org.xmlBlaster.engine
Class TopicAccessor

java.lang.Object
  org.xmlBlaster.engine.TopicAccessor

public final class TopicAccessor

extends java.lang.Object

Singleton in ServerScope to access a TopicHandler instance.

Used to guarantee single threaded access to a TopicHandler instance. Only well defined methods allow dirty reads from other threads simultaneously, further we have a pattern to dispatch the topicHandler access to a worker thread.

Author:

Marcel Ruff

See Also:

The engine.message.lifecylce requirement, TestTopicLifeCycle

Nested Class Summary

private class	TopicAccessor.Consumer Called by msgUnitWrapper.toDestroyed(): this.glob.getTopicAccessor().entryDestroyed_scheduleForExecution(this); Is currently switched off (not used)
private class	TopicAccessor.TopicContainer Helper class to hold the TopicHandler and some additonal locking information.

Field Summary

private edu.emory.mathcs.backport.java.util.concurrent.BlockingQueue	blockingQueue
private static java.util.logging.Logger	log
private ServerScope	serverScope
private java.util.Map	topicHandlerMap Map for TopicContainer.
private java.util.Set	topicListenerSet For listeners who want to be informed about topic creation / deletion events.

Constructor Summary

TopicAccessor(ServerScope serverScope)

Method Summary

TopicHandler	access(java.lang.String oid) Access a topicHandler by its unique oid.
TopicHandler	accessDirtyRead(java.lang.String oid) The topicHandler is not locked, use for read only access only and when you know what you are doing.
private TopicAccessor.TopicContainer	accessTopicContainer(java.lang.String oid)
void	addTopicListener(I_TopicListener l) Adds the specified Topic listener to receive creation/destruction events of Topics.
void	changeDirtyRead(MsgUnitWrapper msgUnitWrapper)
void	entryDestroyed_scheduleForExecution(MsgUnitWrapper msgUnitWrapper) Queue request for later execution, to be outside of sync-locks
void	erase(java.lang.String oid) Remove the given topic
TopicHandler	findOrCreate(SessionInfo sessionInfo, java.lang.String oid) Access a topicHandler by its unique oid or create it if not known.
private void	fireTopicEvent(TopicHandler topicHandler) Is fired on topic creation or destruction.
int	getNumTopics() Access the number of known topics.
I_TopicListener[]	getRemotePropertiesListenerArr() Access a current snapshot of all listeners.
SubscriptionInfo[]	getSubscriptionInfoArrDirtyRead(java.lang.String topicId)
private TopicHandler[]	getTopicHandlerArr() Treat as read only! For class internal use only.
private TopicHandler	getTopicHandlerDirtyRead(java.lang.String topicId)
java.lang.String[]	getTopics() Access oid array
boolean	hasMsgDistributorPluginDirtyRead(java.lang.String topicId)
MsgUnitWrapper	lookupDirtyRead(java.lang.String topicId, long msgUnitWrapperUniqueId) Access the message meat without a lock.
void	release(TopicHandler topicHandler) Return the topicHandler which you previously got with access(String oid).
void	removeTopicListener(I_TopicListener l) Removes the specified listener.
void	spanTopicDestroyTimeout() Called from SessionPersistencePlugin after all sessions / subscriptions are alive after a server startup.
java.lang.String	toXml(java.lang.String extraOffset) Dump all TopicHandler to xml.

Methods inherited from class java.lang.Object

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

Field Detail

serverScope

private final ServerScope serverScope

log

private static java.util.logging.Logger log

topicHandlerMap

private final java.util.Map topicHandlerMap

Map for TopicContainer.

key = oid value from (== topicHandler.getUniqueKey()) value = TopicContainer instance

topicListenerSet

private final java.util.Set topicListenerSet

For listeners who want to be informed about topic creation / deletion events.

blockingQueue

private edu.emory.mathcs.backport.java.util.concurrent.BlockingQueue blockingQueue

Constructor Detail

TopicAccessor

public TopicAccessor(ServerScope serverScope)

Method Detail

access

public TopicHandler access(java.lang.String oid)

Access a topicHandler by its unique oid.

