galileo.dht.hash

Class ConstrainedGeohash

java.lang.Object

galileo.dht.hash.ConstrainedGeohash

All Implemented Interfaces:

HashFunction<Metadata>

public class ConstrainedGeohash
extends java.lang.Object
implements HashFunction<Metadata>

Provides a Geohash-based hash function that acts on a predefined constrained set of hashes.

Author:

malensek

Constructor Summary

Constructors

Constructor and Description
ConstrainedGeohash(java.lang.String[] geohashes)

Method Summary

Modifier and Type	Method and Description
java.math.BigInteger	hash(Metadata data) Maps some given data to an integer location in the implemented hash space.
java.math.BigInteger	maxValue() Determines the maximum hash value that this hash function can produce.
java.math.BigInteger	randomHash() Returns a random location in the hash space.

Methods inherited from class java.lang.Object

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

Constructor Detail

ConstrainedGeohash

public ConstrainedGeohash(java.lang.String[] geohashes)
                   throws HashException

Throws:

HashException

Method Detail

hash

public java.math.BigInteger hash(Metadata data)
                          throws HashException

Description copied from interface: HashFunction

Maps some given data to an integer location in the implemented hash space.

Specified by:

hash in interface HashFunction<Metadata>

Parameters:

data - Data to hash against.

Returns:

location in the hash space for the data.

Throws:

HashException

maxValue

public java.math.BigInteger maxValue()

Description copied from interface: HashFunction

Determines the maximum hash value that this hash function can produce. For example, a 160-bit SHA1 max value would be 2^160.

Specified by:

maxValue in interface HashFunction<Metadata>

Returns:

maximum possible value this hash function will produce.

randomHash

public java.math.BigInteger randomHash()

Description copied from interface: HashFunction

Returns a random location in the hash space. This is used for seeding the first nodes in an overlay, or providing random positions to place nodes.

Specified by:

randomHash in interface HashFunction<Metadata>

Returns:

random position in the hash space.