freenet.node

Class Location

java.lang.Object

freenet.node.Location

public class Location
extends java.lang.Object

Field Summary

Fields

Modifier and Type	Field and Description
static double	LOCATION_INVALID

Constructor Summary

Constructors

Constructor and Description
Location()

Method Summary

Modifier and Type	Method and Description
static double	change(double from, double to) Distance between two locations, including direction of the change (positive/negative).
static double	distance(double a, double b) Distance between two valid locations.
static double	distance(PeerNode p, double loc) Distance between a peer and a location.
static double	distanceAllowInvalid(double a, double b) Distance between two potentially invalid locations.
static boolean	equals(double a, double b) Tests for equality of two locations.
static double	getLocation(java.lang.String init) Parses a location.
static boolean	isValid(double loc) Tests whether a location is valid, e.g.
static double	normalize(double rough) Normalize a location to within the valid range.

Methods inherited from class java.lang.Object

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

Field Detail

LOCATION_INVALID

public static final double LOCATION_INVALID

See Also:

Constant Field Values

Constructor Detail

Location

public Location()

Method Detail

getLocation

public static double getLocation(java.lang.String init)

Parses a location.

Parameters:

init - a location string

Returns:

the location, or LOCATION_INVALID for all invalid locations and on parse errors.

distance

public static double distance(PeerNode p,
                              double loc)

Distance between a peer and a location.

Parameters:

p - a peer with a valid location

loc - a valid location

Returns:

the absolute distance between the peer and the location in the circular location space.

distance

public static double distance(double a,
                              double b)

Distance between two valid locations.

Parameters:

a - a valid location

b - a valid location

Returns:

the absolute distance between the locations in the circular location space.

distanceAllowInvalid

public static double distanceAllowInvalid(double a,
                                          double b)

Distance between two potentially invalid locations.

Parameters:

a - a valid location

b - a valid location

Returns:

the absolute distance between the locations in the circular location space. Invalid locations are considered to be at 2.0, and the result is returned accordingly.

change

public static double change(double from,
                            double to)

Distance between two locations, including direction of the change (positive/negative). When given two values on opposite ends of the keyspace, it will return +0.5. The behaviour is undefined for invalid locations.

Parameters:

from - a valid starting location

to - a valid end location

Returns:

the signed distance from the first to the second location in the circular location space

normalize

public static double normalize(double rough)

Normalize a location to within the valid range. Given an arbitrary double (not bound to [0.0, 1.0)) return the normalized double [0.0, 1.0) which would result in simple wrapping/overflowing. e.g. normalize(0.3+1.0)==0.3, normalize(0.3-1.0)==0.3, normalize(x)==x with x in [0.0, 1.0)

Parameters:

rough - any location

Returns:

the normalized location

equals

public static boolean equals(double a,
                             double b)

Tests for equality of two locations. Locations are considered equal if their distance is (almost) zero, e.g. equals(0.0, 1.0) is true, or if both locations are invalid.

Parameters:

a - any location

b - any location

Returns:

whether the two locations are considered equal

isValid

public static boolean isValid(double loc)

Tests whether a location is valid, e.g. within [0.0, 1.0]

Parameters:

loc - any location

Returns:

whether the location is valid