/*

  * 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.examples;

 import org.apache.giraph.edge.Edge;

 import org.apache.giraph.edge.EdgeFactory;

 import org.apache.giraph.graph.BasicComputation;

 import org.apache.giraph.graph.Vertex;

 import org.apache.giraph.io.VertexReader;

 import org.apache.giraph.io.formats.GeneratedVertexInputFormat;

 import org.apache.giraph.io.formats.TextVertexOutputFormat;

 import org.apache.hadoop.io.FloatWritable;

 import org.apache.hadoop.io.IntWritable;

 import org.apache.hadoop.io.LongWritable;

 import org.apache.hadoop.io.Text;

 import org.apache.hadoop.mapreduce.InputSplit;

 import org.apache.hadoop.mapreduce.TaskAttemptContext;

 import org.apache.log4j.Logger;

 import com.google.common.collect.Lists;

 import java.io.IOException;

 import java.util.List;

 /**

  * Just a simple Vertex compute implementation that executes 3 supersteps, then

  * finishes.

  */

 public class SimpleSuperstepComputation extends BasicComputation<LongWritable,

     IntWritable, FloatWritable, IntWritable> {

   @Override

   public void compute(

       Vertex<LongWritable, IntWritable, FloatWritable> vertex,

       Iterable<IntWritable> messages) throws IOException {

     // Some checks for additional testing

     if (getTotalNumVertices() < 1) {

       throw new IllegalStateException("compute: Illegal total vertices " +

           getTotalNumVertices());

     }

     if (getTotalNumEdges() < 0) {

       throw new IllegalStateException("compute: Illegal total edges " +

           getTotalNumEdges());

     }

     if (vertex.isHalted()) {

       throw new IllegalStateException("compute: Impossible to be halted - " +

           vertex.isHalted());

     }

     if (getSuperstep() > 3) {

       vertex.voteToHalt();

     }

   }

   /**

    * Simple VertexReader that supports {@link SimpleSuperstepComputation}

    */

   public static class SimpleSuperstepVertexReader extends

       GeneratedVertexReader<LongWritable, IntWritable, FloatWritable> {

     /** Class logger */

     private static final Logger LOG =

         Logger.getLogger(SimpleSuperstepVertexReader.class);

     @Override

     public boolean nextVertex() throws IOException, InterruptedException {

       return totalRecords > recordsRead;

     }

     @Override

     public Vertex<LongWritable, IntWritable, FloatWritable> getCurrentVertex()

       throws IOException, InterruptedException {

       Vertex<LongWritable, IntWritable, FloatWritable> vertex =

           getConf().createVertex();

       long tmpId = reverseIdOrder ?

           ((inputSplit.getSplitIndex() + 1) * totalRecords) -

           recordsRead - 1 :

             (inputSplit.getSplitIndex() * totalRecords) + recordsRead;

       LongWritable vertexId = new LongWritable(tmpId);

       IntWritable vertexValue =

           new IntWritable((int) (vertexId.get() * 10));

       List<Edge<LongWritable, FloatWritable>> edges = Lists.newLinkedList();

       long targetVertexId =

           (vertexId.get() + 1) %

           (inputSplit.getNumSplits() * totalRecords);

       float edgeValue = vertexId.get() * 100f;

       edges.add(EdgeFactory.create(new LongWritable(targetVertexId),

           new FloatWritable(edgeValue)));

       vertex.initialize(vertexId, vertexValue, edges);

       ++recordsRead;

       if (LOG.isInfoEnabled()) {

         LOG.info("next: Return vertexId=" + vertex.getId().get() +

             ", vertexValue=" + vertex.getValue() +

             ", targetVertexId=" + targetVertexId +

             ", edgeValue=" + edgeValue);

       }

       return vertex;

     }

   }

   /**

    * Simple VertexInputFormat that supports {@link SimpleSuperstepComputation}

    */

   public static class SimpleSuperstepVertexInputFormat extends

     GeneratedVertexInputFormat<LongWritable, IntWritable, FloatWritable> {

     @Override

     public VertexReader<LongWritable, IntWritable, FloatWritable>

     createVertexReader(InputSplit split, TaskAttemptContext context)

       throws IOException {

       return new SimpleSuperstepVertexReader();

     }

   }

   /**

    * Simple VertexOutputFormat that supports {@link SimpleSuperstepComputation}

    */

   public static class SimpleSuperstepVertexOutputFormat extends

       TextVertexOutputFormat<LongWritable, IntWritable, FloatWritable> {

     @Override

     public TextVertexWriter createVertexWriter(TaskAttemptContext context)

       throws IOException, InterruptedException {

       return new SimpleSuperstepVertexWriter();

     }

     /**

      * Simple VertexWriter that supports {@link SimpleSuperstepComputation}

      */

     public class SimpleSuperstepVertexWriter extends TextVertexWriter {

       @Override

       public void writeVertex(Vertex<LongWritable, IntWritable,

           FloatWritable> vertex) throws IOException, InterruptedException {

         getRecordWriter().write(

             new Text(vertex.getId().toString()),

             new Text(vertex.getValue().toString()));

       }

     }

   }

 }