org.onosproject.store.service.LeaderElector Maven / Gradle / Ivy
/*
* Copyright 2016 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.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.
*
* 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 getLeaderships();
/**
* Registers a listener to be notified of Leadership changes for all topics.
* @param consumer listener to add
*/
void addChangeListener(Consumer> consumer);
/**
* Unregisters a previously registered change notification listener.
*
* If the specified listener was not previously registered, this operation will be a noop.
* @param consumer listener to remove
*/
void removeChangeListener(Consumer> consumer);
}