Java tutorial
/* * Original work Copyright 2012-2017 Amazon.com, Inc. or its affiliates. All Rights Reserved. * Modified work Copyright 2017 University of Hawaii * * Licensed under the Apache License, Version 2.0 (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/apache2.0 * * 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. */ /* * Original work: * https://github.com/aws/aws-sdk-java/blob/1.11.118/src/samples/AmazonKinesis/AmazonKinesisApplicationSampleRecordProcessor.java */ package edu.hawaii.kscmfeedprocessor; import com.amazonaws.services.kinesis.clientlibrary.exceptions.InvalidStateException; import com.amazonaws.services.kinesis.clientlibrary.exceptions.ShutdownException; import com.amazonaws.services.kinesis.clientlibrary.exceptions.ThrottlingException; import com.amazonaws.services.kinesis.clientlibrary.interfaces.IRecordProcessor; import com.amazonaws.services.kinesis.clientlibrary.interfaces.IRecordProcessorCheckpointer; import com.amazonaws.services.kinesis.clientlibrary.lib.worker.ShutdownReason; import com.amazonaws.services.kinesis.model.Record; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.nio.charset.CharacterCodingException; import java.nio.charset.Charset; import java.nio.charset.CharsetDecoder; import java.util.List; /** * Processes records and checkpoints progress. */ public class AmazonKinesisApplicationSampleRecordProcessor implements IRecordProcessor { private final Logger logger = LoggerFactory.getLogger(this.getClass()); private final Config config; private String kinesisShardId; // Backoff and retry settings private static final long BACKOFF_TIME_IN_MILLIS = 3000L; private static final int NUM_RETRIES = 10; // Checkpoint about once a minute private static final long CHECKPOINT_INTERVAL_MILLIS = 60000L; private long nextCheckpointTimeInMillis; private final CharsetDecoder decoder = Charset.forName("UTF-8").newDecoder(); private final KscmRecordProcessor kscmRecordProcessor; public AmazonKinesisApplicationSampleRecordProcessor(Config config) { this.config = config; kscmRecordProcessor = config.getApplicationContext().getBean("kscmRecordProcessor", KscmRecordProcessor.class); } /** * {@inheritDoc} */ @Override public void initialize(String shardId) { logger.info("Initializing record processor for shard: " + shardId); this.kinesisShardId = shardId; } /** * {@inheritDoc} */ @Override public void processRecords(List<Record> records, IRecordProcessorCheckpointer checkpointer) { logger.info("Processing " + records.size() + " records from " + kinesisShardId); // Process records and perform all exception handling. processRecordsWithRetries(records); // Checkpoint once every checkpoint interval. if (System.currentTimeMillis() > nextCheckpointTimeInMillis) { checkpoint(checkpointer); nextCheckpointTimeInMillis = System.currentTimeMillis() + CHECKPOINT_INTERVAL_MILLIS; } } /** * Process records performing retries as needed. Skip "poison pill" records. * * @param records MessageData records to be processed. */ private void processRecordsWithRetries(List<Record> records) { for (Record record : records) { boolean processedSuccessfully = false; for (int i = 0; i < NUM_RETRIES; i++) { try { // // Logic to process record goes here. // processSingleRecord(record); processedSuccessfully = true; break; } catch (Throwable t) { logger.warn("Caught throwable while processing record " + record, t); } // backoff if we encounter an exception. try { Thread.sleep(BACKOFF_TIME_IN_MILLIS); } catch (InterruptedException e) { logger.debug("Interrupted sleep", e); } } if (!processedSuccessfully) { logger.error("Couldn't process record " + record + ". Skipping the record."); } } } /** * Process a single record. * * @param record The record to be processed. */ private void processSingleRecord(Record record) throws Exception { // TODO Add your own record processing logic here String data = null; try { // For this app, we interpret the payload as UTF-8 chars. data = decoder.decode(record.getData()).toString(); kscmRecordProcessor.processRecord(record.getSequenceNumber(), record.getPartitionKey(), data); } catch (CharacterCodingException e) { logger.error("Malformed data: " + data, e); } } /** * {@inheritDoc} */ @Override public void shutdown(IRecordProcessorCheckpointer checkpointer, ShutdownReason reason) { logger.info("Shutting down record processor for shard: " + kinesisShardId); // Important to checkpoint after reaching end of shard, so we can start processing data from child shards. if (reason == ShutdownReason.TERMINATE) { checkpoint(checkpointer); } } /** Checkpoint with retries. * @param checkpointer */ private void checkpoint(IRecordProcessorCheckpointer checkpointer) { logger.info("Checkpointing shard " + kinesisShardId); for (int i = 0; i < NUM_RETRIES; i++) { try { checkpointer.checkpoint(); break; } catch (ShutdownException se) { // Ignore checkpoint if the processor instance has been shutdown (fail over). logger.info("Caught shutdown exception, skipping checkpoint.", se); break; } catch (ThrottlingException e) { // Backoff and re-attempt checkpoint upon transient failures if (i >= (NUM_RETRIES - 1)) { logger.error("Checkpoint failed after " + (i + 1) + "attempts.", e); break; } else { logger.info("Transient issue when checkpointing - attempt " + (i + 1) + " of " + NUM_RETRIES, e); } } catch (InvalidStateException e) { // This indicates an issue with the DynamoDB table (check for table, provisioned IOPS). logger.error( "Cannot save checkpoint to the DynamoDB table used by the Amazon Kinesis Client Library.", e); break; } try { Thread.sleep(BACKOFF_TIME_IN_MILLIS); } catch (InterruptedException e) { logger.debug("Interrupted sleep", e); } } } }