Package org.onosproject.store.service

Interface LeaderElector

All Superinterfaces:

DistributedPrimitive

All Known Implementing Classes:

DefaultLeaderElector

public interface LeaderElector
extends DistributedPrimitive

LeaderElector provides the same functionality as AsyncLeaderElector with the only difference that all its methods block until the corresponding operation completes.

Nested Class Summary

Nested classes/interfaces inherited from interface org.onosproject.store.service.DistributedPrimitive

DistributedPrimitive.Status, DistributedPrimitive.Type

Field Summary

Fields inherited from interface org.onosproject.store.service.DistributedPrimitive

DEFAULT_OPERATION_TIMEOUT_MILLIS

Method Summary

Modifier and Type	Method	Description
void	addChangeListener(Consumer<Change<Leadership>> consumer)	Registers a listener to be notified of Leadership changes for all topics.
boolean	anoint(String topic, NodeId nodeId)	Attempts to promote a node to leadership displacing the current leader.
boolean	demote(String topic, NodeId nodeId)	Attempts to demote a node to the bottom of the candidate list.
void	evict(NodeId nodeId)	Attempts to evict a node from all leadership elections it is registered for.
Leadership	getLeadership(String topic)	Returns the Leadership for the specified topic.
Map<String,Leadership>	getLeaderships()	Returns the current Leaderships for all topics.
default DistributedPrimitive.Type	primitiveType()	Returns the type of primitive.
boolean	promote(String topic, NodeId nodeId)	Attempts to promote a node to top of candidate list.
void	removeChangeListener(Consumer<Change<Leadership>> consumer)	Unregisters a previously registered change notification listener.
Leadership	run(String topic, NodeId nodeId)	Attempts to become leader for a topic.
void	withdraw(String topic)	Withdraws from leadership race for a topic.

Methods inherited from interface org.onosproject.store.service.DistributedPrimitive

addStatusChangeListener, applicationId, destroy, name, removeStatusChangeListener, statusChangeListeners

Method Detail

primitiveType

default DistributedPrimitive.Type primitiveType()

Description copied from interface: DistributedPrimitive

Returns the type of primitive.

Specified by:

primitiveType in interface DistributedPrimitive

Returns:

primitive type

run

Leadership run(String topic,
               NodeId nodeId)

Attempts to become leader for a topic.

Parameters:

topic - leadership topic

nodeId - instance identifier of the node

Returns:

current Leadership state of the topic

withdraw

void withdraw(String topic)

Withdraws from leadership race for a topic.

Parameters:

topic - leadership topic

anoint

boolean anoint(String topic,
               NodeId nodeId)

Attempts to promote a node to leadership displacing the current leader.

Parameters:

topic - leadership topic

nodeId - instance identifier of the new leader

Returns:

true if leadership transfer was successfully executed; false if it failed. This operation can return false if the node to be made new leader is not registered to run for election for the topic.

promote

boolean promote(String topic,
                NodeId nodeId)

Attempts to promote a node to top of candidate list.

Parameters:

topic - leadership topic

nodeId - instance identifier of the new top candidate

Returns:

true if node is now the top candidate. This operation can fail (i.e. return false) if the node is not registered to run for election for the topic.

evict

void evict(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.

Parameters:

nodeId - node instance identifier

getLeadership

Leadership getLeadership(String topic)

Returns the Leadership for the specified topic.

Parameters:

topic - leadership topic

Returns:

current Leadership state of the topic

getLeaderships

Map<String,Leadership> getLeaderships()

Returns the current Leaderships for all topics.

Returns:

topic name to Leadership mapping

addChangeListener

void addChangeListener(Consumer<Change<Leadership>> consumer)

Registers a listener to be notified of Leadership changes for all topics.

Parameters:

consumer - listener to add

removeChangeListener

void removeChangeListener(Consumer<Change<Leadership>> consumer)

Unregisters a previously registered change notification listener.

If the specified listener was not previously registered, this operation will be a noop.

Parameters:

consumer - listener to remove

demote

boolean demote(String topic,
               NodeId nodeId)

Attempts to demote a node to the bottom of the candidate list. It is not allowed to demote the current leader

Parameters:

topic - leadership topic

nodeId - identifier of node to be demoted

Returns:

true if nodeId is now the bottom candidate. This method returns false if nodeId is not one of the candidates for the topic or if it is the leader.