org.apache.hadoop.hive.metastore.leader

Interface LeaderElection<T>

Type Parameters:

T - the type of mutex

All Superinterfaces:

AutoCloseable, Closeable

All Known Implementing Classes:

LeaseLeaderElection, StaticLeaderElection

public interface LeaderElection<T>
extends Closeable

Interface for leader election. As a result of leader election, an instance is changed to either leader or follower(non-leader). Leader means that the instance has won the leader election. To receive leadership change event, please register LeaderElection.LeadershipStateListener before election happens.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	LeaderElection.LeadershipStateListener

Method Summary

Modifier and Type	Method and Description
void	addStateListener(LeaderElection.LeadershipStateListener listener) Register listeners to get notified when leadership changes.
String	getName() Get the name of this leader candidate
boolean	isLeader() Getting the result of election.
void	setName(String name) Set the name of this leader candidate
void	tryBeLeader(org.apache.hadoop.conf.Configuration conf, T mutex) Place where election happens

Methods inherited from interface java.io.Closeable

close

Method Detail

tryBeLeader

void tryBeLeader(org.apache.hadoop.conf.Configuration conf,
                 T mutex)
          throws LeaderException

Place where election happens

Parameters:

conf - configuration

mutex - a global mutex for leader election. It can be a path in Zookeeper, or a table that going to be locked.

Throws:

LeaderException

isLeader

boolean isLeader()

Getting the result of election.

Returns:

true if wins the election, false otherwise.

addStateListener

void addStateListener(LeaderElection.LeadershipStateListener listener)

Register listeners to get notified when leadership changes.

Parameters:

listener - The listener to be added

setName

void setName(String name)

Set the name of this leader candidate

Parameters:

name - the name

getName

String getName()

Get the name of this leader candidate