Package jade.core

Class ExtendedMessageQueue

java.lang.Object

jade.core.ExtendedMessageQueue

All Implemented Interfaces:

MessageQueue

Direct Known Subclasses:

TemplateBasedMessageQueue

public class ExtendedMessageQueue
extends Object
implements MessageQueue

Extended version of the Agent MessageQueue supporting additional features that can be useful when dealing with heavy load of messages. - When message queue max size is exceeded last message is discarded (standard MessageQueue enqueues the incoming message and removes the first in queue - the eldest one) - A warningLimit and a warningTemplate can be defined so that, when the warningLimit is exceeded, incoming messages matching the warningTemplate are discarded - Whenever a message is discarded the handleDiscarded() callback method is invoked. Application agents can redefine this method to provide custom discarding actions

Author:

Caire

Field Summary

Fields

Modifier and Type	Field	Description
protected LinkedList<ACLMessage>	list
protected int	maxSize
protected Agent	myAgent
protected Logger	myLogger
protected MessageTemplate	warningDiscardTemplate
protected int	warningLimit

Constructor Summary

Constructors

Constructor	Description
ExtendedMessageQueue()
ExtendedMessageQueue(int maxSize, int warningLimit, MessageTemplate warningDiscardTemplate, Agent a)

Method Summary

Modifier and Type	Method	Description
void	addFirst(ACLMessage msg)	Add a message to the front of this queue.
void	addLast(ACLMessage msg)	Add a message to the end of this queue.
void	copyTo(List messages)	Copy all messages to a given list.
String	dump(int limit)
int	getMaxSize()	Return the maximum size of this queue.
protected void	handleDiscarded(ACLMessage msg, boolean warningLimitExceeded)	This method is invoked when a message is discarded because the queue max size has been reached or the warning limit has been exceeded and the discard-message-template matches.
boolean	isEmpty()	Return true when this queue contains no messages.
ACLMessage	receive(MessageTemplate pattern)	Return and remove the first message that matches the specified message template.
List<ACLMessage>	receive(MessageTemplate pattern, int max)	Return and remove the first n messages that match the specified message template.
void	setMaxSize(int maxSize)	Set the maximum size of this queue.
int	size()

Methods inherited from class java.lang.Object

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

Field Detail

list

protected LinkedList<ACLMessage> list

maxSize

protected int maxSize

warningLimit

protected int warningLimit

warningDiscardTemplate

protected MessageTemplate warningDiscardTemplate

myAgent

protected Agent myAgent

myLogger

protected Logger myLogger

Constructor Detail

ExtendedMessageQueue

public ExtendedMessageQueue(int maxSize,
                            int warningLimit,
                            MessageTemplate warningDiscardTemplate,
                            Agent a)

ExtendedMessageQueue

public ExtendedMessageQueue()

Method Detail

setMaxSize

public void setMaxSize(int maxSize)
                throws IllegalArgumentException

Description copied from interface: MessageQueue

Set the maximum size of this queue. This queue may remove old messages to prevent exeding the maximum size.

Specified by:

setMaxSize in interface MessageQueue

Throws:

IllegalArgumentException

getMaxSize

public int getMaxSize()

Description copied from interface: MessageQueue

Return the maximum size of this queue. This queue may remove old messages to prevent exeding the maximum size.

Specified by:

getMaxSize in interface MessageQueue

size

public int size()

Specified by:

size in interface MessageQueue

Returns:

the number of messages currently in the queue

isEmpty

public boolean isEmpty()

Description copied from interface: MessageQueue

Return true when this queue contains no messages.

Specified by:

isEmpty in interface MessageQueue

addFirst

public void addFirst(ACLMessage msg)

Description copied from interface: MessageQueue

Add a message to the front of this queue.

Specified by:

addFirst in interface MessageQueue

addLast

public void addLast(ACLMessage msg)

Description copied from interface: MessageQueue

Add a message to the end of this queue.

Specified by:

addLast in interface MessageQueue

handleDiscarded

protected void handleDiscarded(ACLMessage msg,
                               boolean warningLimitExceeded)

This method is invoked when a message is discarded because the queue max size has been reached or the warning limit has been exceeded and the discard-message-template matches. The default implementation just print a WARNING. Subclasses may redefine this method to implement application specific discard actions such as sending back a FAILURE to the sender

Parameters:

msg - The message that was discarded

warningLimitExceeded - A boolean indication stating that the message was discarded because the warning limit has been exceeded.

receive

public ACLMessage receive(MessageTemplate pattern)

Description copied from interface: MessageQueue

Return and remove the first message that matches the specified message template.

Specified by:

receive in interface MessageQueue

receive

public List<ACLMessage> receive(MessageTemplate pattern,
                                int max)

Description copied from interface: MessageQueue

Return and remove the first n messages that match the specified message template.

Specified by:

receive in interface MessageQueue

copyTo

public void copyTo(List messages)

Description copied from interface: MessageQueue

Copy all messages to a given list.

Specified by:

copyTo in interface MessageQueue

dump

public String dump(int limit)