/**
* 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.
*/
package org.apache.hadoop.io.serializer;
import java.io.IOException;
import java.io.InputStream;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
/**
* <p>
* Provides a facility for deserializing objects of type <T> from an
* {@link InputStream}.
* </p>
*
* <p>
* Deserializers are stateful, but must not buffer the input since
* other producers may read from the input between calls to
* {@link #deserialize(Object)}.
* </p>
* @param <T>
*/
@InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"})
@InterfaceStability.Evolving
public interface Deserializer<T> {
/**
* <p>Prepare the deserializer for reading.</p>
*/
void open(InputStream in) throws IOException;
/**
* <p>
* Deserialize the next object from the underlying input stream.
* If the object <code>t</code> is non-null then this deserializer
* <i>may</i> set its internal state to the next object read from the input
* stream. Otherwise, if the object <code>t</code> is null a new
* deserialized object will be created.
* </p>
* @return the deserialized object
*/
T deserialize(T t) throws IOException;
/**
* <p>Close the underlying input stream and clear up any resources.</p>
*/
void close() throws IOException;
}