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Java > Open Source Codes > org > apache > ojb > broker > locking > LockManager


1 package org.apache.ojb.broker.locking;
2
3 /* Copyright 2002-2005 The Apache Software Foundation
4  *
5  * Licensed under the Apache License, Version 2.0 (the "License");
6  * you may not use this file except in compliance with the License.
7  * You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17
18
19 /**
20  * This interface declares the functionality of the OJB locking-api for support of
21  * pessimistic locking.
22  * <p>
23  * OJB allows to provide user defined implementations of this interface.
24  * To activate a user defined LockManager implementation it must be configured in
25  * the OJB.properties file.
26  * </p>
27  * <p>
28  * All locks have to be reentrant, this means if you already have a lock for
29  * writing and you try to acquire write access again you will not be blocked
30  * by this first lock.
31  * </p>
32  * <p>
33  * It's optional to support the <em>lockTimeout</em> and <em>blockTimeout</em> properties.
34  * </p>
35  *
36  * @see LockManagerInMemoryImpl
37  * @see LockManagerCommonsImpl
38  * @version $Id: LockManager.java,v 1.1.2.5 2005/12/21 22:25:32 tomdz Exp $
39  */
40 public interface LockManager extends IsolationLevels
41 {
42     /**
43      * Default lock timeout value - set to 60000 ms.
44      */
45     public final static long DEFAULT_LOCK_TIMEOUT = 60000;
46
47     /**
48      * Default lock wait time in millisecond - set to 1000 ms;
49      */
50     public final static long DEFAULT_BLOCK_TIMEOUT = 1000;
51
52     /**
53      * The maximal time to wait for acquire a lock.
54      *
55      * @return
56      */
57     public long getBlockTimeout();
58
59     /**
60      * Set the maximal time to wait for acquire a lock in milliseconds.
61      * All so called <em>non-blocking</em> implementation will ignore this setting.
62      *
63      * @param timeout The time to wait for acquire a lock.
64      */
65     public void setBlockTimeout(long timeout);
66
67     /**
68      * Get the current used lock timeout value in milliseconds.
69      * @return Current used locking timeout value in ms.
70      */
71     public long getLockTimeout();
72
73     /**
74      * Set the lock timeout value in milliseconds. If timeout was set to <em>-1</em>
75      * the never will never timeout.
76      *
77      * @param timeout The lock timeout in <em>ms</em> of acquired read/write/upgrade locks.
78       */
79     public void setLockTimeout(long timeout);
80
81     /**
82      * Returns info about the used lock manager implementation and the state
83      * of the lock manager.
84      */
85     public String JavaDoc getLockInfo();
86
87     /**
88      * Acquires a readlock for lock key on resource object.
89      * Returns true if successful, else false.
90      *
91      * @param key The owner key of the lock.
92      * @param resourceId The resource to lock.
93      * @param isolationLevel The isolation level of the lock.
94      * @return <em>True</em> if the lock was successfully acquired.
95      */
96     public boolean readLock(Object JavaDoc key, Object JavaDoc resourceId, int isolationLevel);
97
98     /**
99      * Acquires a write lock for lock key on resource object.
100      * Returns true if successful, else false.
101      *
102      * @param key The owner key of the lock.
103      * @param resourceId The resource to lock.
104      * @param isolationLevel The isolation level of the lock.
105      * @return <em>True</em> if the lock was successfully acquired.
106      */
107     public boolean writeLock(Object JavaDoc key, Object JavaDoc resourceId, int isolationLevel);
108
109     /**
110      * Acquire an upgrade lock.
111      * (Current implementations always acquire a write lock instead).
112      *
113      * @param key The owner key of the lock.
114      * @param resourceId The resource to lock.
115      * @param isolationLevel The isolation level of the lock.
116      * @return <em>True</em> if the lock was successfully acquired.
117      */
118     public boolean upgradeLock(Object JavaDoc key, Object JavaDoc resourceId, int isolationLevel);
119
120     /**
121      * Releases a lock for lock key on resource object.
122      * Returns true if successful, else false.
123      *
124      * @param key The owner key of the lock.
125      * @param resourceId The resource to release.
126      * @return <em>True</em> if the lock was successfully released.
127      */
128     public boolean releaseLock(Object JavaDoc key, Object JavaDoc resourceId);
129
130     /**
131      * Release all resource locks hold by the specified owner key.
132      *
133      * @param key The owner key to release all associated locks.
134      */
135     public void releaseLocks(Object JavaDoc key);
136
137     /**
138      * Checks if there is a read lock for owner key on resource object.
139      * Returns true if so, else false.
140      *
141      * @param key The owner key of the lock.
142      * @param resourceId The resource to check.
143      * @return <em>True</em> if the lock exists.
144      */
145     public boolean hasRead(Object JavaDoc key, Object JavaDoc resourceId);
146
147     /**
148      * Checks if there is a write lock for lock key on resource object.
149      * Returns true if so, else false.
150      *
151      * @param key The owner key of the lock.
152      * @param resourceId The resource to check.
153      * @return <em>True</em> if the lock exists.
154      */
155     public boolean hasWrite(Object JavaDoc key, Object JavaDoc resourceId);
156
157     /**
158      * Checks if there is a upgrade lock for lock key on resource object.
159      * Returns true if so, else false.
160      *
161      * @param key The owner key of the lock.
162      * @param resourceId The resource to check.
163      * @return <em>True</em> if the lock exists.
164      */
165     public boolean hasUpgrade(Object JavaDoc key, Object JavaDoc resourceId);
166 }
167
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