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.ByteArrayInputStream;
033import java.io.DataInputStream;
034import java.io.IOException;
035import org.apache.hadoop.io.BytesWritable;
036import org.apache.hadoop.io.RawComparator;
037import org.apache.log4j.Logger;
038
039
040/**
041 * Read a tokenpair and make sure the single words appear before the pair words
042 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
043 *
044 */
045public class TokenPairKeyComparator implements RawComparator<BytesWritable> {
046        Logger logger = Logger.getLogger(TokenPairKeyComparator.class);
047        @Override
048        public int compare(BytesWritable o1, BytesWritable o2) {
049                return compareData(o1.getBytes(),0,o1.getLength(),o2.getBytes(),0,o2.getLength());
050        }
051
052        @Override
053        public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
054                return compareData(b1,s1+4,l1-4,b2,s2+4,l2-4); // Expecting bytes writeable, skip the BytesWritable length
055        }
056        
057        private int compareData(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2){
058                DataInputStream dis1  = null;
059                DataInputStream dis2  = null;
060                try{
061                        dis1 = new DataInputStream(new ByteArrayInputStream(b1,s1,l1));
062                        dis2 = new DataInputStream(new ByteArrayInputStream(b2,s2,l2));
063                        
064                        // first check the time, return early if they are not the same time!
065                        long time1 = dis1.readLong();
066                        long time2 = dis2.readLong();
067                        if(time1<time2){
068                                return -1;
069                        }
070                        else if(time1>time2){
071                                return 1;
072                        }
073                        
074                        // now check if they are both pair counts, if not, make sure the unary count goes first
075                        boolean single1 = dis1.readBoolean();
076                        boolean single2 = dis2.readBoolean();
077                        if(single1 && !single2){
078                                return -1;
079                        }
080                        else if(!single1 && single2){
081                                return 1;
082                        }
083                        
084                        // now either they are both single, or they are both pairs, either way compare the first strings first
085                        int cmpFirstString = dis1.readUTF().compareTo(dis2.readUTF());
086                        if(single1){
087                                return cmpFirstString;
088                        }
089                        // Both are pairs, were their first strings unequal?
090                        if(cmpFirstString != 0){
091                                return cmpFirstString;
092                        }
093                        
094                        // Shared the first string! right! now compare the final string!
095                        return dis1.readUTF().compareTo(dis2.readUTF());
096                } catch (IOException e) {
097                        return 0;
098                }
099                finally{
100                        try {
101                                dis1.close();
102                                dis2.close();
103                        } catch (IOException e) {
104                                // eep!
105                        }
106                }
107        }
108}