org.exolab.jms.messagemgr
Class QueueDestinationCache

java.lang.Object
  |
  +--org.exolab.jms.messagemgr.AbstractDestinationCache
        |
        +--org.exolab.jms.messagemgr.QueueDestinationCache

All Implemented Interfaces:

DestinationCache, GarbageCollectable, LeaseEventListenerIfc, MessageManagerEventListener

public class QueueDestinationCache

extends AbstractDestinationCache

A DestinationCache for queues.

Version:

$Revision: 1.9 $ $Date: 2006/06/09 12:58:56 $

Author:

Jim Alateras, Tim Anderson

Constructor Summary

QueueDestinationCache(JmsQueue queue, DatabaseService database, LeaseManager leases, ServerConnectionManager connections)
Construct a new QueueDestinationCache.

Method Summary

protected void	addMessage(MessageRef reference, MessageImpl message, MessageHandle handle) Add a message, and notify any listeners.
void	addQueueListener(QueueBrowserEndpoint listener) A Queue can also hav a queue listener, which simply gets informed of all messages that arrive at this destination.
boolean	canDestroy() Determines if this cache can be destroyed.
void	destroy() Destroy this object.
MessageHandle	getMessage(Selector selector, Condition cancel) Returns the first available message matching the supplied message selector.
int	getMessageCount() Returns the number of messages in the cache.
boolean	hasConsumers() Determines if there are any registered consumers.
protected void	init() Initialise the cache.
void	messageAdded(JmsDestination destination, MessageImpl message) Invoked when the MessageMgr receives a non-persistent message.
protected void	messageExpired(MessageRef reference) Remove an expired non-peristent message, and notify any listeners.
protected void	notifyQueueListeners(MessageHandle handle, MessageImpl message) Notify queue browsers that a message has arrived.
void	persistentMessageAdded(JmsDestination destination, MessageImpl message) Invoked when the MessageMgr receives a persistent message.
protected void	persistentMessageExpired(MessageRef reference) Remove an expired persistent message, and notify any listeners.
void	playbackMessages(QueueBrowserEndpoint browser) Playback all the messages in the cache to the specified QueueBrowserEndpoint.
void	removeQueueListener(QueueBrowserEndpoint listener) Remove the queue listener associated with this cache
void	returnMessageHandle(MessageHandle handle) Return a message handle back to the cache, to recover unsent or unacknowledged messages.

Methods inherited from class org.exolab.jms.messagemgr.AbstractDestinationCache

addConsumer, addMessage, checkMessageExpiry, checkMessageExpiry, collectGarbage, getConsumerArray, getConsumerEndpoint, getDestination, getMessageCache, onLeaseExpired, removeConsumer

Methods inherited from class java.lang.Object

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

Constructor Detail

QueueDestinationCache

public QueueDestinationCache(JmsQueue queue,
                             DatabaseService database,
                             LeaseManager leases,
                             ServerConnectionManager connections)
                      throws javax.jms.JMSException

Construct a new QueueDestinationCache.

Parameters:

queue - the queue to cache messages for

database - the database service

leases - the lease manager

connections - the connection manager

Throws:

javax.jms.JMSException - if the cache can't be initialised

Method Detail

addQueueListener

public void addQueueListener(QueueBrowserEndpoint listener)

A Queue can also hav a queue listener, which simply gets informed of all messages that arrive at this destination.

Parameters:

listener - - queue listener

removeQueueListener

public void removeQueueListener(QueueBrowserEndpoint listener)

Remove the queue listener associated with this cache

Parameters:

listener - - queue listener to remove

messageAdded

public void messageAdded(JmsDestination destination,
                         MessageImpl message)
                  throws javax.jms.JMSException

Invoked when the MessageMgr receives a non-persistent message.

Parameters:

destination - the message's destination

message - the message

Throws:

javax.jms.JMSException - if the listener fails to handle the message

persistentMessageAdded

public void persistentMessageAdded(JmsDestination destination,
                                   MessageImpl message)
                            throws javax.jms.JMSException,
                                   PersistenceException

Invoked when the MessageMgr receives a persistent message.

Parameters:

destination - the message's destination

message - the message

Throws:

javax.jms.JMSException - if the listener fails to handle the message

PersistenceException - if there is a persistence related problem

getMessage

public MessageHandle getMessage(Selector selector,
                                Condition cancel)
                         throws javax.jms.JMSException

Returns the first available message matching the supplied message selector.

Parameters:

selector - the message selector to use. May be null

cancel -

Returns:

handle to the first message, or null if there are no messages, or none matching selector

Throws:

javax.jms.JMSException - for any error

playbackMessages

public void playbackMessages(QueueBrowserEndpoint browser)
                      throws javax.jms.JMSException

Playback all the messages in the cache to the specified QueueBrowserEndpoint.

Parameters:

browser - the queue browser

Throws:

javax.jms.JMSException - for any error

returnMessageHandle

public void returnMessageHandle(MessageHandle handle)

Return a message handle back to the cache, to recover unsent or unacknowledged messages.

Parameters:

handle - the message handle to return

hasConsumers

public boolean hasConsumers()

Determines if there are any registered consumers.

Overrides:

hasConsumers in class AbstractDestinationCache

Returns:

true if there are registered consumers

getMessageCount

public int getMessageCount()

Returns the number of messages in the cache.

Overrides:

getMessageCount in class AbstractDestinationCache

Returns:

the number of messages in the cache

canDestroy

public boolean canDestroy()

Determines if this cache can be destroyed. A QueueDestinationCache can be destroyed if there are no active consumers and:

• the queue is persistent and there are no messages
• the queue is temporary and the corresponding connection is closed

Overrides:

canDestroy in class AbstractDestinationCache

Returns:

true if the cache can be destroyed, otherwise false

destroy

public void destroy()

Destroy this object.

Overrides:

destroy in class AbstractDestinationCache

init

protected void init()
             throws javax.jms.JMSException

Initialise the cache. This removes all the expired messages, and then retrieves all unacked messages from the database and stores them locally.

Throws:

javax.jms.JMSException - if the cache can't be initialised

addMessage

protected void addMessage(MessageRef reference,
                          MessageImpl message,
                          MessageHandle handle)
                   throws javax.jms.JMSException

Add a message, and notify any listeners.

Parameters:

reference - a reference to the message

message - the message

handle - the handle to add

Throws:

javax.jms.JMSException - for any error

notifyQueueListeners

protected void notifyQueueListeners(MessageHandle handle,
                                    MessageImpl message)
                             throws javax.jms.JMSException

Notify queue browsers that a message has arrived.

Parameters:

handle - a handle to the message

message - the message

Throws:

javax.jms.JMSException - if a browser fails to handle the message

messageExpired

protected void messageExpired(MessageRef reference)
                       throws javax.jms.JMSException

Remove an expired non-peristent message, and notify any listeners.

Overrides:

messageExpired in class AbstractDestinationCache

Parameters:

reference - the reference to the expired message

Throws:

javax.jms.JMSException - for any error

persistentMessageExpired

protected void persistentMessageExpired(MessageRef reference)
                                 throws javax.jms.JMSException,
                                        PersistenceException

Remove an expired persistent message, and notify any listeners.

Overrides:

persistentMessageExpired in class AbstractDestinationCache

Parameters:

reference - the reference to the expired message

Throws:

javax.jms.JMSException - if a listener fails to handle the expiration

PersistenceException - if there is a persistence related problem