| /* |
| * 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.samza.coordinator; |
| |
| import org.apache.samza.annotation.InterfaceStability; |
| |
| |
| /** |
| * Leader elector async primitives, implemented based on ZK. |
| * The callback is a async, and run in a separate (common) thread. |
| * So the caller should never block in the callback. |
| * Callbacks will be delivered on callback at a time. Others will wait. |
| * |
| */ |
| @InterfaceStability.Evolving |
| public interface LeaderElector { |
| /** |
| * Register a LeaderElectorListener |
| * |
| * @param listener {@link LeaderElectorListener} interfaces to be invoked upon completion of leader election participation |
| */ |
| void setLeaderElectorListener(LeaderElectorListener listener); |
| |
| /** |
| * Async method that helps the caller participate in leader election. |
| **/ |
| void tryBecomeLeader(); |
| |
| /** |
| * Method that allows a caller to resign from leadership role. Caller can resign from leadership due to various |
| * reasons such as shutdown, connection failures etc. |
| * This method should clear any state created by the leader and clean-up the resources used by the leader. |
| */ |
| void resignLeadership(); |
| |
| /** |
| * Method that can be used to know if the caller is the current leader or not |
| * |
| * @return True, if the caller is the current leader. False, otherwise |
| */ |
| boolean amILeader(); |
| } |