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[SPARK-35329][SQL] Split generated switch code into pieces in ExpandExec #32457

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[SPARK-35329][SQL] Split generated switch code into pieces in ExpandExec #32457

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maropu May 6, 2021
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maropu May 7, 2021
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maropu May 7, 2021
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maropu May 7, 2021
a1873d9
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maropu May 7, 2021
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maropu May 11, 2021
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maropu May 12, 2021
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90 changes: 66 additions & 24 deletions sql/core/src/main/scala/org/apache/spark/sql/execution/ExpandExec.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -21,9 +21,9 @@ import org.apache.spark.rdd.RDD
import org.apache.spark.sql.catalyst.InternalRow
import org.apache.spark.sql.catalyst.expressions._
import org.apache.spark.sql.catalyst.expressions.codegen._
import org.apache.spark.sql.catalyst.expressions.codegen.Block._
import org.apache.spark.sql.catalyst.plans.physical.{Partitioning, UnknownPartitioning}
import org.apache.spark.sql.execution.metric.SQLMetrics
import org.apache.spark.sql.internal.SQLConf

/**
* Apply all of the GroupExpressions to every input row, hence we will get
Expand Down Expand Up @@ -152,40 +152,82 @@ case class ExpandExec(
// This column is the same across all output rows. Just generate code for it here.
BindReferences.bindReference(firstExpr, attributeSeq).genCode(ctx)
} else {
val isNull = ctx.freshName("isNull")
val value = ctx.freshName("value")
val code = code"""
|boolean $isNull = true;
|${CodeGenerator.javaType(firstExpr.dataType)} $value =
| ${CodeGenerator.defaultValue(firstExpr.dataType)};
""".stripMargin
val isNull = ctx.addMutableState(
CodeGenerator.JAVA_BOOLEAN,
"resultIsNull",
v => s"$v = true;")
val value = ctx.addMutableState(
CodeGenerator.javaType(firstExpr.dataType),
"resultValue",
v => s"$v = ${CodeGenerator.defaultValue(firstExpr.dataType)};")

ExprCode(
code,
JavaCode.isNullVariable(isNull),
JavaCode.variable(value, firstExpr.dataType))
}
}

// Part 2: switch/case statements
val cases = projections.zipWithIndex.map { case (exprs, row) =>
var updateCode = ""
for (col <- exprs.indices) {
val switchCaseExprs = projections.zipWithIndex.map { case (exprs, row) =>
val (exprCodesWithIndices, inputVarSets) = exprs.indices.flatMap { col =>
if (!sameOutput(col)) {
val ev = BindReferences.bindReference(exprs(col), attributeSeq).genCode(ctx)
updateCode +=
val boundExpr = BindReferences.bindReference(exprs(col), attributeSeq)
val exprCode = boundExpr.genCode(ctx)
val inputVars = CodeGenerator.getLocalInputVariableValues(ctx, boundExpr)._1
Some(((col, exprCode), inputVars))
} else {
None
}
}.unzip

val inputVars = inputVarSets.foldLeft(Set.empty[VariableValue])(_ ++ _)
(row, exprCodesWithIndices, inputVars.toSeq)
}

val updateCodes = switchCaseExprs.map { case (_, exprCodes, _) =>
exprCodes.map { case (col, ev) =>
s"""
|${ev.code}
|${outputColumns(col).isNull} = ${ev.isNull};
|${outputColumns(col).value} = ${ev.value};
""".stripMargin
}.mkString("\n")
}

val splitThreshold = SQLConf.get.methodSplitThreshold
val cases = if (switchCaseExprs.flatMap(_._2.map(_._2.code.length)).sum > splitThreshold) {
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@kiszk kiszk May 12, 2021

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Can we call generateUpdateCode only once before line 198?
IMHO, code in all three cases (line 203-, line 216, and line 225-) is generated by generateUpdateCode().

switchCaseExprs.zip(updateCodes).map { case ((row, _, inputVars), updateCode) =>
val paramLength = CodeGenerator.calculateParamLengthFromExprValues(inputVars)
val maybeSplitUpdateCode = if (CodeGenerator.isValidParamLength(paramLength)) {
val switchCaseFunc = ctx.freshName("switchCaseCode")
val argList = inputVars.map { v =>
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s"${CodeGenerator.typeName(v.javaType)} ${v.variableName}"
}
ctx.addNewFunction(switchCaseFunc,
s"""
|${ev.code}
|${outputColumns(col).isNull} = ${ev.isNull};
|${outputColumns(col).value} = ${ev.value};
""".stripMargin
|private void $switchCaseFunc(${argList.mkString(", ")}) {
| $updateCode
|}
""".stripMargin)

s"$switchCaseFunc(${inputVars.map(_.variableName).mkString(", ")});"
} else {
updateCode
}
s"""
|case $row:
| $maybeSplitUpdateCode
| break;
""".stripMargin
}
} else {
switchCaseExprs.map(_._1).zip(updateCodes).map { case (row, updateCode) =>
s"""
|case $row:
| $updateCode
| break;
""".stripMargin
}

s"""
|case $row:
| ${updateCode.trim}
| break;
""".stripMargin
}

val numOutput = metricTerm(ctx, "numOutputRows")
Expand Down