[SPARK-12914] [SQL] generate aggregation with grouping keys

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/codegen/CodeGenerator.scala

@@ -55,6 +55,20 @@ class CodegenContext {
    */
   val references: mutable.ArrayBuffer[Any] = new mutable.ArrayBuffer[Any]()
 
+  /**
+    * Add an object to `references`, create a class member to access it.
+    *
+    * Returns the name of class member.
+    */
+  def addReferenceObj(name: String, obj: Any, className: String = null): String = {
+    val term = freshName(name)
+    val idx = references.length
+    references += obj
+    val clsName = Option(className).getOrElse(obj.getClass.getName)
+    addMutableState(clsName, term, s"this.$term = ($clsName) references[$idx];")
+    term
+  }
+
   /**
     * Holding a list of generated columns as input of current operator, will be used by
     * BoundReference to generate code.
@@ -198,6 +212,39 @@ class CodegenContext {
     }
   }
 
+  /**
+    * Update a column in MutableRow from ExprCode.
+    */
+  def updateColumn(
+      row: String,
+      dataType: DataType,
+      ordinal: Int,
+      ev: ExprCode,
+      nullable: Boolean): String = {
+    if (nullable) {
+      // Can't call setNullAt on DecimalType, because we need to keep the offset
+      if (dataType.isInstanceOf[DecimalType]) {
+        s"""
+           if (!${ev.isNull}) {
+             ${setColumn(row, dataType, ordinal, ev.value)};
+           } else {
+             ${setColumn(row, dataType, ordinal, "null")};
+           }
+         """
+      } else {
+        s"""
+           if (!${ev.isNull}) {
+             ${setColumn(row, dataType, ordinal, ev.value)};
+           } else {
+             $row.setNullAt($ordinal);
+           }
+         """
+      }
+    } else {
+      s"""${setColumn(row, dataType, ordinal, ev.value)};"""
+    }
+  }
+
   /**
    * Returns the name used in accessor and setter for a Java primitive type.
    */

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/codegen/GenerateMutableProjection.scala

@@ -88,31 +88,8 @@ object GenerateMutableProjection extends CodeGenerator[Seq[Expression], () => Mu
 
     val updates = validExpr.zip(index).map {
       case (e, i) =>
-        if (e.nullable) {
-          if (e.dataType.isInstanceOf[DecimalType]) {
-            // Can't call setNullAt on DecimalType, because we need to keep the offset
-            s"""
-              if (this.isNull_$i) {
-                ${ctx.setColumn("mutableRow", e.dataType, i, "null")};
-              } else {
-                ${ctx.setColumn("mutableRow", e.dataType, i, s"this.value_$i")};
-              }
-            """
-          } else {
-            s"""
-              if (this.isNull_$i) {
-                mutableRow.setNullAt($i);
-              } else {
-                ${ctx.setColumn("mutableRow", e.dataType, i, s"this.value_$i")};
-              }
-            """
-          }
-        } else {
-          s"""
-            ${ctx.setColumn("mutableRow", e.dataType, i, s"this.value_$i")};
-          """
-        }
-
+        val ev = ExprCode("", s"this.isNull_$i", s"this.value_$i")
+        ctx.updateColumn("mutableRow", e.dataType, i, ev, e.nullable)
     }
 
     val allProjections = ctx.splitExpressions(ctx.INPUT_ROW, projectionCodes)

sql/core/src/main/scala/org/apache/spark/sql/execution/BufferedRowIterator.java

@@ -17,6 +17,8 @@
 
 package org.apache.spark.sql.execution;
 
+import java.io.IOException;
+
 import scala.collection.Iterator;
 
 import org.apache.spark.sql.catalyst.InternalRow;
@@ -34,7 +36,7 @@ public class BufferedRowIterator {
   // used when there is no column in output
   protected UnsafeRow unsafeRow = new UnsafeRow(0);
 
-  public boolean hasNext() {
+  public boolean hasNext() throws IOException {
     if (currentRow == null) {
       processNext();
     }
@@ -56,7 +58,7 @@ public void setInput(Iterator<InternalRow> iter) {
    *
    * After it's called, if currentRow is still null, it means no more rows left.
    */
-  protected void processNext() {
+  protected void processNext() throws IOException {
     if (input.hasNext()) {
       currentRow = input.next();
     }