co.cask.hydrator.plugin.batchSource.KafkaRecordReader.java Source code

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Here is the source code for co.cask.hydrator.plugin.batchSource.KafkaRecordReader.java

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/*
 * Copyright  2017 Cask Data, Inc.
 *
 * Licensed 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 co.cask.hydrator.plugin.batchSource;

import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;

import java.io.IOException;

/**
 * Kafka Record Reader to be used by {@link KafkaInputFormat}.
 */
public class KafkaRecordReader extends RecordReader<KafkaKey, KafkaMessage> {

    private KafkaSplit split;
    private long totalBytes;
    private KafkaReader reader;
    private long readBytes = 0;
    private final KafkaKey key = new KafkaKey();
    private KafkaMessage value;

    @Override
    public void initialize(InputSplit split, TaskAttemptContext context) throws IOException, InterruptedException {
        this.split = (KafkaSplit) split;
        this.totalBytes = this.split.getLength();
    }

    @Override
    public synchronized void close() throws IOException {
        if (reader != null) {
            reader.close();
        }
    }

    @Override
    public float getProgress() throws IOException {
        if (getPos() == 0) {
            return 0f;
        }

        if (getPos() >= totalBytes) {
            return 1f;
        }
        return (float) ((double) getPos() / totalBytes);
    }

    private long getPos() throws IOException {
        return readBytes;
    }

    @Override
    public KafkaKey getCurrentKey() throws IOException, InterruptedException {
        return key;
    }

    @Override
    public KafkaMessage getCurrentValue() throws IOException, InterruptedException {
        return value;
    }

    @Override
    public boolean nextKeyValue() throws IOException, InterruptedException {
        if (reader == null || !reader.hasNext()) {
            KafkaRequest request = split.popRequest();
            if (request == null) {
                return false;
            }

            key.set(request.getTopic(), request.getLeaderId(), request.getPartition(), request.getOffset(),
                    request.getOffset(), 0);
            value = null;

            if (reader != null) {
                closeReader();
            }
            reader = new KafkaReader(request);
        }
        KafkaMessage message;
        if ((message = reader.getNext(key)) != null) {
            readBytes += key.getMessageSize();
            value = message;
            return true;
        }
        return false;
    }

    private void closeReader() throws IOException {
        if (reader != null) {
            try {
                reader.close();
            } catch (Exception e) {
                // not much to do here but skip the task
            } finally {
                reader = null;
            }
        }
    }
}