org.apache.curator.framework.recipes.cache

Class TreeCache

java.lang.Object

org.apache.curator.framework.recipes.cache.TreeCache

All Implemented Interfaces:

Closeable, AutoCloseable

public class TreeCache
extends Object
implements Closeable

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.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	TreeCache.Builder

Constructor Summary

Constructors

Constructor and Description
TreeCache(org.apache.curator.framework.CuratorFramework client, String path) Create a TreeCache for the given client and path with default options.

Method Summary

Modifier and Type	Method and Description
void	close() Close/end the cache.
Map<String,ChildData>	getCurrentChildren(String fullPath) Return the current set of children at the given path, mapped by child name.
ChildData	getCurrentData(String fullPath) Return the current data for the given path.
org.apache.curator.framework.listen.Listenable<TreeCacheListener>	getListenable() Return the cache listenable
org.apache.curator.framework.listen.Listenable<org.apache.curator.framework.api.UnhandledErrorListener>	getUnhandledErrorListenable() Allows catching unhandled errors in asynchornous operations.
static TreeCache.Builder	newBuilder(org.apache.curator.framework.CuratorFramework client, String path) Create a TreeCache builder for the given client and path to configure advanced options.
TreeCache	start() Start the cache.

Methods inherited from class java.lang.Object

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

Constructor Detail

TreeCache

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

Create a TreeCache for the given client and path with default options.

If the client is namespaced, all operations on the resulting TreeCache will be in terms of the namespace, including all published events. The given path is the root at which the TreeCache will watch and explore. If no node exists at the given path, the TreeCache will be initially empty.

Parameters:

client - the client to use; may be namespaced

path - the path to the root node to watch/explore; this path need not actually exist on the server

See Also:

newBuilder(CuratorFramework, String)

Method Detail

newBuilder

public static TreeCache.Builder newBuilder(org.apache.curator.framework.CuratorFramework client,
                                           String path)

Create a TreeCache builder for the given client and path to configure advanced options.

If the client is namespaced, all operations on the resulting TreeCache will be in terms of the namespace, including all published events. The given path is the root at which the TreeCache will watch and explore. If no node exists at the given path, the TreeCache will be initially empty.

Parameters:

client - the client to use; may be namespaced

path - the path to the root node to watch/explore; this path need not actually exist on the server

Returns:

a new builder

start

public TreeCache start()
                throws Exception

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

Returns:

this

Throws:

Exception - errors

close

public void close()

Close/end the cache.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

getListenable

public org.apache.curator.framework.listen.Listenable<TreeCacheListener> getListenable()

Return the cache listenable

Returns:

listenable

getUnhandledErrorListenable

public org.apache.curator.framework.listen.Listenable<org.apache.curator.framework.api.UnhandledErrorListener> getUnhandledErrorListenable()

Allows catching unhandled errors in asynchornous operations. TODO: consider making public.

getCurrentChildren

public Map<String,ChildData> getCurrentChildren(String fullPath)

Return the current set of children at the given path, mapped by child name. There are no guarantees of accuracy; this is merely the most recent view of the data. If there is no node at this path, null is returned.

Parameters:

fullPath - full path to the node to check

Returns:

a possibly-empty list of children if the node is alive, or null

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 node at the given path, null is returned.

Parameters:

fullPath - full path to the node to check

Returns:

data if the node is alive, or null