId-9", "shardId-5", null, range4,
-                                           ShardObjectHelper.newHashKeyRange("500", "799")),
-                ShardObjectHelper.newShard("shardId-10", null, "shardId-5", range4,
-                                           ShardObjectHelper.newHashKeyRange("800", ShardObjectHelper.MAX_HASH_KEY)));
     }
 
 }

amazon-kinesis-client/src/test/java/software/amazon/kinesis/retrieval/fanout/FanOutRecordsPublisherTest.java

@@ -26,6 +26,7 @@ import software.amazon.awssdk.core.SdkBytes;
 import software.amazon.awssdk.core.async.SdkPublisher;
 import software.amazon.awssdk.core.exception.SdkClientException;
 import software.amazon.awssdk.services.kinesis.KinesisAsyncClient;
+import software.amazon.awssdk.services.kinesis.model.ChildShard;
 import software.amazon.awssdk.services.kinesis.model.Record;
 import software.amazon.awssdk.services.kinesis.model.ResourceNotFoundException;
 import software.amazon.awssdk.services.kinesis.model.ShardIteratorType;
@@ -35,6 +36,7 @@ import software.amazon.awssdk.services.kinesis.model.SubscribeToShardEventStream
 import software.amazon.awssdk.services.kinesis.model.SubscribeToShardRequest;
 import software.amazon.kinesis.common.InitialPositionInStream;
 import software.amazon.kinesis.common.InitialPositionInStreamExtended;
+import software.amazon.kinesis.leases.ShardObjectHelper;
 import software.amazon.kinesis.lifecycle.ShardConsumerNotifyingSubscriber;
 import software.amazon.kinesis.lifecycle.events.ProcessRecordsInput;
 import software.amazon.kinesis.retrieval.BatchUniqueIdentifier;
@@ -47,6 +49,7 @@ import software.amazon.kinesis.utils.SubscribeToShardRequestMatcher;
 import java.nio.ByteBuffer;
 import java.time.Instant;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Optional;
@@ -89,6 +92,7 @@ public class FanOutRecordsPublisherTest {
 
     private static final String SHARD_ID = "Shard-001";
     private static final String CONSUMER_ARN = "arn:consumer";
+    private static final String CONTINUATION_SEQUENCE_NUMBER = "continuationSequenceNumber";
 
     @Mock
     private KinesisAsyncClient kinesisClient;
@@ -148,7 +152,12 @@ public class FanOutRecordsPublisherTest {
         List<KinesisClientRecordMatcher> matchers = records.stream().map(KinesisClientRecordMatcher::new)
                 .collect(Collectors.toList());
 
-        batchEvent = SubscribeToShardEvent.builder().millisBehindLatest(100L).records(records).build();
+        batchEvent = SubscribeToShardEvent.builder()
+                                          .millisBehindLatest(100L)
+                                          .records(records)
+                                          .continuationSequenceNumber("test")
+                                          .childShards(Collections.emptyList())
+                                          .build();
 
         captor.getValue().onNext(batchEvent);
         captor.getValue().onNext(batchEvent);
@@ -166,6 +175,73 @@ public class FanOutRecordsPublisherTest {
 
