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* Licensed to the Apache Software Foundation (ASF) under one
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* 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,
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* See the License for the specific language governing permissions and
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package org.apache.flink.test.iterative.nephele.danglingpagerank;
import java.util.Iterator;
import java.util.Set;
import org.apache.flink.api.java.record.functions.CoGroupFunction;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.test.iterative.nephele.ConfigUtils;
import org.apache.flink.types.DoubleValue;
import org.apache.flink.types.LongValue;
import org.apache.flink.types.Record;
import org.apache.flink.util.Collector;
public class CompensatableDotProductCoGroup extends CoGroupFunction {
private static final long serialVersionUID = 1L;
public static final String AGGREGATOR_NAME = "pagerank.aggregator";
private Record accumulator = new Record();
private int workerIndex;
private int currentIteration;
private int failingIteration;
private Set<Integer> failingWorkers;
private PageRankStatsAggregator aggregator;
private long numVertices;
private long numDanglingVertices;
private double dampingFactor;
private double danglingRankFactor;
private static final double BETA = 0.85;
private final DoubleValue newRank = new DoubleValue();
private BooleanValue isDangling = new BooleanValue();
private LongValue vertexID = new LongValue();
private DoubleValue doubleInstance = new DoubleValue();
@Override
public void open(Configuration parameters) {
workerIndex = getRuntimeContext().getIndexOfThisSubtask();
currentIteration = getIterationRuntimeContext().getSuperstepNumber();
failingIteration = ConfigUtils.asInteger("compensation.failingIteration", parameters);
failingWorkers = ConfigUtils.asIntSet("compensation.failingWorker", parameters);
numVertices = ConfigUtils.asLong("pageRank.numVertices", parameters);
numDanglingVertices = ConfigUtils.asLong("pageRank.numDanglingVertices", parameters);
dampingFactor = (1d - BETA) / (double) numVertices;
aggregator = getIterationRuntimeContext().getIterationAggregator(AGGREGATOR_NAME);
if (currentIteration == 1) {
danglingRankFactor = BETA * (double) numDanglingVertices / ((double) numVertices * (double) numVertices);
} else {
PageRankStats previousAggregate = getIterationRuntimeContext().getPreviousIterationAggregate(AGGREGATOR_NAME);
danglingRankFactor = BETA * previousAggregate.danglingRank() / (double) numVertices;
}
}
@Override
public void coGroup(Iterator<Record> currentPageRankIterator, Iterator<Record> partialRanks, Collector<Record> collector) {
if (!currentPageRankIterator.hasNext()) {
long missingVertex = partialRanks.next().getField(0, LongValue.class).getValue();
throw new IllegalStateException("No current page rank for vertex [" + missingVertex + "]!");
}
Record currentPageRank = currentPageRankIterator.next();
long edges = 0;
double summedRank = 0;
while (partialRanks.hasNext()) {
Record pr = partialRanks.next();
summedRank += pr.getField(1, doubleInstance).getValue();
edges++;
}
double rank = BETA * summedRank + dampingFactor + danglingRankFactor;
double currentRank = currentPageRank.getField(1, doubleInstance).getValue();
isDangling = currentPageRank.getField(2, isDangling);
double danglingRankToAggregate = isDangling.get() ? rank : 0;
long danglingVerticesToAggregate = isDangling.get() ? 1 : 0;
double diff = Math.abs(currentRank - rank);
aggregator.aggregate(diff, rank, danglingRankToAggregate, danglingVerticesToAggregate, 1, edges, summedRank, 0);
newRank.setValue(rank);
accumulator.setField(0, currentPageRank.getField(0, vertexID));
accumulator.setField(1, newRank);
accumulator.setField(2, isDangling);
collector.collect(accumulator);
}
@Override
public void close() throws Exception {
if (currentIteration == failingIteration && failingWorkers.contains(workerIndex)) {
aggregator.reset();
}
}
}