parakhnr commented on code in PR #2488: URL: https://github.com/apache/helix/pull/2488#discussion_r1195751673
########## meta-client/src/main/java/org/apache/helix/metaclient/recipes/leaderelection/LeaderElectionClient.java: ########## @@ -0,0 +1,125 @@ +package org.apache.helix.metaclient.recipes.leaderelection; + +/* + * 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. + */ + +import java.util.List; + +import org.apache.helix.metaclient.api.MetaClientInterface; +import org.apache.helix.metaclient.factories.MetaClientConfig; + + +/** + * LeaderElectionClient does distributed leader election using CRUD and change notification APIs + * provided by underlying metadata client. Leader election config can provide many + * configs like base path for all participating nodes, sync/async mode, TTL etc. + * + * Participants join a leader election group by calling the following API. + * The Leader Election client maintains and elect an active leader from participant pool + * All participants wanted to be elected as leader joins a pool + * LeaderElection client maintains an active leader, by monitoring liveness of current leader and + * re-elect if needed and user no need to call elect or re-elect explicitly. + * This LeaderElection client will notify registered listeners for any leadership change. + */ +public class LeaderElectionClient { + + /** + * Construct a LeaderElectionClient using a user passed in leaderElectionConfig. It creates a MetaClient + * instance underneath. + * When MetaClient is auto closed be cause of being disconnected and auto retry connection timed out, A new + * MetaClient instance will be created and keeps retry connection. + */ + public LeaderElectionClient(MetaClientConfig metaClientConfig) { + + } + + /** + * Construct a LeaderElectionClient using a user passed in MetaClient object + * When MetaClient is auto closed be cause of being disconnected and auto retry connection timed out, user + * will need to create a new MetaClient and a new LeaderElectionClient instance. + */ + public LeaderElectionClient(MetaClientInterface MetaClient) { + + } + + /** + * Returns true if current participant is able to acquire leadership. + */ + public boolean isLeader(String leaderPath, String participant) { Review Comment: Yeah, the comment made me think like it's acquiring leadership, so an update would be helpful. When you say there is no explicit elect leader call, do you mean `joinLeaderElectionParticipantPool()` will trigger a leader election for that path if there isn't a leader elected? If so can you update the description of the method. -- 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] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
