UserCache


1   /**
2    * Copyright (C) 2001-2004 France Telecom R&D
3    *
4    * This library is free software; you can redistribute it and/or
5    * modify it under the terms of the GNU Lesser General Public
6    * License as published by the Free Software Foundation; either
7    * version 2 of the License, or (at your option) any later version.
8    *
9    * This library is distributed in the hope that it will be useful,
10   * but WITHOUT ANY WARRANTY; without even the implied warranty of
11   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12   * Lesser General Public License for more details.
13   *
14   * You should have received a copy of the GNU Lesser General Public
15   * License along with this library; if not, write to the Free Software
16   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
17   */
18  package org.objectweb.speedo.usercache.api;
19  
20  /**
21   * Defines an user cache of persistent objects. The user cache maintains 
22   * bindings between an object identifier and the user key. This cache can be
23   * implemented such as a coherent double map (oid=>key and key=>oid). 
24   * The user cache entry can be removed (unbound) from the user key or from the
25   * object identifier. Indeed when an object is removed from the real cache, the
26   * persistent object is no more availlable, its user key too.
27   * 
28   * @author S.Chassande-Barrioz
29   */
30  public interface UserCache {
31  
32      /**
33       * Look for an identifier of persistent instance from an user key 
34       * @param key is the user key of the searched persistent instance (not null)
35       * @return the identifier of the persistent instance corresponding to the
36       * user key. If not found, a null value is returned.
37       */
38      Object   lookup(Object   key);
39  
40      /**
41       * Adds an entry into user cache. If an entry already exists with the same
42       * identifier or the same key, it has been replaced. 
43       * 
44       * @param key is the user key the user of the persistent instance (not null)
45       * @param oid is the identifier of the persistent instance (not null)
46       * 
47       * @return the previous associated identifier of a persistent instance 
48       * associated to the specified user key. The null value is returned if no 
49       * entry was previously bound.
50       */
51      Object   bind(Object   key, Object   oid);
52          
53      /**
54       * Forces the eviction of an entry from an user key
55       * @param key is the user key of a persistent instance (not null)
56       * @return the object identifier if found, otherwise null
57       */
58      Object   unbindFromKey(Object   key);
59  
60      /**
61       * Forces the eviction of an entry from an object identifier
62       * @param oid is the identifier of a persistent instance (not null)
63       * @return the user key if found, otherwise null
64       */
65      Object   unbindFromOID(Object   oid);
66      
67      String   getName();
68      
69      int getId();
70      
71      boolean isActive();
72      
73      String  [] getIndexFieldNames();
74      
75  }
76
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