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SimpleMsgComputation xref
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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  
19  package org.apache.giraph.examples;
20  
21  import org.apache.giraph.graph.BasicComputation;
22  import org.apache.giraph.graph.Vertex;
23  import org.apache.hadoop.io.FloatWritable;
24  import org.apache.hadoop.io.IntWritable;
25  import org.apache.hadoop.io.LongWritable;
26  import org.apache.log4j.Logger;
27  
28  import java.io.IOException;
29  
30  /**
31   * Test whether messages can be sent and received by vertices.
32   */
33  public class SimpleMsgComputation extends
34      BasicComputation<LongWritable, IntWritable, FloatWritable, IntWritable> {
35    /** Class logger */
36    private static Logger LOG = Logger.getLogger(SimpleMsgComputation.class);
37    @Override
38    public void compute(
39        Vertex<LongWritable, IntWritable, FloatWritable> vertex,
40        Iterable<IntWritable> messages) throws IOException {
41      if (vertex.getId().equals(new LongWritable(2))) {
42        sendMessage(new LongWritable(1), new IntWritable(101));
43        sendMessage(new LongWritable(1), new IntWritable(102));
44        sendMessage(new LongWritable(1), new IntWritable(103));
45      }
46      if (!vertex.getId().equals(new LongWritable(1))) {
47        vertex.voteToHalt();
48      } else {
49        /* Check the messages */
50        int sum = 0;
51        for (IntWritable message : messages) {
52          sum += message.get();
53        }
54        LOG.info("compute: Received a sum of " + sum +
55            " (will stop on 306)");
56  
57        if (sum == 306) {
58          vertex.voteToHalt();
59        }
60      }
61      if (getSuperstep() > 3) {
62        System.err.println("compute: Vertex 1 failed to receive " +
63            "messages in time");
64        vertex.voteToHalt();
65      }
66    }
67  }