Package org.apache.camel.component.zookeepermaster.group.internal

Class ZooKeeperGroup<T extends NodeState>

java.lang.Object

org.apache.camel.component.zookeepermaster.group.internal.ZooKeeperGroup<T>

All Implemented Interfaces:

Closeable, AutoCloseable, Group<T>

Direct Known Subclasses:

ZooKeeperMultiGroup

public class ZooKeeperGroup<T extends NodeState>
extends Object
implements Group<T>

A utility that attempts to keep all data from all children of a ZK path locally cached. This class will watch the ZK path, respond to update/create/delete events, pull down the data, etc. You can register a listener that will get notified when changes occur.

IMPORTANT - it's not possible to stay transactionally in sync. Users of this class must be prepared for false-positives and false-negatives. Additionally, always use the version number when updating data to avoid overwriting another process' change.

Constructor Summary

Constructors

Constructor	Description
ZooKeeperGroup(org.apache.curator.framework.CuratorFramework client, String path, Class<T> clazz)
ZooKeeperGroup(org.apache.curator.framework.CuratorFramework client, String path, Class<T> clazz, ExecutorService executorService)
ZooKeeperGroup(org.apache.curator.framework.CuratorFramework client, String path, Class<T> clazz, ThreadFactory threadFactory)

Method Summary

Modifier and Type	Method	Description
void	add(GroupListener<T> listener)	Registers a listener which will be called when the cluster membership changes or the group is connected or disconnected.
void	clear()	Clears the current data without beginning a new query and without generating any events for listeners.
void	clearAndRefresh()	Clear out current data and begin a new query on the path
void	clearAndRefresh(boolean force, boolean sync)	Clear out current data and begin a new query on the path
void	close()	Close/end the cache
protected void	doUpdate(T state)
protected List<ChildData<T>>	getActiveChildren()	Filter stale nodes and return only active children from the current data.
List<ChildData>	getCurrentData()	Return the current data.
ChildData	getCurrentData(String fullPath)	Return the current data for the given path.
String	getId()
T	getLastState()	Gets the last state.
org.apache.curator.framework.listen.ListenerContainer<GroupListener<T>>	getListenable()	Return the cache listenable
SequenceComparator	getSequenceComparator()
protected void	handleException(Throwable e)	Default behavior is just to log the exception
boolean	isConnected()	Are we connected with the cluster?
boolean	isMaster()	Check if we are the master.
boolean	isUnstable()	Returns an indication that the sequential, ephemeral node may be registered more than once for this group
T	master()	Retrieve the master node.
Map<String,T>	members()	Get the list of members connected to this group.
static <T> Map<String,T>	members(com.fasterxml.jackson.databind.ObjectMapper mapper, org.apache.curator.framework.CuratorFramework curator, String path, Class<T> clazz)
protected void	remove(String fullPath)
void	remove(GroupListener<T> listener)	Removes a previously added listener.
List<T>	slaves()	Retrieve the list of slaves.
void	start()	Start the cache.
void	update(T state)	Update the state of this group member.

Methods inherited from class java.lang.Object

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

Constructor Detail

ZooKeeperGroup

public ZooKeeperGroup(org.apache.curator.framework.CuratorFramework client,
                      String path,
                      Class<T> clazz)

Parameters:

client - the client

path - path to watch

ZooKeeperGroup

public ZooKeeperGroup(org.apache.curator.framework.CuratorFramework client,
                      String path,
                      Class<T> clazz,
                      ThreadFactory threadFactory)

Parameters:

client - the client

path - path to watch

threadFactory - factory to use when creating internal threads

ZooKeeperGroup

public ZooKeeperGroup(org.apache.curator.framework.CuratorFramework client,
                      String path,
                      Class<T> clazz,
                      ExecutorService executorService)

Parameters:

client - the client

path - path to watch

executorService - ExecutorService to use for the ZooKeeperGroup's background thread

Method Detail

start

public void start()

Start the cache. The cache is not started automatically. You must call this method.

