| /* |
| * 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.pig.backend.hadoop.executionengine.spark.converter; |
| |
| import java.io.IOException; |
| import java.util.Iterator; |
| import java.util.List; |
| |
| import org.apache.pig.backend.executionengine.ExecException; |
| import org.apache.pig.backend.hadoop.executionengine.physicalLayer.Result; |
| import org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POLimit; |
| import org.apache.pig.backend.hadoop.executionengine.spark.SparkUtil; |
| import org.apache.pig.data.Tuple; |
| import org.apache.spark.api.java.function.FlatMapFunction; |
| import org.apache.spark.rdd.RDD; |
| |
| @SuppressWarnings({ "serial" }) |
| public class LimitConverter implements RDDConverter<Tuple, Tuple, POLimit> { |
| |
| @Override |
| public RDD<Tuple> convert(List<RDD<Tuple>> predecessors, POLimit poLimit) |
| throws IOException { |
| SparkUtil.assertPredecessorSize(predecessors, poLimit, 1); |
| RDD<Tuple> rdd = predecessors.get(0); |
| LimitFunction limitFunction = new LimitFunction(poLimit); |
| RDD<Tuple> rdd2 = rdd.coalesce(1, false, null); |
| return rdd2.toJavaRDD().mapPartitions(limitFunction, false).rdd(); |
| } |
| |
| private static class LimitFunction implements FlatMapFunction<Iterator<Tuple>, Tuple> { |
| |
| private final POLimit poLimit; |
| |
| public LimitFunction(POLimit poLimit) { |
| this.poLimit = poLimit; |
| } |
| |
| @Override |
| public Iterable<Tuple> call(final Iterator<Tuple> tuples) { |
| |
| return new Iterable<Tuple>() { |
| |
| public Iterator<Tuple> iterator() { |
| return new OutputConsumerIterator(tuples) { |
| |
| @Override |
| protected void attach(Tuple tuple) { |
| poLimit.setInputs(null); |
| poLimit.attachInput(tuple); |
| } |
| |
| @Override |
| protected Result getNextResult() throws ExecException { |
| return poLimit.getNextTuple(); |
| } |
| |
| @Override |
| protected void endOfInput() { |
| } |
| }; |
| } |
| }; |
| } |
| } |
| } |