org.apache.flink.runtime.leaderelection

Class StandaloneLeaderElectionService

java.lang.Object

org.apache.flink.runtime.leaderelection.StandaloneLeaderElectionService

All Implemented Interfaces:

LeaderElectionService

public class StandaloneLeaderElectionService
extends Object
implements LeaderElectionService

Standalone implementation of the LeaderElectionService interface. The standalone implementation assumes that there is only a single LeaderContender and thus directly grants him the leadership upon start up. Furthermore, there is no communication needed between multiple standalone leader election services.

Constructor Summary

Constructors

Constructor and Description
StandaloneLeaderElectionService()

Method Summary

Modifier and Type	Method and Description
void	confirmLeadership(UUID leaderSessionID, String leaderAddress) Confirms that the LeaderContender has accepted the leadership identified by the given leader session id.
boolean	hasLeadership(UUID leaderSessionId) Returns true if the LeaderContender with which the service has been started owns currently the leadership under the given leader session id.
void	start(LeaderContender newContender) Starts the leader election service.
void	stop() Stops the leader election service.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

StandaloneLeaderElectionService

public StandaloneLeaderElectionService()

Method Detail

start

public void start(LeaderContender newContender)
           throws Exception

Description copied from interface: LeaderElectionService

Starts the leader election service. This method can only be called once.

Specified by:

start in interface LeaderElectionService

Parameters:

newContender - LeaderContender which applies for the leadership

Throws:

Exception

stop

public void stop()

Description copied from interface: LeaderElectionService

Stops the leader election service.

Specified by:

stop in interface LeaderElectionService

confirmLeadership

public void confirmLeadership(UUID leaderSessionID,
                              String leaderAddress)

Description copied from interface: LeaderElectionService

Confirms that the LeaderContender has accepted the leadership identified by the given leader session id. It also publishes the leader address under which the leader is reachable.

The rational behind this method is to establish an order between setting the new leader session ID in the LeaderContender and publishing the new leader session ID as well as the leader address to the leader retrieval services.

Specified by:

confirmLeadership in interface LeaderElectionService

Parameters:

leaderSessionID - The new leader session ID

leaderAddress - The address of the new leader

hasLeadership

public boolean hasLeadership(@Nonnull
                             UUID leaderSessionId)

Description copied from interface: LeaderElectionService

Returns true if the LeaderContender with which the service has been started owns currently the leadership under the given leader session id.

Specified by:

hasLeadership in interface LeaderElectionService

Parameters:

leaderSessionId - identifying the current leader

Returns:

true if the associated LeaderContender is the leader, otherwise false