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SimpleOutDegreeCountComputation 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.hadoop.io.LongWritable;
23  import org.apache.hadoop.io.DoubleWritable;
24  import org.apache.giraph.graph.Vertex;
25  
26  import java.io.IOException;
27  
28  /**
29   * Simple function to return the out degree for each vertex.
30   */
31  @Algorithm(
32      name = "Outdegree Count"
33  )
34  public class SimpleOutDegreeCountComputation extends BasicComputation<
35    LongWritable, LongWritable, DoubleWritable, DoubleWritable> {
36  
37    @Override
38    public void compute(
39        Vertex<LongWritable, LongWritable, DoubleWritable> vertex,
40        Iterable<DoubleWritable> messages) throws IOException {
41      LongWritable vertexValue = vertex.getValue();
42      vertexValue.set(vertex.getNumEdges());
43      vertex.setValue(vertexValue);
44      vertex.voteToHalt();
45    }
46  }