LIBHASHKIT(3) libmemcached-awesome LIBHASHKIT(3) NAME libhashkit - libhashkit Documentation SYNOPSIS #include 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 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 o destination -- memory address of a hashkit_st struct; if a nullptr is passed, the struct will be dynamically allocated by libhashkit o 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 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 o hash -- pointer to an initialized hashkit_st struct o 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 o hash -- pointer to initialized hashkit_st struct o function -- hashkit_hash_fn function pointer to use as hash function for HASHKIT_HASH_CUSTOM o 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 o hash -- pointer to an initialized hashkit_st struct o 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 o hash -- pointer to initialized hashkit_st struct o function -- hashkit_hash_fn function pointer to use as distribution hash function for HASHKIT_HASH_CUSTOM o 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 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 Compile and link with -lhashkit uint32_t hashkit_value(hashkit_st *hash, const char *key, size_t key_length) Parameters o hash -- pointer to an initialized hashkit_st struct o key -- the key to genereate a hash of o 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) 1.1 May 1, 2024 LIBHASHKIT(3)