org.apache.sqoop.mapreduce.CombineShimRecordReader.java Source code

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Here is the source code for org.apache.sqoop.mapreduce.CombineShimRecordReader.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.sqoop.mapreduce;

import java.io.IOException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.lib.input.FileSplit;
import org.apache.hadoop.mapreduce.lib.input.LineRecordReader;
import org.apache.hadoop.mapreduce.lib.input.SequenceFileRecordReader;
import org.apache.hadoop.util.ReflectionUtils;

/**
 * RecordReader that CombineFileRecordReader can instantiate, which itself
 * translates a CombineFileSplit into a FileSplit.
 */
public class CombineShimRecordReader extends RecordReader<LongWritable, Object> {

    public static final Log LOG = LogFactory.getLog(CombineShimRecordReader.class.getName());

    private CombineFileSplit split;
    private TaskAttemptContext context;
    private int index;
    private RecordReader<LongWritable, Object> rr;

    /**
     * Constructor invoked by CombineFileRecordReader that identifies part of a
     * CombineFileSplit to use.
     */
    public CombineShimRecordReader(CombineFileSplit split, TaskAttemptContext context, Integer index)
            throws IOException, InterruptedException {
        this.index = index;
        this.split = (CombineFileSplit) split;
        this.context = context;

        createChildReader();
    }

    @Override
    public void initialize(InputSplit curSplit, TaskAttemptContext curContext)
            throws IOException, InterruptedException {
        this.split = (CombineFileSplit) curSplit;
        this.context = curContext;

        if (null == rr) {
            createChildReader();
        }

        FileSplit fileSplit = new FileSplit(this.split.getPath(index), this.split.getOffset(index),
                this.split.getLength(index), this.split.getLocations());
        this.rr.initialize(fileSplit, this.context);
    }

    @Override
    public float getProgress() throws IOException, InterruptedException {
        return rr.getProgress();
    }

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

    @Override
    public LongWritable getCurrentKey() throws IOException, InterruptedException {
        return rr.getCurrentKey();
    }

    @Override
    public Object getCurrentValue() throws IOException, InterruptedException {
        return rr.getCurrentValue();
    }

    @Override
    public boolean nextKeyValue() throws IOException, InterruptedException {
        return rr.nextKeyValue();
    }

    /**
     * Actually instantiate the user's chosen RecordReader implementation.
     */
    @SuppressWarnings("unchecked")
    private void createChildReader() throws IOException, InterruptedException {
        LOG.debug("ChildSplit operates on: " + split.getPath(index));

        Configuration conf = context.getConfiguration();

        // Determine the file format we're reading.
        Class rrClass;
        if (ExportJobBase.isSequenceFiles(conf, split.getPath(index))) {
            rrClass = SequenceFileRecordReader.class;
        } else {
            rrClass = LineRecordReader.class;
        }

        // Create the appropriate record reader.
        this.rr = (RecordReader<LongWritable, Object>) ReflectionUtils.newInstance(rrClass, conf);
    }
}