kl0u commented on a change in pull request #14216: URL: https://github.com/apache/flink/pull/14216#discussion_r530848583
########## File path: flink-streaming-java/src/main/java/org/apache/flink/streaming/api/transformations/BroadcastStateTransformation.java ########## @@ -0,0 +1,160 @@ +/* + * 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.streaming.api.transformations; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.api.common.typeinfo.TypeInformation; +import org.apache.flink.api.dag.Transformation; +import org.apache.flink.api.java.functions.KeySelector; +import org.apache.flink.streaming.api.datastream.BroadcastStream; +import org.apache.flink.streaming.api.datastream.DataStream; +import org.apache.flink.streaming.api.datastream.KeyedStream; +import org.apache.flink.streaming.api.operators.ChainingStrategy; +import org.apache.flink.streaming.api.operators.StreamOperatorFactory; + +import java.util.ArrayList; +import java.util.List; + +import static org.apache.flink.util.Preconditions.checkNotNull; + +/** + * This is the transformation for the Broadcast State pattern. In a nutshell, this transformation + * allows to take a broadcasted (non-keyed) stream, connect it with another keyed or non-keyed + * stream, and apply a function on the resulting connected stream. This function will have access + * to all the elements that belong to the non-keyed, broadcasted side, as this is kept in Flink's + * state. + * + * <p>For more information see the + * <a href="https://ci.apache.org/projects/flink/flink-docs-stable/dev/stream/state/broadcast_state.html";> + * Broadcast State Pattern documentation page</a>. + * + * @param <IN1> The type of the elements in the non-broadcasted input. + * @param <IN2> The type of the elements in the broadcasted input. + * @param <OUT> The type of the elements that result from this transformation. + */ +@Internal +public class BroadcastStateTransformation<IN1, IN2, OUT> extends PhysicalTransformation<OUT> { + + private final DataStream<IN1> inputStream; Review comment: I like this comment. You are right! ---------------------------------------------------------------- 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]
