carloea2 commented on code in PR #3774: URL: https://github.com/apache/texera/pull/3774#discussion_r2438422320
########## common/workflow-operator/src/main/scala/org/apache/amber/operator/sort/StableMergeSortOpExec.scala: ########## @@ -0,0 +1,173 @@ +/* + * 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.amber.operator.sort + +import org.apache.amber.core.executor.OperatorExecutor +import org.apache.amber.core.tuple.{AttributeType, Schema, Tuple, TupleLike} +import org.apache.amber.util.JSONUtils.objectMapper + +import scala.collection.mutable.ArrayBuffer + +class StableMergeSortOpExec(descString: String) extends OperatorExecutor { + + private val desc: StableMergeSortOpDesc = + objectMapper.readValue(descString, classOf[StableMergeSortOpDesc]) + + private var inputSchema: Schema = _ + + private case class ResolvedKey( + index: Int, + attributeType: AttributeType, + descending: Boolean + ) + + private var resolved: Array[ResolvedKey] = _ + + private var runs: ArrayBuffer[ArrayBuffer[Tuple]] = _ + + override def open(): Unit = { + runs = ArrayBuffer.empty[ArrayBuffer[Tuple]] + } + + override def close(): Unit = { + if (runs != null) runs.clear() + } + + override def processTuple(tuple: Tuple, port: Int): Iterator[TupleLike] = { + if (inputSchema == null) { + inputSchema = tuple.getSchema + resolved = resolveKeys(inputSchema) + } + val run = ArrayBuffer[Tuple](tuple) // size-1 sorted run + pushRun(run) + Iterator.empty + } + + override def onFinish(port: Int): Iterator[TupleLike] = { + if (runs.isEmpty) return Iterator.empty + + // Collapse all remaining runs left-to-right, preserving stability + var acc = runs(0) + var i = 1 + while (i < runs.length) { + acc = mergeRuns(acc, runs(i)) + i += 1 + } + + runs.clear() + runs.append(acc) + + acc.iterator + } + + private def resolveKeys(schema: Schema): Array[ResolvedKey] = { + desc.keys.map { k: SortCriteriaUnit => + val name = k.attributeName + val idx = schema.getIndex(name) + val tpe = schema.getAttribute(name).getType + val descOrder = k.sortPreference == SortPreference.DESC + ResolvedKey(idx, tpe, descOrder) + }.toArray + } + + private def pushRun(initial: ArrayBuffer[Tuple]): Unit = { + runs.append(initial) + // merge top two runs if they have equal sizes; preserve left-before-right for stability + while (runs.length >= 2 && runs(runs.length - 1).size == runs(runs.length - 2).size) { + val right = runs.remove(runs.length - 1) // newer + val left = runs.remove(runs.length - 1) // older + val merged = mergeRuns(left, right) + runs.append(merged) + } + } + + private def mergeRuns(left: ArrayBuffer[Tuple], right: ArrayBuffer[Tuple]): ArrayBuffer[Tuple] = { + val out = new ArrayBuffer[Tuple](left.size + right.size) + var i = 0 + var j = 0 + while (i < left.size && j < right.size) { + if (compareTuples(left(i), right(j)) <= 0) { + out += left(i); i += 1 + } else { + out += right(j); j += 1 + } + } + while (i < left.size) { out += left(i); i += 1 } + while (j < right.size) { out += right(j); j += 1 } + out + } + + private def compareTuples(a: Tuple, b: Tuple): Int = { + var k = 0 + while (k < resolved.length) { + val r = resolved(k) + val va = a.getField[Any](r.index) + val vb = b.getField[Any](r.index) + + // Null policy: ALWAYS last, regardless of ASC/DESC + if (va == null || vb == null) { + if (va == null && vb == null) { + k += 1 + } else { + return if (va == null) 1 else -1 + } + } else { + val base = compareNonNull(va, vb, r.attributeType) + if (base != 0) return if (r.descending) -base else base + k += 1 + } + } + 0 + } + + private def compareNonNull(va: Any, vb: Any, tpe: AttributeType): Int = { Review Comment: https://github.com/apache/texera/issues/3923 -- 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]
