View Javadoc

1   package org.apache.jcs.auxiliary.disk;
2   
3   /*
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *   http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.
20   */
21  
22  import org.apache.commons.logging.Log;
23  import org.apache.commons.logging.LogFactory;
24  import org.apache.jcs.utils.struct.LRUMap;
25  
26  /***
27   * Extension of LRUMap for logging of removals. Can switch this back to a HashMap easily. This
28   * provides some abstraction. It also makes it easy to log overflow.
29   */
30  public class LRUMapJCS
31      extends LRUMap
32  {
33      /*** Don't change */
34      private static final long serialVersionUID = 776964015449842672L;
35  
36      /*** The logger */
37      private static final Log log = LogFactory.getLog( LRUMapJCS.class );
38  
39      /***
40       * This creates an unbounded version.
41       */
42      public LRUMapJCS()
43      {
44          super();
45      }
46  
47      /***
48       * This creates a list bounded by the max key size argument. The Boundary is enforces by an LRU
49       * eviction policy.
50       * <p>
51       * This is used in the Disk cache to store keys and purgatory elements if a boundary is
52       * requested.
53       * <p>
54       * The LRU memory cache uses its own LRU implementation.
55       * <p>
56       * @param maxKeySize
57       */
58      public LRUMapJCS( int maxKeySize )
59      {
60          super( maxKeySize );
61      }
62  
63      /***
64       * This is called when an item is removed from the LRU. We just log some information.
65       * <p>
66       * @param key
67       * @param value
68       */
69      protected void processRemovedLRU( Object key, Object value )
70      {
71          if ( log.isDebugEnabled() )
72          {
73              log.debug( "Removing key [" + key + "] from key store, value [" + value + "]" );
74              log.debug( "Key store size [" + this.size() + "]" );
75          }
76      }
77  }