org.apache.druid.firehose.kafka.KafkaEightFirehoseFactory.java Source code

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Here is the source code for org.apache.druid.firehose.kafka.KafkaEightFirehoseFactory.java

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/*
 * 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
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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.druid.firehose.kafka;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Sets;
import kafka.consumer.Consumer;
import kafka.consumer.ConsumerConfig;
import kafka.consumer.ConsumerIterator;
import kafka.consumer.KafkaStream;
import kafka.javaapi.consumer.ConsumerConnector;
import kafka.message.InvalidMessageException;
import org.apache.druid.data.input.Firehose;
import org.apache.druid.data.input.FirehoseFactory;
import org.apache.druid.data.input.InputRow;
import org.apache.druid.data.input.impl.InputRowParser;
import org.apache.druid.java.util.common.logger.Logger;

import javax.annotation.Nullable;
import java.io.File;
import java.nio.ByteBuffer;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

/**
 */
public class KafkaEightFirehoseFactory implements FirehoseFactory<InputRowParser<ByteBuffer>> {
    private static final Logger log = new Logger(KafkaEightFirehoseFactory.class);

    @JsonProperty
    private final Properties consumerProps;

    @JsonProperty
    private final String feed;

    @JsonCreator
    public KafkaEightFirehoseFactory(@JsonProperty("consumerProps") Properties consumerProps,
            @JsonProperty("feed") String feed

    ) {
        this.consumerProps = consumerProps;
        this.feed = feed;
    }

    @Override
    public Firehose connect(final InputRowParser<ByteBuffer> firehoseParser, File temporaryDirectory) {
        Set<String> newDimExclus = Sets.union(
                firehoseParser.getParseSpec().getDimensionsSpec().getDimensionExclusions(),
                Sets.newHashSet("feed"));

        final InputRowParser<ByteBuffer> theParser = firehoseParser
                .withParseSpec(firehoseParser.getParseSpec().withDimensionsSpec(
                        firehoseParser.getParseSpec().getDimensionsSpec().withDimensionExclusions(newDimExclus)));

        final ConsumerConnector connector = Consumer.createJavaConsumerConnector(new ConsumerConfig(consumerProps));

        final Map<String, List<KafkaStream<byte[], byte[]>>> streams = connector
                .createMessageStreams(ImmutableMap.of(feed, 1));

        final List<KafkaStream<byte[], byte[]>> streamList = streams.get(feed);
        if (streamList == null || streamList.size() != 1) {
            return null;
        }

        final KafkaStream<byte[], byte[]> stream = streamList.get(0);
        final ConsumerIterator<byte[], byte[]> iter = stream.iterator();

        return new Firehose() {
            Iterator<InputRow> nextIterator = Collections.emptyIterator();

            @Override
            public boolean hasMore() {
                return nextIterator.hasNext() || iter.hasNext();
            }

            @Nullable
            @Override
            public InputRow nextRow() {
                try {
                    if (!nextIterator.hasNext()) {
                        final byte[] message = iter.next().message();

                        if (message == null) {
                            return null;
                        }
                        nextIterator = theParser.parseBatch(ByteBuffer.wrap(message)).iterator();
                    }

                    return nextIterator.next();

                } catch (InvalidMessageException e) {
                    /*
                    IF the CRC is caused within the wire transfer, this is not the best way to handel CRC.
                    Probably it is better to shutdown the fireHose without commit and start it again.
                     */
                    log.error(e, "Message failed its checksum and it is corrupt, will skip it");
                    return null;
                }
            }

            @Override
            public Runnable commit() {
                return new Runnable() {
                    @Override
                    public void run() {
                        /*
                          This is actually not going to do exactly what we want, cause it will be called asynchronously
                          after the persist is complete.  So, it's going to commit that it's processed more than was actually
                          persisted.  This is unfortunate, but good enough for now.  Should revisit along with an upgrade
                          of our Kafka version.
                        */

                        log.info("committing offsets");
                        connector.commitOffsets();
                    }
                };
            }

            @Override
            public void close() {
                connector.shutdown();
            }
        };
    }

}