cfmcgrady commented on code in PR #4662: URL: https://github.com/apache/kyuubi/pull/4662#discussion_r1157044280
########## externals/kyuubi-spark-sql-engine/src/main/scala/org/apache/spark/sql/execution/arrow/ArrowConvertersHelper.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.execution.arrow + +import java.io.ByteArrayOutputStream +import java.nio.channels.Channels + +import org.apache.arrow.vector._ +import org.apache.arrow.vector.ipc.{ArrowStreamWriter, WriteChannel} +import org.apache.arrow.vector.ipc.message.{IpcOption, MessageSerializer} +import org.apache.spark.TaskContext +import org.apache.spark.internal.Logging +import org.apache.spark.sql.catalyst.InternalRow +import org.apache.spark.sql.catalyst.expressions.UnsafeRow +import org.apache.spark.sql.types._ +import org.apache.spark.sql.util.ArrowUtils +import org.apache.spark.util.Utils + +object ArrowConvertersHelper extends Logging { + + /** + * Different from [[org.apache.spark.sql.execution.arrow.ArrowConvertersHelper.toBatchIterator]], + * each output arrow batch contains this batch row count. + */ + def toBatchIterator( + rowIter: Iterator[InternalRow], + schema: StructType, + maxRecordsPerBatch: Long, + maxEstimatedBatchSize: Long, + limit: Long, + timeZoneId: String): ArrowBatchIterator = { + new ArrowBatchIterator( + rowIter, + schema, + maxRecordsPerBatch, + maxEstimatedBatchSize, + limit, + timeZoneId, + TaskContext.get) + } + + private[sql] class ArrowBatchIterator( + rowIter: Iterator[InternalRow], + schema: StructType, + maxRecordsPerBatch: Long, + maxEstimatedBatchSize: Long, + limit: Long, + timeZoneId: String, + context: TaskContext) + extends Iterator[Array[Byte]] { + + protected val arrowSchema = ArrowUtils.toArrowSchema(schema, timeZoneId) + private val allocator = + ArrowUtils.rootAllocator.newChildAllocator( + s"to${this.getClass.getSimpleName}", + 0, + Long.MaxValue) + + private val root = VectorSchemaRoot.create(arrowSchema, allocator) + protected val unloader = new VectorUnloader(root) + protected val arrowWriter = ArrowWriter.create(root) + + Option(context).foreach { + _.addTaskCompletionListener[Unit] { _ => + root.close() + allocator.close() + } + } + + override def hasNext: Boolean = (rowIter.hasNext && rowCount < limit) || { + root.close() + allocator.close() + false + } + + var rowCountInLastBatch: Long = 0 + var rowCount: Long = 0 + + override def next(): Array[Byte] = { + val out = new ByteArrayOutputStream() + val writeChannel = new WriteChannel(Channels.newChannel(out)) + + rowCountInLastBatch = 0 + var estimatedBatchSize = 0 + Utils.tryWithSafeFinally { + + // Always write the first row. + while (rowIter.hasNext && ( + // For maxBatchSize and maxRecordsPerBatch, respect whatever smaller. + // If the size in bytes is positive (set properly), always write the first row. + rowCountInLastBatch == 0 && maxEstimatedBatchSize > 0 || + // If the size in bytes of rows are 0 or negative, unlimit it. + estimatedBatchSize <= 0 || + estimatedBatchSize < maxEstimatedBatchSize || + // If the size of rows are 0 or negative, unlimit it. + maxRecordsPerBatch <= 0 || + rowCountInLastBatch < maxRecordsPerBatch || + rowCount < limit)) { + val row = rowIter.next() + arrowWriter.write(row) + estimatedBatchSize += (row match { + case ur: UnsafeRow => ur.getSizeInBytes + // Trying to estimate the size of the current row, assuming 16 bytes per value. + case ir: InternalRow => ir.numFields * 16 Review Comment: sorry for the lack of documentation. This class `ArrowBatchIterator` is derived from `org.apache.spark.sql.execution.arrow.ArrowConverters.ArrowBatchWithSchemaIterator`, with two key differences: 1. there is no requirement to write the schema at the batch header 2. iteration halts when `rowCount` equals `limit` -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