     }
 
+    @Test
+    public void InvalidEventTest() throws Exception {
+        FanOutRecordsPublisher source = new FanOutRecordsPublisher(kinesisClient, SHARD_ID, CONSUMER_ARN);
+
+        ArgumentCaptor<FanOutRecordsPublisher.RecordSubscription> captor = ArgumentCaptor
+                .forClass(FanOutRecordsPublisher.RecordSubscription.class);
+        ArgumentCaptor<FanOutRecordsPublisher.RecordFlow> flowCaptor = ArgumentCaptor
+                .forClass(FanOutRecordsPublisher.RecordFlow.class);
+
+        doNothing().when(publisher).subscribe(captor.capture());
+
+        source.start(ExtendedSequenceNumber.LATEST,
+                     InitialPositionInStreamExtended.newInitialPosition(InitialPositionInStream.LATEST));
+
+        List<ProcessRecordsInput> receivedInput = new ArrayList<>();
+
+        source.subscribe(new ShardConsumerNotifyingSubscriber(new Subscriber<RecordsRetrieved>() {
+            Subscription subscription;
+
+            @Override public void onSubscribe(Subscription s) {
+                subscription = s;
+                subscription.request(1);
+            }
+
+            @Override public void onNext(RecordsRetrieved input) {
+                receivedInput.add(input.processRecordsInput());
+                subscription.request(1);
+            }
+
+            @Override public void onError(Throwable t) {
+                log.error("Caught throwable in subscriber", t);
+                fail("Caught throwable in subscriber");
+            }
+
+            @Override public void onComplete() {
+                fail("OnComplete called when not expected");
+            }
+        }, source));
+
+        verify(kinesisClient).subscribeToShard(any(SubscribeToShardRequest.class), flowCaptor.capture());
+        flowCaptor.getValue().onEventStream(publisher);
+        captor.getValue().onSubscribe(subscription);
+
+        List<Record> records = Stream.of(1, 2, 3).map(this::makeRecord).collect(Collectors.toList());
+        List<KinesisClientRecordMatcher> matchers = records.stream().map(KinesisClientRecordMatcher::new)
+                                                           .collect(Collectors.toList());
+
+        batchEvent = SubscribeToShardEvent.builder().millisBehindLatest(100L).records(records).continuationSequenceNumber(CONTINUATION_SEQUENCE_NUMBER).build();
+        SubscribeToShardEvent invalidEvent = SubscribeToShardEvent.builder().millisBehindLatest(100L).records(records).childShards(Collections.emptyList()).build();
+
+        captor.getValue().onNext(batchEvent);
+        captor.getValue().onNext(invalidEvent);
+        captor.getValue().onNext(batchEvent);
+
+        // When the second request failed with invalid event, it should stop sending requests and cancel the flow.
+        verify(subscription, times(2)).request(1);
+        assertThat(receivedInput.size(), equalTo(1));
+
+        receivedInput.stream().map(ProcessRecordsInput::records).forEach(clientRecordsList -> {
+            assertThat(clientRecordsList.size(), equalTo(matchers.size()));
+            for (int i = 0; i < clientRecordsList.size(); ++i) {
+                assertThat(clientRecordsList.get(i), matchers.get(i));
+            }
+        });
+
+    }
+
     @Test
     public void testIfAllEventsReceivedWhenNoTasksRejectedByExecutor() throws Exception {
         FanOutRecordsPublisher source = new FanOutRecordsPublisher(kinesisClient, SHARD_ID, CONSUMER_ARN);
@@ -225,7 +301,9 @@ public class FanOutRecordsPublisherTest {
                         SubscribeToShardEvent.builder()
                                 .millisBehindLatest(100L)
                                 .continuationSequenceNumber(contSeqNum)
-                                .records(records).build())
+                                .records(records)
+                                .childShards(Collections.emptyList())
+                                .build())
                 .forEach(batchEvent -> captor.getValue().onNext(batchEvent));
 
         verify(subscription, times(4)).request(1);
@@ -301,7 +379,9 @@ public class FanOutRecordsPublisherTest {
                         SubscribeToShardEvent.builder()
                                 .millisBehindLatest(100L)
                                 .continuationSequenceNumber(contSeqNum)
-                                .records(records).build())
+                                .records(records)
+                                .childShards(Collections.emptyList())
+                                .build())
                 .forEach(batchEvent -> captor.getValue().onNext(batchEvent));
 
         verify(subscription, times(2)).request(1);
@@ -334,6 +414,7 @@ public class FanOutRecordsPublisherTest {
                         .millisBehindLatest(100L)
                         .continuationSequenceNumber(contSeqNum + "")
                         .records(records)
+                        .childShards(Collections.emptyList())
                         .build());
 
         CountDownLatch servicePublisherTaskCompletionLatch = new CountDownLatch(2);
@@ -436,6 +517,7 @@ public class FanOutRecordsPublisherTest {
                         .millisBehindLatest(100L)
                         .continuationSequenceNumber(contSeqNum + "")
                         .records(records)
+                        .childShards(Collections.emptyList())
                         .build());
 
         CountDownLatch servicePublisherTaskCompletionLatch = new CountDownLatch(2);
@@ -536,13 +618,30 @@ public class FanOutRecordsPublisherTest {
                         .millisBehindLatest(100L)
                         .continuationSequenceNumber(contSeqNum + "")
                         .records(records)
+                        .childShards(Collections.emptyList())
                         .build());
 
