nwangtw commented on a change in pull request #3324: Kafka bolt URL: https://github.com/apache/incubator-heron/pull/3324#discussion_r310376008
########## File path: contrib/bolts/kafka/src/java/org/apache/heron/bolts/kafka/KafkaBolt.java ########## @@ -0,0 +1,106 @@ +/** + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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 + * <p> + * http://www.apache.org/licenses/LICENSE-2.0 + * <p> + * 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 org.apache.heron.bolts.kafka; + +import java.util.Map; +import java.util.concurrent.ExecutionException; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import org.apache.heron.api.Config; +import org.apache.heron.api.bolt.BaseRichBolt; +import org.apache.heron.api.bolt.OutputCollector; +import org.apache.heron.api.topology.OutputFieldsDeclarer; +import org.apache.heron.api.topology.TopologyContext; +import org.apache.heron.api.tuple.Tuple; +import org.apache.kafka.clients.producer.Producer; +import org.apache.kafka.clients.producer.ProducerRecord; +import org.apache.kafka.common.KafkaException; + +import static org.apache.heron.api.Config.TopologyReliabilityMode.ATMOST_ONCE; + +@SuppressWarnings("unused") +public class KafkaBolt<K, V> extends BaseRichBolt { + private static final long serialVersionUID = -3301619269473733618L; + private static final Logger LOG = LoggerFactory.getLogger(KafkaBolt.class); + private KafkaProducerFactory<K, V> kafkaProducerFactory; + private TupleTransformer<K, V> tupleTransformer; + private transient Producer<K, V> producer; + private Config.TopologyReliabilityMode topologyReliabilityMode; + private transient OutputCollector outputCollector; + + @SuppressWarnings("WeakerAccess") + public KafkaBolt(KafkaProducerFactory<K, V> kafkaProducerFactory, + TupleTransformer<K, V> tupleTransformer) { + this.kafkaProducerFactory = kafkaProducerFactory; + this.tupleTransformer = tupleTransformer; + } + + @Override + public void prepare(Map<String, Object> heronConf, TopologyContext context, + OutputCollector collector) { + topologyReliabilityMode = Config.TopologyReliabilityMode + .valueOf(heronConf.getOrDefault(Config.TOPOLOGY_RELIABILITY_MODE, ATMOST_ONCE).toString()); + producer = kafkaProducerFactory.create(); + outputCollector = collector; + } + + @Override + public void cleanup() { + super.cleanup(); + if (producer != null) { + producer.close(); + } + } + + @Override + public void execute(Tuple input) { + ProducerRecord<K, V> producerRecord = new ProducerRecord<>( + tupleTransformer.getTopicName(input), + tupleTransformer.transformToKey(input), + tupleTransformer.transformToValue(input)); + if (topologyReliabilityMode == Config.TopologyReliabilityMode.EFFECTIVELY_ONCE) { + try { + producer.send(producerRecord).get(); + } catch (InterruptedException e) { + LOG.error("interrupted while waiting for the record to be sent", e); + Thread.currentThread().interrupt(); + } catch (ExecutionException e) { + LOG.error("error has occurred when sending record to Kafka", e); + throw new KafkaException(e); + } + } else { + producer.send(producerRecord, (recordMetadata, e) -> { Review comment: I am wondering if using "try {} catch {}" is more consistent. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
