1 /*
2 * $Source$
3 * $Revision$
4 *
5 * Copyright (C) 2000 William Chesters
6 *
7 * Part of Melati (http://melati.org), a framework for the rapid
8 * development of clean, maintainable web applications.
9 *
10 * Melati is free software; Permission is granted to copy, distribute
11 * and/or modify this software under the terms either:
12 *
13 * a) the GNU General Public License as published by the Free Software
14 * Foundation; either version 2 of the License, or (at your option)
15 * any later version,
16 *
17 * or
18 *
19 * b) any version of the Melati Software License, as published
20 * at http://melati.org
21 *
22 * You should have received a copy of the GNU General Public License and
23 * the Melati Software License along with this program;
24 * if not, write to the Free Software Foundation, Inc.,
25 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA to obtain the
26 * GNU General Public License and visit http://melati.org to obtain the
27 * Melati Software License.
28 *
29 * Feel free to contact the Developers of Melati (http://melati.org),
30 * if you would like to work out a different arrangement than the options
31 * outlined here. It is our intention to allow Melati to be used by as
32 * wide an audience as possible.
33 *
34 * This program is distributed in the hope that it will be useful,
35 * but WITHOUT ANY WARRANTY; without even the implied warranty of
36 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
37 * GNU General Public License for more details.
38 *
39 * Contact details for copyright holder:
40 *
41 * William Chesters <williamc At paneris.org>
42 * http://paneris.org/~williamc
43 * Obrechtstraat 114, 2517VX Den Haag, The Netherlands
44 */
45
46 package org.melati.poem.transaction;
47
48 /**
49 * A serial id of an object which is incremented each time
50 * that object is loaded or locked.
51 */
52 public class TransactionedSerial extends Transactioned {
53
54 private long serial = 0L;
55
56 /**
57 * Constructor.
58 * @param transactionPool the TransactionPool this is relevant to
59 */
60 public TransactionedSerial(TransactionPool transactionPool) {
61 super(transactionPool);
62 }
63
64 /**
65 * On load increment the Serial for this object.
66 *
67 * {@inheritDoc}
68 * @see org.melati.poem.transaction.Transactioned#load(org.melati.poem.transaction.Transaction)
69 */
70 protected void load(Transaction transaction) {
71 ++serial;
72 }
73
74 /**
75 * Return the inheritted validity flag.
76 *
77 * {@inheritDoc}
78 * @see org.melati.poem.transaction.Transactioned#upToDate(org.melati.poem.transaction.Transaction)
79 */
80 protected boolean upToDate(Transaction transaction) {
81 return valid;
82 }
83
84 /**
85 * This implementation does nothing.
86 *
87 * {@inheritDoc}
88 * @see org.melati.poem.transaction.Transactioned#writeDown(org.melati.poem.transaction.Transaction)
89 */
90 protected void writeDown(Transaction transaction) {
91 }
92
93 //
94 // ---------------------
95 // TransactionedSerial
96 // ---------------------
97 //
98
99 /**
100 * Readlock and return the serial for the given Transaction.
101 * @param transaction the Transaction
102 * @return the serial for the given Transaction
103 */
104 public long current(Transaction transaction) {
105 readLock(transaction);
106 return serial;
107 }
108
109 /**
110 * Write lock and increment.
111 * @param transaction the Transaction
112 */
113 public void increment(Transaction transaction) {
114 writeLock(transaction);
115 increment_unlocked();
116 }
117
118 /**
119 * Increment.
120 */
121 public void increment_unlocked() {
122 ++serial;
123 }
124 }