/*
* 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.IntWritable;
import org.apache.hadoop.io.NullWritable;
import java.io.IOException;
/**
* Simple algorithm that computes the max value in the graph.
*/
public class MaxComputation extends BasicComputation<IntWritable, IntWritable,
NullWritable, IntWritable> {
@Override
public void compute(Vertex<IntWritable, IntWritable, NullWritable> vertex,
Iterable<IntWritable> messages) throws IOException {
boolean changed = false;
for (IntWritable message : messages) {
if (vertex.getValue().get() < message.get()) {
vertex.setValue(message);
changed = true;
}
}
if (getSuperstep() == 0 || changed) {
sendMessageToAllEdges(vertex, vertex.getValue());
}
vertex.voteToHalt();
}
}