001/* 002 * Copyright (c) 2007-2017 Xplenty, Inc. All Rights Reserved. 003 * 004 * Project and contact information: http://www.cascading.org/ 005 * 006 * This file is part of the Cascading project. 007 * 008 * Licensed under the Apache License, Version 2.0 (the "License"); 009 * you may not use this file except in compliance with the License. 010 * You may obtain a copy of the License at 011 * 012 * http://www.apache.org/licenses/LICENSE-2.0 013 * 014 * Unless required by applicable law or agreed to in writing, software 015 * distributed under the License is distributed on an "AS IS" BASIS, 016 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 017 * See the License for the specific language governing permissions and 018 * limitations under the License. 019 */ 020 021package cascading.tuple.hadoop.util; 022 023import java.io.Serializable; 024import java.util.Arrays; 025import java.util.Comparator; 026 027import cascading.tuple.Hasher; 028import cascading.tuple.StreamComparator; 029import cascading.tuple.hadoop.io.BufferedInputStream; 030import org.apache.hadoop.io.WritableComparator; 031 032/** 033 * Class BytesComparator is used to compare arrays of bytes. 034 * <p/> 035 * Note that BytesComparator implements {@link Hasher}, but for the Hasher interface to be applied during grouping, 036 * sorting or joining, it must be set on a {@link cascading.tuple.Fields} instance via 037 * {@link cascading.tuple.Fields#setComparator(Comparable, java.util.Comparator)}. 038 */ 039public class BytesComparator implements StreamComparator<BufferedInputStream>, Hasher<byte[]>, Comparator<byte[]>, Serializable 040 { 041 @Override 042 public int compare( byte[] lhs, byte[] rhs ) 043 { 044 if( lhs == rhs ) 045 return 0; 046 047 return WritableComparator.compareBytes( lhs, 0, lhs.length, rhs, 0, rhs.length ); 048 } 049 050 @Override 051 public int compare( BufferedInputStream lhsStream, BufferedInputStream rhsStream ) 052 { 053 byte[] lhs = lhsStream.getBuffer(); 054 int lhsPos = lhsStream.getPosition(); 055 int lhsLen = readLen( lhs, lhsPos ); 056 057 lhsStream.skip( lhsLen + 4 ); 058 059 byte[] rhs = rhsStream.getBuffer(); 060 int rhsPos = rhsStream.getPosition(); 061 int rhsLen = readLen( rhs, rhsPos ); 062 063 rhsStream.skip( rhsLen + 4 ); 064 065 return WritableComparator.compareBytes( lhs, lhsPos + 4, lhsLen, rhs, rhsPos + 4, rhsLen ); 066 } 067 068 private int readLen( byte[] buffer, int off ) 069 { 070 return ( ( buffer[ off ] & 0xff ) << 24 ) + 071 ( ( buffer[ off + 1 ] & 0xff ) << 16 ) + 072 ( ( buffer[ off + 2 ] & 0xff ) << 8 ) + 073 ( buffer[ off + 3 ] & 0xff ); 074 } 075 076 @Override 077 public int hashCode( byte[] value ) 078 { 079 return Arrays.hashCode( value ); 080 } 081 }