+        List<ChildShard> childShards = new ArrayList<>();
+        List<String> parentShards = new ArrayList<>();
+        parentShards.add(SHARD_ID);
+        ChildShard leftChild = ChildShard.builder()
+                                         .shardId("Shard-002")
+                                         .parentShards(parentShards)
+                                         .hashKeyRange(ShardObjectHelper.newHashKeyRange("0", "49"))
+                                         .build();
+        ChildShard rightChild = ChildShard.builder()
+                                          .shardId("Shard-003")
+                                          .parentShards(parentShards)
+                                          .hashKeyRange(ShardObjectHelper.newHashKeyRange("50", "99"))
+                                          .build();
+        childShards.add(leftChild);
+        childShards.add(rightChild);
         Consumer<Integer> servicePublisherShardEndAction = contSeqNum -> captor.getValue().onNext(
                 SubscribeToShardEvent.builder()
                         .millisBehindLatest(100L)
                         .continuationSequenceNumber(null)
                         .records(records)
+                        .childShards(childShards)
                         .build());
 
         CountDownLatch servicePublisherTaskCompletionLatch = new CountDownLatch(2);
@@ -648,6 +747,7 @@ public class FanOutRecordsPublisherTest {
                         .millisBehindLatest(100L)
                         .continuationSequenceNumber(contSeqNum + "")
                         .records(records)
+                        .childShards(Collections.emptyList())
                         .build());
 
         CountDownLatch servicePublisherTaskCompletionLatch = new CountDownLatch(2);
@@ -750,6 +850,7 @@ public class FanOutRecordsPublisherTest {
                         .millisBehindLatest(100L)
                         .continuationSequenceNumber(contSeqNum + "")
                         .records(records)
+                        .childShards(Collections.emptyList())
                         .build());
 
         CountDownLatch servicePublisherTaskCompletionLatch = new CountDownLatch(2);
@@ -842,6 +943,7 @@ public class FanOutRecordsPublisherTest {
                         .millisBehindLatest(100L)
                         .continuationSequenceNumber(contSeqNum + "")
                         .records(records)
+                        .childShards(Collections.emptyList())
                         .build());
 
         CountDownLatch servicePublisherTaskCompletionLatch = new CountDownLatch(1);
@@ -1004,7 +1106,12 @@ public class FanOutRecordsPublisherTest {
         List<KinesisClientRecordMatcher> matchers = records.stream().map(KinesisClientRecordMatcher::new)
                 .collect(Collectors.toList());
 
-        batchEvent = SubscribeToShardEvent.builder().millisBehindLatest(100L).records(records).build();
+        batchEvent = SubscribeToShardEvent.builder()
+                                          .millisBehindLatest(100L)
+                                          .records(records)
+                                          .continuationSequenceNumber(CONTINUATION_SEQUENCE_NUMBER)
+                                          .childShards(Collections.emptyList())
+                                          .build();
 
         captor.getValue().onNext(batchEvent);
         captor.getValue().onNext(batchEvent);
@@ -1098,7 +1205,7 @@ public class FanOutRecordsPublisherTest {
                 .collect(Collectors.toList());
 
         batchEvent = SubscribeToShardEvent.builder().millisBehindLatest(100L).records(records)
-                .continuationSequenceNumber("3").build();
+                .continuationSequenceNumber("3").childShards(Collections.emptyList()).build();
 
         captor.getValue().onNext(batchEvent);
         captor.getValue().onComplete();
@@ -1126,7 +1233,7 @@ public class FanOutRecordsPublisherTest {
                 .collect(Collectors.toList());
 
         batchEvent = SubscribeToShardEvent.builder().millisBehindLatest(100L).records(nextRecords)
-                .continuationSequenceNumber("6").build();
+                .continuationSequenceNumber("6").childShards(Collections.emptyList()).build();
         nextSubscribeCaptor.getValue().onNext(batchEvent);
 
         verify(subscription, times(4)).request(1);

amazon-kinesis-client/src/test/java/software/amazon/kinesis/retrieval/polling/KinesisDataFetcherTest.java

