cascading.tap.hadoop.io.CombineFileRecordReaderWrapper.java Source code

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Here is the source code for cascading.tap.hadoop.io.CombineFileRecordReaderWrapper.java

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/*
 * Copyright (c) 2007-2015 Concurrent, Inc. All Rights Reserved.
 *
 * Project and contact information: http://www.cascading.org/
 *
 * This file is part of the Cascading project.
 *
 * 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 cascading.tap.hadoop.io;

import java.io.IOException;

import org.apache.hadoop.conf.Configurable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapred.FileInputFormat;
import org.apache.hadoop.mapred.FileSplit;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.RecordReader;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.lib.CombineFileSplit;

/**
 * A wrapper class for a record reader that handles a single file split. It delegates most of the
 * methods to the wrapped instance. We need this wrapper to satisfy the constructor requirement to
 * be used with hadoop's CombineFileRecordReader class.
 *
 * @see org.apache.hadoop.mapred.lib.CombineFileRecordReader
 * @see org.apache.hadoop.mapred.lib.CombineFileInputFormat
 */
public class CombineFileRecordReaderWrapper<K, V> implements RecordReader<K, V> {
    /** property that indicates how individual input format is to be interpreted */
    public static final String INDIVIDUAL_INPUT_FORMAT = "cascading.individual.input.format";

    private final RecordReader<K, V> delegate;

    // this constructor signature is required by CombineFileRecordReader
    public CombineFileRecordReaderWrapper(CombineFileSplit split, Configuration conf, Reporter reporter,
            Integer idx) throws Exception {
        FileSplit fileSplit = new FileSplit(split.getPath(idx), split.getOffset(idx), split.getLength(idx),
                split.getLocations());

        Class<?> clz = conf.getClass(INDIVIDUAL_INPUT_FORMAT, null);
        FileInputFormat<K, V> inputFormat = (FileInputFormat<K, V>) clz.newInstance();

        if (inputFormat instanceof Configurable)
            ((Configurable) inputFormat).setConf(conf);

        delegate = inputFormat.getRecordReader(fileSplit, (JobConf) conf, reporter);
    }

    public boolean next(K key, V value) throws IOException {
        return delegate.next(key, value);
    }

    public K createKey() {
        return delegate.createKey();
    }

    public V createValue() {
        return delegate.createValue();
    }

    public long getPos() throws IOException {
        return delegate.getPos();
    }

    public void close() throws IOException {
        delegate.close();
    }

    public float getProgress() throws IOException {
        return delegate.getProgress();
    }
}