EnronMailReducer.java

/*
 * Copyright 2011 10gen Inc.
 *
 * 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 com.mongodb.hadoop.examples.enron;

import com.mongodb.BasicDBObjectBuilder;
import com.mongodb.hadoop.io.BSONWritable;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapreduce.Reducer;
import org.bson.BSONObject;

import java.io.IOException;
import java.util.Iterator;

public class EnronMailReducer extends Reducer<MailPair, IntWritable, BSONWritable, IntWritable> 
    implements org.apache.hadoop.mapred.Reducer<MailPair, IntWritable, BSONWritable, IntWritable> {

    private static final Log LOG = LogFactory.getLog(EnronMailReducer.class);
    private BSONWritable reduceResult;
    private IntWritable intw;

    public EnronMailReducer() {
        super();
        reduceResult = new BSONWritable();
        intw = new IntWritable();
    }

    @Override
    public void reduce(final MailPair pKey, final Iterable<IntWritable> pValues, final Context pContext)
        throws IOException, InterruptedException {
        int sum = 0;
        for (final IntWritable value : pValues) {
            sum += value.get();
        }
        BSONObject outDoc = BasicDBObjectBuilder.start()
          .add("f", pKey.getFrom())
          .add("t", pKey.getTo()).get();
        reduceResult.setDoc(outDoc);
        intw.set(sum);

        pContext.write(reduceResult, intw);
    }

    @Override
    public void reduce(final MailPair key, final Iterator<IntWritable> values, final OutputCollector<BSONWritable, IntWritable> output,
                       final Reporter reporter)
        throws IOException {
        int sum = 0;
        while (values.hasNext()) {
            sum += values.next().get();
        }
        BSONObject outDoc = BasicDBObjectBuilder.start()
          .add("f", key.getFrom())
          .add("t", key.getTo()).get();
        reduceResult.setDoc(outDoc);
        intw.set(sum);

        output.collect(reduceResult, intw);
    }

    @Override
    public void close() throws IOException {
    }

    @Override
    public void configure(final JobConf job) {
    }
}