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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *  
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *  
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License. 
18   *  
19   */
20  package org.apache.directory.mitosis.common;
21  
22  
23  /**
24   * A default {@link CSNFactory} implementation.
25   * 
26   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
27   */
28  public class DefaultCSNFactory implements CSNFactory
29  {
30      private static int operationSequence;
31  
32  
33      public DefaultCSNFactory()
34      {
35      }
36  
37  
38      /**
39       * Returns a new {@link CSN}.
40       * Generated CSN can be duplicate if user generates CSNs more than 2G 
41       * times a milliseconds.
42       * 
43       * @param replicaId Replica ID.  ReplicaID must be 1-8 digit alphanumeric
44       *        string.
45       */
46      public synchronized CSN newInstance( String replicaId )
47      {
48          long newTimestamp = System.currentTimeMillis();
49          
50          if ( operationSequence == Integer.MAX_VALUE )
51          {
52              // Roll over when reaching the limit.
53              operationSequence = 0;
54          }
55  
56          CSN newCSN = new DefaultCSN( newTimestamp, replicaId, operationSequence++ );
57          return newCSN;
58      }
59  }