Class XxHash64

java.lang.Object
org.apache.datasketches.hash.XxHash64
public final 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 adapted from 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. See LICENSE.

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

Author:
Lee Rhodes

  • Method Summary

    Modifier and Type
    Method
    Description
    static long
    hash(long in, long seed)
    Returns a 64-bit hash from a single long.
    static long
    hash(MemorySegment seg, long offsetBytes, long lengthBytes, long seed)
    Returns the 64-bit hash of the sequence of bytes in the given MemorySegment
    static long
    hashBytes(byte[] arr, int offsetBytes, int 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, int offsetChars, int 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, int offsetDoubles, int 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, int offsetFloats, int 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, int offsetInts, int 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, int offsetLongs, int 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, int offsetShorts, int lengthShorts, long seed)
    Hash the given arr starting at the given offset and continuing for the given length using the given seed.
    static long
    hashString(String str, int offsetChars, int lengthChars, 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 Object

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

  • Method Details

    • hash

      public static long hash(MemorySegment seg, long offsetBytes, long lengthBytes, long seed)
      Returns the 64-bit hash of the sequence of bytes in the given MemorySegment
      Parameters:
      seg - A reference to the relevant MemorySegment.
      offsetBytes - offset in bytes in the given segment.
      lengthBytes - the length in bytes to be hashed
      seed - a given seed
      Returns:
      the 64-bit hash of the sequence of bytes.

    • hash

      public static long hash(long in, long seed)
      Returns a 64-bit hash from a single long. This method has been optimized for speed when only a single hash of a long is required.
      Parameters:
      in - A long.
      seed - A long valued seed.
      Returns:
      the hash.

    • hashBytes

      public static long hashBytes(byte[] arr, int offsetBytes, int 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
      offsetBytes - starting at this offset
      lengthBytes - continuing for this length
      seed - the given seed
      Returns:
      the hash

    • hashShorts

      public static long hashShorts(short[] arr, int offsetShorts, int 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
      offsetShorts - starting at this offset
      lengthShorts - continuing for this length
      seed - the given seed
      Returns:
      the hash

    • hashChars

      public static long hashChars(char[] arr, int offsetChars, int 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
      offsetChars - starting at this offset
      lengthChars - continuing for this length
      seed - the given seed
      Returns:
      the hash

    • hashInts

      public static long hashInts(int[] arr, int offsetInts, int 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
      offsetInts - starting at this offset
      lengthInts - continuing for this length
      seed - the given seed
      Returns:
      the hash

    • hashLongs

      public static long hashLongs(long[] arr, int offsetLongs, int 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
      offsetLongs - starting at this offset
      lengthLongs - continuing for this length
      seed - the given seed
      Returns:
      the hash

    • hashFloats

      public static long hashFloats(float[] arr, int offsetFloats, int 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
      offsetFloats - starting at this offset
      lengthFloats - continuing for this length
      seed - the given seed
      Returns:
      the hash

    • hashDoubles

      public static long hashDoubles(double[] arr, int offsetDoubles, int 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
      offsetDoubles - starting at this offset
      lengthDoubles - continuing for this length
      seed - the given seed
      Returns:
      the hash

    • hashString

      public static long hashString(String str, int offsetChars, int lengthChars, long seed)
      Hash the given arr starting at the given offset and continuing for the given length using the given seed.
      Parameters:
      str - the given string
      offsetChars - starting at this offset
      lengthChars - continuing for this length
      seed - the given seed
      Returns:
      the hash