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SimpleCombinerComputation 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 go through a combiner.
32   */
33  public class SimpleCombinerComputation extends
34      BasicComputation<LongWritable, IntWritable, FloatWritable, IntWritable> {
35    /** Class logger */
36    private static Logger LOG = Logger.getLogger(SimpleCombinerComputation.class);
37  
38    @Override
39    public void compute(
40        Vertex<LongWritable, IntWritable, FloatWritable> vertex,
41        Iterable<IntWritable> messages) throws IOException {
42      if (vertex.getId().equals(new LongWritable(2))) {
43        sendMessage(new LongWritable(1), new IntWritable(101));
44        sendMessage(new LongWritable(1), new IntWritable(102));
45        sendMessage(new LongWritable(1), new IntWritable(103));
46      }
47      if (!vertex.getId().equals(new LongWritable(1))) {
48        vertex.voteToHalt();
49      } else {
50        // Check the messages
51        int sum = 0;
52        int num = 0;
53        for (IntWritable message : messages) {
54          sum += message.get();
55          num++;
56        }
57        LOG.info("TestCombinerVertex: Received a sum of " + sum +
58            " (should have 306 with a single message value)");
59  
60        if (num == 1 && sum == 306) {
61          vertex.voteToHalt();
62        }
63      }
64      if (getSuperstep() > 3) {
65        throw new IllegalStateException(
66            "TestCombinerVertex: Vertex 1 failed to receive " +
67            "messages in time");
68      }
69    }
70  }