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The Amazon Kinesis Client Library for Java enables Java developers to easily consume and process data
from Amazon Kinesis.
/*
* Copyright 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Amazon Software License (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/asl/
*
* or in the "license" file accompanying this file. This file 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 com.amazonaws.services.kinesis.clientlibrary.lib.worker;
import java.util.Optional;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.RejectedExecutionException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import com.amazonaws.services.kinesis.clientlibrary.exceptions.internal.BlockedOnParentShardException;
import com.amazonaws.services.kinesis.clientlibrary.interfaces.ICheckpoint;
import com.amazonaws.services.kinesis.clientlibrary.interfaces.v2.IRecordProcessor;
import com.amazonaws.services.kinesis.leases.impl.KinesisClientLease;
import com.amazonaws.services.kinesis.leases.interfaces.ILeaseManager;
import com.amazonaws.services.kinesis.metrics.interfaces.IMetricsFactory;
import com.google.common.annotations.VisibleForTesting;
import lombok.Getter;
/**
* Responsible for consuming data records of a (specified) shard.
* The instance should be shutdown when we lose the primary responsibility for a shard.
* A new instance should be created if the primary responsibility is reassigned back to this process.
*/
class ShardConsumer {
private static final Log LOG = LogFactory.getLog(ShardConsumer.class);
private final StreamConfig streamConfig;
private final IRecordProcessor recordProcessor;
private final KinesisClientLibConfiguration config;
private final RecordProcessorCheckpointer recordProcessorCheckpointer;
private final ExecutorService executorService;
private final ShardInfo shardInfo;
private final KinesisDataFetcher dataFetcher;
private final IMetricsFactory metricsFactory;
private final ILeaseManager leaseManager;
private ICheckpoint checkpoint;
// Backoff time when polling to check if application has finished processing parent shards
private final long parentShardPollIntervalMillis;
private final boolean cleanupLeasesOfCompletedShards;
private final long taskBackoffTimeMillis;
private final boolean skipShardSyncAtWorkerInitializationIfLeasesExist;
private ITask currentTask;
private long currentTaskSubmitTime;
private Future future;
@Getter
private final GetRecordsCache getRecordsCache;
private static final GetRecordsRetrievalStrategy makeStrategy(KinesisDataFetcher dataFetcher,
Optional retryGetRecordsInSeconds,
Optional maxGetRecordsThreadPool,
ShardInfo shardInfo) {
Optional getRecordsRetrievalStrategy = retryGetRecordsInSeconds.flatMap(retry ->
maxGetRecordsThreadPool.map(max ->
new AsynchronousGetRecordsRetrievalStrategy(dataFetcher, retry, max, shardInfo.getShardId())));
return getRecordsRetrievalStrategy.orElse(new SynchronousGetRecordsRetrievalStrategy(dataFetcher));
}
/*
* Tracks current state. It is only updated via the consumeStream/shutdown APIs. Therefore we don't do
* much coordination/synchronization to handle concurrent reads/updates.
*/
private ConsumerStates.ConsumerState currentState = ConsumerStates.INITIAL_STATE;
/*
* Used to track if we lost the primary responsibility. Once set to true, we will start shutting down.
* If we regain primary responsibility before shutdown is complete, Worker should create a new ShardConsumer object.
