Source code: ojb/odmg/locking/LockManager.java
1 /*
2 * ObJectRelationalBridge - Bridging Java Objects and Relational Databases
3 * http://objectbridge.sourceforge.net
4 * Copyright (C) 2000, 2001 Thomas Mahler, et al.
5 *
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 */
20 package ojb.odmg.locking;
21
22 import ojb.odmg.TransactionImpl;
23
24 /**
25 * This interface declares the functionality of the OJB internal Locking mechanism.
26 * A default implementaion LockManagerDefaultImpl is provided. This implementaion
27 * keeps distributed locks in the database. The locking mechanisms thus involves a
28 * lot of database lookups and writes. For some environments this solution may not
29 * be adequate. OJB allows to provide user defined implementations of this interface.
30 * To activate a user defined LockManagerDefaultImpl it must be configured in the OJB.properties file.
31 *
32 *
33 * @author thma
34 */
35 public interface LockManager
36 {
37 /**
38 * aquires a readlock for transaction tx on object obj.
39 * Returns true if successful, else false.
40 */
41 public abstract boolean readLock(TransactionImpl tx, Object obj);
42
43 /**
44 * aquires a writelock for transaction tx on object obj.
45 * Returns true if successful, else false.
46 */
47 public abstract boolean writeLock(TransactionImpl tx, Object obj);
48
49 /**
50 * upgrades readlock for transaction tx on object obj to a writelock.
51 * If no readlock existed a writelock is acquired anyway.
52 * Returns true if successful, else false.
53 */
54 public abstract boolean upgradeLock(TransactionImpl tx, Object obj);
55
56 /**
57 * releases a lock for transaction tx on object obj.
58 * Returns true if successful, else false.
59 */
60 public abstract boolean releaseLock(TransactionImpl tx, Object obj);
61
62 /**
63 * checks if there is a readlock for transaction tx on object obj.
64 * Returns true if so, else false.
65 */
66 public abstract boolean checkRead(TransactionImpl tx, Object obj);
67
68 /**
69 * checks if there is a writelock for transaction tx on object obj.
70 * Returns true if so, else false.
71 */
72 public abstract boolean checkWrite(TransactionImpl tx, Object obj);
73
74
75 }