Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/1465#discussion_r48282226
--- Diff:
flink-staging/flink-table/src/main/scala/org/apache/flink/api/table/typeinfo/RowComparator.scala
---
@@ -0,0 +1,463 @@
+/*
+ * 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.flink.api.table.typeinfo
+
+import java.util
+
+import org.apache.flink.api.common.typeutils.base.BasicTypeComparator
+import org.apache.flink.api.common.typeutils.{CompositeTypeComparator,
TypeComparator, TypeSerializer}
+import org.apache.flink.api.java.typeutils.runtime.TupleComparatorBase
+import org.apache.flink.api.table.Row
+import org.apache.flink.api.table.typeinfo.NullMaskUtils.readIntoNullMask
+import
org.apache.flink.api.table.typeinfo.RowComparator.createAuxiliaryFields
+import org.apache.flink.api.table.typeinfo.RowComparator.NullChecker
+import org.apache.flink.core.memory.{MemorySegment, DataOutputView,
DataInputView}
+import org.apache.flink.types.{KeyFieldOutOfBoundsException,
NullKeyFieldException}
+
+/**
+ * Comparator for [[Row]].
+ */
+class RowComparator private (
+ /** key positions describe which fields are keys in what order */
+ val keyPositions: Array[Int],
+ /** comparators for the key fields, in the same order as the key
fields */
+ val comparators: Array[TypeComparator[_]],
+ /** serializers to deserialize the first n fields for comparison */
+ val serializers: Array[TypeSerializer[_]],
+ /** auxiliary fields for normalized key support */
+ private val auxiliaryFields: (List[Int], Int, Int))
+ extends CompositeTypeComparator[Row] with Serializable {
+
+ // null masks for serialized comparison
+ private val nullMask1 = new Array[Boolean](serializers.length)
+ private val nullMask2 = new Array[Boolean](serializers.length)
+
+ // cache for the deserialized key field objects
+ @transient
+ private lazy val deserializedKeyFields1: Array[Any] =
instantiateDeserializationFields()
+
+ @transient
+ private lazy val deserializedKeyFields2: Array[Any] =
instantiateDeserializationFields()
+
+ // null checker for reference comparison
+ private val nullChecker = new NullChecker()
+
+ // create auxiliary fields
+ private val normalizedKeyLengths: Array[Int] =
auxiliaryFields._1.toArray[Int]
+ private val numLeadingNormalizableKeys: Int = auxiliaryFields._2
+ private val normalizableKeyPrefixLen: Int = auxiliaryFields._3
+
+ // first comparator decides invert the key direction
+ private val invertNormKey: Boolean = comparators(0).invertNormalizedKey()
+
+ def this(
+ keyPositions: Array[Int],
+ comparators: Array[TypeComparator[_]],
+ serializers: Array[TypeSerializer[_]]) = {
+ this(
+ keyPositions,
+ comparators,
+ serializers,
+ createAuxiliaryFields(comparators))
+ }
+
+ private def instantiateDeserializationFields(): Array[Any] = {
+ val newFields = new Array[Any](serializers.length)
+ var i = 0
+ while (i < serializers.length) {
+ newFields(i) = serializers(i).createInstance()
+ i += 1
+ }
+ newFields
+ }
+
+ //
--------------------------------------------------------------------------------------------
+ // Comparator Methods
+ //
--------------------------------------------------------------------------------------------
+
+ override def getFlatComparator(flatComparators:
util.List[TypeComparator[_]]): Unit =
+ comparators.foreach {
+ case ctc: CompositeTypeComparator[_] =>
ctc.getFlatComparator(flatComparators)
+ case c@_ => flatComparators.add(c)
+ }
+
+ override def compareToReference(referencedComparator:
TypeComparator[Row]): Int = {
+ val other: RowComparator =
referencedComparator.asInstanceOf[RowComparator]
+ var i = 0
+ try {
+ while (i < keyPositions.length) {
+ val comparator = comparators(i).asInstanceOf[TypeComparator[Any]]
+ val otherComparator =
other.comparators(i).asInstanceOf[TypeComparator[Any]]
+
+ val nullCheck = comparator.equalToReference(nullChecker)
+ val nullCheckOther = otherComparator.equalToReference(nullChecker)
+
+ var cmp = 0
+ // both values are null -> equality
+ if (nullCheck && nullCheckOther) {
+ cmp = 0
+ }
+ // one value is null -> inequality
+ // order is considered for basic types
+ else if (nullCheck || nullCheckOther) {
+ if (comparator.isInstanceOf[BasicTypeComparator[_]]) {
+ val basicComp = comparator.asInstanceOf[BasicTypeComparator[_]]
+ if (nullCheck) {
+ return if (basicComp.isAscendingComparison) 1 else -1
+ }
+ else if (nullCheckOther) {
+ return if (basicComp.isAscendingComparison) -1 else 1
+ }
+ }
+ else {
+ return if (nullCheck) 1 else -1
+ }
+ }
+ else {
+ cmp = comparator.compareToReference(otherComparator)
+ }
+
+ if (cmp != 0) {
+ return cmp
+ }
+ i = i + 1
+ }
+ 0
+ }
+ catch {
+ case npex: NullPointerException =>
+ throw new NullKeyFieldException(keyPositions(i))
+ case iobex: IndexOutOfBoundsException =>
+ throw new KeyFieldOutOfBoundsException(keyPositions(i))
+ }
+ }
+
+ override def compareSerialized(firstSource: DataInputView, secondSource:
DataInputView): Int = {
+ val len = serializers.length
+ val keyLen = keyPositions.length
+
+ readIntoNullMask(len, firstSource, nullMask1)
+ readIntoNullMask(len, secondSource, nullMask2)
+
+ // deserialize
+ var i = 0
+ while (i < len) {
+ val serializer = serializers(i).asInstanceOf[TypeSerializer[Any]]
+
+ // deserialize field 1
+ if (nullMask1(i)) {
+ deserializedKeyFields1(i) = null
--- End diff --
If you use `nullMask1` during the comparison step to check if a field
`null` is, you don't have to set the field to `null` here and read the object
the next time without a `reuse` object.
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