--- name: "libhashkit" section: "3" platform: "linux" package: "libmemcached-awesome" version: "1.1.4-4" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/libhashkit" --- # libhashkit(3) libhashkit Documentation ## 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 \<#\_CPPv410hashkit\_st\> hashkit\_st** - **hashkit\_st \<#\_CPPv410hashkit\_st\> \*hashkit\_create(hashkit\_st \<#\_CPPv410hashkit\_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 \<#\_CPPv410hashkit\_st\> \*hashkit\_clone(hashkit\_st \<#\_CPPv410hashkit\_st\> \*destination, const hashkit\_st \<#\_CPPv410hashkit\_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 \<#\_CPPv410hashkit\_st\> \*hash)** - **Parameters** **hash** -- pointer to an initialized **hashkit\_st** struct - **bool hashkit\_is\_allocated(const hashkit\_st \<#\_CPPv410hashkit\_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)](/libhashkit/3.md) \** **[hashkit\_value(3)](/hashkit_value/3.md) \** **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 \<#c.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 \<#c.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 \<#\_CPPv416hashkit\_return\_t\> hashkit\_set\_function(hashkit\_st \<#\_CPPv410hashkit\_st\> \*hash, hashkit\_hash\_algorithm\_t \<#\_CPPv424hashkit\_hash\_algorithm\_t\> hash\_algorithm)** - **Parameters** - • **hash** -- pointer to an initialized **hashkit\_st** \<#\_CPPv410hashkit\_st\> struct - • **hash\_algorithm** -- valid **hashkit\_hash\_algorithm\_t** constant - **Returns** **hashkit\_return\_t** indicating success or failure - **hashkit\_return\_t \<#\_CPPv416hashkit\_return\_t\> hashkit\_set\_custom\_function(hashkit\_st \<#\_CPPv410hashkit\_st\> \*hash, hashkit\_hash\_fn \<#\_CPPv415hashkit\_hash\_fn\> function, void \*context)** - **Parameters** - • **hash** -- pointer to initialized **hashkit\_st** \<#\_CPPv410hashkit\_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 \<#\_CPPv424hashkit\_hash\_algorithm\_t\> hashkit\_get\_function(const hashkit\_st \<#\_CPPv410hashkit\_st\> \*hash)** - **Parameters** **hash** -- pointer to an initialized **hashkit\_st** \<#\_CPPv410hashkit\_st\> struct - **Returns** **hashkit\_hash\_algorithm\_t** indicating the currently set hash algorithm to use - **hashkit\_return\_t \<#\_CPPv416hashkit\_return\_t\> hashkit\_set\_distribution\_function(hashkit\_st \<#\_CPPv410hashkit\_st\> \*hash, hashkit\_hash\_algorithm\_t \<#\_CPPv424hashkit\_hash\_algorithm\_t\> hash\_algorithm)** - **Parameters** - • **hash** -- pointer to an initialized **hashkit\_st** \<#\_CPPv410hashkit\_st\> struct - • **hash\_algorithm** -- valid **hashkit\_hash\_algrothm\_t** constant - **Returns** **hashkit\_return\_t** indicating success or failure - **hashkit\_return\_t \<#\_CPPv416hashkit\_return\_t\> hashkit\_set\_custom\_distribution\_function(hashkit\_st \<#\_CPPv410hashkit\_st\> \*hash, hashkit\_hash\_fn \<#\_CPPv415hashkit\_hash\_fn\> function, void \*context)** - **Parameters** - • **hash** -- pointer to initialized **hashkit\_st** \<#\_CPPv410hashkit\_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 \<#\_CPPv424hashkit\_hash\_algorithm\_t\> hashkit\_get\_distribution\_function(const hashkit\_st \<#\_CPPv410hashkit\_st\> \*hash)** - **Parameters** **hash** -- pointer to an initialized **hashkit\_st** \<#\_CPPv410hashkit\_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)](/libhashkit/3.md) \** **[hashkit\_create(3)](/hashkit_create/3.md) \** **[hashkit\_functions(3)](/hashkit_functions/3.md) \** ### 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()** \<#\_CPPv420hashkit\_set\_functionP10hashkit\_st24hashkit\_hash\_algorithm\_t\> or **hashkit\_set\_distribution\_function()** \<#\_CPPv433hashkit\_set\_distribution\_functionP10hashkit\_st24hashkit\_hash\_algorithm\_t\>. 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)](/libhashkit/3.md) \** **[hashkit\_create(3)](/hashkit_create/3.md) \** **[hashkit\_function(3)](/hashkit_function/3.md) \** ### Generate hash value ### SYNOPSIS - **#include \** Compile and link with -lhashkit - **uint32\_t hashkit\_value(hashkit\_st \<#\_CPPv410hashkit\_st\> \*hash, const char \*key, size\_t key\_length)** - **Parameters** - • **hash** -- pointer to an initialized **hashkit\_st** \<#\_CPPv410hashkit\_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)](/libhashkit/3.md) \** **[hashkit\_create(3)](/hashkit_create/3.md) \** **[hashkit\_function(3)](/hashkit_function/3.md) \** **[hashkit\_functions(3)](/hashkit_functions/3.md) \** ## SEE ALSO **[libmemcached(3)](/libmemcached/3.md) \** **[hashkit\_create(3)](/hashkit_create/3.md) \** **[hashkit\_function(3)](/hashkit_function/3.md) \** **[hashkit\_functions(3)](/hashkit_functions/3.md) \** **[hashkit\_value(3)](/hashkit_value/3.md) \**