Package org.apache.lucene.codecs.bloom

Class MurmurHash64

java.lang.Object

org.apache.lucene.codecs.bloom.HashFunction

org.apache.lucene.codecs.bloom.MurmurHash64

public class MurmurHash64
extends HashFunction

This is a very fast, non-cryptographic hash suitable for general hash-based lookup. See http://murmurhash.googlepages.com/ for more details.

The code from Apache Commons was adapted in the form here to work with BytesRefs with offsets and lengths rather than raw byte arrays.

Field Summary

Fields

Modifier and Type	Field	Description
static HashFunction	INSTANCE

Constructor Summary

Constructors

Constructor	Description
MurmurHash64()

Method Summary

Modifier and Type	Method	Description
long	hash(BytesRef br)	Hashes the contents of the referenced bytes
static long	hash64(byte[] data, int seed, int offset, int length)	Generates a 64-bit hash from byte array of the given length and seed.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

INSTANCE

public static final HashFunction INSTANCE

Constructor Detail

MurmurHash64

public MurmurHash64()

Method Detail

hash64

public static long hash64(byte[] data,
                          int seed,
                          int offset,
                          int length)

Generates a 64-bit hash from byte array of the given length and seed.

Parameters:

data - The input byte array

seed - The initial seed value

length - The length of the array

Returns:

The 64-bit hash of the given array

hash

public final long hash(BytesRef br)

Description copied from class: HashFunction

Hashes the contents of the referenced bytes

Specified by:

hash in class HashFunction

Parameters:

br - the data to be hashed

Returns:

the hash of the bytes referenced by bytes.offset and length bytes.length

toString

public String toString()

Overrides:

toString in class Object