001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 * 019 */ 020 package org.apache.directory.shared.ldap.schema.comparators; 021 022 023 import org.apache.directory.shared.ldap.csn.Csn; 024 import org.apache.directory.shared.ldap.schema.LdapComparator; 025 import org.slf4j.Logger; 026 import org.slf4j.LoggerFactory; 027 028 029 /** 030 * A comparator for CSN. 031 * 032 * The CSN are ordered depending on an evaluation of its component, in this order : 033 * - time, 034 * - changeCount, 035 * - sid 036 * - modifierNumber 037 * 038 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> 039 * @version $Rev$ 040 */ 041 public class CsnComparator extends LdapComparator<String> 042 { 043 /** A logger for this class */ 044 private static final Logger LOG = LoggerFactory.getLogger( CsnComparator.class ); 045 046 /** The serialVersionUID */ 047 private static final long serialVersionUID = 1L; 048 049 /** 050 * The CsnComparator constructor. Its OID is the CsnMatch matching 051 * rule OID. 052 */ 053 public CsnComparator( String oid ) 054 { 055 super( oid ); 056 } 057 058 059 /** 060 * @see java.util.Comparator#compare(java.lang.Object, java.lang.Object) 061 */ 062 public int compare( String csnStr1, String csnStr2 ) 063 { 064 LOG.debug( "comparing CSN objects '{}' with '{}'", csnStr1, csnStr2 ); 065 066 // ------------------------------------------------------------------- 067 // Handle some basis cases 068 // ------------------------------------------------------------------- 069 if ( csnStr1 == null ) 070 { 071 return ( csnStr2 == null ) ? 0 : -1; 072 } 073 074 if ( csnStr2 == null ) 075 { 076 return 1; 077 } 078 079 Csn csn1 = new Csn( csnStr1 ); 080 Csn csn2 = new Csn( csnStr2 ); 081 082 if ( csn1.getTimestamp() != csn2.getTimestamp() ) 083 { 084 return ( csn1.getTimestamp() < csn2.getTimestamp() ? -1 : 1 ); 085 } 086 087 if ( csn1.getChangeCount() != csn2.getChangeCount() ) 088 { 089 return ( csn1.getChangeCount() < csn2.getChangeCount() ? -1 : 1 ); 090 } 091 092 if ( csn1.getReplicaId() != csn2.getReplicaId() ) 093 { 094 return ( csn1.getReplicaId() < csn2.getReplicaId() ? -1 : 1 ); 095 } 096 097 if ( csn1.getOperationNumber() != csn2.getOperationNumber() ) 098 { 099 return ( csn1.getOperationNumber() < csn2.getOperationNumber() ? -1 : 1 ); 100 } 101 102 return 0; 103 } 104 }