Github user dbtsai commented on the issue:
https://github.com/apache/spark/pull/18346
Thanks, @viirya for this PR.
We hit this issue, and @viirya was kindly helping us to find the root
cause. This approach LGTM. One alternative approach we took in the end to
unblock our use-case is having the CodeGenFallback to generate the code for all
the children instead of going through the eval paths, and this works for us. I
think the approach we took have benefits that we still can do the wholestage
codegen together with the expression with CodeGenFallback without separating
them into different path.
@gatorsmile @cloud-fan any feedback?
Thanks.
```scala
import org.apache.spark.sql.catalyst.expressions.{Expression,
LeafExpression, Nondeterministic, TernaryExpression}
import org.apache.spark.sql.catalyst.expressions.codegen.{CodegenContext,
ExprCode}
trait TernaryCodegenFallback extends Expression { self: TernaryExpression =>
private val className = classOf[TernaryCodegenFallback].getName
def evalFromCodegen(value1: Any, value2: Any, value3: Any): Any =
nullSafeEval(value1, value2, value3)
protected def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
foreach {
case n: Nondeterministic => n.setInitialValues()
case _ =>
}
// LeafNode does not need `input`
val input = if (this.isInstanceOf[LeafExpression]) "null" else
ctx.INPUT_ROW
val idx = ctx.references.length
ctx.references += this
val objectTerm = ctx.freshName("obj")
val placeHolder = ctx.registerComment(this.toString)
val Seq(code1, code2, code3) = children.map(expr => expr.genCode(ctx))
if (nullable) {
ev.copy(code = s"""
$placeHolder
${code1.code}
${code2.code}
${code3.code}
Object $objectTerm = null;
boolean ${ev.isNull} = ${code1.isNull} || ${code2.isNull} ||
${code3.isNull};
if (!${ev.isNull}) {
$objectTerm = (($className) references[$idx]).evalFromCodegen(
${code1.value}, ${code2.value}, ${code3.value}
);
${ev.isNull} = $objectTerm == null;
}
${ctx.javaType(this.dataType)} ${ev.value} =
${ctx.defaultValue(this.dataType)};
if (!${ev.isNull}) {
${ev.value} = (${ctx.boxedType(this.dataType)}) $objectTerm;
}""")
} else {
ev.copy(code = s"""
$placeHolder
${code1.code}
${code2.code}
${code3.code}
Object $objectTerm = (($className)
references[$idx]).evalFromCodegen(
${code1.value}, ${code2.value}, ${code3.value}
);
${ctx.javaType(this.dataType)} ${ev.value} =
(${ctx.boxedType(this.dataType)}) $objectTerm;
""", isNull = "false")
}
}
}
```
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