/*

  * 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.graph.BasicVertex;

 import org.apache.giraph.graph.VertexWriter;

 import org.apache.giraph.lib.TextVertexOutputFormat;

 import org.apache.hadoop.io.IntWritable;

 import org.apache.hadoop.io.NullWritable;

 import org.apache.hadoop.io.Text;

 import org.apache.hadoop.mapreduce.RecordWriter;

 import org.apache.hadoop.mapreduce.TaskAttemptContext;

 import java.io.IOException;

 /**

  * Text-based {@link org.apache.giraph.graph.VertexOutputFormat} for usage with

  * {@link ConnectedComponentsVertex}

  *

  * Each line consists of a vertex and its associated component (represented

  *  by the smallest vertex id in the component)

  */

 public class VertexWithComponentTextOutputFormat extends

     TextVertexOutputFormat<IntWritable, IntWritable, NullWritable> {

   @Override

   public VertexWriter<IntWritable, IntWritable, NullWritable>

   createVertexWriter(TaskAttemptContext context)

     throws IOException, InterruptedException {

     RecordWriter<Text, Text> recordWriter =

         textOutputFormat.getRecordWriter(context);

     return new VertexWithComponentWriter(recordWriter);

   }

   /**

    * Vertex writer used with {@link VertexWithComponentTextOutputFormat}.

    */

   public static class VertexWithComponentWriter extends

       TextVertexOutputFormat.TextVertexWriter<IntWritable, IntWritable,

       NullWritable> {

     /**

      * Constructor with record writer.

      *

      * @param writer Where the vertices will finally be written.

      */

     public VertexWithComponentWriter(RecordWriter<Text, Text> writer) {

       super(writer);

     }

     @Override

     public void writeVertex(BasicVertex<IntWritable, IntWritable,

         NullWritable, ?> vertex) throws IOException,

         InterruptedException {

       StringBuilder output = new StringBuilder();

       output.append(vertex.getVertexId().get());

       output.append('\t');

       output.append(vertex.getVertexValue().get());

       getRecordWriter().write(new Text(output.toString()), null);

     }

   }

 }