org.xmlBlaster.client
Class SynchronousCache

java.lang.Object
  org.xmlBlaster.client.SynchronousCache

public final class SynchronousCache
extends java.lang.Object

Caches the messages updated from xmlBlaster.

It is used to allow local (client side) cached messages which you can access with the synchronous getCached() method.

If XmlBlasterAccess has switched this cache on, a getCached() automatically makes a subscribe() behind the scenes as well and subsequent getCached() are high performing local calls.

Author:

konrad.krafft@doubleslash.de, xmlblaster@marcelruff.info

See Also:

XmlBlasterAccess.getCached(GetKey, GetQos), TestSynchronousCache, client.cache requirement

Field Summary

private Global	glob
private int	maxQueriesCached
private static java.lang.String	ME
private java.util.Hashtable	query2SubId key==getQueryString(GetKey getKey), value=subscriptionId
private java.util.Hashtable	subscriptions key==subscriptionId, value=dataHashtable And dataHashtable key=keyOid, value=MsgUnit

Constructor Summary

SynchronousCache(Global glob, int maxQueriesCached)
Create a cache instance.

Method Summary

void	clear() Destroy all entries in the cash
MsgUnit[]	get(GetKey getKey, GetQos getQos) Access messages from cache
int	getNumQueriesCached() Return how full is this cache.
java.lang.String	getQueryString(GetKey getKey) Create a unique key for our Hashtable from a GetKey
private java.lang.String	getQueryString(java.lang.String subscriptionId) Access the query key for a given subscriptionId.
java.util.Hashtable	getSubscriptions() Return the registered subscriptions, for internal use only (to check cache).
boolean	newEntry(java.lang.String subId, GetKey getKey, MsgUnit[] units) Creates an new entry in the cache
void	removeEntry(java.lang.String subId) Remove a cache entry with the given subscriptionId.
void	removeEntryByQueryString(java.lang.String query) Remove a cache entry with the given query key string.
void	removeEntryByQueryString(java.lang.String query, java.lang.String keyOid) Remove a MsgUnit from cache with the given query key string and keyOid.
java.lang.String	toXml(java.lang.String extraOffset) Dump state of this object into a XML ASCII string.
boolean	update(java.lang.String subId, UpdateKey updateKey, byte[] content, UpdateQos updateQos) Updated the cache (add a new entry or replaces an existing or removes one).

Methods inherited from class java.lang.Object

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

Field Detail

ME

private static final java.lang.String ME

See Also:

Constant Field Values

glob

private final Global glob

query2SubId

private java.util.Hashtable query2SubId

key==getQueryString(GetKey getKey), value=subscriptionId

subscriptions

private java.util.Hashtable subscriptions

key==subscriptionId, value=dataHashtable
And dataHashtable key=keyOid, value=MsgUnit

maxQueriesCached

private int maxQueriesCached

Constructor Detail

SynchronousCache

public SynchronousCache(Global glob,
                        int maxQueriesCached)

Create a cache instance.

Method Detail

removeEntry

public void removeEntry(java.lang.String subId)

Remove a cache entry with the given subscriptionId.

This is usually called by the update() ERASE event

removeEntryByQueryString

public void removeEntryByQueryString(java.lang.String query,
                                     java.lang.String keyOid)

Remove a MsgUnit from cache with the given query key string and keyOid.

This is usually called by the update() ERASE event for XPATH queries, when the last oid disappears the cache entry is removed

removeEntryByQueryString

public void removeEntryByQueryString(java.lang.String query)

Remove a cache entry with the given query key string.

This is usually called by the update() ERASE event for EXACT queries.

getQueryString

private java.lang.String getQueryString(java.lang.String subscriptionId)

Access the query key for a given subscriptionId. Slow linear lookup ...

Returns:

null if not found

update

public boolean update(java.lang.String subId,
                      UpdateKey updateKey,
                      byte[] content,
                      UpdateQos updateQos)
               throws XmlBlasterException

Updated the cache (add a new entry or replaces an existing or removes one).

Returns:

true if message was for cache, false if we are not interested in such a message.

Throws:

XmlBlasterException

get

public MsgUnit[] get(GetKey getKey,
                     GetQos getQos)
              throws XmlBlasterException

Access messages from cache

Returns:

null if no messages are found in cache

Throws:

XmlBlasterException

getQueryString

public java.lang.String getQueryString(GetKey getKey)

Create a unique key for our Hashtable from a GetKey

newEntry

public boolean newEntry(java.lang.String subId,
                        GetKey getKey,
                        MsgUnit[] units)
                 throws XmlBlasterException

Creates an new entry in the cache

Returns:

true - entry has been created false- cache is full

Throws:

XmlBlasterException

clear

public void clear()

Destroy all entries in the cash

getNumQueriesCached

public int getNumQueriesCached()

Return how full is this cache.

getSubscriptions

public java.util.Hashtable getSubscriptions()

Return the registered subscriptions, for internal use only (to check cache).

Returns:

key==getQueryString(GetKey getKey), value=subscriptionId

toXml

public final java.lang.String toXml(java.lang.String extraOffset)

Dump state of this object into a XML ASCII string.

Parameters:

extraOffset - indenting of tags for nice output

Returns:

internal state of SynchronousCache as a XML ASCII string