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

Modifier and Type	Field and Description
private List<ServerName>	backupMasters

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.
static int	getBackupMasterInfoPort(ZKWatcher zkw, ServerName sn) Get backup master info port.
List<ServerName>	getBackupMasters()
static List<ServerName>	getBackupMastersAndRenewWatch(ZKWatcher zkw) Retrieves the list of registered backup masters and renews a watch on the znode for children updates.
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.
private void	loadBackupMasters()
void	nodeChildrenChanged(String path) Called when an existing node has a child node added or removed.
static org.apache.hadoop.hbase.shaded.protobuf.generated.ZooKeeperProtos.Master	parse(byte[] data)
protected void	postStart() Called after start is called.
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.
(package private) static byte[]	toByteArray(ServerName sn, int infoPort)

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

Methods inherited from class java.lang.Object

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

Field Detail

backupMasters

private volatile List<ServerName> backupMasters

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

loadBackupMasters

private void loadBackupMasters()

postStart

protected void postStart()

Description copied from class: ZKNodeTracker

Called after start is called. Sub classes could implement this method to load more data on zk.

Overrides:

postStart in class ZKNodeTracker

nodeChildrenChanged

public void nodeChildrenChanged(String path)

Description copied from class: ZKListener

Called when an existing node has a child node added or removed.

Overrides:

nodeChildrenChanged in class ZKListener

Parameters:

path - full path of the node whose children have changed

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

getBackupMasterInfoPort

public static int getBackupMasterInfoPort(ZKWatcher zkw,
                                          ServerName sn)
                                   throws org.apache.zookeeper.KeeperException,
                                          IOException

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

Parameters:

zkw - ZKWatcher to use

sn - ServerName of the backup master

Returns:

backup master info port in the the master address znode or 0 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

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.

toByteArray

static byte[] toByteArray(ServerName sn,
                          int infoPort)

Parameters:

sn - must not be null

Returns:

Content of the master znode as a serialized pb with the pb magic as prefix.

parse

public static org.apache.hadoop.hbase.shaded.protobuf.generated.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

getBackupMasters

public List<ServerName> getBackupMasters()

getBackupMastersAndRenewWatch

public static List<ServerName> getBackupMastersAndRenewWatch(ZKWatcher zkw)
                                                      throws InterruptedIOException

Retrieves the list of registered backup masters and renews a watch on the znode for children updates.

Parameters:

zkw - Zookeeper watcher to use

Returns:

List of backup masters.

Throws:

InterruptedIOException - if there is any issue fetching the required data from Zookeeper.