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

   1 =head1 NAME
   2
   3 memcached_callback_get memcached_callback_set - Get and set a callback
   4
   5 =head1 LIBRARY
   6
   7 C Client Library for memcached (libmemcached, -lmemcached)
   8
   9 =head1 SYNOPSIS
  10
  11   #include <memcached.h>
  12
  13   memcached_return
  14     memcached_callback_set (memcached_st *ptr,
  15                             memcached_callback flag,
  16                             void *data);
  17
  18   void *
  19     memcached_callback_get (memcached_st *ptr,
  20                             memcached_callback flag,
  21                             memcached_return *error);
  22
  23 =head1 DESCRIPTION
  24
  25 libmemcached(3) can have callbacks set key execution points. These either
  26 provide function calls at points in the code, or return pointers to
  27 structures for particular usages.
  28
  29 memcached_callback_get() takes a callback flag and returns the structure or
  30 function set by memcached_callback_set().
  31
  32 memcached_callback_set() changes the function/structure assigned by a
  33 callback flag. No connections are reset.
  34
  35 You can use MEMCACHED_CALLBACK_USER_DATA to provide custom context if required for any
  36 of the callbacks
  37
  38 =over 4
  39
  40 =item MEMCACHED_CALLBACK_CLEANUP_FUNCTION
  41
  42 When memcached_delete() is called this function will be excuted. At the
  43 point of its execution all connections have been closed.
  44
  45 =item MEMCACHED_CALLBACK_CLONE_FUNCTION
  46
  47 When memcached_delete() is called this function will be excuted. At the
  48 point of its execution all connections have been closed.
  49
  50 =item MEMCACHED_CALLBACK_PREFIX_KEY
  51
  52 You can set a value which will be used to create a domain for your keys.
  53 The value specified here will be prefixed to each of your keys. The value can not
  54 be greater then MEMCACHED_PREFIX_KEY_MAX_SIZE - 1 and will reduce MEMCACHED_MAX_KEY by
  55 the value of your key. The prefix key is only applied to the primary key,
  56 not the master key. MEMCACHED_FAILURE will be returned if no key is set. In the case
  57 of a key which is too long MEMCACHED_BAD_KEY_PROVIDED will be returned.
  58
  59 =item MEMCACHED_CALLBACK_USER_DATA
  60
  61 This allows you to store a pointer to a specifc piece of data. This can be
  62 retrieved from inside of memcached_fetch_execute(). Cloning a memcached_st
  63 will copy the pointer to the clone.
  64
  65 =item  MEMCACHED_CALLBACK_MALLOC_FUNCTION
  66
  67 This alllows yout to pass in a customized version of malloc that will be used instead of the builtin malloc(3) call.
  68 Your malloc must zero all memory.
  69 The prototype for this is:
  70
  71 void *(*memcached_malloc_function)(memcached_st *ptr, const size_t size);
  72
  73 =item  MEMCACHED_CALLBACK_REALLOC_FUNCTION
  74
  75 This alllows yout to pass in a customized version of realloc that will be used instead of the builtin realloc(3) call.
  76 The prototype for this is:
  77
  78 void *(*memcached_realloc_function)(memcached_st *ptr, void *mem, const size_t size);
  79
  80 =item  MEMCACHED_CALLBACK_FREE_FUNCTION
  81
  82 This alllows yout to pass in a customized version of realloc that will be used instead of the builtin free(3) call.
  83 The prototype for this is:
  84
  85 typedef void (*memcached_free_function)(memcached_st *ptr, void *mem);
  86
  87 =item  MEMCACHED_CALLBACK_GET_FAILURE
  88
  89 This function implements the read through cache behavior. On failure of retrieval this callback will be called.
  90 You are responsible for populating the result object provided. This result object will then be stored in the server and
  91 returned to the calling process. You must clone the memcached_st in order to
  92 make use of it. The value will be stored only if you return
  93 MEMCACHED_SUCCESS or MEMCACHED_BUFFERED. Returning MEMCACHED_BUFFERED will
  94 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).
  95
  96 The prototype for this is:
  97 memcached_return (*memcached_trigger_key)(memcached_st *ptr, char *key, size_t key_length, memcached_result_st *result);
  98
  99 =item  MEMCACHED_CALLBACK_DELETE_TRIGGER
 100
 101 This function implements a trigger upon successful deletion of a key. The memcached_st structure will need to be cloned
 102 in order to make use of it.
 103
 104 The prototype for this is:
 105 typedef memcached_return (*memcached_trigger_delete_key)(memcached_st *ptr, char *key, size_t key_length);
 106
 107
 108 =back
 109
 110 =head1 RETURN
 111
 112 memcached_callback_get() return the function or structure that was provided.
 113 Upon error, nothing is set, null is returned, and the memcached_return
 114 argument is set to MEMCACHED_FAILURE.
 115
 116 memcached_callback_set() returns MEMCACHED_SUCCESS upon successful setting,
 117 otherwise MEMCACHED_FAILURE on error.
 118
 119 =head1 HOME
 120
 121 To find out more information please check:
 122 L<http://tangent.org/552/libmemcached.html>
 123
 124 =head1 AUTHOR
 125
 126 Brian Aker, E<lt>brian@tangent.orgE<gt>
 127
 128 =head1 SEE ALSO
 129
 130 memcached(1) libmemcached(3) memcached_strerror(3)
 131
 132 =cut
 133