Specified by:

start in interface Group<T extends NodeState>

close

public void close()
           throws IOException

Close/end the cache

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Specified by:

close in interface Group<T extends NodeState>

Throws:

IOException - errors

isConnected

public boolean isConnected()

Description copied from interface: Group

Are we connected with the cluster?

Specified by:

isConnected in interface Group<T extends NodeState>

add

public void add(GroupListener<T> listener)

Description copied from interface: Group

Registers a listener which will be called when the cluster membership changes or the group is connected or disconnected.

Specified by:

add in interface Group<T extends NodeState>

remove

public void remove(GroupListener<T> listener)

Description copied from interface: Group

Removes a previously added listener.

Specified by:

remove in interface Group<T extends NodeState>

update

public void update(T state)

Description copied from interface: Group

Update the state of this group member. If the state is null, the member will leave the group. This method can be called even if the group is not started, in which case the state will be stored and updated when the group becomes started.

Specified by:

update in interface Group<T extends NodeState>

Parameters:

state - the new state of this group member

doUpdate

protected void doUpdate(T state)
                 throws Exception

Throws:

Exception

members

public Map<String,T> members()

Description copied from interface: Group

Get the list of members connected to this group.

Specified by:

members in interface Group<T extends NodeState>

isMaster

public boolean isMaster()

Description copied from interface: Group

Check if we are the master.

Specified by:

isMaster in interface Group<T extends NodeState>

master

public T master()

Description copied from interface: Group

Retrieve the master node.

Specified by:

master in interface Group<T extends NodeState>

slaves

public List<T> slaves()

Description copied from interface: Group

Retrieve the list of slaves.

Specified by:

slaves in interface Group<T extends NodeState>

getActiveChildren

protected List<ChildData<T>> getActiveChildren()

Filter stale nodes and return only active children from the current data.

Returns:

list of active children and data

getLastState

public T getLastState()

Description copied from interface: Group

Gets the last state.

This can be used by clients to access that last state, such as when the clients is being added as a listener but wants to retrieve the last state to be up to date when the client is added.

Specified by:

getLastState in interface Group<T extends NodeState>

Returns:

the state, or null if no last state yet.

getSequenceComparator

public SequenceComparator getSequenceComparator()

getListenable

public org.apache.curator.framework.listen.ListenerContainer<GroupListener<T>> getListenable()

Return the cache listenable

Returns:

listenable

getCurrentData

public List<ChildData> getCurrentData()

Return the current data. There are no guarantees of accuracy. This is merely the most recent view of the data. The data is returned in sorted order.

Returns:

list of children and data

getCurrentData

public ChildData getCurrentData(String fullPath)

Return the current data for the given path. There are no guarantees of accuracy. This is merely the most recent view of the data. If there is no child with that path, null is returned.

Parameters:

fullPath - full path to the node to check

Returns:

data or null

clearAndRefresh

public void clearAndRefresh()
                     throws Exception

Clear out current data and begin a new query on the path

Throws:

Exception - errors

clearAndRefresh

public void clearAndRefresh(boolean force,
                            boolean sync)
                     throws Exception

Clear out current data and begin a new query on the path

Parameters:

force - - whether to force clear and refresh to trigger updates

sync - - whether to run this synchronously (block current thread) or asynchronously

Throws:

Exception - errors

clear

public void clear()

Clears the current data without beginning a new query and without generating any events for listeners.

handleException

protected void handleException(Throwable e)

Default behavior is just to log the exception

Parameters:

e - the exception

remove

protected void remove(String fullPath)

members

public static <T> Map<String,T> members(com.fasterxml.jackson.databind.ObjectMapper mapper,
                                              org.apache.curator.framework.CuratorFramework curator,
                                              String path,
                                              Class<T> clazz)
                                       throws Exception

Throws:

Exception

getId

public String getId()

isUnstable

public boolean isUnstable()

Returns an indication that the sequential, ephemeral node may be registered more than once for this group