001    /*
002     * Copyright (c) 2007-2015 Concurrent, Inc. All Rights Reserved.
003     *
004     * Project and contact information: http://www.cascading.org/
005     *
006     * This file is part of the Cascading project.
007     *
008     * Licensed under the Apache License, Version 2.0 (the "License");
009     * you may not use this file except in compliance with the License.
010     * You may obtain a copy of the License at
011     *
012     *     http://www.apache.org/licenses/LICENSE-2.0
013     *
014     * Unless required by applicable law or agreed to in writing, software
015     * distributed under the License is distributed on an "AS IS" BASIS,
016     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
017     * See the License for the specific language governing permissions and
018     * limitations under the License.
019     */
020    
021    package cascading.util.cache;
022    
023    import java.io.Serializable;
024    import java.util.Map;
025    
026    /**
027     * CacheEvictionCallBack is an interface to be used in conjunction with {@link CascadingCache} instances.
028     * This enables a to do processing whenever an entry is evicted from the Cache.
029     */
030    public interface CacheEvictionCallback<Key, Value> extends Serializable
031      {
032      /**
033       * NO-OP implementation of {@link cascading.util.cache.CacheEvictionCallback}.
034       */
035      public static final CacheEvictionCallback NULL = new CacheEvictionCallback()
036      {
037      @Override
038      public void evict( Map.Entry entry )
039        {
040        // NO-OP
041        }
042      };
043    
044      /**
045       * Method will be called by the {@link CascadingCache} implementation whenever a key is evicted.
046       *
047       * @param entry The entry being removed from the cache.
048       */
049      void evict( Map.Entry<Key, Value> entry );
050    
051      }