bundles/org.simantics.utils.datastructures/src/org/simantics/utils/datastructures/cache/CachedMapProvider.java

   1 /*******************************************************************************\r
   2  * Copyright (c) 2007, 2010 Association for Decentralized Information Management\r
   3  * in Industry THTH ry.\r
   4  * All rights reserved. This program and the accompanying materials\r
   5  * are made available under the terms of the Eclipse Public License v1.0\r
   6  * which accompanies this distribution, and is available at\r
   7  * http://www.eclipse.org/legal/epl-v10.html\r
   8  *\r
   9  * Contributors:\r
  10  *     VTT Technical Research Centre of Finland - initial API and implementation\r
  11  *******************************************************************************/\r
  12 /*\r
  13  *\r
  14  * @author Toni Kalajainen\r
  15  */\r
  16 package org.simantics.utils.datastructures.cache;\r
  17 \r
  18 import java.util.HashMap;\r
  19 import java.util.Map;\r
  20 import java.util.Set;\r
  21 \r
  22 import org.simantics.utils.datastructures.disposable.AbstractDisposable;\r
  23 \r
  24 /**\r
  25  * CachedProvider provides values and stores the results in a cache.\r
  26  * Cached values must be explicitly released with clear, retain or remove.\r
  27  * Values are held with strong references.\r
  28  *\r
  29  * @param <K> the key\r
  30  * @param <V> the value\r
  31  */\r
  32 public class CachedMapProvider<K, V> extends AbstractDisposable implements IMapProvider<K, V> {\r
  33 \r
  34         private Map<K, V> cache;\r
  35         \r
  36         private final IMapProvider<K, V> provider;\r
  37         \r
  38         /**\r
  39          * Constructs new strong cache\r
  40          * \r
  41          * @param provider provider of values\r
  42          */\r
  43         public CachedMapProvider(IMapProvider<K, V> provider)\r
  44         {\r
  45                 assert(provider!=null);\r
  46                 this.provider = provider;\r
  47                 this.cache = new HashMap<K, V>();\r
  48         }               \r
  49 \r
  50         /**\r
  51          * Constructs new strong cache\r
  52          * \r
  53          * @param provider provider of values\r
  54          * @param cacheMap the map to use\r
  55          */\r
  56         public CachedMapProvider(IMapProvider<K, V> provider, Map<K, V> cacheMap)\r
  57         {\r
  58                 assert(provider!=null);\r
  59                 this.provider = provider;\r
  60                 this.cache = cacheMap;\r
  61         }               \r
  62         \r
  63         @Override\r
  64         public synchronized V get(K key) {\r
  65                 assertNotDisposed();\r
  66                 V value = cache.get(key);\r
  67                 if (value!=null) return value;\r
  68                 value = provider.get(key);\r
  69                 assert(value!=null);\r
  70                 cache.put(key, value);                  \r
  71                 return value;\r
  72         }\r
  73         \r
  74         public synchronized void clear()\r
  75         {\r
  76                 cache.clear();\r
  77         }\r
  78         \r
  79         public synchronized void retain(Set<K> keys)\r
  80         {\r
  81                 cache.keySet().retainAll(keys);\r
  82         }\r
  83 \r
  84         public synchronized void remove(Set<K> keys)\r
  85         {\r
  86                 cache.keySet().removeAll(keys);\r
  87         }\r
  88         \r
  89         public synchronized void load(Set<K> keys)\r
  90         {\r
  91                 for (K key : keys)\r
  92                         get(key);\r
  93         }\r
  94         \r
  95         public synchronized void addAll(CachedMapProvider<K, V> anotherCache)\r
  96         {\r
  97                 assertNotDisposed();\r
  98                 cache.putAll(anotherCache.cache);\r
  99         }       \r
 100         \r
 101         public IMapProvider<K, V> getProvider() {\r
 102                 return provider;\r
 103         }\r
 104         \r
 105         public synchronized Map<K, V> getAll()\r
 106         {\r
 107                 assertNotDisposed();\r
 108                 return new HashMap<K, V>(cache);\r
 109         }\r
 110 \r
 111         @Override\r
 112         protected void doDispose() {\r
 113                 clear();\r
 114         }\r
 115         \r
 116 }\r