*/
private volatile ShutdownReason shutdownReason;
private volatile ShutdownNotification shutdownNotification;
/**
* @param shardInfo Shard information
* @param streamConfig Stream configuration to use
* @param checkpoint Checkpoint tracker
* @param recordProcessor Record processor used to process the data records for the shard
* @param config Kinesis library configuration
* @param leaseManager Used to create leases for new shards
* @param parentShardPollIntervalMillis Wait for this long if parent shards are not done (or we get an exception)
* @param executorService ExecutorService used to execute process tasks for this shard
* @param metricsFactory IMetricsFactory used to construct IMetricsScopes for this shard
* @param backoffTimeMillis backoff interval when we encounter exceptions
*/
// CHECKSTYLE:IGNORE ParameterNumber FOR NEXT 10 LINES
ShardConsumer(ShardInfo shardInfo,
StreamConfig streamConfig,
ICheckpoint checkpoint,
IRecordProcessor recordProcessor,
ILeaseManager leaseManager,
long parentShardPollIntervalMillis,
boolean cleanupLeasesOfCompletedShards,
ExecutorService executorService,
IMetricsFactory metricsFactory,
long backoffTimeMillis,
boolean skipShardSyncAtWorkerInitializationIfLeasesExist,
KinesisClientLibConfiguration config) {
this(shardInfo,
streamConfig,
checkpoint,
recordProcessor,
leaseManager,
parentShardPollIntervalMillis,
cleanupLeasesOfCompletedShards,
executorService,
metricsFactory,
backoffTimeMillis,
skipShardSyncAtWorkerInitializationIfLeasesExist,
Optional.empty(),
Optional.empty(),
config);
}
/**
* @param shardInfo Shard information
* @param streamConfig Stream configuration to use
* @param checkpoint Checkpoint tracker
* @param recordProcessor Record processor used to process the data records for the shard
* @param leaseManager Used to create leases for new shards
* @param parentShardPollIntervalMillis Wait for this long if parent shards are not done (or we get an exception)
* @param executorService ExecutorService used to execute process tasks for this shard
* @param metricsFactory IMetricsFactory used to construct IMetricsScopes for this shard
* @param backoffTimeMillis backoff interval when we encounter exceptions
* @param retryGetRecordsInSeconds time in seconds to wait before the worker retries to get a record.
* @param maxGetRecordsThreadPool max number of threads in the getRecords thread pool.
* @param config Kinesis library configuration
*/
// CHECKSTYLE:IGNORE ParameterNumber FOR NEXT 10 LINES
ShardConsumer(ShardInfo shardInfo,
StreamConfig streamConfig,
ICheckpoint checkpoint,
IRecordProcessor recordProcessor,
ILeaseManager leaseManager,
long parentShardPollIntervalMillis,
boolean cleanupLeasesOfCompletedShards,
ExecutorService executorService,
IMetricsFactory metricsFactory,
long backoffTimeMillis,
boolean skipShardSyncAtWorkerInitializationIfLeasesExist,
Optional retryGetRecordsInSeconds,
Optional maxGetRecordsThreadPool,
KinesisClientLibConfiguration config) {
this(
shardInfo,
streamConfig,
checkpoint,
recordProcessor,
new RecordProcessorCheckpointer(
shardInfo,
checkpoint,
new SequenceNumberValidator(
streamConfig.getStreamProxy(),
shardInfo.getShardId(),
streamConfig.shouldValidateSequenceNumberBeforeCheckpointing())),
leaseManager,
parentShardPollIntervalMillis,
cleanupLeasesOfCompletedShards,
executorService,
metricsFactory,
backoffTimeMillis,
skipShardSyncAtWorkerInitializationIfLeasesExist,
new KinesisDataFetcher(streamConfig.getStreamProxy(), shardInfo),
retryGetRecordsInSeconds,
maxGetRecordsThreadPool,
config
);
}
/**
* @param shardInfo Shard information
* @param streamConfig Stream Config to use
* @param checkpoint Checkpoint tracker
* @param recordProcessor Record processor used to process the data records for the shard
* @param recordProcessorCheckpointer RecordProcessorCheckpointer to use to checkpoint progress
* @param leaseManager Used to create leases for new shards
* @param parentShardPollIntervalMillis Wait for this long if parent shards are not done (or we get an exception)
* @param cleanupLeasesOfCompletedShards clean up the leases of completed shards
* @param executorService ExecutorService used to execute process tasks for this shard
* @param metricsFactory IMetricsFactory used to construct IMetricsScopes for this shard
* @param backoffTimeMillis backoff interval when we encounter exceptions
* @param skipShardSyncAtWorkerInitializationIfLeasesExist Skip sync at init if lease exists
* @param kinesisDataFetcher KinesisDataFetcher to fetch data from Kinesis streams.
