dingxin-tech commented on code in PR #3254: URL: https://github.com/apache/flink-cdc/pull/3254#discussion_r1650294562
########## flink-cdc-connect/flink-cdc-pipeline-connectors/flink-cdc-pipeline-connector-maxcompute/src/main/java/org/apache/flink/cdc/connectors/maxcompute/utils/SessionCommitCoordinator.java: ########## @@ -0,0 +1,158 @@ +/* + * 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.cdc.connectors.maxcompute.utils; + +import org.apache.flink.cdc.common.utils.Preconditions; +import org.apache.flink.cdc.connectors.maxcompute.common.Constant; +import org.apache.flink.cdc.connectors.maxcompute.coordinator.message.CommitSessionResponse; +import org.apache.flink.cdc.runtime.operators.schema.event.CoordinationResponseUtils; +import org.apache.flink.runtime.operators.coordination.CoordinationResponse; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.ArrayDeque; +import java.util.Comparator; +import java.util.HashMap; +import java.util.Map; +import java.util.Queue; +import java.util.concurrent.CompletableFuture; + +/** + * The SessionCommitCoordinator class is responsible for coordinating and controlling the order of + * session submissions by multiple concurrent executors in a distributed processing environment. It + * ensures that: 1. Each executor must submit sessions in ascending order by session ID. 2. Each + * executor must submit a Constant.END_OF_SESSION as a terminator after completing its session + * submissions. + * + * <p>Working Principle: - Maintains an array of queues (toCommitSessionIds), with each queue + * corresponding to an executor, to isolate the session submissions of different executors. This + * maintains the independence and submission order of each executor. - Executors submit session IDs + * sequentially by invoking the commit() method. The commit operation simply enqueues the session ID + * into the corresponding executor's queue. - The getToCommitSessionId() method is tasked with + * selecting the smallest session ID across all executors that has been "submitted" or is "no longer + * required" for submission, allowing for further processing. "Submitted" means that the session ID + * has been submitted by all executors; "no longer required" assumes that any subsequent session IDs + * that are yet to be submitted will always be greater than the currently chosen ID. - Once a + * session ID is selected by the getToCommitSessionId() method, it's removed from all executors' + * queues, indicating that the session ID has been processed. This process ensures ordered + * processing of the sessions and allows the system to efficiently progress. - Each processing step + * of the session IDs is based on a key assumption: that any subsequent session ID submissions will + * always be greater than the current processed session ID. This is guaranteed by the fact that each + * executor commits to submitting session IDs in order and submits a special terminator + * (Constant.END_OF_SESSION) at the end. + * + * <p>Note: - The class presupposes that all session IDs are comparable, and each executor strictly + * adheres to the submission order of session IDs in ascending order. Any behavior that deviates + * from this principle may lead to unpredictable outcomes, as it contravenes the fundamental + * assumption of the class's design. - The introduction of Constant.END_OF_SESSION as a terminator + * is a key aspect of this coordination strategy, as it provides a clear signal for recognizing the + * completion status of an executor, allowing the system to determine whether all relevant sessions + * have been processed. + */ +public class SessionCommitCoordinator { Review Comment: Sure, I didn't think of such a suitable name when I was naming it. -- 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]
