org.apache.hadoop.hbase.zookeeper

Class MasterAddressTracker

java.lang.Object

org.apache.hadoop.hbase.zookeeper.ZKListener

org.apache.hadoop.hbase.zookeeper.ZKNodeTracker

org.apache.hadoop.hbase.zookeeper.MasterAddressTracker

@InterfaceAudience.Private
public class MasterAddressTracker
extends ZKNodeTracker

Manages the location of the current active Master for the RegionServer.

Listens for ZooKeeper events related to the master address. The node /master will contain the address of the current master. This listener is interested in NodeDeleted and NodeCreated events on /master.

Utilizes ZKNodeTracker for zk interactions.

You can get the current master via getMasterAddress() or via getMasterAddress(ZKWatcher) if you do not have a running instance of this Tracker in your context.

This class also includes utility for interacting with the master znode, for writing and reading the znode content.

Field Summary

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

abortable, LOG, node

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

watcher

Constructor Summary

Constructors

Constructor and Description
MasterAddressTracker(ZKWatcher watcher, Abortable abortable) Construct a master address listener with the specified zookeeper reference.

Method Summary

Modifier and Type	Method and Description
static boolean	deleteIfEquals(ZKWatcher zkw, String content) delete the master znode if its content is same as the parameter
int	getBackupMasterInfoPort(ServerName sn) Get the info port of the backup master if it is available.
ServerName	getMasterAddress() Get the address of the current master if one is available.
ServerName	getMasterAddress(boolean refresh) Get the address of the current master if one is available.
static ServerName	getMasterAddress(ZKWatcher zkw) Get master address.
int	getMasterInfoPort() Get the info port of the current master of one is available.
static int	getMasterInfoPort(ZKWatcher zkw) Get master info port.
boolean	hasMaster() Check if there is a master available.
static ZooKeeperProtos.Master	parse(byte[] data)
static boolean	setMasterAddress(ZKWatcher zkw, String znode, ServerName master, int infoPort) Set master address into the master znode or into the backup subdirectory of backup masters; switch off the passed in znode path.

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

blockUntilAvailable, blockUntilAvailable, checkIfBaseNodeAvailable, getData, getNode, nodeCreated, nodeDataChanged, nodeDeleted, start, stop, toString

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

getWatcher, nodeChildrenChanged

Methods inherited from class java.lang.Object

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

Constructor Detail

MasterAddressTracker

public MasterAddressTracker(ZKWatcher watcher,
                            Abortable abortable)

Construct a master address listener with the specified zookeeper reference.

This constructor does not trigger any actions, you must call methods explicitly. Normally you will just want to execute ZKNodeTracker.start() to begin tracking of the master address.

Parameters:

watcher - zk reference and watcher

abortable - abortable in case of fatal error

Method Detail

getMasterAddress

public ServerName getMasterAddress()

Get the address of the current master if one is available. Returns null if no current master.

Returns:

Server name or null if timed out.

getMasterInfoPort

public int getMasterInfoPort()

Get the info port of the current master of one is available. Return 0 if no current master or zookeeper is unavailable

Returns:

info port or 0 if timed out

getBackupMasterInfoPort

public int getBackupMasterInfoPort(ServerName sn)

Get the info port of the backup master if it is available. Return 0 if no backup master or zookeeper is unavailable

Parameters:

sn - server name of backup master

Returns:

info port or 0 if timed out or exceptions

getMasterAddress

public ServerName getMasterAddress(boolean refresh)

Get the address of the current master if one is available. Returns null if no current master. If refresh is set, try to load the data from ZK again, otherwise, cached data will be used.

Parameters:

refresh - whether to refresh the data by calling ZK directly.

Returns:

Server name or null if timed out.

getMasterAddress

public static ServerName getMasterAddress(ZKWatcher zkw)
                                   throws org.apache.zookeeper.KeeperException,
                                          IOException

Get master address. Use this instead of getMasterAddress() if you do not have an instance of this tracker in your context.

Parameters:

zkw - ZKWatcher to use

Returns:

ServerName stored in the the master address znode or null if no znode present.

Throws:

org.apache.zookeeper.KeeperException - if a ZooKeeper operation fails

IOException - if the address of the ZooKeeper master cannot be retrieved

getMasterInfoPort

public static int getMasterInfoPort(ZKWatcher zkw)
                             throws org.apache.zookeeper.KeeperException,
                                    IOException

Get master info port. Use this instead of getMasterInfoPort() if you do not have an instance of this tracker in your context.

Parameters:

zkw - ZKWatcher to use

Returns:

master info port in the the master address znode or null if no znode present. // TODO can't return null for 'int' return type. non-static verison returns 0

Throws:

org.apache.zookeeper.KeeperException - if a ZooKeeper operation fails

IOException - if the address of the ZooKeeper master cannot be retrieved

setMasterAddress

public static boolean setMasterAddress(ZKWatcher zkw,
                                       String znode,
                                       ServerName master,
                                       int infoPort)
                                throws org.apache.zookeeper.KeeperException

Set master address into the master znode or into the backup subdirectory of backup masters; switch off the passed in znode path.

Parameters:

zkw - The ZKWatcher to use.

znode - Where to create the znode; could be at the top level or it could be under backup masters

master - ServerName of the current master must not be null.

Returns:

true if node created, false if not; a watch is set in both cases

Throws:

org.apache.zookeeper.KeeperException - if a ZooKeeper operation fails

hasMaster

public boolean hasMaster()

Check if there is a master available.

Returns:

true if there is a master set, false if not.

parse

public static ZooKeeperProtos.Master parse(byte[] data)
                                    throws DeserializationException

Parameters:

data - zookeeper data. may be null

Returns:

pb object of master, null if no active master

Throws:

DeserializationException - if the parsing fails

deleteIfEquals

public static boolean deleteIfEquals(ZKWatcher zkw,
                                     String content)

delete the master znode if its content is same as the parameter

Parameters:

zkw - must not be null

content - must not be null