PersistenceListener


1   /*
2    * Copyright (c) 2002-2003 by OpenSymphony
3    * All rights reserved.
4    */
5   package com.opensymphony.oscache.base.persistence;
6   
7   import com.opensymphony.oscache.base.Config;
8   
9   import java.util.Set  ;
10  
11  /**
12   * Defines the methods that are required to persist cache data.
13   * To provide a custom persistence mechanism you should implement this
14   * interface and supply the fully-qualified classname to the cache via
15   * the <code>cache.persistence.class</code> configuration property.
16   *
17   * @version        $Revision: 1.1 $
18   * @author <a HREF="mailto:fbeauregard@pyxis-tech.com">Francois Beauregard</a>
19   */
20  public interface PersistenceListener {
21      /**
22       * Verify if an object is currently stored in the persistent cache.
23       *
24       * @param key The cache key of the object to check.
25       */
26      public boolean isStored(String   key) throws CachePersistenceException;
27  
28      /**
29       * Verify if a group is currently stored in the persistent cache.
30       *
31       * @param groupName The name of the group to check.
32       */
33      public boolean isGroupStored(String   groupName) throws CachePersistenceException;
34  
35      /**
36       * Clear the entire persistent cache (including the root)
37       */
38      public void clear() throws CachePersistenceException;
39  
40      /**
41       * Allow the persistence code to initialize itself based on the supplied
42       * cache configuration.
43       */
44      public PersistenceListener configure(Config config);
45  
46      /**
47       * Removes an object from the persistent cache
48       */
49      public void remove(String   key) throws CachePersistenceException;
50  
51      /**
52       * Removes a group from the persistent cache.
53       *
54       * @param groupName The name of the cache group to remove.
55       */
56      public void removeGroup(String   groupName) throws CachePersistenceException;
57  
58      /**
59       * Retrieves an object from the persistent cache.
60       *
61       * @param key The unique cache key that maps to the object
62       * being retrieved.
63       * @return The object, or <code>null</code> if no object was found
64       * matching the supplied key.
65       */
66      public Object   retrieve(String   key) throws CachePersistenceException;
67  
68      /**
69       * Stores an object in the persistent cache.
70       *
71       * @param key The key to uniquely identify this object.
72       * @param obj The object to persist. Most implementations
73       * of this interface will require this object implements
74       * <code>Serializable</code>.
75       */
76      public void store(String   key, Object   obj) throws CachePersistenceException;
77  
78      /**
79       * Stores a group in the persistent cache.
80       *
81       * @param groupName The name of the group to persist.
82       * @param group A set containing the keys of all the <code>CacheEntry</code>
83       * objects that belong to this group.
84       */
85      public void storeGroup(String   groupName, Set   group) throws CachePersistenceException;
86  
87      /**
88       * Retrieves a group from the persistent cache.
89       *
90       * @param groupName The name of the group to retrieve.
91       * @return The returned set should contain the keys
92       * of all the <code>CacheEntry</code> objects that belong
93       * to this group.
94       */
95      Set   retrieveGroup(String   groupName) throws CachePersistenceException;
96  }
97
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