src/main/java/org/apache/commons/ognl/internal/HashMapCache.java

package org.apache.commons.ognl.internal;

/*
 * 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.
 */

/*
 * $Id$
 */

import org.apache.commons.ognl.internal.entry.CacheEntryFactory;

import java.util.HashMap;
import java.util.Map;

public class HashMapCache<K, V>
    implements Cache<K, V>
{
    private final Map<K, V> cache = new HashMap<K, V>( 512 );

    private final CacheEntryFactory<K, V> cacheEntryFactory;

    public HashMapCache( CacheEntryFactory<K, V> cacheEntryFactory )
    {
        this.cacheEntryFactory = cacheEntryFactory;
    }

    public void clear()
    {
        synchronized ( cache )
        {
            cache.clear();
        }
    }

    public int getSize()
    {
        synchronized ( cache )
        {
            return cache.size();
        }
    }

    public V get( K key )
        throws CacheException
    {
        V v = cache.get( key );
        if ( shouldCreate( cacheEntryFactory, v ) )
        {
            synchronized ( cache )
            {
                v = cache.get( key );
                if ( v != null )
                {
                    return v;
                }
                return put( key, cacheEntryFactory.create( key ) );
            }
        }
        return v;
    }

    protected boolean shouldCreate( CacheEntryFactory<K, V> cacheEntryFactory, V v )
        throws CacheException
    {
        return cacheEntryFactory != null && v == null;
    }

    public V put( K key, V value )
    {
        synchronized ( cache )
        {
            cache.put( key, value );
            return value;
        }
    }


    public boolean contains( K key )
    {
        return this.cache.containsKey( key );
    }
}