/*

  * 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.BasicComputation;

 import org.apache.giraph.graph.Vertex;

 import org.apache.hadoop.io.FloatWritable;

 import org.apache.hadoop.io.IntWritable;

 import org.apache.hadoop.io.LongWritable;

 import org.apache.log4j.Logger;

 import java.io.IOException;

 /**

  * Test whether messages can go through a combiner.

  */

 public class SimpleCombinerComputation extends

     BasicComputation<LongWritable, IntWritable, FloatWritable, IntWritable> {

   /** Class logger */

   private static Logger LOG = Logger.getLogger(SimpleCombinerComputation.class);

   @Override

   public void compute(

       Vertex<LongWritable, IntWritable, FloatWritable> vertex,

       Iterable<IntWritable> messages) throws IOException {

     if (vertex.getId().equals(new LongWritable(2))) {

       sendMessage(new LongWritable(1), new IntWritable(101));

       sendMessage(new LongWritable(1), new IntWritable(102));

       sendMessage(new LongWritable(1), new IntWritable(103));

     }

     if (!vertex.getId().equals(new LongWritable(1))) {

       vertex.voteToHalt();

     } else {

       // Check the messages

       int sum = 0;

       int num = 0;

       for (IntWritable message : messages) {

         sum += message.get();

         num++;

       }

       LOG.info("TestCombinerVertex: Received a sum of " + sum +

           " (should have 306 with a single message value)");

       if (num == 1 && sum == 306) {

         vertex.voteToHalt();

       }

     }

     if (getSuperstep() > 3) {

       throw new IllegalStateException(

           "TestCombinerVertex: Vertex 1 failed to receive " +

           "messages in time");

     }

   }

 }