* @param retryGetRecordsInSeconds time in seconds to wait before the worker retries to get a record
* @param maxGetRecordsThreadPool max number of threads in the getRecords thread pool
* @param config Kinesis library configuration
*/
ShardConsumer(ShardInfo shardInfo,
StreamConfig streamConfig,
ICheckpoint checkpoint,
IRecordProcessor recordProcessor,
RecordProcessorCheckpointer recordProcessorCheckpointer,
ILeaseManager leaseManager,
long parentShardPollIntervalMillis,
boolean cleanupLeasesOfCompletedShards,
ExecutorService executorService,
IMetricsFactory metricsFactory,
long backoffTimeMillis,
boolean skipShardSyncAtWorkerInitializationIfLeasesExist,
KinesisDataFetcher kinesisDataFetcher,
Optional retryGetRecordsInSeconds,
Optional maxGetRecordsThreadPool,
KinesisClientLibConfiguration config) {
this.shardInfo = shardInfo;
this.streamConfig = streamConfig;
this.checkpoint = checkpoint;
this.recordProcessor = recordProcessor;
this.recordProcessorCheckpointer = recordProcessorCheckpointer;
this.leaseManager = leaseManager;
this.parentShardPollIntervalMillis = parentShardPollIntervalMillis;
this.cleanupLeasesOfCompletedShards = cleanupLeasesOfCompletedShards;
this.executorService = executorService;
this.metricsFactory = metricsFactory;
this.taskBackoffTimeMillis = backoffTimeMillis;
this.skipShardSyncAtWorkerInitializationIfLeasesExist = skipShardSyncAtWorkerInitializationIfLeasesExist;
this.config = config;
this.dataFetcher = kinesisDataFetcher;
this.getRecordsCache = config.getRecordsFetcherFactory().createRecordsFetcher(
makeStrategy(this.dataFetcher, retryGetRecordsInSeconds, maxGetRecordsThreadPool, this.shardInfo),
this.getShardInfo().getShardId(), this.metricsFactory, this.config.getMaxRecords());
}
/**
* No-op if current task is pending, otherwise submits next task for this shard.
* This method should NOT be called if the ShardConsumer is already in SHUTDOWN_COMPLETED state.
*
* @return true if a new process task was submitted, false otherwise
*/
synchronized boolean consumeShard() {
return checkAndSubmitNextTask();
}
private boolean readyForNextTask() {
return future == null || future.isCancelled() || future.isDone();
}
private synchronized boolean checkAndSubmitNextTask() {
boolean submittedNewTask = false;
if (readyForNextTask()) {
TaskOutcome taskOutcome = TaskOutcome.NOT_COMPLETE;
if (future != null && future.isDone()) {
taskOutcome = determineTaskOutcome();
}
updateState(taskOutcome);
ITask nextTask = getNextTask();
if (nextTask != null) {
currentTask = nextTask;
try {
future = executorService.submit(currentTask);
currentTaskSubmitTime = System.currentTimeMillis();
submittedNewTask = true;
LOG.debug("Submitted new " + currentTask.getTaskType()
+ " task for shard " + shardInfo.getShardId());
} catch (RejectedExecutionException e) {
LOG.info(currentTask.getTaskType() + " task was not accepted for execution.", e);
} catch (RuntimeException e) {
LOG.info(currentTask.getTaskType() + " task encountered exception ", e);
}
} else {
if (LOG.isDebugEnabled()) {
LOG.debug(String.format("No new task to submit for shard %s, currentState %s",
shardInfo.getShardId(),
currentState.toString()));
}
}
} else {
final long timeElapsed = System.currentTimeMillis() - currentTaskSubmitTime;
final String commonMessage = String.format("Previous %s task still pending for shard %s since %d ms ago. ",
currentTask.getTaskType(), shardInfo.getShardId(), timeElapsed);
if (LOG.isDebugEnabled()) {
LOG.debug(commonMessage + "Not submitting new task.");
}
config.getLogWarningForTaskAfterMillis().ifPresent(value -> {
if (timeElapsed > value) {
LOG.warn(commonMessage);
}
});
}
return submittedNewTask;
}
public boolean isSkipShardSyncAtWorkerInitializationIfLeasesExist() {
return skipShardSyncAtWorkerInitializationIfLeasesExist;
}
private enum TaskOutcome {
SUCCESSFUL, END_OF_SHARD, NOT_COMPLETE, FAILURE
}
private TaskOutcome determineTaskOutcome() {
try {
TaskResult result = future.get();
if (result.getException() == null) {
if (result.isShardEndReached()) {
return TaskOutcome.END_OF_SHARD;
}
return TaskOutcome.SUCCESSFUL;
}
logTaskException(result);
} catch (Exception e) {
throw new RuntimeException(e);
} finally {
// Setting future to null so we don't misinterpret task completion status in case of exceptions
future = null;
}
return TaskOutcome.FAILURE;
}
private void logTaskException(TaskResult taskResult) {
if (LOG.isDebugEnabled()) {
Exception taskException = taskResult.getException();
if (taskException instanceof BlockedOnParentShardException) {
// No need to log the stack trace for this exception (it is very specific).
