/*

  * 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.giraph.writable.kryo.serializers;

 import java.io.DataInputStream;

 import java.io.DataOutputStream;

 import java.io.IOException;

 import org.apache.giraph.utils.ReflectionUtils;

 import org.apache.giraph.utils.WritableUtils;

 import org.apache.hadoop.io.Writable;

 import com.esotericsoftware.kryo.Kryo;

 import com.esotericsoftware.kryo.Serializer;

 import com.esotericsoftware.kryo.io.Input;

 import com.esotericsoftware.kryo.io.Output;

 /**

  * A custom Serializer that will call the Writable methods defined by the

  * object itself to serialize the object, instead of Kryo auto-magically

  * serializing

  *

  * @param <T> Object type, should implement Writable

  */

 public class DirectWritableSerializer<T extends Writable>

     extends Serializer<T> {

   @Override

   public void write(Kryo kryo, Output output, T object) {

     try {

       object.write(new DataOutputStream(output));

     } catch (IOException e) {

       throw new RuntimeException(

           "DirectWritableSerializer.write calling Writable method of class: " +

             object.getClass().getName() + " encountered issues", e);

     }

   }

   @Override

   public T read(Kryo kryo, Input input, Class<T> type) {

     try {

       T object = create(kryo, input, type);

       kryo.reference(object);

       object.readFields(new DataInputStream(input));

       return object;

     } catch (IOException e) {

       throw new RuntimeException(

           "DirectWritableSerializer.read calling Writable method of class: " +

           type.getName() + " encountered issues", e);

     }

   }

   @Override

   public T copy(Kryo kryo, T original) {

     return WritableUtils.createCopy(original);

   }

   /**

    * Used by {@link #read(Kryo, Input, Class)} to create the new object.

    * This can be overridden to customize object creation, eg to call a

    * constructor with arguments. The default implementation

    * uses {@link Kryo#newInstance(Class)}.

    *

    * @param kryo Kryo object instance

    * @param input Input

    * @param type Type of the class to create

    * @return New instance of wanted type

    */

   protected T create(Kryo kryo, Input input, Class<T> type) {

     return ReflectionUtils.newInstance(type);

   }

 }