tillrohrmann commented on a change in pull request #17485: URL: https://github.com/apache/flink/pull/17485#discussion_r791514100
########## File path: flink-runtime/src/main/java/org/apache/flink/runtime/highavailability/zookeeper/ZooKeeperMultipleComponentLeaderElectionHaServices.java ########## @@ -0,0 +1,179 @@ +/* + * 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.highavailability.zookeeper; + +import org.apache.flink.api.common.JobID; +import org.apache.flink.configuration.Configuration; +import org.apache.flink.runtime.blob.BlobStoreService; +import org.apache.flink.runtime.leaderelection.DefaultLeaderElectionService; +import org.apache.flink.runtime.leaderelection.DefaultMultipleComponentLeaderElectionService; +import org.apache.flink.runtime.leaderelection.LeaderElectionService; +import org.apache.flink.runtime.leaderelection.MultipleComponentLeaderElectionService; +import org.apache.flink.runtime.leaderelection.ZooKeeperMultipleComponentLeaderElectionDriverFactory; +import org.apache.flink.runtime.leaderretrieval.LeaderRetrievalService; +import org.apache.flink.runtime.rpc.FatalErrorHandler; +import org.apache.flink.runtime.util.ZooKeeperUtils; +import org.apache.flink.util.ExceptionUtils; +import org.apache.flink.util.FlinkRuntimeException; + +import org.apache.flink.shaded.curator4.org.apache.curator.framework.CuratorFramework; + +import javax.annotation.Nullable; +import javax.annotation.concurrent.GuardedBy; + +import java.util.concurrent.Executor; + +/** + * ZooKeeper HA services that only use a single leader election per process. + * + * <pre> + * /flink + * +/cluster_id_1/leader/latch + * | | /resource_manager/connection_info + * | | /dispatcher/connection_info + * | | /rest_server/connection_info + * | | /job-id-1/connection_info + * | | /job-id-2/connection_info + * | | + * | | + * | +jobgraphs/job-id-1 + * | | /job-id-2 + * | +jobs/job-id-1/checkpoints/latest + * | | /latest-1 + * | | /latest-2 + * | | /checkpoint_id_counter + * </pre> + */ +public class ZooKeeperMultipleComponentLeaderElectionHaServices + extends AbstractZooKeeperHaServices { + + private final Object lock = new Object(); + + private final CuratorFramework leaderNamespacedCuratorFramework; + + private final FatalErrorHandler fatalErrorHandler; + + @Nullable + @GuardedBy("lock") + private MultipleComponentLeaderElectionService multipleComponentLeaderElectionService = null; + + public ZooKeeperMultipleComponentLeaderElectionHaServices( + CuratorFrameworkWithUnhandledErrorListener curatorFrameworkWrapper, + Configuration config, + Executor ioExecutor, + BlobStoreService blobStoreService, + FatalErrorHandler fatalErrorHandler) + throws Exception { + super(curatorFrameworkWrapper, ioExecutor, config, blobStoreService); + this.leaderNamespacedCuratorFramework = + ZooKeeperUtils.useNamespaceAndEnsurePath( + getCuratorFramework(), ZooKeeperUtils.getLeaderPath()); + this.fatalErrorHandler = fatalErrorHandler; + } + + @Override + protected LeaderElectionService createLeaderElectionService(String leaderName) { + final MultipleComponentLeaderElectionService multipleComponentLeaderElectionService; + + synchronized (lock) { + multipleComponentLeaderElectionService = getOrInitializeSingleLeaderElectionService(); + } + + return new DefaultLeaderElectionService( + multipleComponentLeaderElectionService.createDriverFactory(leaderName)); + } + + @GuardedBy("lock") + private MultipleComponentLeaderElectionService getOrInitializeSingleLeaderElectionService() { + if (multipleComponentLeaderElectionService == null) { + try { + multipleComponentLeaderElectionService = + new DefaultMultipleComponentLeaderElectionService( + fatalErrorHandler, + "Single leader election service.", + new ZooKeeperMultipleComponentLeaderElectionDriverFactory( + leaderNamespacedCuratorFramework)); + } catch (Exception e) { + throw new FlinkRuntimeException( + String.format( + "Could not initialize the %s", + DefaultMultipleComponentLeaderElectionService.class + .getSimpleName()), + e); + } + } + + return multipleComponentLeaderElectionService; + } + + @Override + protected LeaderRetrievalService createLeaderRetrievalService(String leaderPath) { Review comment: Yes, I think what we would save by moving it to the `AbstractZooKeeperHaServices` does not offset the potential costs that the leader election and retrieval service are not close together which makes it easier to keep them in sync. -- This is an automated message from the Apache Git Service. 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