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 }