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1   package org.apache.velocity.runtime.resource;
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 java.util.Collections;
23  import java.util.Iterator;
24  import java.util.Map;
25  
26  import org.apache.commons.collections.map.LRUMap;
27  import org.apache.velocity.runtime.RuntimeConstants;
28  import org.apache.velocity.runtime.RuntimeServices;
29  import org.apache.velocity.util.MapFactory;
30  
31  /**
32   * Default implementation of the resource cache for the default
33   * ResourceManager.  The cache uses a <i>least recently used</i> (LRU)
34   * algorithm, with a maximum size specified via the
35   * <code>resource.manager.cache.size</code> property (idenfied by the
36   * {@link
37   * org.apache.velocity.runtime.RuntimeConstants#RESOURCE_MANAGER_DEFAULTCACHE_SIZE}
38   * constant).  This property get be set to <code>0</code> or less for
39   * a greedy, unbounded cache (the behavior from pre-v1.5).
40   *
41   * @author <a href="mailto:geirm@apache.org">Geir Magnusson Jr.</a>
42   * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a>
43   * @version $Id: ResourceCacheImpl.java 898032 2010-01-11 19:51:03Z nbubna $
44   */
45  public class ResourceCacheImpl implements ResourceCache
46  {
47      /**
48       * Cache storage, assumed to be thread-safe.
49       */
50      protected Map cache = MapFactory.create(512, 0.5f, 30, false);
51  
52      /**
53       * Runtime services, generally initialized by the
54       * <code>initialize()</code> method.
55       */
56      protected RuntimeServices rsvc = null;
57  
58      /**
59       * @see org.apache.velocity.runtime.resource.ResourceCache#initialize(org.apache.velocity.runtime.RuntimeServices)
60       */
61      public void initialize( RuntimeServices rs )
62      {
63          rsvc = rs;
64  
65          int maxSize =
66              rsvc.getInt(RuntimeConstants.RESOURCE_MANAGER_DEFAULTCACHE_SIZE, 89);
67          if (maxSize > 0)
68          {
69              // Create a whole new Map here to avoid hanging on to a
70              // handle to the unsynch'd LRUMap for our lifetime.
71              Map lruCache = Collections.synchronizedMap(new LRUMap(maxSize));
72              lruCache.putAll(cache);
73              cache = lruCache;
74          }
75          rsvc.getLog().debug("ResourceCache: initialized ("+this.getClass()+") with "+
76                 cache.getClass()+" cache map.");
77      }
78  
79      /**
80       * @see org.apache.velocity.runtime.resource.ResourceCache#get(java.lang.Object)
81       */
82      public Resource get( Object key )
83      {
84          return (Resource) cache.get( key );
85      }
86  
87      /**
88       * @see org.apache.velocity.runtime.resource.ResourceCache#put(java.lang.Object, org.apache.velocity.runtime.resource.Resource)
89       */
90      public Resource put( Object key, Resource value )
91      {
92          return (Resource) cache.put( key, value );
93      }
94  
95      /**
96       * @see org.apache.velocity.runtime.resource.ResourceCache#remove(java.lang.Object)
97       */
98      public Resource remove( Object key )
99      {
100         return (Resource) cache.remove( key );
101     }
102 
103     /**
104      * @see org.apache.velocity.runtime.resource.ResourceCache#enumerateKeys()
105      */
106     public Iterator enumerateKeys()
107     {
108         return cache.keySet().iterator();
109     }
110 }
111