zentol commented on code in PR #22384: URL: https://github.com/apache/flink/pull/22384#discussion_r1196648554
########## flink-runtime/src/main/java/org/apache/flink/runtime/leaderelection/AbstractLeaderElectionService.java: ########## @@ -0,0 +1,86 @@ +/* + * 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.runtime.leaderelection; + +import org.apache.flink.util.Preconditions; + +import javax.annotation.Nullable; + +import java.util.UUID; + +/** + * {@code AbstractLeaderElectionService} provides a generic implementation of the {@link + * LeaderElection} handling. + */ +public abstract class AbstractLeaderElectionService implements LeaderElectionService { + @Override + public LeaderElection createLeaderElection() { + return new LeaderElectionImpl(this); + } + + /** + * Registers the given {@link LeaderContender} with the underlying {@code + * LeaderElectionService}. Leadership changes are starting to be reported to the {@code + * LeaderContender}. + */ + protected abstract void register(LeaderContender contender) throws Exception; + + /** Confirms the leadership with the given session ID and address. */ + protected abstract void confirmLeadership(UUID leaderSessionID, String leaderAddress); + + /** + * Checks whether the {@code LeaderElectionService} has the leadership acquired for the given + * session ID. + * + * @return {@code true} if the service has leadership with the passed session ID acquired; + * {@code false} otherwise. + */ + protected abstract boolean hasLeadership(UUID leaderSessionId); + + /** {@code LeaderElectionImpl} is the default implementation of {@link LeaderElection}. */ + private static class LeaderElectionImpl implements LeaderElection { Review Comment: can we move this into a dedicated class and rename it to `DefaultLeaderElection`? ########## flink-runtime/src/test/java/org/apache/flink/runtime/leaderelection/TestingLeaderElectionService.java: ########## @@ -28,7 +28,7 @@ * Test {@link LeaderElectionService} implementation which directly forwards isLeader and notLeader * calls to the contender. */ -public class TestingLeaderElectionService implements LeaderElectionService { +public class TestingLeaderElectionService extends AbstractLeaderElectionService { Review Comment: I don't know, it seems odd that this relies on a concrete implementation. ########## flink-runtime/src/test/java/org/apache/flink/runtime/rest/util/DocumentingDispatcherRestEndpoint.java: ########## @@ -86,20 +86,20 @@ public List<Tuple2<RestHandlerSpecification, ChannelInboundHandler>> initializeH return super.initializeHandlers(localAddressFuture); } - private enum NoOpElectionService implements LeaderElectionService { - INSTANCE; + private static class NoOpElectionService extends AbstractLeaderElectionService { Review Comment: Shouldn't this keep implementing `LeaderElectionService` to avoid dependencies on runtime internals? ########## flink-runtime/src/test/java/org/apache/flink/runtime/leaderelection/TestingContender.java: ########## @@ -41,13 +42,20 @@ public TestingContender( this.leaderElectionService = leaderElectionService; } + public LeaderElection startLeaderElection() throws Exception { + leaderElection = leaderElectionService.createLeaderElection(); Review Comment: should this maybe be set up in the constructor? Maybe even the leader election start. So far, all prod usages set this up when a component is started, and the equivalent in this class for that is the constructor. ########## flink-runtime/src/test/java/org/apache/flink/runtime/leaderretrieval/ZooKeeperLeaderRetrievalTest.java: ########## @@ -120,6 +121,7 @@ void testConnectingAddressRetrievalWithDelayedLeaderElection() throws Exception long sleepingTime = 1000; LeaderElectionService leaderElectionService = null; + LeaderElection leaderElection = null; Review Comment: unused? ########## flink-runtime/src/test/java/org/apache/flink/runtime/leaderelection/ZooKeeperLeaderElectionConnectionHandlingTest.java: ########## @@ -147,7 +147,8 @@ private void runTestWithZooKeeperConnectionProblem( client.getConnectionStateListenable().addListener(connectionStateListener); final TestingContender contender = new TestingContender(); - leaderElectionService.start(contender); + final LeaderElection leaderElection = leaderElectionService.createLeaderElection(); Review Comment: nit: variable may be unnecessary. -- This is an automated message from the Apache Git Service. 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