[SPARK-8635] [SQL] improve performance of CatalystTypeConverters

In `CatalystTypeConverters.createToCatalystConverter`, we add special handling for primitive types. We can apply this strategy to more places to improve performance.

Author: Wenchen Fan <cloud0fan@outlook.com>

Closes #7018 from cloud-fan/converter and squashes the following commits:

8b16630 [Wenchen Fan] another fix
326c82c [Wenchen Fan] optimize type converter

2 files changed, 38 insertions, 25 deletions

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/CatalystTypeConverters.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/CatalystTypeConverters.scala
index 429fc4077b..012f8bbecb 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/CatalystTypeConverters.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/CatalystTypeConverters.scala
@@ -52,6 +52,13 @@ object CatalystTypeConverters {
     }
   }
 
+  private def isWholePrimitive(dt: DataType): Boolean = dt match {
+    case dt if isPrimitive(dt) => true
+    case ArrayType(elementType, _) => isWholePrimitive(elementType)
+    case MapType(keyType, valueType, _) => isWholePrimitive(keyType) && isWholePrimitive(valueType)
+    case _ => false
+  }
+
   private def getConverterForType(dataType: DataType): CatalystTypeConverter[Any, Any, Any] = {
     val converter = dataType match {
       case udt: UserDefinedType[_] => UDTConverter(udt)
@@ -148,6 +155,8 @@ object CatalystTypeConverters {
 
     private[this] val elementConverter = getConverterForType(elementType)
 
+    private[this] val isNoChange = isWholePrimitive(elementType)
+
     override def toCatalystImpl(scalaValue: Any): Seq[Any] = {
       scalaValue match {
         case a: Array[_] => a.toSeq.map(elementConverter.toCatalyst)
@@ -166,8 +175,10 @@ object CatalystTypeConverters {
     override def toScala(catalystValue: Seq[Any]): Seq[Any] = {
       if (catalystValue == null) {
         null
+      } else if (isNoChange) {
+        catalystValue
       } else {
-        catalystValue.asInstanceOf[Seq[_]].map(elementConverter.toScala)
+        catalystValue.map(elementConverter.toScala)
       }
     }
 
@@ -183,6 +194,8 @@ object CatalystTypeConverters {
     private[this] val keyConverter = getConverterForType(keyType)
     private[this] val valueConverter = getConverterForType(valueType)
 
+    private[this] val isNoChange = isWholePrimitive(keyType) && isWholePrimitive(valueType)
+
     override def toCatalystImpl(scalaValue: Any): Map[Any, Any] = scalaValue match {
       case m: Map[_, _] =>
         m.map { case (k, v) =>
@@ -203,6 +216,8 @@ object CatalystTypeConverters {
     override def toScala(catalystValue: Map[Any, Any]): Map[Any, Any] = {
       if (catalystValue == null) {
         null
+      } else if (isNoChange) {
+        catalystValue
       } else {
         catalystValue.map { case (k, v) =>
           keyConverter.toScala(k) -> valueConverter.toScala(v)
@@ -258,16 +273,13 @@ object CatalystTypeConverters {
       toScala(row(column).asInstanceOf[InternalRow])
   }
 
-  private object StringConverter extends CatalystTypeConverter[Any, String, Any] {
+  private object StringConverter extends CatalystTypeConverter[Any, String, UTF8String] {
     override def toCatalystImpl(scalaValue: Any): UTF8String = scalaValue match {
       case str: String => UTF8String.fromString(str)
       case utf8: UTF8String => utf8
     }
-    override def toScala(catalystValue: Any): String = catalystValue match {
-      case null => null
-      case str: String => str
-      case utf8: UTF8String => utf8.toString()
-    }
+    override def toScala(catalystValue: UTF8String): String =
+      if (catalystValue == null) null else catalystValue.toString
     override def toScalaImpl(row: InternalRow, column: Int): String = row(column).toString
   }
 
