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.benchmark;
2021import org.apache.giraph.graph.BasicComputation;
22import org.apache.giraph.graph.Vertex;
23import org.apache.hadoop.io.FloatWritable;
24import org.apache.hadoop.io.IntWritable;
25import org.apache.hadoop.io.NullWritable;
2627import java.io.IOException;
2829/**30 * Implementation of PageRank in which vertex ids are ints, page rank values31 * are floats, and graph is unweighted.32 */33publicclassPageRankComputationextends BasicComputation<IntWritable,
34 FloatWritable, NullWritable, FloatWritable> {
35/** Number of supersteps */36publicstaticfinal String SUPERSTEP_COUNT =
37"giraph.pageRank.superstepCount";
3839 @Override
40publicvoid compute(
41 Vertex<IntWritable, FloatWritable, NullWritable> vertex,
42 Iterable<FloatWritable> messages) throws IOException {
43if (getSuperstep() >= 1) {
44float sum = 0;
45for (FloatWritable message : messages) {
46 sum += message.get();
47 }
48 vertex.getValue().set((0.15f / getTotalNumVertices()) + 0.85f * sum);
49 }
5051if (getSuperstep() < getConf().getInt(SUPERSTEP_COUNT, 0)) {
52 sendMessageToAllEdges(vertex,
53new FloatWritable(vertex.getValue().get() / vertex.getNumEdges()));
54 } else {
55 vertex.voteToHalt();
56 }
57 }
58 }