当前页面: 在线文档首页 > JBoss 4.0.1 sp1 cluster API Documentation 英文版文档

DistributedTimedCachePolicy (JBoss Cluster API) - JBoss 4.0.1 sp1 cluster API Documentation 英文版文档

Overview  Package   Class  Use  Tree  Deprecated  Index  Help
PREV CLASS   NEXT CLASS	FRAMES    NO FRAMES
SUMMARY: NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

---

org.jboss.ha.framework.server.util
Class DistributedTimedCachePolicy

java.lang.Object
  java.util.TimerTask
      org.jboss.ha.framework.server.util.DistributedTimedCachePolicy

All Implemented Interfaces:

org.jboss.util.CachePolicy, Runnable

---

public class DistributedTimedCachePolicy

extends TimerTask

implements org.jboss.util.CachePolicy

An implementation of a timed cache. This is a cache whose entries have a limited lifetime with the ability to refresh their lifetime. The entries managed by the cache implement the TimedCachePolicy.TimedEntry interface. If an object inserted into the cache does not implement this interface, it will be wrapped in a DefaultTimedEntry and will expire without the possibility of refresh after getDefaultLifetime() seconds. This is a lazy cache policy in that objects are not checked for expiration until they are accessed.

Version:

$Revision: 1.2 $

Author:

Scott Stark.

---

Nested Class Summary
static interface	DistributedTimedCachePolicy.TimedEntry           The interface that cache entries support.

 

Field Summary
protected  String	category
protected  int	defaultLifetime           The lifetime in seconds to use for objects inserted that do not implement the TimedEntry interface.
protected  DistributedState	entryMap           The map of cached TimedEntry objects.
protected static org.jboss.logging.Logger	log
protected  long	now           The caches notion of the current time
protected  String	partitionName
protected  int	resolution           The resolution in seconds of the cach current time
protected static Timer	resolutionTimer

 

Constructor Summary

DistributedTimedCachePolicy(String category, String partitionName, int defaultLifetime)           Creates a new TimedCachePolicy with the given default entry lifetime that does not synchronized access to its policy store and uses a 60 second resolution.

DistributedTimedCachePolicy(String category, String partitionName, int defaultLifetime, int resolution)           Creates a new TimedCachePolicy with the given default entry lifetime that does/does not synchronized access to its policy store depending on the value of threadSafe.

 

Method Summary
void	create()           Initializes the cache for use.
long	currentTimeMillis()           Get the cache time.
void	destroy()           Clears the cache of all entries.
void	flush()           Remove all entries from the cache.
Object	get(Object key)           Get the cache value for key if it has not expired.
int	getDefaultLifetime()           Get the default lifetime of cache entries.
void	insert(Object key, Object value)           Insert a value into the cache.
Object	peek(Object key)           Get the cache value for key.
DistributedTimedCachePolicy.TimedEntry	peekEntry(Object key)           Get the raw TimedEntry for key without performing any expiration check.
void	remove(Object key)           Remove the entry associated with key and call destroy on the entry if found.
void	run()           The TimerTask run method.
void	setDefaultLifetime(int defaultLifetime)           Set the default lifetime of cache entries for new values added to the cache.
int	size()
void	start()           Schedules this with the class resolutionTimer Timer object for execution every resolution seconds.
void	stop()           Stop cancels the resolution timer and flush()es the cache.

 

Methods inherited from class java.util.TimerTask

cancel, scheduledExecutionTime

 

Methods inherited from class java.lang.Object

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

 

Field Detail

resolutionTimer

protected static Timer resolutionTimer

---

log

protected static org.jboss.logging.Logger log

---

entryMap

protected DistributedState entryMap

The map of cached TimedEntry objects.

---

category

protected String category

---

partitionName

protected String partitionName

---

defaultLifetime

protected int defaultLifetime

The lifetime in seconds to use for objects inserted that do not implement the TimedEntry interface.

---

now

protected long now

The caches notion of the current time

---

resolution

protected int resolution

The resolution in seconds of the cach current time

Constructor Detail

DistributedTimedCachePolicy

public DistributedTimedCachePolicy(String category,
                                   String partitionName,
                                   int defaultLifetime)

Creates a new TimedCachePolicy with the given default entry lifetime that does not synchronized access to its policy store and uses a 60 second resolution.

