org.apache.curator.framework.recipes.cache

Class NodeCache

java.lang.Object

org.apache.curator.framework.recipes.cache.NodeCache

All Implemented Interfaces:

Closeable, AutoCloseable

public class NodeCache
extends Object
implements Closeable

A utility that attempts to keep the data from a node locally cached. This class will watch the node, 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 and Description
NodeCache(org.apache.curator.framework.CuratorFramework client, String path)
NodeCache(org.apache.curator.framework.CuratorFramework client, String path, boolean dataIsCompressed)

Method Summary

Modifier and Type	Method and Description
void	close()
ChildData	getCurrentData() Return the current data.
org.apache.curator.framework.listen.ListenerContainer<NodeCacheListener>	getListenable() Return the cache listenable
protected void	handleException(Throwable e) Default behavior is just to log the exception
void	rebuild() NOTE: this is a BLOCKING method.
void	start() Start the cache.
void	start(boolean buildInitial) Same as start() but gives the option of doing an initial build

Methods inherited from class java.lang.Object

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

Constructor Detail

NodeCache

public NodeCache(org.apache.curator.framework.CuratorFramework client,
                 String path)

Parameters:

client - curztor client

path - the full path to the node to cache

NodeCache

public NodeCache(org.apache.curator.framework.CuratorFramework client,
                 String path,
                 boolean dataIsCompressed)

Parameters:

client - curztor client

path - the full path to the node to cache

dataIsCompressed - if true, data in the path is compressed

Method Detail

start

public void start()
           throws Exception

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

Throws:

Exception - errors

start

public void start(boolean buildInitial)
           throws Exception

Same as start() but gives the option of doing an initial build

Parameters:

buildInitial - if true, rebuild() will be called before this method returns in order to get an initial view of the node

Throws:

Exception - errors

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException

getListenable

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

Return the cache listenable

Returns:

listenable

rebuild

public void rebuild()
             throws Exception

NOTE: this is a BLOCKING method. Completely rebuild the internal cache by querying for all needed data WITHOUT generating any events to send to listeners.

Throws:

Exception - errors

getCurrentData

public ChildData getCurrentData()

Return the current data. There are no guarantees of accuracy. This is merely the most recent view of the data. If the node does not exist, this returns null

Returns:

data or null

handleException

protected void handleException(Throwable e)

Default behavior is just to log the exception

Parameters:

e - the exception