| /* |
| * 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.tinkerpop.gremlin.spark.process.computer; |
| |
| import org.apache.tinkerpop.gremlin.hadoop.structure.io.VertexWritable; |
| import org.apache.tinkerpop.gremlin.process.computer.MapReduce; |
| import org.apache.tinkerpop.gremlin.process.computer.util.ComputerGraph; |
| import org.apache.tinkerpop.gremlin.process.traversal.util.FastNoSuchElementException; |
| import scala.Tuple2; |
| |
| import java.util.Iterator; |
| import java.util.LinkedList; |
| import java.util.Queue; |
| |
| /** |
| * @author Marko A. Rodriguez (http://markorodriguez.com) |
| */ |
| public final class MapIterator<K, V> implements Iterator<Tuple2<K, V>> { |
| |
| private final Iterator<Tuple2<Object, VertexWritable>> inputIterator; |
| private final MapReduce<K, V, ?, ?, ?> mapReduce; |
| private final Queue<Tuple2<K, V>> queue = new LinkedList<>(); |
| private final MapIteratorEmitter mapIteratorEmitter = new MapIteratorEmitter(); |
| |
| public MapIterator(final MapReduce<K, V, ?, ?, ?> mapReduce, final Iterator<Tuple2<Object, VertexWritable>> inputIterator) { |
| this.inputIterator = inputIterator; |
| this.mapReduce = mapReduce; |
| this.mapReduce.workerStart(MapReduce.Stage.MAP); |
| } |
| |
| |
| @Override |
| public boolean hasNext() { |
| if (!this.queue.isEmpty()) |
| return true; |
| else if (!this.inputIterator.hasNext()) { |
| this.mapReduce.workerEnd(MapReduce.Stage.MAP); |
| return false; |
| } else { |
| this.processNext(); |
| return this.hasNext(); |
| } |
| } |
| |
| @Override |
| public Tuple2<K, V> next() { |
| if (!this.queue.isEmpty()) |
| return this.queue.remove(); |
| else if (!this.inputIterator.hasNext()) { |
| this.mapReduce.workerEnd(MapReduce.Stage.MAP); |
| throw FastNoSuchElementException.instance(); |
| } else { |
| this.processNext(); |
| return this.next(); |
| } |
| } |
| |
| private void processNext() { |
| this.mapReduce.map(ComputerGraph.mapReduce(this.inputIterator.next()._2().get()), this.mapIteratorEmitter); |
| } |
| |
| private class MapIteratorEmitter implements MapReduce.MapEmitter<K, V> { |
| |
| @Override |
| public void emit(final K key, V value) { |
| queue.add(new Tuple2<>(key, value)); |
| } |
| } |
| } |