git.m6w6.name Git - awesomized/libmemcached/blob - libmemcached/memcached_memory_allocators.rst

   1 Use custom allocators for embedded usage
   2 ========================================
   3
   4 Manage memory allocator functions
   5
   6 SYNOPSIS
   7 --------
   8
   9 #include <libmemcached/memcached.h>
  10   Compile and link with -lmemcached
  11
  12 .. function:: 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)
  13
  14     :param ptr: pointer to an initialized `memcached_st` struct
  15     :param mem_malloc: pointer to a `memcached_malloc_fn` callback
  16     :param mem_free: pointer to a `memcached_free_fn` callback
  17     :param mem_realloc: pointer to a `memcached_realloc_fn` callback
  18     :param mem_calloc: pointer to a `memcached_calloc_fn` callback
  19     :param context: pointer to a user supplied context
  20     :returns: `memcached_return_t` indicating success
  21
  22 .. function:: 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)
  23
  24     :param ptr: pointer to an initialized `memcached_st` struct
  25     :param mem_malloc: pointer to store the address of the `memcached_malloc_fn` callback
  26     :param mem_free: pointer to store the address of the `memcached_free_fn` callback
  27     :param mem_realloc: pointer to store the address of the `memcached_realloc_fn` callback
  28     :param mem_calloc: pointer to store the address of the `memcached_calloc_fn` callback
  29
  30 .. function:: void * memcached_get_memory_allocators_context(const memcached_st *ptr)
  31
  32     :param ptr: pointer to an initialized `memcached_st` struct
  33     :returns: pointer to the user supplied context
  34
  35 .. type:: void * (*memcached_malloc_fn) (memcached_st *ptr, const size_t size, void *context)
  36
  37     :param ptr: pointer to an initialized `memcached_st` struct
  38     :param size: the number of bytes to allocate
  39     :param context: pointer to the user supplied context
  40     :returns: pointer to at least `size` bytes of allocated memory
  41
  42 .. type:: void * (*memcached_realloc_fn) (memcached_st *ptr, void *mem, const size_t size, void *context)
  43
  44     :param ptr: pointer to an initialized `memcached_st` struct
  45     :param mem: pointer to previously allocated memory
  46     :param size: the number of bytes to allocate
  47     :param context: pointer to the user supplied context
  48     :returns: pointer to at least `size` bytes of allocated memory
  49
  50 .. type:: void (*memcached_free_fn) (memcached_st *ptr, void *mem, void *context)
  51
  52     :param ptr: pointer to an initialized `memcached_st` struct
  53     :param mem: pointer to previously allocated memory
  54     :param context: pointer to the user supplied context
  55
  56 .. type:: void * (*memcached_calloc_fn) (memcached_st *ptr, size_t nelem, const size_t elsize, void *context)
  57
  58     :param ptr: pointer to an initialized `memcached_st` struct
  59     :param nelem: number of elements to allocate
  60     :param elsize: the number of bytes to allocate per element
  61     :param context: pointer to the user supplied context
  62     :returns: pointer to at least `elsize` \* `nelem`  bytes of allocated and zeroed memory
  63
  64 DESCRIPTION
  65 -----------
  66
  67 `libmemcached` allows you to specify your own memory allocators, optimized for
  68 your application. This enables libmemcached to be used inside of applications
  69 that have their own malloc implementation.
  70
  71 :func:`memcached_set_memory_allocators` is used to set the memory allocators
  72 used by the memcached instance specified by ptr. Please note that you cannot
  73 override only one of the memory allocators, you have to specify a complete new
  74 set if you want to override one of them. All of the memory allocation functions
  75 should behave as specified in the C99 standard. Specify NULL as all functions to
  76 reset them to the default values.
  77
  78 :func:`memcached_get_memory_allocators` is used to get the currently used memory
  79 allocators by a memcached handle.
  80
  81 :func:`memcached_get_memory_allocators_context` returns the void \* that was
  82 passed in during the call to :func:`memcached_set_memory_allocators`.
  83
  84 The first argument to the memory allocator functions is a pointer to a memcached
  85 structure, the is passed as const and you will need to clone it in order to make
  86 use of any operation which would modify it.
  87
  88 NOTES
  89 -----
  90
  91 In version 0.38 all functions were modified to have a context void pointer
  92 passed to them. This was so that custom allocators could have their own space
  93 for memory.
  94
  95 RETURN VALUE
  96 ------------
  97
  98 :func:`memcached_set_memory_allocators` returns `MEMCACHED_SUCCESS` upon success,
  99 and `MEMCACHED_FAILURE` if you don't pass a complete set of function pointers.
 100
 101 SEE ALSO
 102 --------
 103
 104 .. only:: man
 105
 106     :manpage:`memcached(1)`
 107     :manpage:`libmemcached(3)`
 108     :manpage:`memcached_strerror(3)`
 109
 110 .. only:: html
 111
 112     * :manpage:`memcached(1)`
 113     * :doc:`../libmemcached`
 114     * :doc:`memcached_strerror`