[SPARK-5534] [graphx] Graph getStorageLevel fix

This fixes getStorageLevel for EdgeRDDImpl and VertexRDDImpl (and therefore for Graph).

See code example on JIRA which failed before but works with this patch: [https://issues.apache.org/jira/browse/SPARK-5534]
(The added unit tests also failed before but work with this fix.)

Note: I used partitionsRDD, assuming that getStorageLevel will only be called on the driver.

CC: mengxr  (related to LDA PR), rxin  ankurdave   Thanks in advance!

Author: Joseph K. Bradley <joseph@databricks.com>

Closes #4317 from jkbradley/graphx-storagelevel and squashes the following commits:

1c21e49 [Joseph K. Bradley] made graph getStorageLevel test more robust
18d64ca [Joseph K. Bradley] Added tests for getStorageLevel in VertexRDDSuite, EdgeRDDSuite, GraphSuite
17b488b [Joseph K. Bradley] overrode getStorageLevel in Vertex/EdgeRDDImpl to use partitionsRDD

graphx/src/main/scala/org/apache/spark/graphx/impl/EdgeRDDImpl.scala

@@ -70,6 +70,8 @@ class EdgeRDDImpl[ED: ClassTag, VD: ClassTag] private[graphx] (
     this
   }
 
+  override def getStorageLevel = partitionsRDD.getStorageLevel
+
   override def checkpoint() = {
     partitionsRDD.checkpoint()
   }

graphx/src/main/scala/org/apache/spark/graphx/impl/VertexRDDImpl.scala

@@ -71,6 +71,8 @@ class VertexRDDImpl[VD] private[graphx] (
     this
   }
 
+  override def getStorageLevel = partitionsRDD.getStorageLevel
+
   override def checkpoint() = {
     partitionsRDD.checkpoint()
   }

graphx/src/test/scala/org/apache/spark/graphx/EdgeRDDSuite.scala

+/*
+ * 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.spark.graphx
+
+import org.scalatest.FunSuite
+
+import org.apache.spark.storage.StorageLevel
+
+class EdgeRDDSuite extends FunSuite with LocalSparkContext {
+
+  test("cache, getStorageLevel") {
+    // test to see if getStorageLevel returns correct value after caching
+    withSpark { sc =>
+      val verts = sc.parallelize(List((0L, 0), (1L, 1), (1L, 2), (2L, 3), (2L, 3), (2L, 3)))
+      val edges = EdgeRDD.fromEdges(sc.parallelize(List.empty[Edge[Int]]))
+      assert(edges.getStorageLevel == StorageLevel.NONE)
+      edges.cache()
+      assert(edges.getStorageLevel == StorageLevel.MEMORY_ONLY)
+    }
+  }
+
+}

graphx/src/test/scala/org/apache/spark/graphx/GraphSuite.scala

@@ -25,6 +25,7 @@ import org.apache.spark.SparkContext
 import org.apache.spark.graphx.Graph._
 import org.apache.spark.graphx.PartitionStrategy._
 import org.apache.spark.rdd._
+import org.apache.spark.storage.StorageLevel
 
 class GraphSuite extends FunSuite with LocalSparkContext {
 
@@ -390,6 +391,20 @@ class GraphSuite extends FunSuite with LocalSparkContext {
     }
   }
 
+  test("cache, getStorageLevel") {
+    // test to see if getStorageLevel returns correct value
+    withSpark { sc =>
+      val verts = sc.parallelize(List((1: VertexId, "a"), (2: VertexId, "b")), 1)
+      val edges = sc.parallelize(List(Edge(1, 2, 0), Edge(2, 1, 0)), 2)
+      val graph = Graph(verts, edges, "", StorageLevel.MEMORY_ONLY, StorageLevel.MEMORY_ONLY)
+      // Note: Before caching, graph.vertices is cached, but graph.edges is not (but graph.edges'
+      //       parent RDD is cached).
+      graph.cache()
+      assert(graph.vertices.getStorageLevel == StorageLevel.MEMORY_ONLY)
+      assert(graph.edges.getStorageLevel == StorageLevel.MEMORY_ONLY)
+    }
+  }
+
   test("non-default number of edge partitions") {
     val n = 10
     val defaultParallelism = 3

graphx/src/test/scala/org/apache/spark/graphx/VertexRDDSuite.scala

@@ -17,12 +17,11 @@
 
 package org.apache.spark.graphx
 
-import org.apache.spark.SparkContext
-import org.apache.spark.graphx.Graph._
-import org.apache.spark.graphx.impl.EdgePartition
-import org.apache.spark.rdd._
 import org.scalatest.FunSuite
 
+import org.apache.spark.SparkContext
+import org.apache.spark.storage.StorageLevel
+
 class VertexRDDSuite extends FunSuite with LocalSparkContext {
 
   def vertices(sc: SparkContext, n: Int) = {
@@ -110,4 +109,16 @@ class VertexRDDSuite extends FunSuite with LocalSparkContext {
     }
   }
 
+  test("cache, getStorageLevel") {
+    // test to see if getStorageLevel returns correct value after caching
+    withSpark { sc =>
+      val verts = sc.parallelize(List((0L, 0), (1L, 1), (1L, 2), (2L, 3), (2L, 3), (2L, 3)))
+      val edges = EdgeRDD.fromEdges(sc.parallelize(List.empty[Edge[Int]]))
+      val rdd = VertexRDD(verts, edges, 0, (a: Int, b: Int) => a + b)
+      assert(rdd.getStorageLevel == StorageLevel.NONE)
+      rdd.cache()
+      assert(rdd.getStorageLevel == StorageLevel.MEMORY_ONLY)
+    }
+  }
+
 }