cascading.scheme.SequenceFile.java Source code

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Here is the source code for cascading.scheme.SequenceFile.java

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/*
 * Copyright (c) 2007-2010 Concurrent, Inc. All Rights Reserved.
 *
 * Project and contact information: http://www.cascading.org/
 *
 * This file is part of the Cascading project.
 *
 * Cascading is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Cascading is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Cascading.  If not, see <http://www.gnu.org/licenses/>.
 */

package cascading.scheme;

import java.beans.ConstructorProperties;
import java.io.IOException;

import cascading.tap.Tap;
import cascading.tuple.Fields;
import cascading.tuple.Tuple;
import cascading.tuple.TupleEntry;
import cascading.tuple.Tuples;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.SequenceFileInputFormat;
import org.apache.hadoop.mapred.SequenceFileOutputFormat;

/**
 * A SequenceFile is a type of {@link Scheme}, which is a flat file consisting of
 * binary key/value pairs. This is a space and time efficient means to store data.
 */
public class SequenceFile extends Scheme {
    /** Field serialVersionUID */
    private static final long serialVersionUID = 1L;

    /** Protected for use by TempDfs and other subclasses. Not for general consumption. */
    protected SequenceFile() {
        super(null);
    }

    /**
     * Creates a new SequenceFile instance that stores the given field names.
     *
     * @param fields
     */
    @ConstructorProperties({ "fields" })
    public SequenceFile(Fields fields) {
        super(fields, fields);
    }

    @Override
    public void sourceInit(Tap tap, JobConf conf) {
        conf.setInputFormat(SequenceFileInputFormat.class);
    }

    @Override
    public void sinkInit(Tap tap, JobConf conf) {
        conf.setOutputKeyClass(Tuple.class); // supports TapCollector
        conf.setOutputValueClass(Tuple.class); // supports TapCollector
        conf.setOutputFormat(SequenceFileOutputFormat.class);
    }

    @Override
    public Tuple source(Object key, Object value) {
        return (Tuple) value;
    }

    @Override
    public void sink(TupleEntry tupleEntry, OutputCollector outputCollector) throws IOException {
        Tuple result = getSinkFields() != null ? tupleEntry.selectTuple(getSinkFields()) : tupleEntry.getTuple();

        outputCollector.collect(Tuples.NULL, result);
    }
}