Github user godfreyhe commented on a diff in the pull request:
https://github.com/apache/flink/pull/3696#discussion_r110534493
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/plan/nodes/datastream/DataStreamRetractionRule.scala
---
@@ -0,0 +1,341 @@
+/*
+ * 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.table.plan.nodes.datastream
+
+import org.apache.calcite.plan.{RelOptRule, RelOptRuleCall, RelTraitSet}
+import org.apache.calcite.plan.RelOptRule._
+import org.apache.calcite.plan.hep.HepRelVertex
+import org.apache.calcite.rel.RelNode
+
+import scala.collection.JavaConverters._
+import scala.collection.mutable.ListBuffer
+
+/**
+ * Collection of retraction rules that apply various transformations on
DataStreamRel trees.
+ * Currently, there are three transformations: InitProcessRule,
NeedToRetractProcessRule and
+ * AccModeProcessRule. Note: these rules must be called in order
(InitProcessRule ->
+ * NeedToRetractProcessRule -> AccModeProcessRule).
+ */
+object DataStreamRetractionRule {
+
+ /**
+ * Singleton rule that init retraction trait inside a [[DataStreamRel]]
+ */
+ val INIT_INSTANCE = new InitProcessRule()
+
+ /**
+ * Singleton rule that decide needToRetract property inside a
[[DataStreamRel]]
+ */
+ val NEEDTORETRACT_INSTANCE = new NeedToRetractProcessRule()
+
+ /**
+ * Singleton rule that decide accMode inside a [[DataStreamRel]]
+ */
+ val ACCMODE_INSTANCE = new AccModeProcessRule()
+
+ /**
+ * Get all child RelNodes of a RelNode
+ * @param topRel The input RelNode
+ * @return All child nodes
+ */
+ def getChildRelNodes(topRel: RelNode): ListBuffer[RelNode] = {
+ val topRelInputs = new ListBuffer[RelNode]()
+ topRelInputs.++=(topRel.getInputs.asScala)
+ topRelInputs.transform(e => e.asInstanceOf[HepRelVertex].getCurrentRel)
+ }
+
+ def traitSetContainNeedToRetract(traitSet: RelTraitSet): Boolean = {
+ val retractionTrait = traitSet.getTrait(RetractionTraitDef.INSTANCE)
+ if (null == retractionTrait) {
+ false
+ } else {
+ retractionTrait.getNeedToRetract
+ }
+ }
+
+
+ /**
+ * Find all needToRetract nodes. A node needs to retract means that
there are downstream
+ * nodes need retraction from it. Currently,
[[DataStreamOverAggregate]] and
+ * [[DataStreamGroupWindowAggregate]] need retraction from upstream
nodes, besides, a
+ * needToRetract node also need retraction from it's upstream nodes.
+ */
+ class NeedToRetractProcessRule extends RelOptRule(
+ operand(
+ classOf[DataStreamRel], none()),
+ "NeedToRetractProcessRule") {
+
+ /**
+ * Return true if bottom RelNode does not contain needToRetract and
top RelNode need
+ * retraction from bottom RelNode. Currently, operators which contain
aggregations need
+ * retraction from upstream nodes, besides, a needToRetract node also
needs retraction from
+ * it's upstream nodes.
+ */
+ def bottomNeedToRetract(topRel: RelNode, bottomRel: RelNode): Boolean
= {
+ val bottomTraits = bottomRel.getTraitSet
+ if(!traitSetContainNeedToRetract(bottomTraits)){
+ topRel match {
+ case _: DataStreamGroupAggregate => true
+ case _: DataStreamGroupWindowAggregate => true
+ case _: DataStreamOverAggregate => true
+ case _ if traitSetContainNeedToRetract(topRel.getTraitSet) =>
true
+ case _ => false
--- End diff --
case _ if traitSetContainNeedToRetract(topRel.getTraitSet) => true
case _ => false
=>
case _ -> traitSetContainNeedToRetract(topRel.getTraitSet)
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