org.apache.hadoop.hive.metastore.leader

Class LeaseLeaderElection

java.lang.Object

org.apache.hadoop.hive.metastore.leader.LeaseLeaderElection

All Implemented Interfaces:

Closeable, AutoCloseable, LeaderElection<TableName>

public class LeaseLeaderElection
extends Object
implements LeaderElection<TableName>

Hive Lock based leader election. If wins, the current instance becomes the leader, and a heartbeat daemon will be spawned to refresh the lock before timeout. If loses, a non-leader watcher will also be spawned to check the lock periodically to see if he can grab the lock to be the leader. The change of Leadership can be received by registering the listeners through LeaderElection.addStateListener(org.apache.hadoop.hive.metastore.leader.LeaderElection.LeadershipStateListener).

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.hadoop.hive.metastore.leader.LeaderElection

LeaderElection.LeadershipStateListener

Field Summary

Fields

Modifier and Type	Field and Description
static String	METASTORE_RENEW_LEASE

Constructor Summary

Constructors

Constructor and Description
LeaseLeaderElection()

Method Summary

Modifier and Type	Method and Description
void	addStateListener(LeaderElection.LeadershipStateListener listener) Register listeners to get notified when leadership changes.
void	close()
long	getLockId()
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, TableName table) Place where election happens

Methods inherited from class java.lang.Object

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

Field Detail

METASTORE_RENEW_LEASE

public static final String METASTORE_RENEW_LEASE

See Also:

Constant Field Values

Constructor Detail

LeaseLeaderElection

public LeaseLeaderElection()
                    throws IOException

Throws:

IOException

Method Detail

tryBeLeader

public void tryBeLeader(org.apache.hadoop.conf.Configuration conf,
                        TableName table)
                 throws LeaderException

Description copied from interface: LeaderElection

Place where election happens

Specified by:

tryBeLeader in interface LeaderElection<TableName>

Parameters:

conf - configuration

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

Throws:

LeaderException

addStateListener

public void addStateListener(LeaderElection.LeadershipStateListener listener)

Description copied from interface: LeaderElection

Register listeners to get notified when leadership changes.

Specified by:

addStateListener in interface LeaderElection<TableName>

Parameters:

listener - The listener to be added

isLeader

public boolean isLeader()

Description copied from interface: LeaderElection

Getting the result of election.

Specified by:

isLeader in interface LeaderElection<TableName>

Returns:

true if wins the election, false otherwise.

close

public void close()

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

getLockId

public long getLockId()

setName

public void setName(String name)

Description copied from interface: LeaderElection

Set the name of this leader candidate

Specified by:

setName in interface LeaderElection<TableName>

Parameters:

name - the name

getName

public String getName()

Description copied from interface: LeaderElection

Get the name of this leader candidate

Specified by:

getName in interface LeaderElection<TableName>