content: package org.apache.lucene.util.cache;
  
  /**
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Set;
  
  /**
   * Simple cache implementation that uses a HashMap to store (key, value) pairs.
   * This cache is not synchronized, use {@link Cache#synchronizedCache(Cache)}
   * if needed.
   */
  public class SimpleMapCache<K,V> extends Cache<K,V> {
    protected Map<K,V> map;
    
    public SimpleMapCache() {
      this(new HashMap<K,V>());
    }
  
    public SimpleMapCache(Map<K,V> map) {
      this.map = map;
    }
    
    @Override
    public V get(Object key) {
      return map.get(key);
    }
    
    public int size()
    {
  	  return map.size();
    }
  
    @Override
    public void put(K key, V value) {
      map.put(key, value);
    }
  
    @Override
    public void close() {
      // NOOP
    }
  
    @Override
    public boolean containsKey(Object key) {
      return map.containsKey(key);
    }
    
  
    @Override
    public V remove(Object key) {
    	return map.remove(key);
    }
    
    /**
     * Returns a Set containing all keys in this cache.
     */
    public Set<K> keySet() {
      return map.keySet();
    }
    
    @Override
    Cache<K,V> getSynchronizedCache() {
      return new SynchronizedSimpleMapCache<K,V>(this);
    }
    
    private static class SynchronizedSimpleMapCache<K,V> extends SimpleMapCache<K,V> {
      private Object mutex;
      private SimpleMapCache<K,V> cache;
      
      SynchronizedSimpleMapCache(SimpleMapCache<K,V> cache) {
          this.cache = cache;
          this.mutex = this;
      }
      
      @Override
      public void put(K key, V value) {
          synchronized(mutex) {cache.put(key, value);}
      }
      
      @Override
      public V get(Object key) {
          synchronized(mutex) {return cache.get(key);}
      }
      
      @Override
      public V remove(Object key) {
          synchronized(mutex) {return cache.remove(key);}
      }
      
      public int size()
      {
          synchronized(mutex) {return cache.size();}
      }
      
      @Override
      public boolean containsKey(Object key) {
          synchronized(mutex) {return cache.containsKey(key);}
      }
      
      @Override
      public void close() {
          synchronized(mutex) {cache.close();}
      }
      
      @Override
      public Set<K> keySet() {
        synchronized(mutex) {return cache.keySet();}
      }
      
      @Override
      Cache<K,V> getSynchronizedCache() {
        return this;
      }
    }
  
  }
  