content: /*
   * Copyright 2022 Alibaba Group Holding Limited.
   *
   * Licensed 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 com.alibaba.graphscope.example.giraph;
  
  import org.apache.giraph.graph.BasicComputation;
  import org.apache.giraph.graph.Vertex;
  import org.apache.hadoop.io.DoubleWritable;
  import org.apache.hadoop.io.LongWritable;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.IOException;
  
  public class MaxApp
          extends BasicComputation<LongWritable, LongWritable, DoubleWritable, LongWritable> {
  
      private static Logger logger = LoggerFactory.getLogger(MaxApp.class);
  
      /**
       * Must be defined by user to do computation on a single Vertex.
       *
       * @param vertex   Vertex
       * @param messages Messages that were sent to this vertex in the previous superstep. Each
       *                 message is only guaranteed to have
       */
      @Override
      public void compute(
              Vertex<LongWritable, LongWritable, DoubleWritable> vertex,
              Iterable<LongWritable> messages)
              throws IOException {
          boolean changed = false;
          for (LongWritable message : messages) {
              if (vertex.getValue().get() < message.get()) {
                  vertex.setValue(message);
                  changed = true;
              }
          }
          if (getSuperstep() == 0 || changed) {
              sendMessageToAllEdges(vertex, vertex.getValue());
          }
          vertex.voteToHalt();
      }
  }
  