scala.util.hashing

MurmurHash3

object MurmurHash3 extends MurmurHash3

An implementation of Austin Appleby's MurmurHash 3 algorithm (MurmurHash3_x86_32). This object contains methods that hash values of various types as well as means to construct Hashing objects.

This algorithm is designed to generate well-distributed non-cryptographic hashes. It is designed to hash data in 32 bit chunks (ints).

The mix method needs to be called at each step to update the intermediate hash value. For the last chunk to incorporate into the hash mixLast may be used instead, which is slightly faster. Finally finalizeHash needs to be called to compute the final hash value.

This is based on the earlier MurmurHash3 code by Rex Kerr, but the MurmurHash3 algorithm was since changed by its creator Austin Appleby to remedy some weaknesses and improve performance. This represents the latest and supposedly final version of the algortihm (revision 136).

Source
MurmurHash3.scala
See also

http://code.google.com/p/smhasher

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Type Members

  1. class ArrayHashing[T] extends Hashing[Array[T]]

Value Members

  1. final def !=(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  2. final def !=(arg0: Any): Boolean

    Definition Classes
    Any
  3. final def ##(): Int

    Definition Classes
    AnyRef → Any
  4. final def ==(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  5. final def ==(arg0: Any): Boolean

    Definition Classes
    Any
  6. def arrayHash[T](a: Array[T]): Int

  7. final def arrayHash[T](a: Array[T], seed: Int): Int

    Compute the hash of an array.

    Compute the hash of an array.

    Definition Classes
    MurmurHash3
  8. def arrayHashing[T]: ArrayHashing[T]

  9. final val arraySeed: Int(1007110753)

  10. final def asInstanceOf[T0]: T0

    Definition Classes
    Any
  11. def bytesHash(data: Array[Byte]): Int

  12. final def bytesHash(data: Array[Byte], seed: Int): Int

    Compute the hash of a byte array.

    Compute the hash of a byte array. Faster than arrayHash, because it hashes 4 bytes at once.

    Definition Classes
    MurmurHash3
  13. def bytesHashing: Hashing[Array[Byte]]

  14. def clone(): AnyRef

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws()
  15. final def eq(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  16. def equals(arg0: Any): Boolean

    Definition Classes
    AnyRef → Any
  17. def finalize(): Unit

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws()
  18. final def finalizeHash(hash: Int, length: Int): Int

    Finalize a hash to incorporate the length and make sure all bits avalanche.

    Finalize a hash to incorporate the length and make sure all bits avalanche.

    Definition Classes
    MurmurHash3
  19. final def getClass(): Class[_]

    Definition Classes
    AnyRef → Any
  20. def hashCode(): Int

    Definition Classes
    AnyRef → Any
  21. final def isInstanceOf[T0]: Boolean

    Definition Classes
    Any
  22. final def listHash(xs: collection.immutable.List[_], seed: Int): Int

    Definition Classes
    MurmurHash3
  23. def mapHash(xs: Map[_, _]): Int

  24. final val mapSeed: Int

  25. final def mix(hash: Int, data: Int): Int

    Mix in a block of data into an intermediate hash value.

    Mix in a block of data into an intermediate hash value.

    Definition Classes
    MurmurHash3
  26. final def mixLast(hash: Int, data: Int): Int

    May optionally be used as the last mixing step.

    May optionally be used as the last mixing step. Is a little bit faster than mix, as it does no further mixing of the resulting hash. For the last element this is not necessary as the hash is thoroughly mixed during finalization anyway.

    Definition Classes
    MurmurHash3
  27. final def ne(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  28. final def notify(): Unit

    Definition Classes
    AnyRef
  29. final def notifyAll(): Unit

    Definition Classes
    AnyRef
  30. def orderedHash(xs: TraversableOnce[Any]): Int

  31. final def orderedHash(xs: TraversableOnce[Any], seed: Int): Int

    Compute a hash that depends on the order of its arguments.

    Compute a hash that depends on the order of its arguments.

    Definition Classes
    MurmurHash3
  32. def orderedHashing: Hashing[TraversableOnce[Any]]

  33. def productHash(x: Product): Int

  34. final def productHash(x: Product, seed: Int): Int

    Compute the hash of a product

    Compute the hash of a product

    Definition Classes
    MurmurHash3
  35. def productHashing: Hashing[Product]

  36. final val productSeed: Int(-889275714)

  37. def seqHash(xs: collection.Seq[_]): Int

    To offer some potential for optimization.

  38. final val seqSeed: Int

  39. def setHash(xs: Set[_]): Int

  40. final val setSeed: Int

  41. def stringHash(x: String): Int

  42. final def stringHash(str: String, seed: Int): Int

    Compute the hash of a string

    Compute the hash of a string

    Definition Classes
    MurmurHash3
  43. def stringHashing: Hashing[String]

  44. final val stringSeed: Int(-137723950)

  45. final val symmetricSeed: Int(-1248659538)

  46. final def synchronized[T0](arg0: ⇒ T0): T0

    Definition Classes
    AnyRef
  47. def toString(): String

    Definition Classes
    AnyRef → Any
  48. final val traversableSeed: Int(-415593707)

  49. def unorderedHash(xs: TraversableOnce[Any]): Int

  50. final def unorderedHash(xs: TraversableOnce[Any], seed: Int): Int

    Compute a hash that is symmetric in its arguments - that is a hash where the order of appearance of elements does not matter.

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

    Definition Classes
    MurmurHash3
  51. def unorderedHashing: Hashing[TraversableOnce[Any]]

  52. final def wait(): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws()
  53. final def wait(arg0: Long, arg1: Int): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws()
  54. final def wait(arg0: Long): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws()

Deprecated Value Members

  1. final def symmetricHash[T](xs: GenTraversableOnce[T], seed: Int = symmetricSeed): Int

    def linearSeqHash(xs: scala.

    def linearSeqHash(xs: scala.collection.LinearSeq[_], seed: Int): Int = { var n = 0 var h = seed var elems = xs while (elems.nonEmpty) { h = mix(h, elems.head.##) n += 1 elems = elems.tail } finalizeHash(h, n) }

    def indexedSeqHash(xs: scala.collection.IndexedSeq[_], seed: Int): Int = { var n = 0 var h = seed val len = xs.length while (n < len) { h = mix(h, xs(n).##) n += 1 } finalizeHash(h, n) }

    Annotations
    @deprecated
    Deprecated

    (Since version 2.10.0) Use unorderedHash

  2. final def traversableHash[T](xs: GenTraversableOnce[T], seed: Int = traversableSeed): Int

    Annotations
    @deprecated
    Deprecated

    (Since version 2.10.0) Use orderedHash

Inherited from MurmurHash3

Inherited from AnyRef

Inherited from Any

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