/*
* Cloud9: A Hadoop toolkit for working with big data
*
* 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.trec;
import java.io.IOException;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.FileSplit;
import org.apache.hadoop.mapred.InputFormat;
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 {@link InputFormat} for processing the TREC collection.
*
* @author Jimmy Lin
*/
public class TrecDocumentInputFormatOld extends IndexableFileInputFormatOld<LongWritable, TrecDocument> {
/**
* Returns a {@code RecordReader} for this {@code InputFormat}.
*/
public RecordReader<LongWritable, TrecDocument> getRecordReader(InputSplit inputSplit,
JobConf conf, Reporter reporter) throws IOException {
return new TrecDocumentRecordReader((FileSplit) inputSplit, conf);
}
/**
* Hadoop {@link RecordReader} for reading TREC-formatted documents.
*/
public static class TrecDocumentRecordReader
implements RecordReader<LongWritable, TrecDocument> {
private XMLRecordReader reader;
private Text text = new Text();
private LongWritable pos = new LongWritable();
/**
* Creates a {@code TrecDocumentRecordReader}.
*/
public TrecDocumentRecordReader(FileSplit split, JobConf conf) throws IOException {
conf.set(XMLInputFormatOld.START_TAG_KEY, TrecDocument.XML_START_TAG);
conf.set(XMLInputFormatOld.END_TAG_KEY, TrecDocument.XML_END_TAG);
reader = new XMLRecordReader(split, conf);
}
/**
* Reads the next key-value pair.
*/
public boolean next(LongWritable key, TrecDocument value) throws IOException {
if (reader.next(pos, text) == false) {
return false;
}
key.set(pos.get());
TrecDocument.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 TrecDocument createValue() {
return new TrecDocument();
}
/**
* Returns the current position in the input.
*/
public long getPos() throws IOException {
return reader.getPos();
}
/**
* Closes this {@code 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()));
}
}
}