| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| * |
| */ |
| package org.apache.directory.api.ldap.model.csn; |
| |
| |
| /** |
| * Generates a new {@link Csn}. |
| * |
| * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> |
| */ |
| public class CsnFactory |
| { |
| /** The last timestamp */ |
| private static volatile long lastTimestamp; |
| |
| /** The integer used to disambiguate CSN generated at the same time */ |
| private int changeCount; |
| |
| /** The replicaId to use for every CSN created by this factory */ |
| private int replicaId; |
| |
| /** A special instance ID for a purge CSN */ |
| private static final int PURGE_INSTANCEID = 0x0FFF; |
| |
| /** A lock used during the instance creation */ |
| private Object lock = new Object(); |
| |
| |
| public CsnFactory( int replicaId ) |
| { |
| changeCount = 0; |
| this.replicaId = replicaId; |
| } |
| |
| |
| /** |
| * Returns a new {@link Csn}. |
| * Generated CSN can be duplicate if user generates CSNs more than 2G |
| * times a milliseconds. |
| */ |
| public Csn newInstance() |
| { |
| int tmpChangeCount = 0; |
| |
| synchronized ( lock ) |
| { |
| long newTimestamp = System.currentTimeMillis(); |
| |
| // We will be able to generate 2 147 483 647 CSNs each 10 ms max |
| if ( lastTimestamp == newTimestamp ) |
| { |
| changeCount++; |
| } |
| else |
| { |
| lastTimestamp = newTimestamp; |
| changeCount = 0; |
| } |
| |
| tmpChangeCount = changeCount; |
| } |
| |
| return new Csn( lastTimestamp, tmpChangeCount, replicaId, 0 ); |
| } |
| |
| |
| /** |
| * Returns a new {@link Csn} created from the given values. |
| * |
| * This method is <b>not</b> to be used except for test purposes. |
| * |
| * @param timestamp The timestamp to use |
| * @param changeCount The change count to use |
| */ |
| public Csn newInstance( long timestamp, int changeCount ) |
| { |
| return new Csn( timestamp, changeCount, replicaId, 0 ); |
| } |
| |
| |
| /** |
| * Generates a CSN used to purge data. Its replicaID is not associated |
| * to a server. |
| * |
| * @param expirationDate The time up to the first CSN we want to keep |
| */ |
| public Csn newPurgeCsn( long expirationDate ) |
| { |
| return new Csn( expirationDate, Integer.MAX_VALUE, PURGE_INSTANCEID, Integer.MAX_VALUE ); |
| } |
| |
| |
| public void setReplicaId( int replicaId ) |
| { |
| this.replicaId = replicaId; |
| } |
| } |