/***********************************************************************************************************************
* 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.customdanglingpagerank;
import eu.stratosphere.api.common.functions.AbstractFunction;
import eu.stratosphere.api.common.functions.GenericCollectorMap;
import eu.stratosphere.configuration.Configuration;
import eu.stratosphere.test.iterative.nephele.ConfigUtils;
import eu.stratosphere.test.iterative.nephele.customdanglingpagerank.types.VertexWithRankAndDangling;
import eu.stratosphere.test.iterative.nephele.danglingpagerank.PageRankStats;
import eu.stratosphere.util.Collector;
import java.util.Set;
public class CustomCompensatingMap extends AbstractFunction implements GenericCollectorMap<VertexWithRankAndDangling, VertexWithRankAndDangling> {
private static final long serialVersionUID = 1L;
private boolean isFailureIteration;
private boolean isFailingWorker;
private double uniformRank;
private double rescaleFactor;
@Override
public void open(Configuration parameters) throws Exception {
int currentIteration = getIterationRuntimeContext().getSuperstepNumber();
int failingIteration = ConfigUtils.asInteger("compensation.failingIteration", parameters);
isFailureIteration = currentIteration == failingIteration + 1;
int workerIndex = getRuntimeContext().getIndexOfThisSubtask();
Set<Integer> failingWorkers = ConfigUtils.asIntSet("compensation.failingWorker", parameters);
isFailingWorker = failingWorkers.contains(workerIndex);
long numVertices = ConfigUtils.asLong("pageRank.numVertices", parameters);
if (currentIteration > 1) {
PageRankStats stats = (PageRankStats) getIterationRuntimeContext().getPreviousIterationAggregate(CustomCompensatableDotProductCoGroup.AGGREGATOR_NAME);
uniformRank = 1d / (double) numVertices;
double lostMassFactor = (numVertices - stats.numVertices()) / (double) numVertices;
rescaleFactor = (1 - lostMassFactor) / stats.rank();
}
}
@Override
public void map(VertexWithRankAndDangling pageWithRank, Collector<VertexWithRankAndDangling> out) throws Exception {
if (isFailureIteration) {
double rank = pageWithRank.getRank();
if (isFailingWorker) {
pageWithRank.setRank(uniformRank);
} else {
pageWithRank.setRank(rank * rescaleFactor);
}
}
out.collect(pageWithRank);
}
}