orestes.bloomfilter

Class HashProvider

java.lang.Object

orestes.bloomfilter.HashProvider

public class HashProvider
extends java.lang.Object

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	HashProvider.HashFunction An interface which can be implemented to provide custom hash functions.
static class	HashProvider.HashMethod Different types of hash functions that can be used.

Constructor Summary

Constructors

Constructor and Description
HashProvider()

Method Summary

Modifier and Type	Method and Description
static int[]	hashAdler(byte[] value, int m, int k)
static int[]	hashCarterWegman(byte[] value, int m, int k)
static int[]	hashCassandra(byte[] value, int m, int k)
static int[]	hashChecksum(byte[] value, java.util.zip.Checksum cs, int m, int k)
static int[]	hashCRC(byte[] value, int m, int k)
static int[]	hashCrypt(byte[] value, int m, int k, java.lang.String method)
static int[]	hashMurmur2(byte[] value, int em, int ka)
static int[]	hashMurmur3(byte[] value, int m, int k)
static int[]	hashRNG(byte[] value, int m, int k)
static int[]	hashSimpleLCG(byte[] value, int m, int k)
static int	murmur3(int seed, byte[] bytes)
static int[]	rejectionSample(java.util.function.BiFunction<java.lang.Integer,byte[],java.lang.Integer> hashFunction, byte[] value, int m, int k)
static int	rejectionSample(int random, int m) Performs rejection sampling on a random 32bit Java int (sampled from Integer.MIN_VALUE to Integer.MAX_VALUE).

Methods inherited from class java.lang.Object

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

Constructor Detail

HashProvider

public HashProvider()

Method Detail

hashCarterWegman

public static int[] hashCarterWegman(byte[] value,
                                     int m,
                                     int k)

Parameters:

value - the value to be hashed

m - integer output range [1,size]

k - number of hashes to be computed

Returns:

array with hashes integer hash positions in the range [0,size)

hashRNG

public static int[] hashRNG(byte[] value,
                            int m,
                            int k)

Parameters:

value - the value to be hashed

m - integer output range [1,size]

k - number of hashes to be computed

Returns:

array with hashes integer hash positions in the range [0,size)

hashCRC

public static int[] hashCRC(byte[] value,
                            int m,
                            int k)

Parameters:

value - the value to be hashed

m - integer output range [1,size]

k - number of hashes to be computed

Returns:

array with hashes integer hash positions in the range [0,size)

hashAdler

public static int[] hashAdler(byte[] value,
                              int m,
                              int k)

Parameters:

value - the value to be hashed

m - integer output range [1,size]

k - number of hashes to be computed

Returns:

array with hashes integer hash positions in the range [0,size)

hashChecksum

public static int[] hashChecksum(byte[] value,
                                 java.util.zip.Checksum cs,
                                 int m,
                                 int k)

hashSimpleLCG

public static int[] hashSimpleLCG(byte[] value,
                                  int m,
                                  int k)

Parameters:

value - the value to be hashed

m - integer output range [1,size]

k - number of hashes to be computed

Returns:

array with hashes integer hash positions in the range [0,size)

hashMurmur3

public static int[] hashMurmur3(byte[] value,
                                int m,
                                int k)

hashCassandra

public static int[] hashCassandra(byte[] value,
                                  int m,
                                  int k)

murmur3

public static int murmur3(int seed,
                          byte[] bytes)

hashMurmur2

public static int[] hashMurmur2(byte[] value,
                                int em,
                                int ka)

rejectionSample

public static int rejectionSample(int random,
                                  int m)

Performs rejection sampling on a random 32bit Java int (sampled from Integer.MIN_VALUE to Integer.MAX_VALUE).

Parameters:

random - int

m - integer output range [1,size]

Returns:

the number down-sampled to interval [0, size]. Or -1 if it has to be rejected.

rejectionSample

public static int[] rejectionSample(java.util.function.BiFunction<java.lang.Integer,byte[],java.lang.Integer> hashFunction,
                                    byte[] value,
                                    int m,
                                    int k)

hashCrypt

public static int[] hashCrypt(byte[] value,
                              int m,
                              int k,
                              java.lang.String method)

Parameters:

value - the value to be hashed

m - integer output range [1,size]

k - number of hashes to be computed

method - the hash method name used by MessageDigest.getInstance(String)

Returns:

array with hashes integer hash positions in the range [0,size)