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
021package cascading.util.cache;
022
023import java.io.Serializable;
024import 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 */
030public 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  }