CacheAttributeController


1   /**
2    * Copyright (C) 2001-2002
3    * - France Telecom R&D
4    * - Laboratoire Logiciels, Systemes, Reseaux - UMR 5526, CNRS-INPG-UJF
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 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   * Release: 1.0
21   *
22   * Authors:
23   *
24   */
25  
26  package org.objectweb.perseus.cache.api;
27  
28  import org.objectweb.fractal.api.control.AttributeController;
29  
30  import java.util.Collection  ;
31  
32  /**
33   * This interface is management-related. Application code should
34   * not use this interface. Further, this interface is intended to be
35   * used by service tuning through Ping provided tools.
36   *
37   * This is the first draft for the this interface and it is likely to
38   * evolve.
39   *
40   * @author Luciano Garcia-Banuelos (Luciano.Garcia@imag.fr)
41   */
42  public interface CacheAttributeController extends AttributeController {
43  
44      public final static int NO_LIMIT = -1;
45  
46      /**
47       * This method allows to set the maximum number of objects to be
48       * held by the cache manager. However, the actual capacity of
49       * the cache depends on the Java Virtual Machine memory limits
50       * (and eventually by the amount of disk allocated).
51       * That is, if the application allocates a lot of large objects,
52       * and the memory limit is reached, the cache would not be able
53       * to hold more objects.
54       *
55       * The cache replacement task is launched when the maximum number
56       * of objects limit is nearly to be reached.
57       *
58       * @param size The maximum number of objects to be held in cache.
59       *             (It must be a positive number).
60       *
61       * @exception IllegalArgumentException if the size is invalid (e.g. negative).
62       * @exception CacheException if it is not possible to reduce the cache size
63       * because all entries are fixed.
64       */
65      void setMaxObjects(int size) throws IllegalArgumentException  , CacheException;
66  
67      /**
68       * This method retrieves the maximum number of objects to be held by the
69       * cache.
70       */
71      int getMaxObjects();
72  
73      /**
74       *  This  method  allows  to  set  the  maximum  main-memory  size
75       *  allocated to  the cache.  The size  is limited  by  the actual
76       * amount of memory allocated to the Java Virtual Machine.
77       *
78       * @param size The maximum memory size.
79       *             (It must be a positive number).
80       *
81       * @exception IllegalArgumentException if the size is invalid (e.g. negative).
82       */
83      void setMemorySize(int size) throws IllegalArgumentException  ;
84  
85      /**
86       *  This  method  returns the  maximum  main-memory  size
87       *  allocated to  the cache.
88       */
89      int getMemorySize();
90  
91      /**
92       * Assignes the number of element which can be removed when the cache is
93       * full. This value can be an absolute value( ex: "124") or a percent of the
94       * maximal cache size ("8%").
95       */ 
96      void setAutoCleanSize(String   size);
97  
98      String   getAutoCleanSize();
99  
100     /**
101      * Assignes the cache size value since the cache try to decrease the number
102      * of entries. This value can be an absolute value( ex: "124") or a percent
103      * of the maximal cache size ("8%").
104      */
105     void setAutoCleanThreshold(String   size);
106 
107     String   getAutoCleanThreshold();
108 
109     /**
110      * @return an positive integer value. It is the current size of the cache
111      * in term of object number currently managed by the cache.
112      */
113     int getCurrentSize();
114 
115     /**
116      * @return an positive integer value. It is the current size of the cache
117      * in octets. This size matches to the memory foot print of the entries set
118      * managed by the cache. 
119      */
120     int getCurrentMemorySize();
121 
122     /**
123      * @return an unmodifiable collection containing the identifiers of current
124      * cache entries.
125      */
126     Collection   getCurrentEntryIdentifiers();
127 }
128
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