io.jbotsim.core

Class DefaultMessageEngine

java.lang.Object

io.jbotsim.core.DefaultMessageEngine

All Implemented Interfaces:

MessageEngine

Direct Known Subclasses:

DelayMessageEngine

public class DefaultMessageEngine
extends Object
implements MessageEngine

The DefaultMessageEngine is JBotSim's default MessageEngine implementation.

It is responsible for the regular transmission of the available Messages from any sender Node of the Topology to their destination.

Messages sent during round n are delivered at the beginning of round n+1; provided that the corresponding arc (a Link going, at least, from the Message's source Node to its destination) actually exists at the beginning of round n+1.

If a Message can't be delivered during one round, and Message.isRetryModeEnabled() returns true (i.e. it has been sent with Node.sendRetry(Node, Message)), the DefaultMessageEngine will keep re-queuing it until it is actually delivered.

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	debug
protected Topology	topology

Constructor Summary

Constructors

Constructor and Description
DefaultMessageEngine(Topology topology) Creates a DefaultMessageEngine.

Method Summary

Modifier and Type	Method and Description
protected void	clearMailboxes() Clears the mailboxes of all Nodes present in the topology.
protected void	clearMailboxes(Collection<Node> nodes) Clears the mailboxes of the specified Collection of Nodes.
protected void	clearSendQueues() Clears the send queue of all Nodes present in the topology.
protected void	clearSendQueues(Collection<Node> nodes) Clears the send queue of all Nodes present in the topology.
protected List<Message>	collectMessages() Collects outgoing Messages from all Nodes present in the topology.
protected void	collectMessages(Collection<Message> newMessages, Node node) Collects outgoing Messages from the specified Node.
protected List<Message>	collectMessages(Collection<Node> nodes) Collects outgoing Messages from the specified Collection of Nodes.
protected void	deliverMessage(Message message) Delivers the Message to its destination.
protected void	deliverMessages(Collection<Message> messagesToSend) Delivers the provided Messages to send.
protected boolean	isMessageStillRelevant(Message message) Tests whether the provided Message is still relevant.
void	onClock() Method responsible for the delivery of the Messages.
protected void	removeIrrelevantMessages(ListIterator<Message> from, Collection<Node> existingNodes) Removes any irrelevant messages from the ListIterator according to the Collection of existing Nodes.
protected void	removeNextMessageIfIrrelevant(ListIterator<Message> from, Collection<Node> existingNodes) Removes the next messages from the ListIterator if it is irrelevant according to the Collection of existing Nodes.
protected void	requeueIfNeeded(Message message, Collection<Node> existingNodes) Re-queues the specified Message if necessary For a Message to be re-queueable, the following criteria must be met: the message's retry mode must be enabled the message's sender must still exist the message's destination must still exist
protected boolean	requeueMessage(Message message) Re-queues the specified Message in its sender's send queue.
void	reset() Resets the DefaultMessageEngine.
void	setDebug(boolean debug)
void	setTopology(Topology topology) Sets the Topology to which the MessageEngine refers.

Methods inherited from class java.lang.Object

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

Field Detail

topology

protected Topology topology

debug

protected boolean debug

Constructor Detail

DefaultMessageEngine

public DefaultMessageEngine(Topology topology)

Creates a DefaultMessageEngine.

Parameters:

topology - the Topology to use.

Method Detail

setTopology

public void setTopology(Topology topology)

Description copied from interface: MessageEngine

Sets the Topology to which the MessageEngine refers.

Specified by:

setTopology in interface MessageEngine

Parameters:

topology - a Topology.

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

removeIrrelevantMessages

protected void removeIrrelevantMessages(ListIterator<Message> from,
                                        Collection<Node> existingNodes)

Removes any irrelevant messages from the ListIterator according to the Collection of existing Nodes.

Parameters:

from - the ListIterator from which irrelevant messages should be removed.

existingNodes - the Collection of existing Nodes.

removeNextMessageIfIrrelevant

protected void removeNextMessageIfIrrelevant(ListIterator<Message> from,
                                             Collection<Node> existingNodes)

Removes the next messages from the ListIterator if it is irrelevant according to the Collection of existing Nodes.

Parameters:

from - the ListIterator from which the next message should be inspected.

existingNodes - the Collection of existing Nodes.

clearMailboxes

protected void clearMailboxes()

Clears the mailboxes of all Nodes present in the topology.

See Also:

clearMailboxes(Collection)

clearMailboxes

protected void clearMailboxes(Collection<Node> nodes)

Clears the mailboxes of the specified Collection of Nodes.

Parameters:

nodes - a Collection of Node which mailboxes should be cleared.

See Also:

Node.getMailbox()

collectMessages

protected List<Message> collectMessages()

Collects outgoing Messages from all Nodes present in the topology.

Returns:

the List of Messages that have been collected.

See Also:

collectMessages(Collection)

collectMessages

protected List<Message> collectMessages(Collection<Node> nodes)

Collects outgoing Messages from the specified Collection of Nodes.

Parameters:

nodes - a Collection of Node whose outgoing messages should be collected.

Returns:

the List of Messages that have been collected.

collectMessages

protected void collectMessages(Collection<Message> newMessages,
                               Node node)

Collects outgoing Messages from the specified Node.

A message with a null destination will be duplicated for each neighbor of the send.

Parameters:

newMessages - a Collection of Messages in which outgoing messages should be added.

node - the Node whose outgoing messages should be collected.

See Also:

Node.getOutNeighbors()

isMessageStillRelevant

protected boolean isMessageStillRelevant(Message message)

Tests whether the provided Message is still relevant.

To be relevant, an arc must exist between the sender and the destination of the message.

Parameters:

message - the Message to be tested.

Returns:

true if an arc exists between the send and the destination of the message.

See Also:

Node.getOutNeighbors(), Message.getSender(), Message.getDestination()

requeueIfNeeded

protected void requeueIfNeeded(Message message,
                               Collection<Node> existingNodes)

Re-queues the specified Message if necessary

For a Message to be re-queueable, the following criteria must be met:

• the message's retry mode must be enabled
• the message's sender must still exist
• the message's destination must still exist

Parameters:

message - the Message which should be re-queued.

existingNodes - the Collection of existing Nodes.

See Also:

Message.isRetryModeEnabled(), Message.getSender(), Message.getDestination()

requeueMessage

protected boolean requeueMessage(Message message)

Re-queues the specified Message in its sender's send queue.

Parameters:

message - the Message which should be re-queued.

Returns:

true if the re-queue has been successful.

deliverMessages

protected void deliverMessages(Collection<Message> messagesToSend)

Delivers the provided Messages to send.

Parameters:

messagesToSend - a Collection of Messages to deliver.

See Also:

deliverMessage(Message)

deliverMessage

protected void deliverMessage(Message message)

Delivers the Message to its destination.

Parameters:

message - the Message to be delivered.

setDebug

public void setDebug(boolean debug)

reset

public void reset()

Resets the DefaultMessageEngine.

• Any Message (ready to be sent or ready to be received) handled by the DefaultMessageEngine is discarded.
• Other configurations (debug, topology) remain untouched.

Specified by:

reset in interface MessageEngine

clearSendQueues

protected void clearSendQueues()

Clears the send queue of all Nodes present in the topology.

See Also:

clearSendQueues(Collection)

clearSendQueues

protected void clearSendQueues(Collection<Node> nodes)

Clears the send queue of all Nodes present in the topology.

Parameters:

nodes - a Collection of Node whose send queues should be cleared.