Merge pull request #425 from stephenh/toDebugString

Add RDD.toDebugString.

core/src/main/scala/spark/RDD.scala

@@ -654,4 +654,20 @@ abstract class RDD[T: ClassManifest](
   protected def clearDependencies() {
     dependencies_ = null
   }
+
+  /** A description of this RDD and its recursive dependencies for debugging. */
+  def toDebugString(): String = {
+    def debugString(rdd: RDD[_], prefix: String = ""): Seq[String] = {
+      Seq(prefix + rdd + " (" + rdd.splits.size + " splits)") ++
+        rdd.dependencies.flatMap(d => debugString(d.rdd, prefix + "  "))
+    }
+    debugString(this).mkString("\n")
+  }
+
+  override def toString(): String = "%s%s[%d] at %s".format(
+    Option(name).map(_ + " ").getOrElse(""),
+    getClass.getSimpleName,
+    id,
+    origin)
+
 }

core/src/main/scala/spark/api/java/JavaRDDLike.scala

@@ -330,4 +330,9 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends PairFlatMapWorkaround
       case _ => Optional.absent()
     }
   }
+
+  /** A description of this RDD and its recursive dependencies for debugging. */
+  def toDebugString(): String = {
+    rdd.toDebugString()
+  }
 }