Package org.h2.dev.hash

Class MinimalPerfectHash.StringHash

    • Constructor Summary

      Constructors 
      Constructor Description
      StringHash()  

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static int getFastHash​(java.lang.String o, int index, int seed)
      A cryptographically weak hash function.
      static int getSipHash24​(byte[] b, int start, int end, long k0, long k1)
      A cryptographically relatively secure hash function.
      static int getSipHash24​(java.lang.String o, long k0, long k1)
      A cryptographically relatively secure hash function.
      int hashCode​(java.lang.String o, int index, int seed)
      Calculate the hash of the given object.

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • StringHash

        public StringHash()

    • Method Detail

      • hashCode

        public int hashCode​(java.lang.String o,
                    int index,
                    int seed)
        Description copied from interface: MinimalPerfectHash.UniversalHash
        Calculate the hash of the given object.
        Specified by:
        hashCode in interface MinimalPerfectHash.UniversalHash<java.lang.String>
        Parameters:
        o - the object
        index - the hash function index (index 0 is used first, so the method should be very fast with index 0; index 1 and so on are only called when really needed)
        seed - the random seed (always the same for a hash table)
        Returns:
        the hash value

      • getFastHash

        public static int getFastHash​(java.lang.String o,
                              int index,
                              int seed)
        A cryptographically weak hash function. It is supposed to be fast.
        Parameters:
        o - the string
        index - the hash function index
        seed - the seed
        Returns:
        the hash value

      • getSipHash24

        public static int getSipHash24​(java.lang.String o,
                               long k0,
                               long k1)
        A cryptographically relatively secure hash function. It is supposed to protected against hash-flooding denial-of-service attacks.
        Parameters:
        o - the string
        k0 - key 0
        k1 - key 1
        Returns:
        the hash value

      • getSipHash24

        public static int getSipHash24​(byte[] b,
                               int start,
                               int end,
                               long k0,
                               long k1)
        A cryptographically relatively secure hash function. It is supposed to protected against hash-flooding denial-of-service attacks.
        Parameters:
        b - the data
        start - the start position
        end - the end position plus one
        k0 - key 0
        k1 - key 1
        Returns:
        the hash value