@@ -30,6 +30,7 @@ import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Date;
@@ -53,6 +54,7 @@ import org.mockito.runners.MockitoJUnitRunner;
 
 import software.amazon.awssdk.core.exception.SdkException;
 import software.amazon.awssdk.services.kinesis.KinesisAsyncClient;
+import software.amazon.awssdk.services.kinesis.model.ChildShard;
 import software.amazon.awssdk.services.kinesis.model.GetRecordsRequest;
 import software.amazon.awssdk.services.kinesis.model.GetRecordsResponse;
 import software.amazon.awssdk.services.kinesis.model.GetShardIteratorRequest;
@@ -65,6 +67,7 @@ import software.amazon.kinesis.checkpoint.SentinelCheckpoint;
 import software.amazon.kinesis.common.InitialPositionInStream;
 import software.amazon.kinesis.common.InitialPositionInStreamExtended;
 import software.amazon.kinesis.exceptions.KinesisClientLibException;
+import software.amazon.kinesis.leases.ShardObjectHelper;
 import software.amazon.kinesis.metrics.MetricsFactory;
 import software.amazon.kinesis.metrics.NullMetricsFactory;
 import software.amazon.kinesis.processor.Checkpointer;
@@ -330,8 +333,31 @@ public class KinesisDataFetcherTest {
 
     private CompletableFuture<GetRecordsResponse> makeGetRecordsResponse(String nextIterator, List<Record> records)
             throws InterruptedException, ExecutionException {
+        List<ChildShard> childShards = new ArrayList<>();
+        if(nextIterator == null) {
+            childShards = createChildShards();
+        }
         return CompletableFuture.completedFuture(GetRecordsResponse.builder().nextShardIterator(nextIterator)
-                .records(CollectionUtils.isNullOrEmpty(records) ? Collections.emptyList() : records).build());
+                .records(CollectionUtils.isNullOrEmpty(records) ? Collections.emptyList() : records).childShards(childShards).build());
+    }
+
+    private List<ChildShard> createChildShards() {
+        List<ChildShard> childShards = new ArrayList<>();
+        List<String> parentShards = new ArrayList<>();
+        parentShards.add(SHARD_ID);
+        ChildShard leftChild = ChildShard.builder()
+                                         .shardId("Shard-2")
+                                         .parentShards(parentShards)
+                                         .hashKeyRange(ShardObjectHelper.newHashKeyRange("0", "49"))
+                                         .build();
+        ChildShard rightChild = ChildShard.builder()
+                                          .shardId("Shard-3")
+                                          .parentShards(parentShards)
+                                          .hashKeyRange(ShardObjectHelper.newHashKeyRange("50", "99"))
+                                          .build();
+        childShards.add(leftChild);
+        childShards.add(rightChild);
+        return childShards;
     }
 
     @Test
@@ -342,6 +368,7 @@ public class KinesisDataFetcherTest {
         final String initialIterator = "InitialIterator";
         final String nextIterator1 = "NextIteratorOne";
         final String nextIterator2 = "NextIteratorTwo";
+        final String nextIterator3 = "NextIteratorThree";
         final CompletableFuture<GetRecordsResponse> nonAdvancingResult1 = makeGetRecordsResponse(initialIterator, null);
         final CompletableFuture<GetRecordsResponse> nonAdvancingResult2 = makeGetRecordsResponse(nextIterator1, null);
         final CompletableFuture<GetRecordsResponse> finalNonAdvancingResult = makeGetRecordsResponse(nextIterator2,

amazon-kinesis-client/src/test/java/software/amazon/kinesis/retrieval/polling/PrefetchRecordsPublisherIntegrationTest.java

@@ -22,6 +22,7 @@ import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
 import static org.mockito.Matchers.any;
 import static org.mockito.Matchers.anyLong;
+import static org.mockito.Matchers.eq;
 import static org.mockito.Mockito.doNothing;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.spy;
@@ -48,6 +49,7 @@ import org.mockito.runners.MockitoJUnitRunner;
 import org.mockito.stubbing.Answer;
 
 import software.amazon.awssdk.core.SdkBytes;
+import software.amazon.awssdk.services.kinesis.model.GetRecordsRequest;
 import software.amazon.kinesis.common.InitialPositionInStreamExtended;
 
 import lombok.extern.slf4j.Slf4j;
@@ -86,6 +88,7 @@ public class PrefetchRecordsPublisherIntegrationTest {
     private String operation = "ProcessTask";
     private String streamName = "streamName";
     private String shardId = "shardId-000000000000";
+    private String nextShardIterator = "testNextShardIterator";
 
