001/**
002 * Copyright (c) 2011, The University of Southampton and the individual contributors.
003 * All rights reserved.
004 *
005 * Redistribution and use in source and binary forms, with or without modification,
006 * are permitted provided that the following conditions are met:
007 *
008 *   *  Redistributions of source code must retain the above copyright notice,
009 *      this list of conditions and the following disclaimer.
010 *
011 *   *  Redistributions in binary form must reproduce the above copyright notice,
012 *      this list of conditions and the following disclaimer in the documentation
013 *      and/or other materials provided with the distribution.
014 *
015 *   *  Neither the name of the University of Southampton nor the names of its
016 *      contributors may be used to endorse or promote products derived from this
017 *      software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
020 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
021 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
022 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
023 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
026 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
028 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package org.openimaj.hadoop.tools.twitter.token.mode.pointwisemi.count;
031
032import java.io.IOException;
033
034import org.apache.hadoop.io.BytesWritable;
035import org.apache.hadoop.mapreduce.Reducer;
036import org.apache.log4j.Logger;
037import org.openimaj.io.IOUtils;
038
039/**
040 * Assumes each key is a timeperiod split set of words ordered by single/pair words then by word order.
041 * The key is only used to get time.
042 * Using this time the values are combined and used to construct new keys
043 * 
044 * Emit for the given time a combined version of the word's count. 
045 * The word might be a pair or a unary count.
046 * 
047 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
048 *
049 */
050public class PairEmitCombiner extends Reducer<BytesWritable, BytesWritable, BytesWritable, BytesWritable> {
051        
052        Logger logger = Logger.getLogger(PairEmitCombiner.class);
053        
054        @Override
055        protected void reduce(BytesWritable timeword, Iterable<BytesWritable> paircounts, Reducer<BytesWritable,BytesWritable,BytesWritable,BytesWritable>.Context context) throws IOException ,InterruptedException {
056                TokenPairCollector collector = new TokenPairCollector();
057//              
058                long time = TokenPairCount.timeFromBinaryIdentity(timeword.getBytes());
059                
060//              logger.info("Combining time: " + time);
061                for (BytesWritable bytesWritable : paircounts) {
062                        TokenPairCount paircount = IOUtils.deserialize(bytesWritable.getBytes(), TokenPairCount.class);
063                        TokenPairCount collectorRet = collector.add(paircount);
064                        if(collectorRet != null){
065                                context.write(new BytesWritable(collectorRet.identifierBinary(time)), new BytesWritable(IOUtils.serialize(collectorRet)));
066                                if(!collectorRet.isSingle){
067                                        context.getCounter(PairEnum.PAIR_COMBINED).increment(1);
068                                }else{
069                                        context.getCounter(PairEnum.UNARY_COMBINED).increment(1);
070                                }
071                        }
072                }
073                // Final write
074                TokenPairCount collectorRet = collector.getCurrent();
075                context.write(new BytesWritable(collectorRet.identifierBinary(time)), new BytesWritable(IOUtils.serialize(collectorRet)));
076                if(!collectorRet.isSingle){
077                        context.getCounter(PairEnum.PAIR_COMBINED).increment(1);
078                }else{
079                        context.getCounter(PairEnum.UNARY_COMBINED).increment(1);
080                }
081        }
082}