Java tutorial
/* * Copyright 2013-2014 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.kinesis.dataviz.kinesisclient; import java.nio.charset.CharacterCodingException; import java.nio.charset.Charset; import java.nio.charset.CharsetDecoder; import java.util.Iterator; import java.util.List; import java.util.Map; import java.util.Random; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import redis.clients.jedis.Jedis; 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.types.ShutdownReason; import com.amazonaws.services.kinesis.model.Record; import com.fasterxml.jackson.databind.JsonNode; import com.fasterxml.jackson.databind.ObjectMapper; /** * */ public class KinesisRecordProcessor implements IRecordProcessor { private static final Log LOG = LogFactory.getLog(KinesisRecordProcessor.class); 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; // Jackson private ObjectMapper mapper; // Redis private Jedis jedis; private String redisEndpoint; private int redisPort; private Random random; private final CharsetDecoder decoder = Charset.forName("UTF-8").newDecoder(); /** * Constructor. */ public KinesisRecordProcessor(String redisEndpoint, int redisPort) { super(); this.redisEndpoint = redisEndpoint; this.redisPort = redisPort; random = new Random(System.currentTimeMillis()); } /** * {@inheritDoc} */ public void initialize(String shardId) { LOG.info("Initializing record processor for shard: " + shardId); this.kinesisShardId = shardId; mapper = new ObjectMapper(); LOG.info("Connecting to Redis"); jedis = new Jedis(redisEndpoint, redisPort); } /** * {@inheritDoc} */ public void processRecords(List<Record> records, IRecordProcessorCheckpointer checkpointer) { LOG.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 */ private void processRecordsWithRetries(List<Record> records) { for (Record record : records) { boolean processedSuccessfully = false; String data = null; for (int i = 0; i < NUM_RETRIES; i++) { try { Coordinate c = null; try { // For this app, we interpret the payload as UTF-8 chars. data = decoder.decode(record.getData()).toString(); // use the ObjectMapper to read the json string and create a tree JsonNode node = mapper.readTree(data); JsonNode geo = node.findValue("geo"); JsonNode coords = geo.findValue("coordinates"); Iterator<JsonNode> elements = coords.elements(); double lat = elements.next().asDouble(); double lng = elements.next().asDouble(); c = new Coordinate(lat, lng); } catch (Exception e) { // if we get here, its bad data, ignore and move on to next record } if (c != null) { String jsonCoords = mapper.writeValueAsString(c); jedis.publish("loc", jsonCoords); } processedSuccessfully = true; break; } catch (Throwable t) { LOG.warn("Caught throwable while processing record " + record, t); } // backoff if we encounter an exception. try { Thread.sleep(BACKOFF_TIME_IN_MILLIS); } catch (InterruptedException e) { LOG.debug("Interrupted sleep", e); } } if (!processedSuccessfully) { LOG.error("Couldn't process record " + record + ". Skipping the record."); } } } /** * {@inheritDoc} */ public void shutdown(IRecordProcessorCheckpointer checkpointer, ShutdownReason reason) { LOG.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) { LOG.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). LOG.info("Caught shutdown exception, skipping checkpoint.", se); break; } catch (ThrottlingException e) { // Backoff and re-attempt checkpoint upon transient failures if (i >= (NUM_RETRIES - 1)) { LOG.error("Checkpoint failed after " + (i + 1) + "attempts.", e); break; } else { LOG.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). LOG.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) { LOG.debug("Interrupted sleep", e); } } } }