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Java > Open Source Codes > com > caucho > amber > idgen > IdGenerator


1 /*
2  * Copyright (c) 1998-2006 Caucho Technology -- all rights reserved
3  *
4  * This file is part of Resin(R) Open Source
5  *
6  * Each copy or derived work must preserve the copyright notice and this
7  * notice unmodified.
8  *
9  * Resin Open Source is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation; either version 2 of the License, or
12  * (at your option) any later version.
13  *
14  * Resin Open Source is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
17  * of NON-INFRINGEMENT. See the GNU General Public License for more
18  * details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with Resin Open Source; if not, write to the
22  * Free Software Foundation, Inc.
23  * 59 Temple Place, Suite 330
24  * Boston, MA 02111-1307 USA
25  *
26  * @author Scott Ferguson
27  */
28
29 package com.caucho.amber.idgen;
30
31 import com.caucho.amber.manager.AmberConnection;
32 import com.caucho.util.L10N;
33 import com.caucho.util.Log;
34
35 import java.sql.SQLException JavaDoc;
36 import java.util.logging.Logger JavaDoc;
37
38 /**
39  * Generator table.
40  */
41 abstract public class IdGenerator {
42   private static final L10N L = new L10N(IdGenerator.class);
43   private static final Logger JavaDoc log = Log.open(IdGenerator.class);
44   
45   private long _next;
46   private int _remaining;
47
48   private int _groupSize = 50;
49   
50   /**
51    * Gets the group size.
52    */
53   public int getGroupSize()
54   {
55     return _groupSize;
56   }
57   
58   /**
59    * Sets the group size.
60    */
61   public void setGroupSize(int groupSize)
62   {
63     _groupSize = groupSize;
64   }
65
66   /**
67    * Allocates the next id.
68    */
69   public long allocate(AmberConnection aConn)
70     throws SQLException JavaDoc
71   {
72     synchronized (this) {
73       if (_remaining <= 0) {
74     _next = allocateGroup(aConn);
75     _remaining += getGroupSize();
76       }
77       
78       long value = _next;
79       _next++;
80       _remaining--;
81
82       return value;
83     }
84   }
85
86   /**
87    * Allocates the next group of ids.
88    */
89   abstract public long allocateGroup(AmberConnection aConn)
90     throws SQLException JavaDoc;
91 }
92
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