Object

scala.util.hashing

MurmurHash3

Related Doc: package hashing

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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 algorithm (revision 136).

See also

https://github.com/aappleby/smhasher

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Type Members

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

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Value Members

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

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    Definition Classes
    AnyRef → Any
  2. final def ##(): Int

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

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    Definition Classes
    AnyRef → Any
  4. def arrayHash[T](a: Array[T]): Int

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

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    Compute the hash of an array.

    Compute the hash of an array.

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

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  7. final val arraySeed: Int(1007110753)

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  8. final def asInstanceOf[T0]: T0

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

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

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    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
  11. def bytesHashing: Hashing[Array[Byte]]

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  12. def clone(): AnyRef

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

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  14. def equals(arg0: Any): Boolean

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  15. def finalize(): Unit

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    protected[java.lang]
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    @throws( classOf[java.lang.Throwable] )
  16. final def finalizeHash(hash: Int, length: Int): Int

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    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
  17. final def getClass(): Class[_]

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  18. def hashCode(): Int

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  19. final def isInstanceOf[T0]: Boolean

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

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

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  22. final val mapSeed: Int

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

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    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
  24. final def mixLast(hash: Int, data: Int): Int

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    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
  25. final def ne(arg0: AnyRef): Boolean

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    Definition Classes
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  26. final def notify(): Unit

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

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

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

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    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
  30. def orderedHashing: Hashing[TraversableOnce[Any]]

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  31. def productHash(x: Product): Int

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

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    Compute the hash of a product

    Compute the hash of a product

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

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  34. final val productSeed: Int(-889275714)

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

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    To offer some potential for optimization.

  36. final val seqSeed: Int

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

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  38. final val setSeed: Int

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  39. def stringHash(x: String): Int

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

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    Compute the hash of a string

    Compute the hash of a string

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

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  42. final val stringSeed: Int(-137723950)

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  43. final val symmetricSeed: Int(-1248659538)

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

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    Definition Classes
    AnyRef
  45. def toString(): String

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    Definition Classes
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  46. final val traversableSeed: Int(-415593707)

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

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

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    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
  49. def unorderedHashing: Hashing[TraversableOnce[Any]]

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  50. final def wait(): Unit

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

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    @throws( ... )
  52. final def wait(arg0: Long): Unit

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Inherited from MurmurHash3

Inherited from AnyRef

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