Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/5725#discussion_r29220523
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/UnsafeRowConverter.scala
---
@@ -0,0 +1,226 @@
+/*
+ * 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
+
+import org.apache.spark.sql.types._
+import org.apache.spark.unsafe.PlatformDependent
+import org.apache.spark.unsafe.array.ByteArrayMethods
+
+/**
+ * Converts Rows into UnsafeRow format. This class is NOT thread-safe.
+ *
+ * @param fieldTypes the data types of the row's columns.
+ */
+class UnsafeRowConverter(fieldTypes: Array[DataType]) {
+
+ def this(schema: StructType) {
+ this(schema.fields.map(_.dataType))
+ }
+
+ /** Re-used pointer to the unsafe row being written */
+ private[this] val unsafeRow = new UnsafeRow()
+
+ /** Functions for encoding each column */
+ private[this] val writers: Array[UnsafeColumnWriter[Any]] = {
+ fieldTypes.map(t =>
UnsafeColumnWriter.forType(t).asInstanceOf[UnsafeColumnWriter[Any]])
+ }
+
+ /** The size, in bytes, of the fixed-length portion of the row,
including the null bitmap */
+ private[this] val fixedLengthSize: Int =
+ (8 * fieldTypes.length) +
UnsafeRow.calculateBitSetWidthInBytes(fieldTypes.length)
+
+ /**
+ * Compute the amount of space, in bytes, required to encode the given
row.
+ */
+ def getSizeRequirement(row: Row): Int = {
+ var fieldNumber = 0
+ var variableLengthFieldSize: Int = 0
+ while (fieldNumber < writers.length) {
+ if (!row.isNullAt(fieldNumber)) {
+ variableLengthFieldSize +=
writers(fieldNumber).getSize(row(fieldNumber))
+ }
+ fieldNumber += 1
+ }
+ fixedLengthSize + variableLengthFieldSize
+ }
+
+ /**
+ * Convert the given row into UnsafeRow format.
+ *
+ * @param row the row to convert
+ * @param baseObject the base object of the destination address
+ * @param baseOffset the base offset of the destination address
+ * @return the number of bytes written. This should be equal to
`getSizeRequirement(row)`.
+ */
+ def writeRow(row: Row, baseObject: Object, baseOffset: Long): Long = {
+ unsafeRow.pointTo(baseObject, baseOffset, writers.length, null)
+ var fieldNumber = 0
+ var appendCursor: Int = fixedLengthSize
+ while (fieldNumber < writers.length) {
+ if (row.isNullAt(fieldNumber)) {
+ unsafeRow.setNullAt(fieldNumber)
+ } else {
+ appendCursor += writers(fieldNumber).write(
+ row(fieldNumber),
+ fieldNumber,
+ unsafeRow,
+ baseObject,
+ baseOffset,
+ appendCursor)
+ }
+ fieldNumber += 1
+ }
+ appendCursor
+ }
+
+}
+
+/**
+ * Function for writing a column into an UnsafeRow.
+ */
+private abstract class UnsafeColumnWriter[T] {
+ /**
+ * Write a value into an UnsafeRow.
+ *
+ * @param value the value to write
+ * @param columnNumber what column to write it to
+ * @param row a pointer to the unsafe row
+ * @param baseObject the base object of the target row's address
+ * @param baseOffset the base offset of the target row's address
+ * @param appendCursor the offset from the start of the unsafe row to
the end of the row;
+ * used for calculating where variable-length data
should be written
+ * @return the number of variable-length bytes written
+ */
+ def write(
+ value: T,
+ columnNumber: Int,
+ row: UnsafeRow,
+ baseObject: Object,
+ baseOffset: Long,
+ appendCursor: Int): Int
+
+ /**
+ * Return the number of bytes that are needed to write this
variable-length value.
+ */
+ def getSize(value: T): Int
+}
+
+private object UnsafeColumnWriter {
+
+ def forType(dataType: DataType): UnsafeColumnWriter[_] = {
+ dataType match {
+ case IntegerType => IntUnsafeColumnWriter
+ case LongType => LongUnsafeColumnWriter
+ case FloatType => FloatUnsafeColumnWriter
+ case DoubleType => DoubleUnsafeColumnWriter
+ case StringType => StringUnsafeColumnWriter
+ case t =>
+ throw new UnsupportedOperationException(s"Do not know how to write
columns of type $t")
+ }
+ }
+}
+
+//
------------------------------------------------------------------------------------------------
+
+private object IntUnsafeColumnWriter extends IntUnsafeColumnWriter
+private object LongUnsafeColumnWriter extends LongUnsafeColumnWriter
+private object FloatUnsafeColumnWriter extends FloatUnsafeColumnWriter
+private object DoubleUnsafeColumnWriter extends DoubleUnsafeColumnWriter
+private object StringUnsafeColumnWriter extends StringUnsafeColumnWriter
+
+private abstract class PrimitiveUnsafeColumnWriter[T] extends
UnsafeColumnWriter[T] {
+ def getSize(value: T): Int = 0
+}
+
+private class IntUnsafeColumnWriter private() extends
PrimitiveUnsafeColumnWriter[Int] {
+ override def write(
--- End diff --
can u define the return value?
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