/*

  * 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.factories;

 import org.apache.giraph.conf.GiraphConfiguration;

 import org.apache.giraph.conf.GiraphConstants;

 import org.apache.giraph.conf.ImmutableClassesGiraphConfiguration;

 import org.apache.giraph.graph.Computation;

 import org.apache.giraph.utils.ReflectionUtils;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 /**

  * Default computation factory that simply creates java computation object

  *

  * @param <I> Vertex ID

  * @param <V> Vertex Value

  * @param <E> Edge Value

  */

 public class DefaultComputationFactory<I extends WritableComparable,

     V extends Writable, E extends Writable>

     implements ComputationFactory<I, V, E, Writable, Writable> {

   @Override

   public void initialize(ImmutableClassesGiraphConfiguration<I, V, E> conf) {

     // Nothing to do here

   }

   @Override

   public Computation<I, V, E, Writable, Writable> createComputation(

       ImmutableClassesGiraphConfiguration<I, V, E> conf) {

     Class<? extends Computation> klass = conf.getComputationClass();

     return ReflectionUtils.newInstance(klass, conf);

   }

   @Override

   public void checkConfiguration(

       ImmutableClassesGiraphConfiguration<I, V, E> conf) {

     if (conf.getComputationClass() == null) {

       throw new IllegalArgumentException("checkConfiguration: Null " +

           GiraphConstants.COMPUTATION_CLASS.getKey());

     }

   }

   @Override

   public String computationName(GiraphConfiguration conf) {

     return conf.getComputationClass().getSimpleName();

   }

 }