| /** |
| * 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.storm.nimbus; |
| |
| import java.util.List; |
| import java.util.Map; |
| import java.util.concurrent.TimeUnit; |
| import org.apache.storm.shade.com.google.common.annotations.VisibleForTesting; |
| |
| /** |
| * The interface for leader election. |
| */ |
| public interface ILeaderElector extends AutoCloseable { |
| |
| /** |
| * Method guaranteed to be called as part of initialization of leader elector instance. |
| * @param conf configuration |
| */ |
| void prepare(Map<String, Object> conf); |
| |
| /** |
| * queue up for leadership lock. The call returns immediately and the caller must |
| * check isLeader() to perform any leadership action. This method can be called |
| * multiple times so it needs to be idempotent. |
| */ |
| void addToLeaderLockQueue() throws Exception; |
| |
| /** |
| * Removes the caller from leadership election, relinquishing leadership if acquired, then requeues for leadership after the specified |
| * delay. |
| * @param delayMs The delay to wait before re-entering the election |
| */ |
| void quitElectionFor(int delayMs) throws Exception; |
| |
| /** |
| * Decide if the caller currently has the leader lock. |
| * @return true if the caller currently has the leader lock. |
| */ |
| boolean isLeader() throws Exception; |
| |
| /** |
| * Get the current leader's address. |
| * @return the current leader's address, may return null if no one has the lock. |
| */ |
| NimbusInfo getLeader(); |
| |
| /** |
| * Wait for the caller to gain leadership. This should only be used in single-Nimbus clusters, and is only useful to allow testing |
| * code to wait for a LocalCluster's Nimbus to gain leadership before trying to submit topologies. |
| * |
| * @return true is leadership was acquired, false otherwise |
| */ |
| @VisibleForTesting |
| boolean awaitLeadership(long timeout, TimeUnit timeUnit) throws InterruptedException; |
| |
| /** |
| * Get list of current nimbus addresses. |
| * @return list of current nimbus addresses, includes leader. |
| */ |
| List<NimbusInfo> getAllNimbuses() throws Exception; |
| |
| /** |
| * Method called to allow for cleanup. Relinquishes leadership if owned by the caller. |
| */ |
| @Override |
| void close() throws Exception; |
| } |
| |