@@ -275,7 +287,8 @@ object CatalystTypeConverters {
     override def toCatalystImpl(scalaValue: Date): Int = DateTimeUtils.fromJavaDate(scalaValue)
     override def toScala(catalystValue: Any): Date =
       if (catalystValue == null) null else DateTimeUtils.toJavaDate(catalystValue.asInstanceOf[Int])
-    override def toScalaImpl(row: InternalRow, column: Int): Date = toScala(row.getInt(column))
+    override def toScalaImpl(row: InternalRow, column: Int): Date =
+      DateTimeUtils.toJavaDate(row.getInt(column))
   }
 
   private object TimestampConverter extends CatalystTypeConverter[Timestamp, Timestamp, Any] {
@@ -285,7 +298,7 @@ object CatalystTypeConverters {
       if (catalystValue == null) null
       else DateTimeUtils.toJavaTimestamp(catalystValue.asInstanceOf[Long])
     override def toScalaImpl(row: InternalRow, column: Int): Timestamp =
-      toScala(row.getLong(column))
+      DateTimeUtils.toJavaTimestamp(row.getLong(column))
   }
 
   private object BigDecimalConverter extends CatalystTypeConverter[Any, JavaBigDecimal, Decimal] {
@@ -296,10 +309,7 @@ object CatalystTypeConverters {
     }
     override def toScala(catalystValue: Decimal): JavaBigDecimal = catalystValue.toJavaBigDecimal
     override def toScalaImpl(row: InternalRow, column: Int): JavaBigDecimal =
-      row.get(column) match {
-        case d: JavaBigDecimal => d
-        case d: Decimal => d.toJavaBigDecimal
-      }
+      row.get(column).asInstanceOf[Decimal].toJavaBigDecimal
   }
 
   private abstract class PrimitiveConverter[T] extends CatalystTypeConverter[T, Any, Any] {
@@ -363,6 +373,19 @@ object CatalystTypeConverters {
   }
 
   /**
+   * Creates a converter function that will convert Catalyst types to Scala type.
+   * Typical use case would be converting a collection of rows that have the same schema. You will
+   * call this function once to get a converter, and apply it to every row.
+   */
+  private[sql] def createToScalaConverter(dataType: DataType): Any => Any = {
+    if (isPrimitive(dataType)) {
+      identity
+    } else {
+      getConverterForType(dataType).toScala
+    }
+  }
+
+  /**
    *  Converts Scala objects to Catalyst rows / types.
    *
    *  Note: This should be called before do evaluation on Row
@@ -389,15 +412,6 @@ object CatalystTypeConverters {
    * produced by createToScalaConverter.
    */
   def convertToScala(catalystValue: Any, dataType: DataType): Any = {
-    getConverterForType(dataType).toScala(catalystValue)
-  }
-
-  /**
-   * Creates a converter function that will convert Catalyst types to Scala type.
-   * Typical use case would be converting a collection of rows that have the same schema. You will
-   * call this function once to get a converter, and apply it to every row.
-   */
-  private[sql] def createToScalaConverter(dataType: DataType): Any => Any = {
-    getConverterForType(dataType).toScala
+    createToScalaConverter(dataType)(catalystValue)
   }
 }
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/ScalaUdf.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/ScalaUdf.scala
index 3992f1f59d..55df72f102 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/ScalaUdf.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/ScalaUdf.scala
@@ -17,7 +17,6 @@
 
 package org.apache.spark.sql.catalyst.expressions
 
-import org.apache.spark.sql.catalyst
 import org.apache.spark.sql.catalyst.CatalystTypeConverters
 import org.apache.spark.sql.types.DataType
 
@@ -39,7 +38,7 @@ case class ScalaUdf(function: AnyRef, dataType: DataType, children: Seq[Expressi
     (1 to 22).map { x =>
       val anys = (1 to x).map(x => "Any").reduce(_ + ", " + _)
       val childs = (0 to x - 1).map(x => s"val child$x = children($x)").reduce(_ + "\n  " + _)
-      lazy val converters = (0 to x - 1).map(x => s"lazy val converter$x = CatalystTypeConverters.createToScalaConverter(child$x.dataType)").reduce(_ + "\n  " + _)
+      val converters = (0 to x - 1).map(x => s"lazy val converter$x = CatalystTypeConverters.createToScalaConverter(child$x.dataType)").reduce(_ + "\n  " + _)
       val evals = (0 to x - 1).map(x => s"converter$x(child$x.eval(input))").reduce(_ + ",\n      " + _)
 
       s"""case $x =>