Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/7840#discussion_r36028323
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/codegen/GenerateSafeProjection.scala
---
@@ -0,0 +1,148 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.catalyst.expressions.codegen
+
+import scala.collection.mutable.ArrayBuffer
+
+import org.apache.spark.sql.catalyst.expressions._
+import org.apache.spark.sql.catalyst.expressions.aggregate.NoOp
+import org.apache.spark.sql.types.{StringType, StructType, DataType}
+
+
+/**
+ * Generates byte code that produces a [[MutableRow]] object that can
update itself based on a new
+ * input [[InternalRow]] for a fixed set of [[Expression Expressions]].
+ */
+object GenerateSafeProjection extends CodeGenerator[Seq[Expression],
Projection] {
+
+ protected def canonicalize(in: Seq[Expression]): Seq[Expression] =
+ in.map(ExpressionCanonicalizer.execute)
+
+ protected def bind(in: Seq[Expression], inputSchema: Seq[Attribute]):
Seq[Expression] =
+ in.map(BindReferences.bindReference(_, inputSchema))
+
+ private def genUpdater(
+ ctx: CodeGenContext,
+ setter: String,
+ dataType: DataType,
+ ordinal: Int,
+ value: String): String = {
+ dataType match {
+ case StringType => s"$setter.update($ordinal, $value.clone())"
+ case struct: StructType =>
+ val rowTerm = ctx.freshName("row")
+ val updates = struct.map(_.dataType).zipWithIndex.map { case (dt,
i) =>
+ val colTerm = ctx.freshName("col")
+ s"""
+ if ($value.isNullAt($i)) {
+ $rowTerm.setNullAt($i);
+ } else {
+ ${ctx.javaType(dt)} $colTerm = ${ctx.getValue(value, dt,
s"$i")};
+ ${genUpdater(ctx, rowTerm, dt, i, colTerm)};
+ }
+ """
+ }.mkString("\n")
+ s"""
+ $genericMutableRowType $rowTerm = new
$genericMutableRowType(${struct.fields.length});
+ $updates
+ $setter.update($ordinal, $rowTerm.copy());
+ """
+ case _ =>
+ ctx.setColumn(setter, dataType, ordinal, value)
+ }
+ }
+
+ protected def create(expressions: Seq[Expression]): Projection = {
+ val ctx = newCodeGenContext()
+ val projectionCode = expressions.zipWithIndex.map {
+ case (NoOp, _) => ""
+ case (e, i) =>
+ val evaluationCode = e.gen(ctx)
+ evaluationCode.code +
+ s"""
+ if (${evaluationCode.isNull}) {
+ mutableRow.setNullAt($i);
+ } else {
+ ${genUpdater(ctx, "mutableRow", e.dataType, i,
evaluationCode.primitive)};
+ }
+ """
+ }
+ // collect projections into blocks as function has 64kb codesize limit
in JVM
+ val projectionBlocks = new ArrayBuffer[String]()
+ val blockBuilder = new StringBuilder()
+ for (projection <- projectionCode) {
+ if (blockBuilder.length > 16 * 1000) {
+ projectionBlocks.append(blockBuilder.toString())
+ blockBuilder.clear()
+ }
+ blockBuilder.append(projection)
+ }
+ projectionBlocks.append(blockBuilder.toString())
+
+ val (projectionFuns, projectionCalls) = {
+ // inline it if we have only one block
+ if (projectionBlocks.length == 1) {
+ ("", projectionBlocks.head)
+ } else {
+ (
+ projectionBlocks.zipWithIndex.map { case (body, i) =>
+ s"""
+ |private void apply$i(InternalRow i) {
+ | $body
+ |}
+ """.stripMargin
+ }.mkString,
+ projectionBlocks.indices.map(i => s"apply$i(i);").mkString("\n")
+ )
+ }
+ }
+
+ val code = s"""
+ public Object generate($exprType[] expr) {
+ return new SpecificProjection(expr);
+ }
+
+ class SpecificProjection extends ${classOf[BaseProjection].getName} {
--- End diff --
change it to a different name; i noticed it'd help debugging because this
classname does show up in exception stacktraces.
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