added overrides for isCheckpointed, getCheckpointFile in EdgeRDDImpl, VertexRDDImpl. The corresponding Graph methods now work.

Author: jkbradley

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

@@ -73,7 +73,15 @@ class EdgeRDDImpl[ED: ClassTag, VD: ClassTag] private[graphx] (
   override def checkpoint() = {
     partitionsRDD.checkpoint()
   }
-    
+
+  override def isCheckpointed: Boolean = {
+    partitionsRDD.isCheckpointed
+  }
+
+  override def getCheckpointFile: Option[String] = {
+    partitionsRDD.getCheckpointFile
+  }
+
   /** The number of edges in the RDD. */
   override def count(): Long = {
     partitionsRDD.map(_._2.size.toLong).reduce(_ + _)

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

@@ -74,7 +74,15 @@ class VertexRDDImpl[VD] private[graphx] (
   override def checkpoint() = {
     partitionsRDD.checkpoint()
   }
-    
+
+  override def isCheckpointed: Boolean = {
+    partitionsRDD.isCheckpointed
+  }
+
+  override def getCheckpointFile: Option[String] = {
+    partitionsRDD.getCheckpointFile
+  }
+
   /** The number of vertices in the RDD. */
   override def count(): Long = {
     partitionsRDD.map(_.size).reduce(_ + _)