| /* |
| * Copyright 2016-present Open Networking Foundation |
| * |
| * 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.store.service; |
| |
| import java.util.Map; |
| import java.util.function.Consumer; |
| |
| import org.onosproject.cluster.Leadership; |
| import org.onosproject.cluster.NodeId; |
| import org.onosproject.event.Change; |
| |
| /** |
| * {@code LeaderElector} provides the same functionality as {@link AsyncLeaderElector} with |
| * the only difference that all its methods block until the corresponding operation completes. |
| */ |
| public interface LeaderElector extends DistributedPrimitive { |
| |
| @Override |
| default DistributedPrimitive.Type primitiveType() { |
| return DistributedPrimitive.Type.LEADER_ELECTOR; |
| } |
| |
| /** |
| * Attempts to become leader for a topic. |
| * @param topic leadership topic |
| * @param nodeId instance identifier of the node |
| * @return current Leadership state of the topic |
| */ |
| Leadership run(String topic, NodeId nodeId); |
| |
| /** |
| * Withdraws from leadership race for a topic. |
| * @param topic leadership topic |
| */ |
| void withdraw(String topic); |
| |
| /** |
| * Attempts to promote a node to leadership displacing the current leader. |
| * @param topic leadership topic |
| * @param nodeId instance identifier of the new leader |
| * @return {@code true} if leadership transfer was successfully executed; {@code false} if it failed. |
| * This operation can return {@code false} if the node to be made new leader is not registered to |
| * run for election for the topic. |
| */ |
| boolean anoint(String topic, NodeId nodeId); |
| |
| /** |
| * Attempts to promote a node to top of candidate list. |
| * |
| * @param topic leadership topic |
| * @param nodeId instance identifier of the new top candidate |
| * @return {@code true} if node is now the top candidate. This operation can fail (i.e. return |
| * {@code false}) if the node is not registered to run for election for the topic. |
| */ |
| boolean promote(String topic, NodeId nodeId); |
| |
| /** |
| * Attempts to evict a node from all leadership elections it is registered for. |
| * <p> |
| * If the node the current leader for a topic, this call will force the next candidate (if one exists) |
| * to be promoted to leadership. |
| * @param nodeId node instance identifier |
| */ |
| void evict(NodeId nodeId); |
| |
| /** |
| * Returns the {@link Leadership} for the specified topic. |
| * @param topic leadership topic |
| * @return current Leadership state of the topic |
| */ |
| Leadership getLeadership(String topic); |
| |
| /** |
| * Returns the current {@link Leadership}s for all topics. |
| * @return topic name to Leadership mapping |
| */ |
| Map<String, Leadership> getLeaderships(); |
| |
| /** |
| * Registers a listener to be notified of Leadership changes for all topics. |
| * @param consumer listener to add |
| */ |
| void addChangeListener(Consumer<Change<Leadership>> consumer); |
| |
| /** |
| * Unregisters a previously registered change notification listener. |
| * <p> |
| * If the specified listener was not previously registered, this operation will be a noop. |
| * @param consumer listener to remove |
| */ |
| void removeChangeListener(Consumer<Change<Leadership>> consumer); |
| } |