bamboo.vivaldi
Class VirtualCoordinate

java.lang.Object
  bamboo.vivaldi.VirtualCoordinate

All Implemented Interfaces:

ostore.util.QuickSerializable

Direct Known Subclasses:

FiveDVC, SpecialVC

public class VirtualCoordinate
extends Object
implements ostore.util.QuickSerializable

Virtual network coordinates as calculated by Vivaldi. The update algorithm is included in this class.

Version:

$Id: VirtualCoordinate.java,v 1.3 2004/03/10 20:39:43 czerwin Exp $

Author:

Steven E. Czerwinski

Field Summary

protected double[]	_coordinate
protected double	_delta The dampening factor applied to each sample's update.

Constructor Summary

protected	VirtualCoordinate() Creates an virtual coordinate at the origin of the space.
	VirtualCoordinate(ostore.util.InputBuffer buffer)

Method Summary

protected double[]	displacement(VirtualCoordinate remote) Returns a unit vector in the direction towards the remote coordinate.
double	distance(VirtualCoordinate destination) Calculates the distance between this coordinate to the given destination.
boolean	equals(Object other)
double[]	getCoordinates() Returns a copy of the coordinate array.
protected int	getDimensions() Returns the number of dimensions to use for this version of the virtual coordinates.
protected double[]	random_displacement()
protected double[]	random_displacement(double[] dir, int size) Creates a unit vector in a random direction.
protected double[]	random_displacement(int size)
void	serialize(ostore.util.OutputBuffer buffer)
String	toString()
void	update(VirtualCoordinate remote_coord, double latency) Update this coordinate's position with the given latency sample.

Methods inherited from class java.lang.Object

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

Field Detail

_delta

protected double _delta

The dampening factor applied to each sample's update. (From Vivaldi's algorithm.)

_coordinate

protected double[] _coordinate

Constructor Detail

VirtualCoordinate

protected VirtualCoordinate()

Creates an virtual coordinate at the origin of the space.

Parameters:

dimensions - The number of dimensions to have

VirtualCoordinate

public VirtualCoordinate(ostore.util.InputBuffer buffer)
                  throws ostore.util.QSException

Throws:

ostore.util.QSException

Method Detail

getDimensions

protected int getDimensions()

Returns the number of dimensions to use for this version of the virtual coordinates.

serialize

public void serialize(ostore.util.OutputBuffer buffer)

Specified by:

serialize in interface ostore.util.QuickSerializable

distance

public double distance(VirtualCoordinate destination)

Calculates the distance between this coordinate to the given destination. This will be an estimate of the one-way network latencies between the two nodes in milliseconds.

Parameters:

destination - The coordinate to compare this object against.

Returns:

The distance between the coordinates, as expressed by one-way network latency in milliseconds.

displacement

protected double[] displacement(VirtualCoordinate remote)

Returns a unit vector in the direction towards the remote coordinate. If the coordinates are the same, null is returned since you cannot produce a unit vector.

Parameters:

remote - The remote coordinate.

Returns:

A unit vector in the direction towards the remote, or null if the coords are the same.

random_displacement

protected double[] random_displacement(double[] dir,
                                       int size)

Creates a unit vector in a random direction.

random_displacement

protected double[] random_displacement(int size)

random_displacement

protected double[] random_displacement()

update

public void update(VirtualCoordinate remote_coord,
                   double latency)

Update this coordinate's position with the given latency sample.

Parameters:

remote_coord - The node's coordinate used to get the latency sample.

latency - The measured network latency (one-way, in milliseconds) to the remote node.

equals

public boolean equals(Object other)

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object

getCoordinates

public double[] getCoordinates()

Returns a copy of the coordinate array.