| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.giraph.examples; |
| |
| import org.apache.giraph.aggregators.DoubleSumAggregator; |
| import org.apache.giraph.aggregators.LongSumAggregator; |
| import org.apache.giraph.master.DefaultMasterCompute; |
| import org.apache.hadoop.io.DoubleWritable; |
| import org.apache.hadoop.io.LongWritable; |
| import org.apache.log4j.Logger; |
| |
| /** |
| * Master compute associated with {@link RandomWalkVertex}. It handles |
| * dangling nodes. |
| */ |
| public class RandomWalkVertexMasterCompute extends DefaultMasterCompute { |
| |
| /** threshold for the L1 norm of the state vector difference */ |
| static final double CONVERGENCE_THRESHOLD = 0.00001; |
| |
| /** logger */ |
| private static final Logger LOG = |
| Logger.getLogger(RandomWalkVertexMasterCompute.class); |
| |
| @Override |
| public void compute() { |
| double danglingContribution = |
| this.<DoubleWritable>getAggregatedValue( |
| RandomWalkVertex.CUMULATIVE_DANGLING_PROBABILITY).get(); |
| double cumulativeProbability = |
| this.<DoubleWritable>getAggregatedValue( |
| RandomWalkVertex.CUMULATIVE_PROBABILITY).get(); |
| double l1NormOfStateDiff = |
| this.<DoubleWritable>getAggregatedValue( |
| RandomWalkVertex.L1_NORM_OF_PROBABILITY_DIFFERENCE).get(); |
| long numDanglingVertices = |
| this.<LongWritable>getAggregatedValue( |
| RandomWalkVertex.NUM_DANGLING_VERTICES).get(); |
| |
| LOG.info("[Superstep " + getSuperstep() + "] Dangling contribution = " + |
| danglingContribution + ", number of dangling vertices = " + |
| numDanglingVertices + ", cumulative probability = " + |
| cumulativeProbability + ", L1 Norm of state vector difference = " + |
| l1NormOfStateDiff); |
| |
| // Convergence check: halt once the L1 norm of the difference between the |
| // state vectors fall below the threshold |
| if (getSuperstep() > 1 && l1NormOfStateDiff < CONVERGENCE_THRESHOLD) { |
| haltComputation(); |
| } |
| } |
| |
| @Override |
| public void initialize() throws InstantiationException, |
| IllegalAccessException { |
| registerAggregator(RandomWalkVertex.NUM_DANGLING_VERTICES, |
| LongSumAggregator.class); |
| registerAggregator(RandomWalkVertex.CUMULATIVE_DANGLING_PROBABILITY, |
| DoubleSumAggregator.class); |
| registerAggregator(RandomWalkVertex.CUMULATIVE_PROBABILITY, |
| DoubleSumAggregator.class); |
| registerAggregator(RandomWalkVertex.L1_NORM_OF_PROBABILITY_DIFFERENCE, |
| DoubleSumAggregator.class); |
| } |
| } |