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1   /**
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.apache.hadoop.hbase.io.hfile;
19  
20  import java.io.IOException;
21  import java.nio.ByteBuffer;
22  
23  import org.apache.hadoop.classification.InterfaceAudience;
24  
25  /**
26   * Interface for a deserializer. Throws an IOException if the serialized data is
27   * incomplete or wrong.
28   * */
29  @InterfaceAudience.Private
30  public interface CacheableDeserializer<T extends Cacheable> {
31    /**
32     * Returns the deserialized object.
33     *
34     * @return T the deserialized object.
35     */
36    T deserialize(ByteBuffer b) throws IOException;
37  
38    /**
39     * 
40     * @param b
41     * @param reuse true if Cacheable object can use the given buffer as its
42     *          content
43     * @return T the deserialized object.
44     * @throws IOException
45     */
46    T deserialize(ByteBuffer b, boolean reuse) throws IOException;
47  
48    /**
49     * Get the identifier of this deserialiser. Identifier is unique for each
50     * deserializer and generated by {@link CacheableDeserializerIdManager}
51     * @return identifier number of this cacheable deserializer
52     */
53    int getDeserialiserIdentifier();
54  }