org.exolab.jms.messagemgr
Class AbstractDestinationCache

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

All Implemented Interfaces:

DestinationCache, GarbageCollectable, LeaseEventListenerIfc, MessageManagerEventListener

Direct Known Subclasses:

QueueDestinationCache

public abstract class AbstractDestinationCache

extends java.lang.Object

implements DestinationCache, LeaseEventListenerIfc

Abstract implementation of the DestinationCache interface.

Version:

$Revision: 1.4 $ $Date: 2007/01/24 12:00:28 $

Author:

Tim Anderson

Constructor Summary

AbstractDestinationCache(JmsDestination destination, DatabaseService database, LeaseManager leases)
Construct a new AbstractDestinationCache.

Method Summary

boolean	addConsumer(ConsumerEndpoint consumer) Register a consumer with this cache.
protected void	addMessage(MessageRef reference, MessageImpl message) Add a message reference and its corresponding message to the cache
boolean	canDestroy() Determines if this cache can be destroyed.
protected void	checkMessageExpiry(MessageRef reference, long expiryTime) Check to see if the message has a TTL.
protected void	checkMessageExpiry(MessageRef reference, MessageImpl message) Check to see if the message has a TTL.
void	collectGarbage(boolean aggressive) Perform any garbage collection on this resource.
void	destroy() Destroy this cache.
protected ConsumerEndpoint[]	getConsumerArray() Helper to return the consumers as an array.
protected ConsumerEndpoint	getConsumerEndpoint(long consumerId) Returns a consumer endpoint, given its id.
JmsDestination	getDestination() Returns the destination that messages are being cached for.
protected org.exolab.jms.messagemgr.DefaultMessageCache	getMessageCache() Returns the message cache.
int	getMessageCount() Returns the number of messages in the cache.
boolean	hasConsumers() Determines if the cache has any consumers.
protected void	messageExpired(MessageRef reference) Remove an expired non-peristent message, and notify any listeners.
void	onLeaseExpired(java.lang.Object object) Invoked when a message lease has expired.
protected void	persistentMessageExpired(MessageRef reference) Remove an expired persistent message, and notify any listeners.
void	removeConsumer(ConsumerEndpoint consumer) Remove the consumer for the list of registered consumers.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.exolab.jms.messagemgr.DestinationCache

returnMessageHandle

Methods inherited from interface org.exolab.jms.messagemgr.MessageManagerEventListener

messageAdded, persistentMessageAdded

Constructor Detail

AbstractDestinationCache

public AbstractDestinationCache(JmsDestination destination,
                                DatabaseService database,
                                LeaseManager leases)

Construct a new AbstractDestinationCache.

Parameters:

destination - the destination to cache messages for

database - the database service

leases - the lease manager

Method Detail

getDestination

public JmsDestination getDestination()

Returns the destination that messages are being cached for.

Specified by:

getDestination in interface DestinationCache

Returns:

the destination that messages are being cached for

addConsumer

public boolean addConsumer(ConsumerEndpoint consumer)

Register a consumer with this cache.

Specified by:

addConsumer in interface DestinationCache

Parameters:

consumer - the message consumer for this destination

Returns:

true if registered; otherwise false

removeConsumer

public void removeConsumer(ConsumerEndpoint consumer)

Remove the consumer for the list of registered consumers.

Specified by:

removeConsumer in interface DestinationCache

Parameters:

consumer - the consumer to remove

hasConsumers

public boolean hasConsumers()

Determines if the cache has any consumers.

Specified by:

hasConsumers in interface DestinationCache

Returns:

true if the cache has consumers; otherwise false

getMessageCount

public int getMessageCount()

Returns the number of messages in the cache.

Specified by:

getMessageCount in interface DestinationCache

Returns:

the number of messages in the cache

canDestroy

public boolean canDestroy()

Determines if this cache can be destroyed. This implementation returns true if there are no active consumers.

Specified by:

canDestroy in interface DestinationCache

Returns:

true if the cache can be destroyed, otherwise false

destroy

public void destroy()

Destroy this cache.

Specified by:

destroy in interface DestinationCache

onLeaseExpired

public void onLeaseExpired(java.lang.Object object)

Invoked when a message lease has expired.

Specified by:

onLeaseExpired in interface LeaseEventListenerIfc

Parameters:

object - an instance of MessageRef

collectGarbage

public void collectGarbage(boolean aggressive)

Description copied from interface: GarbageCollectable

Perform any garbage collection on this resource. This will have the effect of releasing system resources. If the 'aggressive' flag is set to true then the garbage collection should do more to release memory related resources since it is called when the application memory is low.

Specified by:

collectGarbage in interface GarbageCollectable

Following copied from interface: org.exolab.jms.gc.GarbageCollectable

Parameters:

aggressive - true for aggressive garbage collection

addMessage

protected void addMessage(MessageRef reference,
                          MessageImpl message)

Add a message reference and its corresponding message to the cache

Parameters:

reference - the reference to the message

message - the message

getMessageCache

protected org.exolab.jms.messagemgr.DefaultMessageCache getMessageCache()

Returns the message cache.

Returns:

the message cache

getConsumerEndpoint

protected ConsumerEndpoint getConsumerEndpoint(long consumerId)

Returns a consumer endpoint, given its id.

Parameters:

consumerId - the consumer identity

Returns:

the consumer corresponding to id, or null if none is registered

getConsumerArray

protected ConsumerEndpoint[] getConsumerArray()

Helper to return the consumers as an array.

Returns:

the consumers of this cache

messageExpired

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

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

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.

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

checkMessageExpiry

protected void checkMessageExpiry(MessageRef reference,
                                  MessageImpl message)
                           throws javax.jms.JMSException

Check to see if the message has a TTL. If so then set up a lease for it. An expiry time of 0 means that the message never expires

Parameters:

reference - a reference to the message

message - the message

Throws:

javax.jms.JMSException - if the JMSExpiration property can't be accessed

checkMessageExpiry

protected void checkMessageExpiry(MessageRef reference,
                                  long expiryTime)

Check to see if the message has a TTL. If so then set up a lease for it. An expiry time of 0 means that the message never expires

Parameters:

reference - a reference to the message

expiryTime - the time when the message expires