---

DistributedTimedCachePolicy

public DistributedTimedCachePolicy(String category,
                                   String partitionName,
                                   int defaultLifetime,
                                   int resolution)

Creates a new TimedCachePolicy with the given default entry lifetime that does/does not synchronized access to its policy store depending on the value of threadSafe.

Parameters:

category - the name of the catetegory used in the DistributedState access calls.

partitionName - the name of the HAPartition who's replicated state service will be used as the cache store.

defaultLifetime - the lifetime in seconds to use for objects inserted that do not implement the TimedEntry interface.

resolution - the resolution in seconds of the cache timer. A cache does not query the system time on every get() invocation. Rather the cache updates its notion of the current time every 'resolution' seconds.

See Also:

DistributedState

Method Detail

create

public void create()
            throws Exception

Initializes the cache for use. Prior to this the cache has no store.

Specified by:

create in interface org.jboss.util.CachePolicy

Throws:

Exception

---

start

public void start()

Schedules this with the class resolutionTimer Timer object for execution every resolution seconds.

Specified by:

start in interface org.jboss.util.CachePolicy

---

stop

public void stop()

Stop cancels the resolution timer and flush()es the cache.

Specified by:

stop in interface org.jboss.util.CachePolicy

---

destroy

public void destroy()

Clears the cache of all entries.

Specified by:

destroy in interface org.jboss.util.CachePolicy

---

get

public Object get(Object key)

Get the cache value for key if it has not expired. If the TimedEntry is expired its destroy method is called and then removed from the cache.

Specified by:

get in interface org.jboss.util.CachePolicy

Returns:

the TimedEntry value or the original value if it was not an instance of TimedEntry if key is in the cache, null otherwise.

---

peek

public Object peek(Object key)

Get the cache value for key. This method does not check to see if the entry has expired.

Specified by:

peek in interface org.jboss.util.CachePolicy

Returns:

the TimedEntry value or the original value if it was not an instancee of TimedEntry if key is in the cache, null otherwise.

---

insert

public void insert(Object key,
                   Object value)

Insert a value into the cache. In order to have the cache entry reshresh itself value would have to implement TimedEntry and implement the required refresh() method logic.

Specified by:

insert in interface org.jboss.util.CachePolicy

Parameters:

key - the key for the cache entry

value - Either an instance of TimedEntry that will be inserted without change, or an abitrary value that will be wrapped in a non-refreshing TimedEntry.

---

remove

public void remove(Object key)

Remove the entry associated with key and call destroy on the entry if found.

Specified by:

remove in interface org.jboss.util.CachePolicy

---

flush

public void flush()

Remove all entries from the cache.

Specified by:

flush in interface org.jboss.util.CachePolicy

---

size

public int size()

Specified by:

size in interface org.jboss.util.CachePolicy

---

getDefaultLifetime

public int getDefaultLifetime()

Get the default lifetime of cache entries.

Returns:

default lifetime in seconds of cache entries.

---

setDefaultLifetime

public void setDefaultLifetime(int defaultLifetime)

Set the default lifetime of cache entries for new values added to the cache.

Parameters:

defaultLifetime - lifetime in seconds of cache values that do not implement TimedEntry.

---

run

public void run()

The TimerTask run method. It updates the cache time to the current system time.

Specified by:

run in interface Runnable

---

currentTimeMillis

public long currentTimeMillis()

Get the cache time.

Returns:

the cache time last obtained from System.currentTimeMillis()

---

peekEntry

public DistributedTimedCachePolicy.TimedEntry peekEntry(Object key)

Get the raw TimedEntry for key without performing any expiration check.

Returns:

the TimedEntry value associated with key if one exists, null otherwise.

---

Overview  Package   Class  Use  Tree  Deprecated  Index  Help
PREV CLASS   NEXT CLASS	FRAMES    NO FRAMES
SUMMARY: NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

---

Copyright © 2002 JBoss Group, LLC. All Rights Reserved.