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
  85
  86 MEMCACHED_CALLBACK_USER_DATA
  87
  88  This allows you to store a pointer to a specifc piece of data. This can be
  89  retrieved from inside of memcached_fetch_execute(). Cloning a memcached_st
  90  will copy the pointer to the clone.
  91
  92
  93
  94 MEMCACHED_CALLBACK_MALLOC_FUNCTION
  95
  96  DEPRECATED: use memcached_set_memory_allocators instead.
  97
  98
  99
 100 MEMCACHED_CALLBACK_REALLOC_FUNCTION
 101
 102  DEPRECATED: use memcached_set_memory_allocators instead.
 103
 104
 105
 106 MEMCACHED_CALLBACK_FREE_FUNCTION
 107
 108  DEPRECATED: use memcached_set_memory_allocators instead.
 109
 110
 111
 112 MEMCACHED_CALLBACK_GET_FAILURE
 113
 114  This function implements the read through cache behavior. On failure of retrieval this callback will be called.
 115  You are responsible for populating the result object provided. This result object will then be stored in the server and
 116  returned to the calling process. You must clone the memcached_st in order to
 117  make use of it. The value will be stored only if you return
 118  MEMCACHED_SUCCESS or MEMCACHED_BUFFERED. Returning MEMCACHED_BUFFERED will
 119  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).
 120
 121  The prototype for this is:
 122  memcached_return_t (\*memcached_trigger_key)(memcached_st \*ptr, char \*key, size_t key_length, memcached_result_st \*result);
 123
 124
 125
 126 MEMCACHED_CALLBACK_DELETE_TRIGGER
 127
 128  This function implements a trigger upon successful deletion of a key. The memcached_st structure will need to be cloned
 129  in order to make use of it.
 130
 131  The prototype for this is:
 132  typedef memcached_return_t (\*memcached_trigger_delete_key)(memcached_st \*ptr, char \*key, size_t key_length);
 133
 134
 135
 136
 137 ******
 138 RETURN
 139 ******
 140
 141
 142 memcached_callback_get() return the function or structure that was provided.
 143 Upon error, nothing is set, null is returned, and the memcached_return_t
 144 argument is set to MEMCACHED_FAILURE.
 145
 146 memcached_callback_set() returns MEMCACHED_SUCCESS upon successful setting,
 147 otherwise MEMCACHED_FAILURE on error.
 148
 149
 150 ****
 151 HOME
 152 ****
 153
 154
 155 To find out more information please check:
 156 `https://launchpad.net/libmemcached <https://launchpad.net/libmemcached>`_
 157
 158
 159 ******
 160 AUTHOR
 161 ******
 162
 163
 164 Brian Aker, <brian@tangent.org>
 165
 166
 167 ********
 168 SEE ALSO
 169 ********
 170
 171
 172 memcached(1) libmemcached(3) memcached_strerror(3)
 173