akka.routing
Class MurmurHash$

java.lang.Object
  akka.routing.MurmurHash$

public class MurmurHash$
extends java.lang.Object

An object designed to generate well-distributed non-cryptographic hashes. It is designed to hash a collection of integers; along with the integers to hash, it generates two magic streams of integers to increase the distribution of repetitive input sequences. Thus, three methods need to be called at each step (to start and to incorporate a new integer) to update the values. Only one method needs to be called to finalize the hash.

Field Summary

static MurmurHash$

MODULE$ Static reference to the singleton instance of this Scala object.

Constructor Summary

MurmurHash$()

Method Summary

<T> int	arrayHash(java.lang.Object a) Compute a high-quality hash of an array
int	extendHash(int hash, int value, int magicA, int magicB) Incorporates a new value into an existing hash.
int	finalizeHash(int hash) Once all hashes have been incorporated, this performs a final mixing
int	nextMagicA(int magicA) Given a magic integer from the first stream, compute the next
int	nextMagicB(int magicB) Given a magic integer from the second stream, compute the next
int	startHash(int seed) Begin a new hash with a seed value.
int	startMagicA() The initial magic integers in the first stream.
int	startMagicB() The initial magic integer in the second stream.
int	stringHash(java.lang.String s) Compute a high-quality hash of a string
<T> int	symmetricHash(scala.collection.TraversableOnce<T> xs, int seed) Compute a hash that is symmetric in its arguments--that is, where the order of appearance of elements does not matter.

Methods inherited from class java.lang.Object

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

Field Detail

MODULE$

public static final MurmurHash$ MODULE$

Static reference to the singleton instance of this Scala object.

Constructor Detail

MurmurHash$

public MurmurHash$()

Method Detail

startHash

public int startHash(int seed)

Begin a new hash with a seed value.

startMagicA

public int startMagicA()

The initial magic integers in the first stream.

startMagicB

public int startMagicB()

The initial magic integer in the second stream.

extendHash

public int extendHash(int hash,
                      int value,
                      int magicA,
                      int magicB)

Incorporates a new value into an existing hash.

Parameters:

hash - the prior hash value

value - the new value to incorporate

magicA - a magic integer from the stream

magicB - a magic integer from a different stream

Returns:

the updated hash value

nextMagicA

public int nextMagicA(int magicA)

Given a magic integer from the first stream, compute the next

nextMagicB

public int nextMagicB(int magicB)

Given a magic integer from the second stream, compute the next

finalizeHash

public int finalizeHash(int hash)

Once all hashes have been incorporated, this performs a final mixing

arrayHash

public <T> int arrayHash(java.lang.Object a)

Compute a high-quality hash of an array

stringHash

public int stringHash(java.lang.String s)

Compute a high-quality hash of a string

symmetricHash

public <T> int symmetricHash(scala.collection.TraversableOnce<T> xs,
                             int seed)

Compute a hash that is symmetric in its arguments--that is, where the order of appearance of elements does not matter. This is useful for hashing sets, for example.