git.m6w6.name Git - awesomized/libmemcached/blob - docs/memcached_callback.rst

   1 .. highlight:: perl
   2
   3
   4 ****
   5 NAME
   6 ****
   7
   8
   9 memcached_callback_get, memcached_callback_set - Get and set a callback
  10
  11
  12 *******
  13 LIBRARY
  14 *******
  15
  16
  17 C Client Library for memcached (libmemcached, -lmemcached)
  18
  19
  20 ********
  21 SYNOPSIS
  22 ********
  23
  24
  25
  26 .. code-block:: perl
  27
  28    #include <memcached.h>
  29
  30    memcached_return_t
  31      memcached_callback_set (memcached_st *ptr,
  32                              memcached_callback_t flag,
  33                              void *data);
  34
  35    void *
  36      memcached_callback_get (memcached_st *ptr,
  37                              memcached_callback_t flag,
  38                              memcached_return_t *error);
  39
  40
  41
  42 ***********
  43 DESCRIPTION
  44 ***********
  45
  46
  47 libmemcached(3) can have callbacks set key execution points. These either
  48 provide function calls at points in the code, or return pointers to
  49 structures for particular usages.
  50
  51 memcached_callback_get() takes a callback flag and returns the structure or
  52 function set by memcached_callback_set().
  53
  54 memcached_callback_set() changes the function/structure assigned by a
  55 callback flag. No connections are reset.
  56
  57 You can use MEMCACHED_CALLBACK_USER_DATA to provide custom context if required for any
  58 of the callbacks
  59
  60
  61 MEMCACHED_CALLBACK_CLEANUP_FUNCTION
  62
  63  When memcached_delete() is called this function will be excuted. At the
  64  point of its execution all connections have been closed.
  65
  66
  67
  68 MEMCACHED_CALLBACK_CLONE_FUNCTION
  69
  70  When memcached_delete() is called this function will be excuted. At the
  71  point of its execution all connections have been closed.
  72
  73
  74
  75 MEMCACHED_CALLBACK_PREFIX_KEY
  76
  77  You can set a value which will be used to create a domain for your keys.
  78  The value specified here will be prefixed to each of your keys. The value can not
  79  be greater then MEMCACHED_PREFIX_KEY_MAX_SIZE - 1 and will reduce MEMCACHED_MAX_KEY by
  80  the value of your key. The prefix key is only applied to the primary key,
  81  not the master key. MEMCACHED_FAILURE will be returned if no key is set. In the case
  82  of a key which is too long MEMCACHED_BAD_KEY_PROVIDED will be returned.
  83
  84  If you set a value with the value being NULL then the prefix key is disabled.
  85
  86
  87 MEMCACHED_CALLBACK_USER_DATA
  88
  89  This allows you to store a pointer to a specifc piece of data. This can be
  90  retrieved from inside of memcached_fetch_execute(). Cloning a memcached_st
  91  will copy the pointer to the clone.
  92
  93
  94
  95 MEMCACHED_CALLBACK_MALLOC_FUNCTION
  96
  97  DEPRECATED: use memcached_set_memory_allocators instead.
  98
  99
 100
 101 MEMCACHED_CALLBACK_REALLOC_FUNCTION
 102
 103  DEPRECATED: use memcached_set_memory_allocators instead.
 104
 105
 106
 107 MEMCACHED_CALLBACK_FREE_FUNCTION
 108
 109  DEPRECATED: use memcached_set_memory_allocators instead.
 110
 111
 112
 113 MEMCACHED_CALLBACK_GET_FAILURE
 114
 115  This function implements the read through cache behavior. On failure of retrieval this callback will be called.
 116  You are responsible for populating the result object provided. This result object will then be stored in the server and
 117  returned to the calling process. You must clone the memcached_st in order to
 118  make use of it. The value will be stored only if you return
 119  MEMCACHED_SUCCESS or MEMCACHED_BUFFERED. Returning MEMCACHED_BUFFERED will
 120  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).
 121
 122  The prototype for this is:
 123  memcached_return_t (\*memcached_trigger_key)(memcached_st \*ptr, char \*key, size_t key_length, memcached_result_st \*result);
 124
 125
 126
 127 MEMCACHED_CALLBACK_DELETE_TRIGGER
 128
 129  This function implements a trigger upon successful deletion of a key. The memcached_st structure will need to be cloned
 130  in order to make use of it.
 131
 132  The prototype for this is:
 133  typedef memcached_return_t (\*memcached_trigger_delete_key)(memcached_st \*ptr, char \*key, size_t key_length);
 134
 135
 136
 137
 138 ******
 139 RETURN
 140 ******
 141
 142
 143 memcached_callback_get() return the function or structure that was provided.
 144 Upon error, nothing is set, null is returned, and the memcached_return_t
 145 argument is set to MEMCACHED_FAILURE.
 146
 147 memcached_callback_set() returns MEMCACHED_SUCCESS upon successful setting,
 148 otherwise MEMCACHED_FAILURE on error.
 149
 150
 151 ****
 152 HOME
 153 ****
 154
 155
 156 To find out more information please check:
 157 `https://launchpad.net/libmemcached <https://launchpad.net/libmemcached>`_
 158
 159
 160 ******
 161 AUTHOR
 162 ******
 163
 164
 165 Brian Aker, <brian@tangent.org>
 166
 167
 168 ********
 169 SEE ALSO
 170 ********
 171
 172
 173 memcached(1) libmemcached(3) memcached_strerror(3)
 174