org.aredis.cache

Enum DefaultHashAlgorithm

java.lang.Object

java.lang.Enum<DefaultHashAlgorithm>

org.aredis.cache.DefaultHashAlgorithm

All Implemented Interfaces:

Serializable, Comparable<DefaultHashAlgorithm>, HashAlgorithm

public enum DefaultHashAlgorithm
extends Enum<DefaultHashAlgorithm>
implements HashAlgorithm

Known hashing algorithms for locating a server for a key. Note that all hash algorithms return 64-bits of hash, but only the lower 32-bits are significant. This allows a positive 32-bit number to be returned for all cases.

This has been borrowed from SpyMemcached.

Enum Constant Summary

Enum Constants

Enum Constant and Description
AREDIS_HASH An improvement of String.hashCode which gives near hash codes for keys with a common prefix.
CRC_HASH CRC_HASH as used by the perl API.
FNV1_32_HASH 32-bit FNV1.
FNV1_64_HASH FNV hashes are designed to be fast while maintaining a low collision rate.
FNV1A_32_HASH 32-bit FNV1a.
FNV1A_64_HASH Variation of FNV.
KETAMA_HASH MD5-based hash algorithm used by ketama.
NATIVE_HASH Native hash (String.hashCode()).

Method Summary

Methods

Modifier and Type	Method and Description
static byte[]	computeMd5(String k) Get the md5 of the given key.
int	hash(String k) Compute the hash for the given key.
static DefaultHashAlgorithm	valueOf(String name) Returns the enum constant of this type with the specified name.
static DefaultHashAlgorithm[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

NATIVE_HASH

public static final DefaultHashAlgorithm NATIVE_HASH

Native hash (String.hashCode()).

AREDIS_HASH

public static final DefaultHashAlgorithm AREDIS_HASH

An improvement of String.hashCode which gives near hash codes for keys with a common prefix. The hash algorithm is the same but the characters are read in the order (len-1),0,(len-2),1... where len is the length of the String. Also if the length of the String is less than 8 it is padded with 257 to make the length 8.

CRC_HASH

public static final DefaultHashAlgorithm CRC_HASH

CRC_HASH as used by the perl API. This will be more consistent both across multiple API users as well as java versions, but is mostly likely significantly slower.

FNV1_64_HASH

public static final DefaultHashAlgorithm FNV1_64_HASH

FNV hashes are designed to be fast while maintaining a low collision rate. The FNV speed allows one to quickly hash lots of data while maintaining a reasonable collision rate.

See Also:

fnv comparisons, fnv at wikipedia

FNV1A_64_HASH

public static final DefaultHashAlgorithm FNV1A_64_HASH

Variation of FNV.

FNV1_32_HASH

public static final DefaultHashAlgorithm FNV1_32_HASH

32-bit FNV1.

FNV1A_32_HASH

public static final DefaultHashAlgorithm FNV1A_32_HASH

32-bit FNV1a.

KETAMA_HASH

public static final DefaultHashAlgorithm KETAMA_HASH

MD5-based hash algorithm used by ketama.

Method Detail

values

public static DefaultHashAlgorithm[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (DefaultHashAlgorithm c : DefaultHashAlgorithm.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static DefaultHashAlgorithm valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

hash

public int hash(String k)

Compute the hash for the given key.

Specified by:

hash in interface HashAlgorithm

Returns:

an integer hash

computeMd5

public static byte[] computeMd5(String k)

Get the md5 of the given key.