org.apache.flink.runtime.leaderelection

Interface LeaderElectionEventHandler

All Known Implementing Classes:

DefaultLeaderElectionService

public interface LeaderElectionEventHandler

Interface which should be implemented to respond to leader changes in LeaderElectionDriver.

Important: The LeaderElectionDriver could not guarantee that there is no LeaderElectionEventHandler callbacks happen after AutoCloseable.close(). This means that the implementor of LeaderElectionEventHandler is responsible for filtering out spurious callbacks(e.g. after close has been called on LeaderElectionDriver).

Method Summary

Modifier and Type	Method and Description
void	onGrantLeadership(UUID newLeaderSessionId) Called by specific LeaderElectionDriver when the leadership is granted.
void	onLeaderInformationChange(LeaderInformation leaderInformation) Called by specific LeaderElectionDriver when the leader information is changed.
void	onRevokeLeadership() Called by specific LeaderElectionDriver when the leadership is revoked.

Method Detail

onGrantLeadership

void onGrantLeadership(UUID newLeaderSessionId)

Called by specific LeaderElectionDriver when the leadership is granted.

Parameters:

newLeaderSessionId - the valid leader session id

onRevokeLeadership

void onRevokeLeadership()

Called by specific LeaderElectionDriver when the leadership is revoked.

onLeaderInformationChange

void onLeaderInformationChange(LeaderInformation leaderInformation)

Called by specific LeaderElectionDriver when the leader information is changed. Then the LeaderElectionService could write the leader information again if necessary. This method should only be called when LeaderElectionDriver.hasLeadership() is true. Duplicated leader change events could happen, so the implementation should check whether the passed leader information is really different with internal confirmed leader information.

Parameters:

leaderInformation - leader information which contains leader session id and leader address.