[SPARK-6734] [SQL] Add UDTF.close support in Generate

Some third-party UDTF extensions generate additional rows in the "GenericUDTF.close()" method, which is supported / documented by Hive.
https://cwiki.apache.org/confluence/display/Hive/DeveloperGuide+UDTF
However, Spark SQL ignores the "GenericUDTF.close()", and it causes bug while porting job from Hive to Spark SQL.

Author: Cheng Hao <hao.cheng@intel.com>

Closes #5383 from chenghao-intel/udtf_close and squashes the following commits:

98b4e4b [Cheng Hao] Support UDTF.close

(cherry picked from commit 0da254fb29)
Signed-off-by: Cheng Lian <lian@databricks.com>

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/generators.scala

@@ -56,6 +56,12 @@ abstract class Generator extends Expression {
 
   /** Should be implemented by child classes to perform specific Generators. */
   override def eval(input: Row): TraversableOnce[Row]
+
+  /**
+   * Notifies that there are no more rows to process, clean up code, and additional
+   * rows can be made here.
+   */
+  def terminate(): TraversableOnce[Row] = Nil
 }
 
 /**

sql/core/src/main/scala/org/apache/spark/sql/execution/Generate.scala

@@ -21,6 +21,18 @@ import org.apache.spark.annotation.DeveloperApi
 import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.catalyst.expressions._
 
+/**
+ * For lazy computing, be sure the generator.terminate() called in the very last
+ * TODO reusing the CompletionIterator?
+ */
+private[execution] sealed case class LazyIterator(func: () => TraversableOnce[Row])
+  extends Iterator[Row] {
+
+  lazy val results = func().toIterator
+  override def hasNext: Boolean = results.hasNext
+  override def next(): Row = results.next()
+}
+
 /**
  * :: DeveloperApi ::
  * Applies a [[catalyst.expressions.Generator Generator]] to a stream of input rows, combining the
@@ -47,27 +59,33 @@ case class Generate(
   val boundGenerator = BindReferences.bindReference(generator, child.output)
 
   protected override def doExecute(): RDD[Row] = {
+    // boundGenerator.terminate() should be triggered after all of the rows in the partition
     if (join) {
       child.execute().mapPartitions { iter =>
-        val nullValues = Seq.fill(generator.elementTypes.size)(Literal(null))
-        // Used to produce rows with no matches when outer = true.
-        val outerProjection =
-          newProjection(child.output ++ nullValues, child.output)
-
-        val joinProjection = newProjection(output, output)
+        val generatorNullRow = Row.fromSeq(Seq.fill[Any](generator.elementTypes.size)(null))
         val joinedRow = new JoinedRow
 
-        iter.flatMap {row =>
+        iter.flatMap { row =>
+          // we should always set the left (child output)
+          joinedRow.withLeft(row)
           val outputRows = boundGenerator.eval(row)
           if (outer && outputRows.isEmpty) {
-            outerProjection(row) :: Nil
+            joinedRow.withRight(generatorNullRow) :: Nil
           } else {
-            outputRows.map(or => joinProjection(joinedRow(row, or)))
+            outputRows.map(or => joinedRow.withRight(or))
           }
+        } ++ LazyIterator(() => boundGenerator.terminate()).map { row =>
+          // we leave the left side as the last element of its child output
+          // keep it the same as Hive does
+          joinedRow.withRight(row)
         }
       }
     } else {
-      child.execute().mapPartitions(iter => iter.flatMap(row => boundGenerator.eval(row)))
+      child.execute().mapPartitions { iter =>
+        iter.flatMap(row => boundGenerator.eval(row)) ++
+        LazyIterator(() => boundGenerator.terminate())
+      }
     }
   }
 }
+

sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUdfs.scala

@@ -483,7 +483,11 @@ private[hive] case class HiveGenericUdtf(
   extends Generator with HiveInspectors {
 
