/***********************************************************************************************************************
* Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
*
* Licensed 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 eu.stratosphere.test.iterative.nephele.danglingpagerank;
import eu.stratosphere.api.java.record.functions.CoGroupFunction;
import eu.stratosphere.configuration.Configuration;
import eu.stratosphere.test.iterative.nephele.ConfigUtils;
import eu.stratosphere.types.DoubleValue;
import eu.stratosphere.types.LongValue;
import eu.stratosphere.types.Record;
import eu.stratosphere.util.Collector;
import java.util.Iterator;
import java.util.Set;
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()) {
summedRank += partialRanks.next().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();
}
}
}