org.apache.hadoop.hbase.master

Class ActiveMasterManager

java.lang.Object

org.apache.hadoop.hbase.zookeeper.ZKListener

org.apache.hadoop.hbase.master.ActiveMasterManager

@InterfaceAudience.Private
public class ActiveMasterManager
extends ZKListener

Handles everything on master-side related to master election.

Listens and responds to ZooKeeper notifications on the master znode, both nodeCreated and nodeDeleted.

Contains blocking methods which will hold up backup masters, waiting for the active master to fail.

This class is instantiated in the HMaster constructor and the method #blockUntilBecomingActiveMaster() is called to wait until becoming the active master of the cluster.

Field Summary

Fields

Modifier and Type	Field and Description
(package private) AtomicBoolean	clusterHasActiveMaster
(package private) AtomicBoolean	clusterShutDown
private int	infoPort
private static org.slf4j.Logger	LOG
private Server	master
private ServerName	sn

Fields inherited from class org.apache.hadoop.hbase.zookeeper.ZKListener

watcher

Constructor Summary

Constructors

Constructor and Description
ActiveMasterManager(ZKWatcher watcher, ServerName sn, Server master)

Method Summary

Modifier and Type	Method and Description
(package private) boolean	blockUntilBecomingActiveMaster(int checkInterval, MonitoredTask startupStatus) Block until becoming the active master.
(package private) void	handle(String path)
private void	handleMasterNodeChange() Handle a change in the master node.
(package private) boolean	hasActiveMaster()
void	nodeCreated(String path) Called when a new node has been created.
void	nodeDeleted(String path) Called when a node has been deleted
void	setInfoPort(int infoPort)
void	stop()

Methods inherited from class org.apache.hadoop.hbase.zookeeper.ZKListener

getWatcher, nodeChildrenChanged, nodeDataChanged

Methods inherited from class java.lang.Object

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

Field Detail

LOG

private static final org.slf4j.Logger LOG

clusterHasActiveMaster

final AtomicBoolean clusterHasActiveMaster

clusterShutDown

final AtomicBoolean clusterShutDown

sn

private final ServerName sn

infoPort

private int infoPort

master

private final Server master

Constructor Detail

ActiveMasterManager

ActiveMasterManager(ZKWatcher watcher,
                    ServerName sn,
                    Server master)

Parameters:

watcher -

sn - ServerName

master - In an instance of a Master.

Method Detail

setInfoPort

public void setInfoPort(int infoPort)

nodeCreated

public void nodeCreated(String path)

Description copied from class: ZKListener

Called when a new node has been created.

Overrides:

nodeCreated in class ZKListener

Parameters:

path - full path of the new node

nodeDeleted

public void nodeDeleted(String path)

Description copied from class: ZKListener

Called when a node has been deleted

Overrides:

nodeDeleted in class ZKListener

Parameters:

path - full path of the deleted node

handle

void handle(String path)

handleMasterNodeChange

private void handleMasterNodeChange()

Handle a change in the master node. Doesn't matter whether this was called from a nodeCreated or nodeDeleted event because there are no guarantees that the current state of the master node matches the event at the time of our next ZK request.

Uses the watchAndCheckExists method which watches the master address node regardless of whether it exists or not. If it does exist (there is an active master), it returns true. Otherwise it returns false.

A watcher is set which guarantees that this method will get called again if there is another change in the master node.

blockUntilBecomingActiveMaster

boolean blockUntilBecomingActiveMaster(int checkInterval,
                                       MonitoredTask startupStatus)

Block until becoming the active master. Method blocks until there is not another active master and our attempt to become the new active master is successful. This also makes sure that we are watching the master znode so will be notified if another master dies.

Parameters:

checkInterval - the interval to check if the master is stopped

startupStatus - the monitor status to track the progress

Returns:

True if no issue becoming active master else false if another master was running or if some other problem (zookeeper, stop flag has been set on this Master)

hasActiveMaster

boolean hasActiveMaster()

Returns:

True if cluster has an active master.

stop

public void stop()