| /* |
| * 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.pirk.responder.wideskies.spark; |
| |
| import java.io.IOException; |
| import java.math.BigInteger; |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| import java.util.List; |
| import java.util.Map; |
| |
| import org.apache.hadoop.fs.FileSystem; |
| import org.apache.hadoop.fs.Path; |
| import org.apache.pirk.query.wideskies.Query; |
| import org.apache.pirk.serialization.HadoopFileSystemStore; |
| import org.apache.pirk.utils.SystemConfiguration; |
| import org.apache.spark.api.java.JavaPairRDD; |
| import org.apache.spark.api.java.JavaRDD; |
| import org.apache.spark.api.java.JavaSparkContext; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import scala.Tuple2; |
| |
| /** |
| * Class to compute the distributed lookup table for the modular exponentiations used in performing a query |
| * |
| */ |
| public class ComputeExpLookupTable |
| { |
| private static final Logger logger = LoggerFactory.getLogger(ComputeExpLookupTable.class); |
| |
| /** |
| * Method to create the distributed modular exponentiation lookup table in hdfs for a given Query |
| * <p> |
| * Returns a Pair RDD of the form <queryHash, <<power>,<element^power mod N^2>> |
| */ |
| public static JavaPairRDD<Integer,Iterable<Tuple2<Integer,BigInteger>>> computeExpTable(JavaSparkContext sc, FileSystem fs, BroadcastVars bVars, Query query, |
| String queryInputFile, String outputDirExp) |
| { |
| return computeExpTable(sc, fs, bVars, query, queryInputFile, outputDirExp, false); |
| } |
| |
| /** |
| * Method to create the distributed modular exponentiation lookup table in hdfs for a given Query |
| * <p> |
| * Returns a Pair RDD of the form <queryHash, <<power>,<element^power mod N^2>> |
| */ |
| public static JavaPairRDD<Integer,Iterable<Tuple2<Integer,BigInteger>>> computeExpTable(JavaSparkContext sc, FileSystem fs, BroadcastVars bVars, Query query, |
| String queryInputFile, String outputDirExp, boolean useModExpJoin) |
| { |
| JavaPairRDD<Integer,Iterable<Tuple2<Integer,BigInteger>>> expCalculations; |
| |
| logger.info("Creating expTable in hdfs for query identifier = " + query.getQueryInfo().getIdentifier()); |
| |
| // Prep the output directory |
| Path outPathExp = new Path(outputDirExp); |
| try |
| { |
| if (fs.exists(outPathExp)) |
| { |
| fs.delete(outPathExp, true); |
| } |
| } catch (IOException e) |
| { |
| e.printStackTrace(); |
| } |
| |
| // Write the query hashes to a RDD |
| Map<Integer,BigInteger> queryElements = query.getQueryElements(); |
| List<Integer> keys = new ArrayList<>(queryElements.keySet()); |
| |
| int numSplits = SystemConfiguration.getIntProperty("pir.expCreationSplits", 100); |
| JavaRDD<Integer> queryHashes = sc.parallelize(keys, numSplits); |
| |
| // Generate the exp table |
| // <queryHash, <<power>,<element^power mod N^2>> |
| int numExpLookupPartitions = SystemConfiguration.getIntProperty("pir.numExpLookupPartitions", 100); |
| expCalculations = queryHashes.flatMapToPair(new ExpTableGenerator(bVars)).groupByKey(numExpLookupPartitions); |
| |
| if (!useModExpJoin) |
| { |
| // Generate the queryHash -> filename mapping and write the exp table to hdfs |
| JavaPairRDD<Integer,String> hashToPartition = expCalculations.mapPartitionsToPair(new ExpKeyFilenameMap(bVars)); |
| |
| // Place exp table in query object and in the BroadcastVars |
| Map<Integer,String> queryHashFileNameMap = hashToPartition.collectAsMap(); |
| query.setExpFileBasedLookup(new HashMap<>(queryHashFileNameMap)); |
| try |
| { |
| new HadoopFileSystemStore(fs).store(queryInputFile, query); |
| } catch (IOException e) |
| { |
| e.printStackTrace(); |
| } |
| bVars.setQuery(query); |
| } |
| |
| logger.info("Completed creation of expTable"); |
| |
| return expCalculations; |
| } |
| } |