| /* |
| * Copyright 2014-2015 Open Networking Laboratory |
| * |
| * Licensed 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.onosproject.cluster; |
| |
| import java.util.List; |
| import java.util.Map; |
| import java.util.Set; |
| |
| /** |
| * Service for leader election. |
| * Leadership contests are organized around topics. A instance can join the |
| * leadership race for a topic or withdraw from a race it has previously joined. |
| * Listeners can be added to receive notifications asynchronously for various |
| * leadership contests. |
| */ |
| public interface LeadershipService { |
| |
| /** |
| * Returns the current leader for the topic. |
| * |
| * @param path topic |
| * @return nodeId of the leader, null if so such topic exists. |
| */ |
| NodeId getLeader(String path); |
| |
| /** |
| * Returns the current leadership info for the topic. |
| * |
| * @param path topic |
| * @return leadership info or null if so such topic exists. |
| */ |
| Leadership getLeadership(String path); |
| |
| /** |
| * Returns the set of topics owned by the specified node. |
| * |
| * @param nodeId node Id. |
| * @return set of topics for which this node is the current leader. |
| */ |
| Set<String> ownedTopics(NodeId nodeId); |
| |
| /** |
| * Joins the leadership contest. |
| * |
| * @param path topic for which this controller node wishes to be a leader. |
| */ |
| void runForLeadership(String path); |
| |
| /** |
| * Withdraws from a leadership contest. |
| * |
| * @param path topic for which this controller node no longer wishes to be a leader. |
| */ |
| void withdraw(String path); |
| |
| /** |
| * Returns the current leader board. |
| * |
| * @return mapping from topic to leadership info. |
| */ |
| Map<String, Leadership> getLeaderBoard(); |
| |
| /** |
| * Returns the candidates for all known topics. |
| * |
| * @return A mapping from topics to corresponding list of candidates. |
| */ |
| Map<String, List<NodeId>> getCandidates(); |
| |
| /** |
| * Returns the candidates for a given topic. |
| * |
| * @param path topic |
| * @return A lists of NodeIds, which may be empty. |
| */ |
| List<NodeId> getCandidates(String path); |
| |
| /** |
| * Registers a event listener to be notified of leadership events. |
| * |
| * @param listener listener that will asynchronously notified of leadership events. |
| */ |
| void addListener(LeadershipEventListener listener); |
| |
| /** |
| * Unregisters a event listener for leadership events. |
| * |
| * @param listener listener to be removed. |
| */ |
| void removeListener(LeadershipEventListener listener); |
| } |