     @Mock
     private KinesisAsyncClient kinesisClient;
@@ -249,7 +252,7 @@ public class PrefetchRecordsPublisherIntegrationTest {
 
         @Override
         public DataFetcherResult getRecords() {
-            GetRecordsResponse getRecordsResult = GetRecordsResponse.builder().records(new ArrayList<>(records)).millisBehindLatest(1000L).build();
+            GetRecordsResponse getRecordsResult = GetRecordsResponse.builder().records(new ArrayList<>(records)).nextShardIterator(nextShardIterator).millisBehindLatest(1000L).build();
 
             return new AdvancingResult(getRecordsResult);
         }

amazon-kinesis-client/src/test/java/software/amazon/kinesis/retrieval/polling/PrefetchRecordsPublisherTest.java

@@ -21,6 +21,7 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 import static org.mockito.Matchers.any;
@@ -71,11 +72,13 @@ import io.reactivex.Flowable;
 import io.reactivex.schedulers.Schedulers;
 import lombok.extern.slf4j.Slf4j;
 import software.amazon.awssdk.core.SdkBytes;
+import software.amazon.awssdk.services.kinesis.model.ChildShard;
 import software.amazon.awssdk.services.kinesis.model.ExpiredIteratorException;
 import software.amazon.awssdk.services.kinesis.model.GetRecordsResponse;
 import software.amazon.awssdk.services.kinesis.model.Record;
 import software.amazon.kinesis.common.InitialPositionInStreamExtended;
 import software.amazon.kinesis.common.RequestDetails;
+import software.amazon.kinesis.leases.ShardObjectHelper;
 import software.amazon.kinesis.common.StreamIdentifier;
 import software.amazon.kinesis.lifecycle.ShardConsumerNotifyingSubscriber;
 import software.amazon.kinesis.lifecycle.events.ProcessRecordsInput;
@@ -99,6 +102,7 @@ public class PrefetchRecordsPublisherTest {
     private static final int MAX_SIZE = 5;
     private static final int MAX_RECORDS_COUNT = 15000;
     private static final long IDLE_MILLIS_BETWEEN_CALLS = 0L;
+    private static final String NEXT_SHARD_ITERATOR = "testNextShardIterator";
 
     @Mock
     private GetRecordsRetrievalStrategy getRecordsRetrievalStrategy;
@@ -136,7 +140,7 @@ public class PrefetchRecordsPublisherTest {
                 "shardId");
         spyQueue = spy(getRecordsCache.getPublisherSession().prefetchRecordsQueue());
         records = spy(new ArrayList<>());
-        getRecordsResponse = GetRecordsResponse.builder().records(records).build();
+        getRecordsResponse = GetRecordsResponse.builder().records(records).nextShardIterator(NEXT_SHARD_ITERATOR).childShards(new ArrayList<>()).build();
 
         when(getRecordsRetrievalStrategy.getRecords(eq(MAX_RECORDS_PER_CALL))).thenReturn(getRecordsResponse);
     }
@@ -155,11 +159,67 @@ public class PrefetchRecordsPublisherTest {
                 .processRecordsInput();
 
         assertEquals(expectedRecords, result.records());
+        assertEquals(new ArrayList<>(), result.childShards());
 
         verify(executorService).execute(any());
         verify(getRecordsRetrievalStrategy, atLeast(1)).getRecords(eq(MAX_RECORDS_PER_CALL));
     }
 
