Package edu.umd.cloud9.collection.trecweb

Source Code of edu.umd.cloud9.collection.trecweb.TrecWebDocumentInputFormatOld$TrecWebRecordReader

/*
* 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.umd.cloud9.collection.trecweb;

import java.io.IOException;

import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.FileSplit;
import org.apache.hadoop.mapred.InputSplit;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.RecordReader;
import org.apache.hadoop.mapred.Reporter;

import edu.umd.cloud9.collection.IndexableFileInputFormatOld;
import edu.umd.cloud9.collection.XMLInputFormatOld;
import edu.umd.cloud9.collection.XMLInputFormatOld.XMLRecordReader;

/**
* Hadoop {@code InputFormat} for processing the TREC collection.
*
* @author Jimmy Lin
*/
public class TrecWebDocumentInputFormatOld extends
    IndexableFileInputFormatOld<LongWritable, TrecWebDocument> {

  @Override
  protected boolean isSplitable(FileSystem fs, Path filename) {
    // Don't allow the files to be split.
    return false;
  }

  /**
   * Returns a {@code RecordReader} for this {@code InputFormat}.
   */
  public RecordReader<LongWritable, TrecWebDocument> getRecordReader(InputSplit inputSplit,
      JobConf conf, Reporter reporter) throws IOException {
    return new TrecWebRecordReader((FileSplit) inputSplit, conf);
  }

  /**
   * Hadoop {@code RecordReader} for reading TREC-formatted documents.
   */
  public static class TrecWebRecordReader implements RecordReader<LongWritable, TrecWebDocument> {
    private final XMLRecordReader reader;
    private final Text text = new Text();
    private final LongWritable inputKey = new LongWritable();

    /**
     * Creates a {@code TrecDocumentRecordReader}.
     */
    public TrecWebRecordReader(FileSplit split, JobConf conf) throws IOException {
      conf.set(XMLInputFormatOld.START_TAG_KEY, TrecWebDocument.XML_START_TAG);
      conf.set(XMLInputFormatOld.END_TAG_KEY, TrecWebDocument.XML_END_TAG);

      reader = new XMLRecordReader(split, conf);
    }

    /**
     * Reads the next key-value pair.
     */
    public boolean next(LongWritable key, TrecWebDocument value) throws IOException {
      if (reader.next(inputKey, text) == false) {
        return false;
      }
      key.set(inputKey.get());
      TrecWebDocument.readDocument(value, text.toString());
      return true;
    }

    /**
     * Creates an object for the key.
     */
    public LongWritable createKey() {
      return new LongWritable();
    }

    /**
     * Creates an object for the value.
     */
    public TrecWebDocument createValue() {
      return new TrecWebDocument();
    }

    /**
     * Returns the current position in the input.
     */
    public long getPos() throws IOException {
      return reader.getPos();
    }

    /**
     * Closes this InputSplit.
     */
    public void close() throws IOException {
      reader.close();
    }

    /**
     * Returns progress on how much input has been consumed.
     */
    public float getProgress() throws IOException {
      return ((float) (reader.getPos() - reader.getStart()))
          / ((float) (reader.getEnd() - reader.getStart()));
    }
  }
}
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