edu.umn.cs.spatialHadoop.mapred.TextOutputFormat3.java Source code

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Here is the source code for edu.umn.cs.spatialHadoop.mapred.TextOutputFormat3.java

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/***********************************************************************
* Copyright (c) 2015 by Regents of the University of Minnesota.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Apache License, Version 2.0 which 
* accompanies this distribution and is available at
* http://www.opensource.org/licenses/apache2.0.php.
*
*************************************************************************/
package edu.umn.cs.spatialHadoop.mapred;

import java.io.DataOutputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.apache.hadoop.io.compress.GzipCodec;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
import org.apache.hadoop.util.ReflectionUtils;

import edu.umn.cs.spatialHadoop.io.Text2;
import edu.umn.cs.spatialHadoop.io.TextSerializable;

/**
 * A slightly modified version of {@link TextOutputFormat} that performs special
 * conversion to text for objects of type {@link TextSerializable}.
 * @author Ahmed Eldawy
 *
 * @param <K> The type of key
 * @param <V> The type of value
 */
public class TextOutputFormat3<K, V> extends FileOutputFormat<K, V> {

    protected static class LineRecordWriter<K, V> extends RecordWriter<K, V> {
        private static final String utf8 = "UTF-8";
        private static final byte[] newline;
        static {
            try {
                newline = "\n".getBytes(utf8);
            } catch (UnsupportedEncodingException uee) {
                throw new IllegalArgumentException("can't find " + utf8 + " encoding");
            }
        }

        protected DataOutputStream out;
        private final byte[] keyValueSeparator;

        public LineRecordWriter(DataOutputStream out, String keyValueSeparator) {
            this.out = out;
            try {
                this.keyValueSeparator = keyValueSeparator.getBytes(utf8);
            } catch (UnsupportedEncodingException uee) {
                throw new IllegalArgumentException("can't find " + utf8 + " encoding");
            }
        }

        public LineRecordWriter(DataOutputStream out) {
            this(out, "\t");
        }

        /**
         * Write the object to the byte stream, handling Text as a special
         * case.
         * @param o the object to print
         * @throws IOException if the write throws, we pass it on
         */
        private void writeObject(Object o) throws IOException {
            if (o instanceof Text) {
                Text to = (Text) o;
                out.write(to.getBytes(), 0, to.getLength());
            } else if (o instanceof TextSerializable) {
                // Serialize object to text
                Text to = new Text2();
                ((TextSerializable) o).toText(to);
                out.write(to.getBytes(), 0, to.getLength());
            } else {
                out.write(o.toString().getBytes(utf8));
            }
        }

        @Override
        public synchronized void write(K key, V value) throws IOException {

            boolean nullKey = key == null || key instanceof NullWritable;
            boolean nullValue = value == null || value instanceof NullWritable;
            if (nullKey && nullValue) {
                return;
            }
            if (!nullKey) {
                writeObject(key);
            }
            if (!(nullKey || nullValue)) {
                out.write(keyValueSeparator);
            }
            if (!nullValue) {
                writeObject(value);
            }
            out.write(newline);
        }

        @Override
        public void close(TaskAttemptContext arg0) throws IOException, InterruptedException {
            out.close();
        }
    }

    @Override
    public RecordWriter<K, V> getRecordWriter(TaskAttemptContext task) throws IOException, InterruptedException {
        Configuration conf = task.getConfiguration();
        boolean isCompressed = getCompressOutput(task);
        String keyValueSeparator = conf.get("mapred.textoutputformat.separator", "\t");
        if (!isCompressed) {
            Path file = getDefaultWorkFile(task, "");
            FileSystem fs = file.getFileSystem(conf);
            FSDataOutputStream fileOut = fs.create(file, task);
            return new LineRecordWriter<K, V>(fileOut, keyValueSeparator);
        } else {
            Class<? extends CompressionCodec> codecClass = getOutputCompressorClass(task, GzipCodec.class);
            // create the named codec
            CompressionCodec codec = ReflectionUtils.newInstance(codecClass, conf);
            // build the filename including the extension
            Path file = getDefaultWorkFile(task, codec.getDefaultExtension());
            FileSystem fs = file.getFileSystem(conf);
            FSDataOutputStream fileOut = fs.create(file, task);
            return new LineRecordWriter<K, V>(new DataOutputStream(codec.createOutputStream(fileOut)),
                    keyValueSeparator);
        }
    }
}