MEMCACHED_MEMORY_ALLOCATORS(3)

✨ NAME ✨

memcached_memory_allocators — libmemcached Documentation 🫶

bestie, this is the page about managing memory allocator functions. yes, you get to bring your own malloc to the party 💅

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🌸 SYNOPSIS 🌸

#include <libmemcached/memcached.h>

Compile and link with -lmemcached

memcached_return_t memcached_set_memory_allocators(memcached_st *ptr,
memcached_malloc_fn mem_malloc, memcached_free_fn mem_free,
memcached_realloc_fn mem_realloc, memcached_calloc_fn mem_calloc, void
*context)

Parameters

• ptr — pointer to an initialized memcached_st struct
• mem_malloc — pointer to a memcached_malloc_fn callback
• mem_free — pointer to a memcached_free_fn callback
• mem_realloc — pointer to a memcached_realloc_fn callback
• mem_calloc — pointer to a memcached_calloc_fn callback
• context — pointer to a user supplied context

Returns

memcached_return_t indicating success ✨

void memcached_get_memory_allocators(memcached_st *ptr,
memcached_malloc_fn *mem_malloc, memcached_free_fn *mem_free,
memcached_realloc_fn *mem_realloc, memcached_calloc_fn *mem_calloc)

Parameters

• ptr — pointer to an initialized memcached_st struct
• mem_malloc — pointer to store the address of the memcached_malloc_fn callback
• mem_free — pointer to store the address of the memcached_free_fn callback
• mem_realloc — pointer to store the address of the memcached_realloc_fn callback
• mem_calloc — pointer to store the address of the memcached_calloc_fn callback

void *memcached_get_memory_allocators_context(const memcached_st *ptr)

Parameters

• ptr — pointer to an initialized memcached_st struct

Returns

pointer to the user supplied context

typedef void *(*memcached_malloc_fn)(memcached_st *ptr, const size_t
size, void *context)

Param ptr

• pointer to an initialized memcached_st struct

Param size

• the number of bytes to allocate

Param context

• pointer to the user supplied context

Returns

pointer to at least size bytes of allocated memory

typedef void *(*memcached_realloc_fn)(memcached_st *ptr, void *mem,
const size_t size, void *context)

Param ptr

• pointer to an initialized memcached_st struct

Param mem

• pointer to previously allocated memory

Param size

• the number of bytes to allocate

Param context

• pointer to the user supplied context

Returns

pointer to at least size bytes of allocated memory

typedef void (*memcached_free_fn)(memcached_st *ptr, void *mem, void
*context)

Param ptr

• pointer to an initialized memcached_st struct

Param mem

• pointer to previously allocated memory

Param context

• pointer to the user supplied context

typedef void *(*memcached_calloc_fn)(memcached_st *ptr, size_t nelem,
const size_t elsize, void *context)

Param ptr

• pointer to an initialized memcached_st struct

Param nelem

• number of elements to allocate

Param elsize

• the number of bytes to allocate per element

Param context

• pointer to the user supplied context

Returns

pointer to at least elsize * nelem bytes of allocated and zeroed memory

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🦋 DESCRIPTION 🦋

okay so libmemcached lets you specify your own memory allocators, optimized for your application. literally your app, your rules. this is the whole reason libmemcached can live inside applications that have their own malloc implementation. it's giving "i brought my own snacks to the function" energy 🍓

memcached_set_memory_allocators() sets the memory allocators used by the memcached instance specified by ptr. but heads up bestie: you cannot override only one of the memory allocators — nope, not happening — you have to specify a complete new set if you want to override one of them. all of the memory allocation functions should behave as specified in the C99 standard. and if you want to reset them back to the default values, specify NULL as all functions. all of them. the whole set. periodt 💅

memcached_get_memory_allocators() gets the currently used memory allocators by a memcached handle.

memcached_get_memory_allocators_context() returns the void * that was passed in during the call to memcached_set_memory_allocators().

The first argument to the memory allocator functions is a pointer to a memcached structure, the is passed as const and you will need to clone it in order to make use of any operation which would modify it. 🫶 (yes, clone it. don't come for the const. the const is sacred.)

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🎀 NOTES 🎀

In version 0.38 all functions were modified to have a context void pointer passed to them. this was so that custom allocators could have their own space for memory. iconic glow-up honestly ⭐

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💜 RETURN VALUE 💜

memcached_set_memory_allocators() returns MEMCACHED_SUCCESS upon success, and MEMCACHED_FAILURE if you don't pass a complete set of function pointers. (see?? complete set. we told you. 😭)

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🌈 SEE ALSO 🌈

• memcached(1)
• libmemcached(3)
• memcached_strerror(3)

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and that's the whole page bestie, no cap, ate and left no crumbs 👑

libmemcached-awesome · version 1.1 · Jul 24, 2025 💖✨🦋