Set Hash Function

SYNOPSIS

#include <libhashkit-1.0/hashkit.h>

Compile and link with -lhashkit

typedef uint32_t (*hashkit_hash_fn)(const char *key, size_t key_length, void *context)
Param key:

the key to generate a hash of

Param key_length:

the length of the key without any terminating zero byte

Param context:

the custom hash function context set through hashkit_set_custom_function() or hashkit_set_custom_distribution_function()

Returns:

the custom hash function should return a hash value for key as an unsigned 32bit integer

typedef enum hashkit_return_t hashkit_return_t
enum hashkit_return_t
enumerator HASHKIT_SUCCESS

Operation succeeded.

enumerator HASHKIT_FAILURE

Operation failed.

enumerator HASHKIT_MEMORY_ALLOCATION_FAILURE

Memory allocation failed.

enumerator HASHKIT_INVALID_HASH

Invalid hashkit_hash_algorithm_t passed.

enumerator HASHKIT_INVALID_ARGUMENT

Invalid argument passed.

typedef enum hashkit_hash_algorithm_t hashkit_hash_algorithm_t
enum hashkit_hash_algorithm_t
enumerator HASHKIT_HASH_DEFAULT

Default hash algorithm (one_at_a_time).

enumerator HASHKIT_HASH_MD5
enumerator HASHKIT_HASH_CRC
enumerator HASHKIT_HASH_FNV1_64
enumerator HASHKIT_HASH_FNV1A_64
enumerator HASHKIT_HASH_FNV1_32
enumerator HASHKIT_HASH_FNV1A_32
enumerator HASHKIT_HASH_HSIEH

Only available if libhashkit hash been built with HSIEH support.

enumerator HASHKIT_HASH_MURMUR

Only available if libhashkit has been built with MURMUR support.

enumerator HASHKIT_HASH_MURMUR3

Only available if libhashkit has been built with MURMUR support.

enumerator HASHKIT_HASH_JENKINS
enumerator HASHKIT_HASH_CUSTOM

Use custom hashkit_hash_fn function set through hashkit_set_custom_function() or hashkit_set_custom_distribution_function().

hashkit_return_t hashkit_set_function(hashkit_st *hash, hashkit_hash_algorithm_t hash_algorithm)
Parameters:
Returns:

hashkit_return_t indicating success or failure

hashkit_return_t hashkit_set_custom_function(hashkit_st *hash, hashkit_hash_fn function, void *context)
Parameters:

  • hash -- pointer to initialized hashkit_st struct

  • function -- hashkit_hash_fn function pointer to use as hash function for HASHKIT_HASH_CUSTOM

  • context -- pointer to an opaque user managed context for the custom hash function

Returns:

hashkit_return_t indicating success or failure

hashkit_hash_algorithm_t hashkit_get_function(const hashkit_st *hash)
Parameters:

hash -- pointer to an initialized hashkit_st struct

Returns:

hashkit_hash_algorithm_t indicating the currently set hash algorithm to use

hashkit_return_t hashkit_set_distribution_function(hashkit_st *hash, hashkit_hash_algorithm_t hash_algorithm)
Parameters:

  • hash -- pointer to an initialized hashkit_st struct

  • hash_algorithm -- valid hashkit_hash_algrothm_t constant

Returns:

hashkit_return_t indicating success or failure

hashkit_return_t hashkit_set_custom_distribution_function(hashkit_st *hash, hashkit_hash_fn function, void *context)
Parameters:

  • hash -- pointer to initialized hashkit_st struct

  • function -- hashkit_hash_fn function pointer to use as distribution hash function for HASHKIT_HASH_CUSTOM

  • context -- pointer to an opaque user managed context for the custom distribution hash function

hashkit_hash_algorithm_t hashkit_get_distribution_function(const hashkit_st *hash)
Parameters:

hash -- pointer to an initialized hashkit_st struct

Returns:

hashkit_hash_algorithm_t indicating the currently set distribution hash algorithm to use

DESCRIPTION

These functions are used to set and retrieve the key and distribution hash functions.

RETURN VALUE

hashkit_set_function(), hashkit_set_custom_function() and the distribution equivalents return hashkit_return_t::HASHKIT_SUCCESS on success.

hashkit_get_function() and hashkit_get_distribution_function() return hashkit_hash_algorithm_t indicating the hash function used.

SEE ALSO