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1   /**
2    *
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *     http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing, software
14   * distributed under the License is distributed on an "AS IS" BASIS,
15   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16   * See the License for the specific language governing permissions and
17   * limitations under the License.
18   */
19  
20  package org.apache.hadoop.hbase.io.hfile.slab;
21  
22  import org.apache.hadoop.classification.InterfaceAudience;
23  import org.apache.hadoop.hbase.io.hfile.BlockCacheKey;
24  
25  /**
26   * Interface for objects that want to know when actions occur in a SingleSizeCache.
27   * */
28  @InterfaceAudience.Private
29  interface SlabItemActionWatcher {
30  
31    /**
32     * This is called as a callback when an item is removed from a SingleSizeCache.
33     *
34     * @param key the key of the item being evicted
35     * @param notifier the object notifying the SlabCache of the eviction.
36     */
37    void onEviction(BlockCacheKey key, SingleSizeCache notifier);
38    
39    /**
40     * This is called as a callback when an item is inserted into a SingleSizeCache.
41     *
42     * @param key the key of the item being added
43     * @param notifier the object notifying the SlabCache of the insertion..
44     */
45    void onInsertion(BlockCacheKey key, SingleSizeCache notifier);
46  }