| /* |
| * 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.structure.io; |
| |
| import org.apache.commons.configuration2.Configuration; |
| import org.apache.hadoop.mapred.InputFormat; |
| import org.apache.spark.api.java.JavaPairRDD; |
| import org.apache.spark.api.java.JavaSparkContext; |
| import org.apache.tinkerpop.gremlin.hadoop.structure.io.VertexWritable; |
| import org.apache.tinkerpop.gremlin.spark.process.computer.SparkGraphComputer; |
| import scala.Tuple2; |
| |
| /** |
| * An InputRDD is used to read data from the underlying graph system and yield the respective adjacency list. |
| * Note that {@link InputFormatRDD} is a type of InputRDD that simply uses the specified {@link InputFormat} to generate the respective graphRDD. |
| * |
| * @author Marko A. Rodriguez (http://markorodriguez.com) |
| */ |
| public interface InputRDD { |
| |
| /** |
| * Read the graphRDD from the underlying graph system. |
| * |
| * @param configuration the configuration for the {@link SparkGraphComputer} |
| * @param sparkContext the Spark context with the requisite methods for generating a {@link JavaPairRDD} |
| * @return an adjacency list representation of the underlying graph system. |
| */ |
| public JavaPairRDD<Object, VertexWritable> readGraphRDD(final Configuration configuration, final JavaSparkContext sparkContext); |
| |
| /** |
| * Read a memoryRDD from the storage location. |
| * The default implementation returns an empty RDD. |
| * |
| * @param configuration the configuration for the {@link SparkGraphComputer} |
| * @param memoryKey the memory key of the memoryRDD |
| * @param sparkContext the Spark context with the requisite methods for generating a {@link JavaPairRDD} |
| * @param <K> the key class of the memoryRDD |
| * @param <V> the value class of the memoryRDD |
| * @return the memoryRDD with respective key/value pairs. |
| */ |
| public default <K, V> JavaPairRDD<K, V> readMemoryRDD(final Configuration configuration, final String memoryKey, final JavaSparkContext sparkContext) { |
| return sparkContext.<Tuple2<K, V>>emptyRDD().mapToPair(t -> t); |
| } |
| } |