org.apache.flume.sink.kafka.KafkaSink.java Source code

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Here is the source code for org.apache.flume.sink.kafka.KafkaSink.java

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 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
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 *  
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package org.apache.flume.sink.kafka;

import com.google.common.base.Preconditions;
import kafka.javaapi.producer.Producer;
import kafka.producer.KeyedMessage;

import kafka.producer.ProducerConfig;
import org.apache.commons.lang.StringUtils;
import org.apache.flume.Channel;
import org.apache.flume.Context;
import org.apache.flume.Event;
import org.apache.flume.EventDeliveryException;
import org.apache.flume.Transaction;
import org.apache.flume.conf.Configurable;
import org.apache.flume.conf.ConfigurationException;
import org.apache.flume.sink.AbstractSink;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Properties;

/**
 * A Sink of Kafka which get events from channels and publish to Kafka. I use
 * this in our company production environment which can hit 100k messages per
 * second. <tt>zk.connect: </tt> the zookeeper ip kafka use.
 * <p>
 * <tt>topic: </tt> the topic to read from kafka.
 * <p>
 * <tt>batchSize: </tt> send serveral messages in one request to kafka.
 * <p>
 * <tt>producer.type: </tt> type of producer of kafka, async or sync is
 * available.<o> <tt>serializer.class: </tt>{@kafka.serializer.StringEncoder}
 *
 */
public class KafkaSink extends AbstractSink implements Configurable {
    private static final Logger log = LoggerFactory.getLogger(KafkaSink.class);
    private String topic;
    private Producer<String, String> producer;
    private Context context;
    private Properties parameters;

    public Status process() throws EventDeliveryException {
        Status status = null;
        Channel channel = getChannel();
        Transaction tx = channel.getTransaction();
        tx.begin();
        try {
            Event event = channel.take();
            if (event == null) {
                tx.commit();
                return Status.READY;
            }
            String partitionKey = (String) parameters.get(KafkaFlumeConstants.PARTITION_KEY_NAME);
            String encoding = StringUtils.defaultIfEmpty(
                    (String) this.parameters.get(KafkaFlumeConstants.ENCODING_KEY_NAME),
                    KafkaFlumeConstants.DEFAULT_ENCODING);
            String topic = Preconditions.checkNotNull(
                    (String) this.parameters.get(KafkaFlumeConstants.CUSTOME_TOPIC_KEY_NAME),
                    "custom.topic.name is required");
            String eventData = new String(event.getBody(), encoding);
            KeyedMessage<String, String> data;

            if (StringUtils.isEmpty(partitionKey)) {
                data = new KeyedMessage<String, String>(topic, eventData);
            } else {
                data = new KeyedMessage<String, String>(topic, partitionKey, eventData);
            }

            producer.send(data);
            log.trace("Message: {}", event.getBody());
            tx.commit();
            status = Status.READY;
        } catch (Exception e) {
            tx.rollback();
            log.error("KafkaSink Exception:{}", e);
            status = Status.BACKOFF;
        } finally {
            tx.close();
        }
        return status;
    }

    public void configure(Context context) {
        this.context = context;
        parameters = KafkaSinkUtil.getKafkaConfigProperties(context);
        topic = parameters.getProperty(KafkaFlumeConstants.CUSTOME_TOPIC_KEY_NAME);
        if (topic == null) {
            throw new ConfigurationException("Kafka topic must be specified.");
        }
    }

    @Override
    public synchronized void start() {
        super.start();
        ProducerConfig config = new ProducerConfig(this.parameters);
        this.producer = new Producer<String, String>(config);
    }

    @Override
    public synchronized void stop() {
        producer.close();
        super.stop();
    }
}