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   1 =================
   2 Setting callbacks
   3 =================
   4
   5
   6 Get and set a callback
   7
   8
   9 *******
  10 LIBRARY
  11 *******
  12
  13
  14 C Client Library for memcached (libmemcached, -lmemcached)
  15
  16
  17 --------
  18 SYNOPSIS
  19 --------
  20
  21
  22
  23 .. code-block:: perl
  24
  25    #include <libmemcached/memcached.h>
  26
  27    memcached_return_t
  28      memcached_callback_set (memcached_st *ptr,
  29                              memcached_callback_t flag,
  30                              void *data);
  31
  32    void *
  33      memcached_callback_get (memcached_st *ptr,
  34                              memcached_callback_t flag,
  35                              memcached_return_t *error);
  36
  37
  38
  39 -----------
  40 DESCRIPTION
  41 -----------
  42
  43
  44 libmemcached(3) can have callbacks set key execution points. These either
  45 provide function calls at points in the code, or return pointers to
  46 structures for particular usages.
  47
  48 memcached_callback_get() takes a callback flag and returns the structure or
  49 function set by memcached_callback_set().
  50
  51 memcached_callback_set() changes the function/structure assigned by a
  52 callback flag. No connections are reset.
  53
  54 You can use MEMCACHED_CALLBACK_USER_DATA to provide custom context if required for any
  55 of the callbacks
  56
  57
  58 MEMCACHED_CALLBACK_CLEANUP_FUNCTION
  59
  60  When memcached_delete() is called this function will be excuted. At the
  61  point of its execution all connections have been closed.
  62
  63
  64
  65 MEMCACHED_CALLBACK_CLONE_FUNCTION
  66
  67  When memcached_delete() is called this function will be excuted. At the
  68  point of its execution all connections have been closed.
  69
  70
  71
  72 MEMCACHED_CALLBACK_PREFIX_KEY
  73
  74  You can set a value which will be used to create a domain for your keys.
  75  The value specified here will be prefixed to each of your keys. The value can not
  76  be greater then MEMCACHED_PREFIX_KEY_MAX_SIZE - 1 and will reduce MEMCACHED_MAX_KEY by
  77  the value of your key. The prefix key is only applied to the primary key,
  78  not the master key. MEMCACHED_FAILURE will be returned if no key is set. In the case
  79  of a key which is too long MEMCACHED_BAD_KEY_PROVIDED will be returned.
  80
  81  If you set a value with the value being NULL then the prefix key is disabled.
  82
  83
  84 MEMCACHED_CALLBACK_USER_DATA
  85
  86  This allows you to store a pointer to a specifc piece of data. This can be
  87  retrieved from inside of memcached_fetch_execute(). Cloning a memcached_st
  88  will copy the pointer to the clone.
  89
  90
  91
  92 MEMCACHED_CALLBACK_MALLOC_FUNCTION
  93
  94  DEPRECATED: use memcached_set_memory_allocators instead.
  95
  96
  97
  98 MEMCACHED_CALLBACK_REALLOC_FUNCTION
  99
 100  DEPRECATED: use memcached_set_memory_allocators instead.
 101
 102
 103
 104 MEMCACHED_CALLBACK_FREE_FUNCTION
 105
 106  DEPRECATED: use memcached_set_memory_allocators instead.
 107
 108
 109
 110 MEMCACHED_CALLBACK_GET_FAILURE
 111
 112  This function implements the read through cache behavior. On failure of retrieval this callback will be called.
 113  You are responsible for populating the result object provided. This result object will then be stored in the server and
 114  returned to the calling process. You must clone the memcached_st in order to
 115  make use of it. The value will be stored only if you return
 116  MEMCACHED_SUCCESS or MEMCACHED_BUFFERED. Returning MEMCACHED_BUFFERED will
 117  cause the object to be buffered and not sent immediatly (if this is the default behavior based on your connection setup this will happen automatically).
 118
 119  The prototype for this is:
 120  memcached_return_t (\*memcached_trigger_key)(memcached_st \*ptr, char \*key, size_t key_length, memcached_result_st \*result);
 121
 122
 123
 124 MEMCACHED_CALLBACK_DELETE_TRIGGER
 125
 126  This function implements a trigger upon successful deletion of a key. The memcached_st structure will need to be cloned
 127  in order to make use of it.
 128
 129  The prototype for this is:
 130  typedef memcached_return_t (\*memcached_trigger_delete_key)(memcached_st \*ptr, char \*key, size_t key_length);
 131
 132
 133
 134
 135 ******
 136 RETURN
 137 ******
 138
 139
 140 memcached_callback_get() return the function or structure that was provided.
 141 Upon error, nothing is set, null is returned, and the memcached_return_t
 142 argument is set to MEMCACHED_FAILURE.
 143
 144 memcached_callback_set() returns MEMCACHED_SUCCESS upon successful setting,
 145 otherwise MEMCACHED_FAILURE on error.
 146
 147
 148 ****
 149 HOME
 150 ****
 151
 152
 153 To find out more information please check:
 154 `https://launchpad.net/libmemcached <https://launchpad.net/libmemcached>`_
 155
 156
 157 ******
 158 AUTHOR
 159 ******
 160
 161
 162 Brian Aker, <brian@tangent.org>
 163
 164
 165 --------
 166 SEE ALSO
 167 --------
 168
 169
 170 :manpage:`memcached(1)` :manpage:`libmemcached(3)` :manpage:`memcached_strerror(3)`