1/*2 * Licensed to the Apache Software Foundation (ASF) under one3 * or more contributor license agreements. See the NOTICE file4 * distributed with this work for additional information5 * regarding copyright ownership. The ASF licenses this file6 * to you under the Apache License, Version 2.0 (the7 * "License"); you may not use this file except in compliance8 * with the License. You may obtain a copy of the License at9 *10 * http://www.apache.org/licenses/LICENSE-2.011 *12 * Unless required by applicable law or agreed to in writing, software13 * 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 and16 * limitations under the License.17 */1819package org.apache.giraph.examples;
2021import org.apache.giraph.graph.BasicComputation;
22import org.apache.giraph.edge.Edge;
23import org.apache.giraph.graph.Vertex;
24import org.apache.hadoop.io.DoubleWritable;
25import org.apache.hadoop.io.LongWritable;
2627import java.io.IOException;
2829/**30 * Simple function to return the out degree for each vertex.31 */32 @Algorithm(
33 name = "Indegree Count"34 )
35publicclassSimpleInDegreeCountComputationextends BasicComputation<
36 LongWritable, LongWritable, DoubleWritable, DoubleWritable> {
3738 @Override
39publicvoid compute(
40 Vertex<LongWritable, LongWritable, DoubleWritable> vertex,
41 Iterable<DoubleWritable> messages) throws IOException {
42if (getSuperstep() == 0) {
43 Iterable<Edge<LongWritable, DoubleWritable>> edges = vertex.getEdges();
44for (Edge<LongWritable, DoubleWritable> edge : edges) {
45 sendMessage(edge.getTargetVertexId(), new DoubleWritable(1.0));
46 }
47 } else {
48long sum = 0;
49for (DoubleWritable message : messages) {
50 sum++;
51 }
52 LongWritable vertexValue = vertex.getValue();
53 vertexValue.set(sum);
54 vertex.setValue(vertexValue);
55 vertex.voteToHalt();
56 }
57 }
58 }