[SPARK-11636][SQL] Support classes defined in the REPL with Encoders

#theScaryParts (i.e. changes to the repl, executor classloaders and codegen)...

Author: Michael Armbrust <michael@databricks.com>
Author: Yin Huai <yhuai@databricks.com>

Closes #9825 from marmbrus/dataset-replClasses2.

3 files changed, 41 insertions, 5 deletions

diff --git a/repl/scala-2.10/src/main/scala/org/apache/spark/repl/SparkIMain.scala b/repl/scala-2.10/src/main/scala/org/apache/spark/repl/SparkIMain.scala
index 4ee605fd7f..829b12269f 100644
--- a/repl/scala-2.10/src/main/scala/org/apache/spark/repl/SparkIMain.scala
+++ b/repl/scala-2.10/src/main/scala/org/apache/spark/repl/SparkIMain.scala
@@ -1221,10 +1221,16 @@ import org.apache.spark.annotation.DeveloperApi
         )
       }
 
-      val preamble = """
-        |class %s extends Serializable {
-        |  %s%s%s
-      """.stripMargin.format(lineRep.readName, envLines.map("  " + _ + ";\n").mkString, importsPreamble, indentCode(toCompute))
+      val preamble = s"""
+        |class ${lineRep.readName} extends Serializable {
+        |  ${envLines.map("  " + _ + ";\n").mkString}
+        |  $importsPreamble
+        |
+        |  // If we need to construct any objects defined in the REPL on an executor we will need
+        |  // to pass the outer scope to the appropriate encoder.
+        |  org.apache.spark.sql.catalyst.encoders.OuterScopes.addOuterScope(this)
+        |  ${indentCode(toCompute)}
+      """.stripMargin
       val postamble = importsTrailer + "\n}" + "\n" +
         "object " + lineRep.readName + " {\n" +
         "  val INSTANCE = new " + lineRep.readName + "();\n" +
diff --git a/repl/scala-2.10/src/test/scala/org/apache/spark/repl/ReplSuite.scala b/repl/scala-2.10/src/test/scala/org/apache/spark/repl/ReplSuite.scala
index 5674dcd669..081aa03002 100644
--- a/repl/scala-2.10/src/test/scala/org/apache/spark/repl/ReplSuite.scala
+++ b/repl/scala-2.10/src/test/scala/org/apache/spark/repl/ReplSuite.scala
@@ -262,6 +262,9 @@ class ReplSuite extends SparkFunSuite {
         |import sqlContext.implicits._
         |case class TestCaseClass(value: Int)
         |sc.parallelize(1 to 10).map(x => TestCaseClass(x)).toDF().collect()
+        |
+        |// Test Dataset Serialization in the REPL
+        |Seq(TestCaseClass(1)).toDS().collect()
       """.stripMargin)
     assertDoesNotContain("error:", output)
     assertDoesNotContain("Exception", output)
@@ -278,6 +281,27 @@ class ReplSuite extends SparkFunSuite {
     assertDoesNotContain("java.lang.ClassNotFoundException", output)
   }
 
+  test("Datasets and encoders") {
+    val output = runInterpreter("local",
+      """
+        |import org.apache.spark.sql.functions._
+        |import org.apache.spark.sql.Encoder
+        |import org.apache.spark.sql.expressions.Aggregator
+        |import org.apache.spark.sql.TypedColumn
+        |val simpleSum = new Aggregator[Int, Int, Int] with Serializable {
+        |  def zero: Int = 0                     // The initial value.
+        |  def reduce(b: Int, a: Int) = b + a    // Add an element to the running total
+        |  def merge(b1: Int, b2: Int) = b1 + b2 // Merge intermediate values.
+        |  def finish(b: Int) = b                // Return the final result.
+        |}.toColumn
+        |
+        |val ds = Seq(1, 2, 3, 4).toDS()
+        |ds.select(simpleSum).collect
+      """.stripMargin)
+    assertDoesNotContain("error:", output)
+    assertDoesNotContain("Exception", output)
+  }
+
   test("SPARK-2632 importing a method from non serializable class and not using it.") {
     val output = runInterpreter("local",
     """
diff --git a/repl/src/main/scala/org/apache/spark/repl/ExecutorClassLoader.scala b/repl/src/main/scala/org/apache/spark/repl/ExecutorClassLoader.scala
index 3d2d235a00..a976e96809 100644
--- a/repl/src/main/scala/org/apache/spark/repl/ExecutorClassLoader.scala
+++ b/repl/src/main/scala/org/apache/spark/repl/ExecutorClassLoader.scala
@@ -65,7 +65,13 @@ class ExecutorClassLoader(conf: SparkConf, classUri: String, parent: ClassLoader
           case e: ClassNotFoundException => {
             val classOption = findClassLocally(name)
             classOption match {
-              case None => throw new ClassNotFoundException(name, e)
+              case None =>
+                // If this class has a cause, it will break the internal assumption of Janino
+                // (the compiler used for Spark SQL code-gen).
+                // See org.codehaus.janino.ClassLoaderIClassLoader's findIClass, you will see
+                // its behavior will be changed if there is a cause and the compilation
+                // of generated class will fail.
+                throw new ClassNotFoundException(name)
               case Some(a) => a
             }
           }