   @transient
-  protected lazy val function: GenericUDTF = funcWrapper.createFunction()
+  protected lazy val function: GenericUDTF = {
+    val fun: GenericUDTF = funcWrapper.createFunction()
+    fun.setCollector(collector)
+    fun
+  }
 
   @transient
   protected lazy val inputInspectors = children.map(toInspector)
@@ -494,6 +498,9 @@ private[hive] case class HiveGenericUdtf(
   @transient
   protected lazy val udtInput = new Array[AnyRef](children.length)
 
+  @transient
+  protected lazy val collector = new UDTFCollector
+
   lazy val elementTypes = outputInspector.getAllStructFieldRefs.map {
     field => (inspectorToDataType(field.getFieldObjectInspector), true)
   }
@@ -502,8 +509,7 @@ private[hive] case class HiveGenericUdtf(
     outputInspector // Make sure initialized.
 
     val inputProjection = new InterpretedProjection(children)
-    val collector = new UDTFCollector
-    function.setCollector(collector)
+
     function.process(wrap(inputProjection(input), inputInspectors, udtInput))
     collector.collectRows()
   }
@@ -525,6 +531,12 @@ private[hive] case class HiveGenericUdtf(
     }
   }
 
+  override def terminate(): TraversableOnce[Row] = {
+    outputInspector // Make sure initialized.
+    function.close()
+    collector.collectRows()
+  }
+
   override def toString: String = {
     s"$nodeName#${funcWrapper.functionClassName}(${children.mkString(",")})"
   }

sql/hive/src/test/resources/golden/Test UDTF.close in Lateral Views-0-ac5c96224a534f07b49462ad76620678

@@ -0,0 +1,2 @@
+97	500
+97	500

sql/hive/src/test/resources/golden/Test UDTF.close in SELECT-0-517f834fef35b896ec64399f42b2a151

@@ -0,0 +1,2 @@
+3
+3

sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/HiveQuerySuite.scala

@@ -20,6 +20,9 @@ package org.apache.spark.sql.hive.execution
 import java.io.File
 import java.util.{Locale, TimeZone}
 
+import org.apache.hadoop.hive.ql.udf.generic.GenericUDTF
+import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory
+import org.apache.hadoop.hive.serde2.objectinspector.{ObjectInspectorFactory, StructObjectInspector, ObjectInspector}
 import org.scalatest.BeforeAndAfter
 
 import scala.util.Try
@@ -51,14 +54,32 @@ class HiveQuerySuite extends HiveComparisonTest with BeforeAndAfter {
     TimeZone.setDefault(TimeZone.getTimeZone("America/Los_Angeles"))
     // Add Locale setting
     Locale.setDefault(Locale.US)
+    sql(s"ADD JAR ${TestHive.getHiveFile("TestUDTF.jar").getCanonicalPath()}")
+    // The function source code can be found at:
+    // https://cwiki.apache.org/confluence/display/Hive/DeveloperGuide+UDTF
+    sql(
+      """
+        |CREATE TEMPORARY FUNCTION udtf_count2 
+        |AS 'org.apache.spark.sql.hive.execution.GenericUDTFCount2'
+      """.stripMargin)
   }
 
   override def afterAll() {
     TestHive.cacheTables = false
     TimeZone.setDefault(originalTimeZone)
     Locale.setDefault(originalLocale)
+    sql("DROP TEMPORARY FUNCTION udtf_count2")
   }
 
+  createQueryTest("Test UDTF.close in Lateral Views",
+     """
+       |SELECT key, cc
+       |FROM src LATERAL VIEW udtf_count2(value) dd AS cc
+     """.stripMargin, false) // false mean we have to keep the temp function in registry
+
+  createQueryTest("Test UDTF.close in SELECT",
+     "SELECT udtf_count2(a) FROM (SELECT 1 AS a FROM src LIMIT 3) table", false)
+
   test("SPARK-4908: concurrent hive native commands") {
     (1 to 100).par.map { _ =>
       sql("USE default")