edu.isi.mavuno.input.TrecInputFormat.java Source code

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Here is the source code for edu.isi.mavuno.input.TrecInputFormat.java

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/*
 * Cloud9: A MapReduce Library for Hadoop
 * 
 * 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 edu.isi.mavuno.input;

import java.io.IOException;

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 edu.isi.mavuno.input.TrecDocument;
import edu.isi.mavuno.input.XMLInputFormat.XMLRecordReader;

/**
 * Hadoop <code>InputFormat</code> for processing the TREC collection.
 * 
 * @author Jimmy Lin
 * @author metzler
 */
public class TrecInputFormat extends IndexableFileInputFormat<LongWritable, TrecDocument> {

    /**
     * Returns a <code>RecordReader</code> for this <code>InputFormat</code>.
     */
    @Override
    public RecordReader<LongWritable, TrecDocument> createRecordReader(InputSplit inputSplit,
            TaskAttemptContext context) throws IOException, InterruptedException {
        Configuration conf = context.getConfiguration();
        return new TrecDocumentRecordReader((FileSplit) inputSplit, conf);
    }

    /**
     * Hadoop <code>RecordReader</code> for reading TREC-formatted documents.
     */
    public static class TrecDocumentRecordReader extends RecordReader<LongWritable, TrecDocument> {

        private final LongWritable mCurKey = new LongWritable();
        private final TrecDocument mCurValue = new TrecDocument();

        private XMLRecordReader mReader;

        /**
         * Creates a <code>TrecDocumentRecordReader</code>.
         */
        public TrecDocumentRecordReader(FileSplit split, Configuration conf) throws IOException {
            conf.set(XMLInputFormat.START_TAG_KEY, TrecDocument.XML_START_TAG);
            conf.set(XMLInputFormat.END_TAG_KEY, TrecDocument.XML_END_TAG);

            mReader = new XMLRecordReader(split, conf);
        }

        @Override
        public void close() throws IOException {
            mReader.close();
        }

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

        @Override
        public TrecDocument getCurrentValue() throws IOException, InterruptedException {
            return mCurValue;
        }

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

        @Override
        public void initialize(InputSplit split, TaskAttemptContext context)
                throws IOException, InterruptedException {
        }

        @Override
        public boolean nextKeyValue() throws IOException, InterruptedException {
            if (mReader.nextKeyValue() == false) {
                return false;
            }
            mCurKey.set(mReader.getCurrentKey().get());
            TrecDocument.readDocument(mCurValue, mReader.getCurrentValue().toString());
            return true;
        }
    }
}