Package org.apache.accumulo.core.fate.zookeeper

Class ZooCache

java.lang.Object

org.apache.accumulo.core.fate.zookeeper.ZooCache

public class ZooCache
extends Object

A cache for values stored in ZooKeeper. Values are kept up to date as they change.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ZooCache.ZcStat

Constructor Summary

Constructors

Constructor	Description
ZooCache(ZooReader reader, org.apache.zookeeper.Watcher watcher)	Creates a new cache.

Method Summary

Modifier and Type	Method	Description
void	clear()	Clears this cache.
void	clear(String zPath)	Clears this cache of all information about nodes rooted at the given path.
void	close()
protected void	copyStats(ZooCache.ZcStat userStat, ZooCache.ZcStat cachedStat)	Helper method to copy stats from the cached stat into userStat
byte[]	get(String zPath)	Gets data at the given path.
byte[]	get(String zPath, ZooCache.ZcStat status)	Gets data at the given path, filling status information into the given Stat object.
List<String>	getChildren(String zPath)	Gets the children of the given node.
byte[]	getLockData(ServiceLock.ServiceLockPath path)
long	getUpdateCount()	Returns a monotonically increasing count of the number of time the cache was updated.

Methods inherited from class java.lang.Object

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

Constructor Detail

ZooCache

public ZooCache(ZooReader reader,
                org.apache.zookeeper.Watcher watcher)

Creates a new cache. The given watcher is called whenever a watched node changes.

Parameters:

reader - ZooKeeper reader

watcher - watcher object

Method Detail

getChildren

public List<String> getChildren(String zPath)

Gets the children of the given node. A watch is established by this call.

Parameters:

zPath - path of node

Returns:

children list, or null if node has no children or does not exist

get

public byte[] get(String zPath)

Gets data at the given path. Status information is not returned. A watch is established by this call.

Parameters:

zPath - path to get

Returns:

path data, or null if non-existent

get

public byte[] get(String zPath,
                  ZooCache.ZcStat status)

Gets data at the given path, filling status information into the given Stat object. A watch is established by this call.

Parameters:

zPath - path to get

status - status object to populate

Returns:

path data, or null if non-existent

copyStats

protected void copyStats(ZooCache.ZcStat userStat,
                         ZooCache.ZcStat cachedStat)

Helper method to copy stats from the cached stat into userStat

Parameters:

userStat - user Stat object

cachedStat - cached statistic, that is or will be cached

clear

public void clear()

Clears this cache.

close

public void close()

getUpdateCount

public long getUpdateCount()

Returns a monotonically increasing count of the number of time the cache was updated. If the count is the same, then it means cache did not change.

clear

public void clear(String zPath)

Clears this cache of all information about nodes rooted at the given path.

Parameters:

zPath - path of top node

getLockData

public byte[] getLockData(ServiceLock.ServiceLockPath path)