Provided by: libhashkit-dev_1.1.4-1_amd64 
NAME
libhashkit - libhashkit Documentation
SYNOPSIS
#include <libhashkit-1.0/hashkit.h>
Compile and link with -lhashkit.
DESCRIPTION
libhashkit is a small and thread-safe client library that provides a collection of useful
hashing algorithms.
libhashkit is distributed with libmemcached.
Creating a hashkit structure
SYNOPSIS
#include <libhashkit-1.0/hashkit.h>
Compile and link with -lhashkit
typedef struct hashkit_st hashkit_st
hashkit_st *hashkit_create(hashkit_st *hash)
Parameters
hash -- memory address of a hashkit_st struct; if a nullptr is passed, the
struct will be dynamically allocated by libhashkit
Returns
pointer to initialized hashkit_st structure
hashkit_st *hashkit_clone(hashkit_st *destination, const hashkit_st *ptr)
Parameters
• destination -- memory address of a hashkit_st struct; if a nullptr is
passed, the struct will be dynamically allocated by libhashkit
• ptr -- pointer of the hashkit_st struct to copy
Returns
pointer to a hashkit_st structure (destination, if not nullptr), initialized
from ptr
void hashkit_free(hashkit_st *hash)
Parameters
hash -- pointer to an initialized hashkit_st struct
bool hashkit_is_allocated(const hashkit_st *hash)
Parameters
hash -- pointer to an initialized hashkit_st struct
Returns
bool, whether the hash struct was dynamically allocated
DESCRIPTION
The hashkit_create() function initializes a hashkit object for use. If you pass a nullptr
argument for hash, then the memory for the object is allocated. If you specify a
pre-allocated piece of memory, that is initialized for use.
The hashkit_clone() function initializes a hashkit object much like hashkit_create(), but
instead of using default settings it will use the settings of the ptr hashkit object.
The hashkit_free() frees any resources being consumed by the hashkit objects that were
initialized with hashkit_create() or hashkit_clone().
The hashkit_is_allocated() reports whether the memory was allocated for a hashkit object.
RETURN VALUE
hashkit_create() and hashkit_clone() will return nullptr on failure or pointer to
hashkit_st on success.
hashkit_is_allocated() returns true if the memory for the hashkit object was allocated
inside of hashkit_create() or hashkit_clone(), otherwise it is false and was user-supplied
memory.
SEE ALSO
libhashkit(3) hashkit_value(3) hashkit_function3)
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
• hash -- pointer to an initialized hashkit_st struct
• hash_algorithm -- valid hashkit_hash_algorithm_t constant
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
libhashkit(3) hashkit_create(3) hashkit_functions(3)
Available Hashes
SYNOPSIS
#include <libhashkit-1.0/hashkit.h>
Compile and link with -lhashkit
uint32_t hashkit_default(const char *key, size_t key_length)
uint32_t hashkit_fnv1_64(const char *key, size_t key_length)
uint32_t hashkit_fnv1a_64(const char *key, size_t key_length)
uint32_t hashkit_fnv1_32(const char *key, size_t key_length)
uint32_t hashkit_fnv1a_32(const char *key, size_t key_length)
uint32_t hashkit_crc32(const char *key, size_t key_length)
uint32_t hashkit_hsieh(const char *key, size_t key_length)
uint32_t hashkit_murmur(const char *key, size_t key_length)
uint32_t hashkit_murmur3(const char *key, size_t key_length)
uint32_t hashkit_jenkins(const char *key, size_t key_length)
uint32_t hashkit_md5(const char *key, size_t key_length)
DESCRIPTION
These functions generate hash values from a key using a variety of algorithms. These
functions can be used standalone, or will be used according to the algorithm set with
hashkit_set_function() or hashkit_set_distribution_function().
The hashkit_hsieh(), hashkit_murmur() and hashkit_murmur3() functions are only available
if the library is built with the appropriate flag enabled.
RETURN VALUE
A 32-bit hash value.
SEE ALSO
libhashkit(3) hashkit_create(3) hashkit_function(3)
Generate hash value
SYNOPSIS
#include <libhashkit-1.0/hashkit.h>
Compile and link with -lhashkit
uint32_t hashkit_value(hashkit_st *hash, const char *key, size_t key_length)
Parameters
• hash -- pointer to an initialized hashkit_st struct
• key -- the key to genereate a hash of
• key_length -- the length of the key without any terminating zero byte
DESCRIPTION
The hashkit_value() function generates a 32-bit hash value from the given key and
key_length. The hash argument is an initialized hashkit object, and distribution type and
hash function is used from this object while generating the value.
RETURN VALUE
A 32-bit hash value.
SEE ALSO
libhashkit(3) hashkit_create(3) hashkit_function(3) hashkit_functions(3)
SEE ALSO
libmemcached(3) hashkit_create(3) hashkit_function(3) hashkit_functions(3)
hashkit_value(3)