LOG.debug("Shard " + shardInfo.getShardId() + " is blocked on completion of parent shard.");
} else {
LOG.debug("Caught exception running " + currentTask.getTaskType() + " task: ",
taskResult.getException());
}
}
}
/**
* Requests the shutdown of the this ShardConsumer. This should give the record processor a chance to checkpoint
* before being shutdown.
*
* @param shutdownNotification used to signal that the record processor has been given the chance to shutdown.
*/
void notifyShutdownRequested(ShutdownNotification shutdownNotification) {
this.shutdownNotification = shutdownNotification;
markForShutdown(ShutdownReason.REQUESTED);
}
/**
* Shutdown this ShardConsumer (including invoking the RecordProcessor shutdown API).
* This is called by Worker when it loses responsibility for a shard.
*
* @return true if shutdown is complete (false if shutdown is still in progress)
*/
synchronized boolean beginShutdown() {
markForShutdown(ShutdownReason.ZOMBIE);
checkAndSubmitNextTask();
return isShutdown();
}
synchronized void markForShutdown(ShutdownReason reason) {
// ShutdownReason.ZOMBIE takes precedence over TERMINATE (we won't be able to save checkpoint at end of shard)
if (shutdownReason == null || shutdownReason.canTransitionTo(reason)) {
shutdownReason = reason;
}
}
/**
* Used (by Worker) to check if this ShardConsumer instance has been shutdown
* RecordProcessor shutdown() has been invoked, as appropriate.
*
* @return true if shutdown is complete
*/
boolean isShutdown() {
return currentState.isTerminal();
}
/**
* @return the shutdownReason
*/
ShutdownReason getShutdownReason() {
return shutdownReason;
}
/**
* Figure out next task to run based on current state, task, and shutdown context.
*
* @return Return next task to run
*/
private ITask getNextTask() {
ITask nextTask = currentState.createTask(this);
if (nextTask == null) {
return null;
} else {
return new MetricsCollectingTaskDecorator(nextTask, metricsFactory);
}
}
/**
* Note: This is a private/internal method with package level access solely for testing purposes.
* Update state based on information about: task success, current state, and shutdown info.
*
* @param taskOutcome The outcome of the last task
*/
void updateState(TaskOutcome taskOutcome) {
if (taskOutcome == TaskOutcome.END_OF_SHARD) {
markForShutdown(ShutdownReason.TERMINATE);
}
if (isShutdownRequested() && taskOutcome != TaskOutcome.FAILURE) {
currentState = currentState.shutdownTransition(shutdownReason);
} else if (taskOutcome == TaskOutcome.SUCCESSFUL) {
if (currentState.getTaskType() == currentTask.getTaskType()) {
currentState = currentState.successTransition();
} else {
LOG.error("Current State task type of '" + currentState.getTaskType()
+ "' doesn't match the current tasks type of '" + currentTask.getTaskType()
+ "'. This shouldn't happen, and indicates a programming error. "
+ "Unable to safely transition to the next state.");
}
}
//
// Don't change state otherwise
//
}
@VisibleForTesting
boolean isShutdownRequested() {
return shutdownReason != null;
}
/**
* Private/Internal method - has package level access solely for testing purposes.
*
* @return the currentState
*/
ConsumerStates.ShardConsumerState getCurrentState() {
return currentState.getState();
}
StreamConfig getStreamConfig() {
return streamConfig;
}
IRecordProcessor getRecordProcessor() {
return recordProcessor;
}
RecordProcessorCheckpointer getRecordProcessorCheckpointer() {
return recordProcessorCheckpointer;
}
ExecutorService getExecutorService() {
return executorService;
}
ShardInfo getShardInfo() {
return shardInfo;
}
KinesisDataFetcher getDataFetcher() {
return dataFetcher;
}
ILeaseManager getLeaseManager() {
return leaseManager;
}
ICheckpoint getCheckpoint() {
return checkpoint;
}
long getParentShardPollIntervalMillis() {
return parentShardPollIntervalMillis;
}
boolean isCleanupLeasesOfCompletedShards() {
return cleanupLeasesOfCompletedShards;
}
long getTaskBackoffTimeMillis() {
return taskBackoffTimeMillis;
}
Future getFuture() {
return future;
}
ShutdownNotification getShutdownNotification() {
return shutdownNotification;
}
}