+    @Test
+    public void testGetRecordsWithInvalidResponse() {
+        record = Record.builder().data(createByteBufferWithSize(SIZE_512_KB)).build();
+
+        when(records.size()).thenReturn(1000);
+
+        GetRecordsResponse response = GetRecordsResponse.builder().records(records).build();
+        when(getRecordsRetrievalStrategy.getRecords(eq(MAX_RECORDS_PER_CALL))).thenReturn(response);
+        when(dataFetcher.isShardEndReached()).thenReturn(false);
+
+        getRecordsCache.start(sequenceNumber, initialPosition);
+
+        try {
+            ProcessRecordsInput result = blockUntilRecordsAvailable(() -> evictPublishedEvent(getRecordsCache, "shardId"), 1000L)
+                    .processRecordsInput();
+        } catch (Exception e) {
+            assertEquals("No records found", e.getMessage());
+        }
+    }
+
+    @Test
+    public void testGetRecordsWithShardEnd() {
+        records = new ArrayList<>();
+
+        final List<KinesisClientRecord> expectedRecords = new ArrayList<>();
+
+        List<ChildShard> childShards = new ArrayList<>();
+        List<String> parentShards = new ArrayList<>();
+        parentShards.add("shardId");
+        ChildShard leftChild = ChildShard.builder()
+                                         .shardId("shardId-000000000001")
+                                         .parentShards(parentShards)
+                                         .hashKeyRange(ShardObjectHelper.newHashKeyRange("0", "49"))
+                                         .build();
+        ChildShard rightChild = ChildShard.builder()
+                                          .shardId("shardId-000000000002")
+                                          .parentShards(parentShards)
+                                          .hashKeyRange(ShardObjectHelper.newHashKeyRange("50", "99"))
+                                          .build();
+        childShards.add(leftChild);
+        childShards.add(rightChild);
+
+        GetRecordsResponse response = GetRecordsResponse.builder().records(records).childShards(childShards).build();
+        when(getRecordsRetrievalStrategy.getRecords(eq(MAX_RECORDS_PER_CALL))).thenReturn(response);
+        when(dataFetcher.isShardEndReached()).thenReturn(true);
+
+        getRecordsCache.start(sequenceNumber, initialPosition);
+        ProcessRecordsInput result = blockUntilRecordsAvailable(() -> evictPublishedEvent(getRecordsCache, "shardId"), 1000L)
+                .processRecordsInput();
+
+        assertEquals(expectedRecords, result.records());
+        assertEquals(childShards, result.childShards());
+        assertTrue(result.isAtShardEnd());
+    }
+
     // TODO: Broken test
     @Test
     @Ignore
@@ -270,7 +330,7 @@ public class PrefetchRecordsPublisherTest {
     @Test
     public void testRetryableRetrievalExceptionContinues() {
 
-        GetRecordsResponse response = GetRecordsResponse.builder().millisBehindLatest(100L).records(Collections.emptyList()).build();
+        GetRecordsResponse response = GetRecordsResponse.builder().millisBehindLatest(100L).records(Collections.emptyList()).nextShardIterator(NEXT_SHARD_ITERATOR).build();
         when(getRecordsRetrievalStrategy.getRecords(anyInt())).thenThrow(new RetryableRetrievalException("Timeout", new TimeoutException("Timeout"))).thenReturn(response);
 
         getRecordsCache.start(sequenceNumber, initialPosition);
@@ -293,7 +353,7 @@ public class PrefetchRecordsPublisherTest {
 
         when(getRecordsRetrievalStrategy.getRecords(anyInt())).thenAnswer( i -> GetRecordsResponse.builder().records(
                 Record.builder().data(SdkBytes.fromByteArray(new byte[] { 1, 2, 3 })).sequenceNumber(++sequenceNumberInResponse[0] + "").build())
-                .build());
+                .nextShardIterator(NEXT_SHARD_ITERATOR).build());
 
         getRecordsCache.start(sequenceNumber, initialPosition);
 
@@ -384,7 +444,7 @@ public class PrefetchRecordsPublisherTest {
         // to the subscriber.
         GetRecordsResponse response = GetRecordsResponse.builder().records(
                 Record.builder().data(SdkBytes.fromByteArray(new byte[] { 1, 2, 3 })).sequenceNumber("123").build())
-                .build();
+                .nextShardIterator(NEXT_SHARD_ITERATOR).build();
         when(getRecordsRetrievalStrategy.getRecords(anyInt())).thenReturn(response);
 
         getRecordsCache.start(sequenceNumber, initialPosition);

amazon-kinesis-client/src/test/java/software/amazon/kinesis/utils/ProcessRecordsInputMatcher.java

@@ -45,6 +45,7 @@ public class ProcessRecordsInputMatcher extends TypeSafeDiagnosingMatcher<Proces
         matchers.put("millisBehindLatest",
                 nullOrEquals(template.millisBehindLatest(), ProcessRecordsInput::millisBehindLatest));
         matchers.put("records", nullOrEquals(template.records(), ProcessRecordsInput::records));
+        matchers.put("childShards", nullOrEquals(template.childShards(), ProcessRecordsInput::childShards));
 
         this.template = template;
     }