org.infinispan.commons.hash

Class MurmurHash2Compat

java.lang.Object

org.infinispan.commons.hash.MurmurHash2Compat

All Implemented Interfaces:

Hash

public class MurmurHash2Compat
extends java.lang.Object
implements Hash

An implementation of Austin Appleby's MurmurHash2.0 algorithm, as documented on his website.

This implementation is based on the slower, endian-neutral version of the algorithm as documented on the site, ported from Austin Appleby's original C++ version MurmurHashNeutral2.cpp.

Other implementations are documented on Wikipedia's MurmurHash page.

Note: This is the backward compatible version of this hash. The correct version of this hash is implemented as MurmurHash2. This version contains a slight bug in that it only takes into account 31 bits of the 32 bit range, which will result in poorer distribution. It is still maintained in the source tree to provide backward compatibility with existing clusters prior to 4.2.1, when the bug was identified and fixed. See ISPN-873 for more details.

Version:

4.1

Author:

Manik Surtani

See Also:

MurmurHash website, MurmurHash entry on Wikipedia, MurmurHash2

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	MurmurHash2Compat.Externalizer

Field Summary

Fields

Modifier and Type	Field and Description
private static int	H
private static int	M
private static int	R

Constructor Summary

Constructors

Constructor and Description
MurmurHash2Compat()

Method Summary

Methods

Modifier and Type	Method and Description
boolean	equals(java.lang.Object other)
int	hash(byte[] payload) Hashes a byte array efficiently.
int	hash(int hashcode) An incremental version of the hash function, that spreads a pre-calculated hash code, such as one derived from Object.hashCode().
int	hash(java.lang.Object o) A helper that calculates the hashcode of an object, choosing the optimal mechanism of hash calculation after considering the type of the object (byte array, String or Object).
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

M

private static final int M

See Also:

Constant Field Values

R

private static final int R

See Also:

Constant Field Values

H

private static final int H

See Also:

Constant Field Values

Constructor Detail

MurmurHash2Compat

public MurmurHash2Compat()

Method Detail

hash

public final int hash(byte[] payload)

Description copied from interface: Hash

Hashes a byte array efficiently.

Specified by:

hash in interface Hash

Parameters:

payload - a byte array to hash

Returns:

a hash code for the byte array

hash

public final int hash(int hashcode)

Description copied from interface: Hash

An incremental version of the hash function, that spreads a pre-calculated hash code, such as one derived from Object.hashCode().

Specified by:

hash in interface Hash

Parameters:

hashcode - an object's hashcode

Returns:

a spread and hashed version of the hashcode

hash

public final int hash(java.lang.Object o)

Description copied from interface: Hash

A helper that calculates the hashcode of an object, choosing the optimal mechanism of hash calculation after considering the type of the object (byte array, String or Object).

Specified by:

hash in interface Hash

Parameters:

o - object to hash

Returns:

a hashcode

equals

public boolean equals(java.lang.Object other)

Overrides:

equals in class java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object