simnet
Class RoundRobin

java.lang.Object
  simnet.LinkProcessor
      simnet.RoundRobin

All Implemented Interfaces:

Pluggable, PlugoutListener

public class RoundRobin

extends LinkProcessor

implements Pluggable

A link processor that checks links sequentially for available frames. To make RoundRobin work we must do the following: 1. iterate through Links and if a frame is found return it 2. each time the Link Processor is called (with getFrame) it must start cycling from where it left off the previous time. Neither the Enumeration nor the Iterator classes allow us to do anything like that so we use an array and keep state instead. To use the array we have to copy all the Links from the Link table to a link array. We can' t do it when the RoundRobin object is instantiated because at that time the link table is empty (it gets filled as Links get created) so we need to do the copying only once all the links are present in the Link Table. The only time at which this is garanteed is when getFrame() is called. So we have to do the copying the first time getFrame() is called.

Field Summary

(package private) Link[]	link_array An array containing all the Node' s Links
(package private) java.util.Hashtable	links The link table that holds all the Node' s Links
private int	mark A variable that keeps track of where the RoundRobin processor left off
private boolean	rebuild Keeps track of whether the Link array has been built or not

Fields inherited from class simnet.LinkProcessor

NODE_ID, parent_node

Constructor Summary

RoundRobin()

Method Summary

Frame	getFrame() Returns a Frame from one of the Node' s Links
void	initialize(java.util.Hashtable link_table, Node parent) Initializes a new RoundRobin link processor by initializing its link_table and node fields.
boolean	prePlugout(java.lang.Object replacement) Nothing special for replacing, clean up some memory when removing.
void	rebuild() Constructs the Link Array

Methods inherited from class simnet.LinkProcessor

finalize, plugoutNotification

Methods inherited from class java.lang.Object

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

Field Detail

links

java.util.Hashtable links

The link table that holds all the Node' s Links

link_array

Link[] link_array

An array containing all the Node' s Links

mark

private int mark

A variable that keeps track of where the RoundRobin processor left off

rebuild

private boolean rebuild

Keeps track of whether the Link array has been built or not

Constructor Detail

RoundRobin

public RoundRobin()

Method Detail

initialize

public void initialize(java.util.Hashtable link_table,
                       Node parent)

Initializes a new RoundRobin link processor by initializing its link_table and node fields.

Overrides:

initialize in class LinkProcessor

Parameters:

link_table - the owner' s (Node) Link table

parent - the Node that owns this LinkProcessor

rebuild

public void rebuild()

Constructs the Link Array

getFrame

public Frame getFrame()

Returns a Frame from one of the Node' s Links

Specified by:

getFrame in class LinkProcessor

Returns:

a Frame

prePlugout

public boolean prePlugout(java.lang.Object replacement)

Nothing special for replacing, clean up some memory when removing.

Specified by:

prePlugout in interface Pluggable

Returns:

if this object can now be removed (was the operation sucessful)