org.apache.storm.nimbus

Interface ILeaderElector

All Superinterfaces:

AutoCloseable, Closeable

All Known Implementing Classes:

LeaderElectorImp

public interface ILeaderElector
extends Closeable

The interface for leader election.

Method Summary

Modifier and Type	Method and Description
void	addToLeaderLockQueue() queue up for leadership lock.
void	close() Method called to allow for cleanup.
List<NimbusInfo>	getAllNimbuses()
NimbusInfo	getLeader()
boolean	isLeader()
void	prepare(Map conf) Method guaranteed to be called as part of initialization of leader elector instance.
void	removeFromLeaderLockQueue() Removes the caller from the leader lock queue.

Method Detail

prepare

void prepare(Map conf)

Method guaranteed to be called as part of initialization of leader elector instance.

Parameters:

conf - configuration

addToLeaderLockQueue

void addToLeaderLockQueue()
                   throws Exception

queue up for leadership lock. The call returns immediately and the caller must check isLeader() to perform any leadership action. This method can be called multiple times so it needs to be idempotent.

Throws:

Exception

removeFromLeaderLockQueue

void removeFromLeaderLockQueue()
                        throws Exception

Removes the caller from the leader lock queue. If the caller is leader also releases the lock. This method can be called multiple times so it needs to be idempotent.

Throws:

Exception

isLeader

boolean isLeader()
          throws Exception

Returns:

true if the caller currently has the leader lock.

Throws:

Exception

getLeader

NimbusInfo getLeader()

Returns:

the current leader’s address , may return null if no one has the lock.

getAllNimbuses

List<NimbusInfo> getAllNimbuses()
                         throws Exception

Returns:

list of current nimbus addresses, includes leader.

Throws:

Exception

close

void close()

Method called to allow for cleanup. once close this object can not be reused.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable