io.jbotsim.contrib.messaging

Class AsyncMessageEngine

java.lang.Object

io.jbotsim.core.DefaultMessageEngine

io.jbotsim.core.DelayMessageEngine

io.jbotsim.contrib.messaging.AsyncMessageEngine

All Implemented Interfaces:

MessageEngine

public class AsyncMessageEngine
extends DelayMessageEngine

The AsyncMessageEngine is an asynchronous alternative to JBotSim's default MessageEngine.

It is made to work either as AsyncMessageEngine.Type.FIFO or AsyncMessageEngine.Type.NONFIFO. Currently, for each new message:

• the AsyncMessageEngine.Type.NONFIFO mode uses the provided average duration to compute the delay (f function discussed thereafter);
• the AsyncMessageEngine.Type.FIFO mode also uses the f function to compute a theoretical delay, but also takes the current maximum delay time between the two nodes in order to guaranty a proper FIFO behavior.

In both cases, the f function used to draw the random delay, which follows an exponential distribution law of rate 1./getAverageDuration(), is computed as such:
f(r) = -log(1-r) * getAverageDuration(), where r is a value returned by Math.random().

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	AsyncMessageEngine.Type Delivery queue type.

Field Summary

Fields

Modifier and Type	Field and Description
protected int	averageDuration
static int	DEFAULT_AVERAGE_DURATION The default average duration; value: 10.
static AsyncMessageEngine.Type	DEFAULT_TYPE The default delivery queue type; value: AsyncMessageEngine.Type.FIFO.
protected AsyncMessageEngine.Type	type

Fields inherited from class io.jbotsim.core.DelayMessageEngine

currentTime, DEFAULT_DELAY, DELAY_INSTANT, delayedMessages

Fields inherited from class io.jbotsim.core.DefaultMessageEngine

debug, topology

Constructor Summary

Constructors

Constructor and Description
AsyncMessageEngine(Topology topology) Creates a AsyncMessageEngine object.
AsyncMessageEngine(Topology topology, int averageDuration, AsyncMessageEngine.Type type) Creates a AsyncMessageEngine object.

Method Summary

Modifier and Type	Method and Description
protected int	computeDelayFunction(int lambda) Computes the next value for the delay function.
protected int	drawDelayFIFO(Message message) Draws a delay for the provided Message, in the FIFO case.
protected int	drawDelayNONFIFO(Message message) Draws a delay for the provided Message, in the non-FIFO case.
int	getAverageDuration() Gets the desired average number of rounds needed for a message to be delivered to its destination.
protected int	getCurrentMaximumDeliveryDate(Node sender, Node destination) Retrieves the current maximum delivery date for messages between the provided sender and destination.
int	getDelay() Deprecated.
protected int	getDelayForMessage(Message message) Computes the delay which should be applied to the provided Message.
protected int	getDeliveryDateForMessage(Message message) Computes the delivery date (round number) for the provided Message.
protected boolean	noCachingNeeded(List<Message> newMessages) Tests whether the provided list of Messages should be cached or not.
void	onClock() Method responsible for the delivery of the Messages.
protected Map<Integer,List<Message>>	prepareNewMessagesForCaching(List<Message> newMessages) Transforms the provided List of new Messages for caching into a suitable data structure.
void	setAverageDuration(int averageDuration) Sets the desired average number of rounds needed for a message to be delivered to its destination.
void	setDelay(int delay) Deprecated.
protected boolean	shouldCleanDeliveryDates()

Methods inherited from class io.jbotsim.core.DelayMessageEngine

cacheMessageAtTime, cacheMessagesAtTime, cacheNewMessages, disableLinksContinuityChecks, getCurrentDeliveryDate, getMessagesForCurrentDate, getMessagesToSend, removeIrrelevantMessages, reset, setSpeed, shouldCheckLinksContinuity

Methods inherited from class io.jbotsim.core.DefaultMessageEngine

clearMailboxes, clearMailboxes, clearSendQueues, clearSendQueues, collectMessages, collectMessages, collectMessages, deliverMessage, deliverMessages, isMessageStillRelevant, removeIrrelevantMessages, removeNextMessageIfIrrelevant, requeueIfNeeded, requeueMessage, setDebug, setTopology

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_AVERAGE_DURATION

public static final int DEFAULT_AVERAGE_DURATION

The default average duration; value: 10.

See Also:

Constant Field Values

DEFAULT_TYPE

public static final AsyncMessageEngine.Type DEFAULT_TYPE

The default delivery queue type; value: AsyncMessageEngine.Type.FIFO.

averageDuration

protected int averageDuration

type

protected AsyncMessageEngine.Type type

Constructor Detail

AsyncMessageEngine

public AsyncMessageEngine(Topology topology)

Creates a AsyncMessageEngine object.

The default used are:

• DEFAULT_AVERAGE_DURATION as default average duration;
• DEFAULT_TYPE as default type.

Parameters:

topology - the Topology to use.

AsyncMessageEngine

public AsyncMessageEngine(Topology topology,
                          int averageDuration,
                          AsyncMessageEngine.Type type)

Creates a AsyncMessageEngine object.

Parameters:

topology - the Topology to use.

averageDuration - the desired average number of rounds needed for a message to be delivered to its destination, as an integer.

type - the AsyncMessageEngine.Type of the delivery queue.

Method Detail

onClock

public void onClock()

Description copied from interface: MessageEngine

Method responsible for the delivery of the Messages. It is regularly called by the Scheduler.

Specified by:

onClock in interface MessageEngine

Overrides:

onClock in class DelayMessageEngine

shouldCleanDeliveryDates

protected boolean shouldCleanDeliveryDates()

noCachingNeeded

protected boolean noCachingNeeded(List<Message> newMessages)

Description copied from class: DelayMessageEngine

Tests whether the provided list of Messages should be cached or not.

Overrides:

noCachingNeeded in class DelayMessageEngine

Parameters:

newMessages - a List containing new Messages.

Returns:

true if the provided messages should not be cached.

prepareNewMessagesForCaching

protected Map<Integer,List<Message>> prepareNewMessagesForCaching(List<Message> newMessages)

Description copied from class: DelayMessageEngine

Transforms the provided List of new Messages for caching into a suitable data structure.

Overrides:

prepareNewMessagesForCaching in class DelayMessageEngine

Parameters:

newMessages - a List containing new Messages.

Returns:

a Map containing Lists of Messages indexed by the date at which they should be delivered.

See Also:

DelayMessageEngine.getCurrentDeliveryDate()

getDeliveryDateForMessage

protected int getDeliveryDateForMessage(Message message)

Computes the delivery date (round number) for the provided Message.

Parameters:

message - the Message needing a delivery date.

Returns:

the delivery date (round number) for the message.

getCurrentMaximumDeliveryDate

protected int getCurrentMaximumDeliveryDate(Node sender,
                                            Node destination)

Retrieves the current maximum delivery date for messages between the provided sender and destination.

Parameters:

sender - the sender Node.

destination - the destination Node.

Returns:

the current maximum delivery date (round number), as an integer.

getDelayForMessage

protected int getDelayForMessage(Message message)

Description copied from class: DelayMessageEngine

Computes the delay which should be applied to the provided Message.

Overrides:

getDelayForMessage in class DelayMessageEngine

Parameters:

message - the Message needing a delay.

Returns:

the delay for the provided message.

drawDelayNONFIFO

protected int drawDelayNONFIFO(Message message)

Draws a delay for the provided Message, in the non-FIFO case.

Parameters:

message - the Message needing a delay.

Returns:

the delay, as an integer.

drawDelayFIFO

protected int drawDelayFIFO(Message message)

Draws a delay for the provided Message, in the FIFO case.

Parameters:

message - the Message needing a delay.

Returns:

the delay, as an integer.

computeDelayFunction

protected int computeDelayFunction(int lambda)

Computes the next value for the delay function.

Parameters:

lambda - the lambda parameter, as an integer.

Returns:

the next value for the delay function, as an integer.

getAverageDuration

public int getAverageDuration()

Gets the desired average number of rounds needed for a message to be delivered to its destination.

Returns:

the desired average number of rounds needed for a message to be delivered to its destination, as an integer.

setAverageDuration

public void setAverageDuration(int averageDuration)

Sets the desired average number of rounds needed for a message to be delivered to its destination.

Parameters:

averageDuration - the desired average number of rounds needed for a message to be delivered to its destination, as an Integer.

setDelay

@Deprecated
public void setDelay(int delay)

Deprecated.

Please prefer using setAverageDuration(int).

Overrides:

setDelay in class DelayMessageEngine

Parameters:

delay - the number of round a message should be delayed, as an integer.

See Also:

setAverageDuration(int)

getDelay

@Deprecated
public int getDelay()

Deprecated.

Please prefer using getAverageDuration().

Overrides:

getDelay in class DelayMessageEngine

Returns:

the number of round a message should be delayed, as an integer.

See Also:

getAverageDuration()