| /* |
| * 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.BufferedWriter; |
| import java.io.OutputStreamWriter; |
| import java.math.BigInteger; |
| import java.util.ArrayList; |
| import java.util.Iterator; |
| import java.util.List; |
| |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.fs.FileSystem; |
| import org.apache.hadoop.fs.Path; |
| import org.apache.spark.TaskContext; |
| import org.apache.spark.api.java.function.PairFlatMapFunction; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import scala.Tuple2; |
| |
| /** |
| * Class to map the query hash to its modular exponentiation lookup file in hdfs |
| */ |
| public class ExpKeyFilenameMap implements PairFlatMapFunction<Iterator<Tuple2<Integer,Iterable<Tuple2<Integer,BigInteger>>>>,Integer,String> |
| { |
| private static final long serialVersionUID = 1L; |
| |
| private static final Logger logger = LoggerFactory.getLogger(ExpKeyFilenameMap.class); |
| |
| private String expOutDir = null; |
| |
| public ExpKeyFilenameMap(BroadcastVars bbVarsIn) |
| { |
| expOutDir = bbVarsIn.getExpDir(); |
| } |
| |
| @Override |
| public Iterable<Tuple2<Integer,String>> call(Iterator<Tuple2<Integer,Iterable<Tuple2<Integer,BigInteger>>>> iter) throws Exception |
| { |
| List<Tuple2<Integer,String>> keyFileList = new ArrayList<>(); |
| |
| FileSystem fs = FileSystem.get(new Configuration()); |
| |
| // Form the filename for the exp table portion that corresponds to this partition |
| int taskId = TaskContext.getPartitionId(); |
| logger.info("taskId = " + taskId); |
| |
| String fileName = expOutDir + "/exp-" + String.format("%05d", taskId); |
| logger.info("fileName = " + fileName); |
| |
| // Iterate over the elements of the partition |
| BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(fs.create(new Path(fileName), true))); |
| while (iter.hasNext()) |
| { |
| // <queryHash, <<power>,<element^power mod N^2>> |
| Tuple2<Integer,Iterable<Tuple2<Integer,BigInteger>>> expTuple = iter.next(); |
| int queryHash = expTuple._1; |
| |
| // Record the queryHash -> fileName |
| keyFileList.add(new Tuple2<>(queryHash, fileName)); |
| |
| // Write the partition elements to the corresponding exp table file |
| // each line: queryHash,<power>-<element^power mod N^2> |
| for (Tuple2<Integer,BigInteger> modPow : expTuple._2) |
| { |
| String lineOut = queryHash + "," + modPow._1 + "-" + modPow._2; |
| bw.write(lineOut); |
| bw.newLine(); |
| } |
| } |
| bw.close(); |
| |
| return keyFileList; |
| } |
| } |