org.apache.flink.runtime.leaderelection

Class DefaultLeaderElectionService

java.lang.Object

org.apache.flink.runtime.leaderelection.DefaultLeaderElectionService

All Implemented Interfaces:

AutoCloseable, LeaderElectionDriver.Listener, LeaderElectionService

public class DefaultLeaderElectionService
extends Object
implements LeaderElectionService, LeaderElectionDriver.Listener, AutoCloseable

Default implementation for leader election service. Composed with different LeaderElectionDriver, we could perform a leader election for the contender, and then persist the leader information to various storage.

DefaultLeaderElectionService handles a single LeaderContender.

Constructor Summary

Constructors

Constructor and Description
DefaultLeaderElectionService(LeaderElectionDriverFactory leaderElectionDriverFactory)
DefaultLeaderElectionService(LeaderElectionDriverFactory leaderElectionDriverFactory, FatalErrorHandler fallbackErrorHandler)

Method Summary

Modifier and Type	Method and Description
void	close()
protected void	confirmLeadership(String componentId, UUID leaderSessionID, String leaderAddress) Confirms the leadership with the leaderSessionID and leaderAddress for the LeaderContender that is associated with the componentId.
LeaderElection	createLeaderElection(String componentId) Creates a new LeaderElection instance that is registered to this LeaderElectionService instance.
UUID	getLeaderSessionID(String componentId) Returns the current leader session ID for the given componentId or null, if the session wasn't confirmed.
protected boolean	hasLeadership(String componentId, UUID leaderSessionId) Checks whether the ParentService has the leadership acquired for the componentId and leaderSessionID.
void	onError(Throwable t) Notifies the listener if an error occurred.
void	onGrantLeadership(UUID leaderSessionID) Callback that is called once the driver obtains the leadership.
void	onLeaderInformationChange(LeaderInformationRegister changedLeaderInformation) Notifies the listener about all currently known leader information.
void	onLeaderInformationChange(String componentId, LeaderInformation leaderInformation) Notifies the listener about a changed leader information for the given component.
void	onRevokeLeadership() Callback that is called once the driver loses the leadership.
protected void	register(String componentId, LeaderContender contender) Registers the LeaderContender under the componentId with the underlying ParentService.
protected void	remove(String componentId) Removes the LeaderContender from the ParentService that is associated with the componentId.

Methods inherited from class java.lang.Object

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

Constructor Detail

DefaultLeaderElectionService

public DefaultLeaderElectionService(LeaderElectionDriverFactory leaderElectionDriverFactory)

DefaultLeaderElectionService

@VisibleForTesting
public DefaultLeaderElectionService(LeaderElectionDriverFactory leaderElectionDriverFactory,
                                                       FatalErrorHandler fallbackErrorHandler)

Method Detail

createLeaderElection

public LeaderElection createLeaderElection(String componentId)

Description copied from interface: LeaderElectionService

Creates a new LeaderElection instance that is registered to this LeaderElectionService instance.

Specified by:

createLeaderElection in interface LeaderElectionService

Parameters:

componentId - a unique identifier that refers to the stored leader information that the newly created LeaderElection manages.

register

protected void register(String componentId,
                        LeaderContender contender)
                 throws Exception

Registers the LeaderContender under the componentId with the underlying ParentService. Leadership changes are starting to be reported to the LeaderContender.

Throws:

Exception

remove

protected final void remove(String componentId)
                     throws Exception

Removes the LeaderContender from the ParentService that is associated with the componentId.

Throws:

Exception

close

public void close()
           throws Exception

Specified by:

close in interface AutoCloseable

Throws:

Exception

confirmLeadership

protected void confirmLeadership(String componentId,
                                 UUID leaderSessionID,
                                 String leaderAddress)

Confirms the leadership with the leaderSessionID and leaderAddress for the LeaderContender that is associated with the componentId.

hasLeadership

protected boolean hasLeadership(String componentId,
                                UUID leaderSessionId)

Checks whether the ParentService has the leadership acquired for the componentId and leaderSessionID.

Returns:

true if the service has leadership with the passed leaderSessionID acquired; false otherwise.

getLeaderSessionID

@VisibleForTesting
 @Nullable
public UUID getLeaderSessionID(String componentId)

Returns the current leader session ID for the given componentId or null, if the session wasn't confirmed.

onGrantLeadership

public void onGrantLeadership(UUID leaderSessionID)

Description copied from interface: LeaderElectionDriver.Listener

Callback that is called once the driver obtains the leadership.

Specified by:

onGrantLeadership in interface LeaderElectionDriver.Listener

onRevokeLeadership

public void onRevokeLeadership()

Description copied from interface: LeaderElectionDriver.Listener

Callback that is called once the driver loses the leadership.

Specified by:

onRevokeLeadership in interface LeaderElectionDriver.Listener

onLeaderInformationChange

public void onLeaderInformationChange(String componentId,
                                      LeaderInformation leaderInformation)

Description copied from interface: LeaderElectionDriver.Listener

Notifies the listener about a changed leader information for the given component.

Specified by:

onLeaderInformationChange in interface LeaderElectionDriver.Listener

Parameters:

componentId - identifying the component whose leader information has changed

leaderInformation - new leader information

onLeaderInformationChange

public void onLeaderInformationChange(LeaderInformationRegister changedLeaderInformation)

Description copied from interface: LeaderElectionDriver.Listener

Notifies the listener about all currently known leader information.

Specified by:

onLeaderInformationChange in interface LeaderElectionDriver.Listener

onError

public void onError(Throwable t)

Description copied from interface: LeaderElectionDriver.Listener

Notifies the listener if an error occurred.

Specified by:

onError in interface LeaderElectionDriver.Listener