You need to call release(topicHandler) after usage!

Parameters:

oid - topicHandler.getUniqueKey()

Returns:

The topicHandler instance or null, in case of null you don't need to release anything

accessDirtyRead

public TopicHandler accessDirtyRead(java.lang.String oid)

The topicHandler is not locked, use for read only access only and when you know what you are doing.

Parameters:

oid - topicHandler.getUniqueKey()

Returns:

The topicHandler instance or null, you don't need to release anything

accessTopicContainer

private TopicAccessor.TopicContainer accessTopicContainer(java.lang.String oid)

release

public void release(TopicHandler topicHandler)

Return the topicHandler which you previously got with access(String oid).

Parameters:

topicHandler - Currently logs severe if null

findOrCreate

public TopicHandler findOrCreate(SessionInfo sessionInfo,
                                 java.lang.String oid)
                          throws XmlBlasterException

Access a topicHandler by its unique oid or create it if not known.

You need to call release(topicHandler) after usage.

Parameters:

sessionInfo - Can be null if called by a subscription

oid - topicHandler.getUniqueKey()

Returns:

The topicHandler instance but never null

Throws:

XmlBlasterException

erase

public void erase(java.lang.String oid)
           throws XmlBlasterException

Remove the given topic

Throws:

XmlBlasterException

getTopicHandlerArr

private TopicHandler[] getTopicHandlerArr()

Treat as read only! For class internal use only.

Returns:

A current snapshot of all topics (never null)

getTopics

public java.lang.String[] getTopics()

Access oid array

Returns:

A string array of all topicHandler.getUniqueKey()

getNumTopics

public int getNumTopics()

Access the number of known topics.

Returns:

Number of registered topics

spanTopicDestroyTimeout

public void spanTopicDestroyTimeout()

Called from SessionPersistencePlugin after all sessions / subscriptions are alive after a server startup.

The topic destroy timers where inhibited and can now be activated

lookupDirtyRead

public MsgUnitWrapper lookupDirtyRead(java.lang.String topicId,
                                      long msgUnitWrapperUniqueId)
                               throws XmlBlasterException

Access the message meat without a lock.

Parameters:

topicId - The topic oid

msgUnitWrapperUniqueId - The message instance id

Returns:

null if not found

Throws:

XmlBlasterException

changeDirtyRead

public void changeDirtyRead(MsgUnitWrapper msgUnitWrapper)
                     throws XmlBlasterException

Throws:

XmlBlasterException

getTopicHandlerDirtyRead

private TopicHandler getTopicHandlerDirtyRead(java.lang.String topicId)

hasMsgDistributorPluginDirtyRead

public boolean hasMsgDistributorPluginDirtyRead(java.lang.String topicId)

getSubscriptionInfoArrDirtyRead

public final SubscriptionInfo[] getSubscriptionInfoArrDirtyRead(java.lang.String topicId)

Parameters:

topicId - key oid

Returns:

Never null

toXml

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

Dump all TopicHandler to xml. This is implemented as dirty read to gain performance

Parameters:

extraOffset -

Returns:

The markup of all TopicHandlers

Throws:

XmlBlasterException

entryDestroyed_scheduleForExecution

public void entryDestroyed_scheduleForExecution(MsgUnitWrapper msgUnitWrapper)

Queue request for later execution, to be outside of sync-locks

Parameters:

msgUnitWrapper -

addTopicListener

public void addTopicListener(I_TopicListener l)

Adds the specified Topic listener to receive creation/destruction events of Topics.

Note that the fired event holds a locked topicHandler, you shouldn't spend too much time with it to allow other threads to do their work as well

Parameters:

l - Your listener implementation

removeTopicListener

public void removeTopicListener(I_TopicListener l)

Removes the specified listener.

Parameters:

l - Your listener implementation

getRemotePropertiesListenerArr

public I_TopicListener[] getRemotePropertiesListenerArr()

Access a current snapshot of all listeners.

Returns:

The array of registered listeners

fireTopicEvent

private void fireTopicEvent(TopicHandler topicHandler)

Is fired on topic creation or destruction.

Does never throw any exception

Parameters:

topicHandler - The locked! handler