com.yahoo.memory

Class XxHash64

java.lang.Object

com.yahoo.memory.XxHash64

public class XxHash64
extends Object

The XxHash is a fast, non-cryptographic, 64-bit hash function that has excellent avalanche and 2-way bit independence properties. This java version used the C++ version and the OpenHFT/Zero-Allocation-Hashing implementation referenced below as inspiration.

The C++ source repository: https://github.com/Cyan4973/xxHash. It has a BSD 2-Clause License: http://www.opensource.org/licenses/bsd-license.php

Portions of this code were leveraged from OpenHFT/Zero-Allocation-Hashing, which has an Apache 2 license as does this site.

Author:

Lee Rhodes

Constructor Summary

Constructors

Constructor and Description
XxHash64()

Method Summary

Modifier and Type	Method and Description
static long	hashBooleans(boolean[] arr, long cumOffsetBooleans, long lengthBooleans, long seed) Hash the given arr starting at the given offset and continuing for the given length using the given seed.
static long	hashBytes(byte[] arr, long cumOffsetBytes, long lengthBytes, long seed) Hash the given arr starting at the given offset and continuing for the given length using the given seed.
static long	hashChars(char[] arr, long cumOffsetChars, long lengthChars, long seed) Hash the given arr starting at the given offset and continuing for the given length using the given seed.
static long	hashDoubles(double[] arr, long cumOffsetDoubles, long lengthDoubles, long seed) Hash the given arr starting at the given offset and continuing for the given length using the given seed.
static long	hashFloats(float[] arr, long cumOffsetFloats, long lengthFloats, long seed) Hash the given arr starting at the given offset and continuing for the given length using the given seed.
static long	hashInts(int[] arr, long cumOffsetInts, long lengthInts, long seed) Hash the given arr starting at the given offset and continuing for the given length using the given seed.
static long	hashLongs(long[] arr, long cumOffsetLongs, long lengthLongs, long seed) Hash the given arr starting at the given offset and continuing for the given length using the given seed.
static long	hashShorts(short[] arr, long cumOffsetShorts, long lengthShorts, long seed) Hash the given arr starting at the given offset and continuing for the given length using the given seed.

Methods inherited from class java.lang.Object

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

Constructor Detail

XxHash64

public XxHash64()

Method Detail

hashBooleans

public static long hashBooleans(boolean[] arr,
                                long cumOffsetBooleans,
                                long lengthBooleans,
                                long seed)

Hash the given arr starting at the given offset and continuing for the given length using the given seed.

Parameters:

arr - the given array

cumOffsetBooleans - starting at this offset

lengthBooleans - continuing for this length

seed - the given seed

Returns:

the hash

hashBytes

public static long hashBytes(byte[] arr,
                             long cumOffsetBytes,
                             long lengthBytes,
                             long seed)

Hash the given arr starting at the given offset and continuing for the given length using the given seed.

Parameters:

arr - the given array

cumOffsetBytes - starting at this offset

lengthBytes - continuing for this length

seed - the given seed

Returns:

the hash

hashShorts

public static long hashShorts(short[] arr,
                              long cumOffsetShorts,
                              long lengthShorts,
                              long seed)

Hash the given arr starting at the given offset and continuing for the given length using the given seed.

Parameters:

arr - the given array

cumOffsetShorts - starting at this offset

lengthShorts - continuing for this length

seed - the given seed

Returns:

the hash

hashChars

public static long hashChars(char[] arr,
                             long cumOffsetChars,
                             long lengthChars,
                             long seed)

Hash the given arr starting at the given offset and continuing for the given length using the given seed.

Parameters:

arr - the given array

cumOffsetChars - starting at this offset

lengthChars - continuing for this length

seed - the given seed

Returns:

the hash

hashInts

public static long hashInts(int[] arr,
                            long cumOffsetInts,
                            long lengthInts,
                            long seed)

Hash the given arr starting at the given offset and continuing for the given length using the given seed.

Parameters:

arr - the given array

cumOffsetInts - starting at this offset

lengthInts - continuing for this length

seed - the given seed

Returns:

the hash

hashLongs

public static long hashLongs(long[] arr,
                             long cumOffsetLongs,
                             long lengthLongs,
                             long seed)

Hash the given arr starting at the given offset and continuing for the given length using the given seed.

Parameters:

arr - the given array

cumOffsetLongs - starting at this offset

lengthLongs - continuing for this length

seed - the given seed

Returns:

the hash

hashFloats

public static long hashFloats(float[] arr,
                              long cumOffsetFloats,
                              long lengthFloats,
                              long seed)

Hash the given arr starting at the given offset and continuing for the given length using the given seed.

Parameters:

arr - the given array

cumOffsetFloats - starting at this offset

lengthFloats - continuing for this length

seed - the given seed

Returns:

the hash

hashDoubles

public static long hashDoubles(double[] arr,
                               long cumOffsetDoubles,
                               long lengthDoubles,
                               long seed)

Hash the given arr starting at the given offset and continuing for the given length using the given seed.

Parameters:

arr - the given array

cumOffsetDoubles - starting at this offset

lengthDoubles - continuing for this length

seed - the given seed

Returns:

the hash