/*

  * 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.block_app.framework.piece.messages;

 import org.apache.giraph.conf.ImmutableClassesGiraphConfiguration;

 import org.apache.giraph.factories.DefaultMessageValueFactory;

 import org.apache.giraph.factories.MessageValueFactory;

 import org.apache.giraph.function.Function;

 import org.apache.giraph.writable.kryo.HadoopKryo;

 import org.apache.hadoop.io.Writable;

 /**

  * Supplier from configuration

  * @param <T> Type of object returned

  */

 public interface SupplierFromConf<T>

     extends Function<ImmutableClassesGiraphConfiguration, T> {

   /**

    * Supplier from configuration, by copying given instance every time.

    *

    * @param <T> Type of object returned

    */

   public static class SupplierFromConfByCopy<T> implements SupplierFromConf<T> {

     private final T value;

     public SupplierFromConfByCopy(T value) {

       this.value = value;

     }

     @Override

     public T apply(ImmutableClassesGiraphConfiguration conf) {

       return HadoopKryo.createCopy(value);

     }

   }

   /**

    * Supplier from configuration returning DefaultMessageValueFactory instances.

    *

    * @param <M> Message type

    */

   public static class DefaultMessageFactorySupplierFromConf<M extends Writable>

       implements SupplierFromConf<MessageValueFactory<M>> {

     private final Class<M> messageClass;

     public DefaultMessageFactorySupplierFromConf(Class<M> messageClass) {

       this.messageClass = messageClass;

     }

     @Override

     public MessageValueFactory<M> apply(

         ImmutableClassesGiraphConfiguration conf) {

       return new DefaultMessageValueFactory<>(messageClass, conf);

     }

   }

 }