01: /*
02: * JBoss, Home of Professional Open Source.
03: * Copyright 2006, Red Hat Middleware LLC, and individual contributors
04: * as indicated by the @author tags. See the copyright.txt file in the
05: * distribution for a full listing of individual contributors.
06: *
07: * This is free software; you can redistribute it and/or modify it
08: * under the terms of the GNU Lesser General Public License as
09: * published by the Free Software Foundation; either version 2.1 of
10: * the License, or (at your option) any later version.
11: *
12: * This software is distributed in the hope that it will be useful,
13: * but WITHOUT ANY WARRANTY; without even the implied warranty of
14: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15: * Lesser General Public License for more details.
16: *
17: * You should have received a copy of the GNU Lesser General Public
18: * License along with this software; if not, write to the Free
19: * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
20: * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
21: */
22: package org.jboss.ejb.plugins.lock;
23:
24: /**
25: * This class is an optmistic lock implementation.
26: * It locks tableFields and their values during transaction.
27: * Locked tableFields and their values are added to the WHERE clause of the
28: * UPDATE SQL statement when entity is stored.
29: * The following strategies are supported:
30: * - fixed group of tableFields
31: * Fixed group of tableFields is used for locking . The tableFields and their values are
32: * locked at the beginning of a transaction. The group name must match
33: * one of the entity's load-group-name.
34: * - modified strategy
35: * The tableFields that were modified during transaction are used as lock.
36: * All entity's field values are locked at the beginning of the transaction.
37: * The tableFields are locked only after its actual change.
38: * - read strategy
39: * The tableFields that were read/modified during transaction.
40: * All entity's field values are locked at the beginning of the transaction.
41: * The tableFields are locked only after they were accessed.
42: * - version-column strategy
43: * This adds additional version field of type java.lang.Long. Each update
44: * of the entity will increase the version value by 1.
45: * - timestamp-column strategy
46: * Adds additional timestamp column of type java.util.Date. Each update
47: * of the entity will set the field to the current time.
48: * - key-generator column strategy
49: * Adds additional column. The type is defined by user. The key generator
50: * is used to set the next value.
51: *
52: * Note: all optimistic locking related code should be rewritten when in the
53: * new CMP design.
54: *
55: * Note2: done.
56: *
57: * @author <a href="mailto:aloubyansky@hotmail.com">Alex Loubyansky</a>
58: * @version $Revision: 57209 $
59: */
60: public final class JDBCOptimisticLock extends NoLock {
61: }
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