HeartSaVioR commented on a change in pull request #31986: URL: https://github.com/apache/spark/pull/31986#discussion_r620081071
########## File path: sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/UpdatingSessionsIterator.scala ########## @@ -0,0 +1,219 @@ +/* + * 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.aggregate + +import scala.collection.mutable + +import org.apache.spark.sql.catalyst.InternalRow +import org.apache.spark.sql.catalyst.expressions._ +import org.apache.spark.sql.catalyst.expressions.codegen.GenerateUnsafeProjection +import org.apache.spark.sql.execution.ExternalAppendOnlyUnsafeRowArray + +/** + * This class calculates and updates the session window for each element in the given iterator, + * which makes elements in the same session window having same session spec. Downstream can apply + * aggregation to finally merge these elements bound to the same session window. + * + * This class works on the precondition that given iterator is sorted by "group keys + start time + * of session window", and this iterator still retains the characteristic of the sort. + * + * This class copies the elements to safely update on each element, as well as buffers elements + * which are bound to the same session window. Due to such overheads, [[MergingSessionsIterator]] + * should be used whenever possible. + */ +class UpdatingSessionsIterator( + iter: Iterator[InternalRow], + groupingExpressions: Seq[NamedExpression], + sessionExpression: NamedExpression, + inputSchema: Seq[Attribute], + inMemoryThreshold: Int, + spillThreshold: Int) extends Iterator[InternalRow] { + + private val groupingWithoutSession: Seq[NamedExpression] = + groupingExpressions.diff(Seq(sessionExpression)) + private val groupingWithoutSessionAttributes: Seq[Attribute] = + groupingWithoutSession.map(_.toAttribute) + private[this] val groupingWithoutSessionProjection: UnsafeProjection = + UnsafeProjection.create(groupingWithoutSession, inputSchema) + + private val valuesExpressions: Seq[Attribute] = inputSchema.diff(groupingWithoutSession) + + private[this] val sessionProjection: UnsafeProjection = + UnsafeProjection.create(Seq(sessionExpression), inputSchema) + + private var currentKeys: InternalRow = _ Review comment: Changed variable names, as well as added some information on variables. -- 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. For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
