NAME

       memcached_callback_get - libmemcached Documentation

       Get and set a callback

SYNOPSIS

       #include <libmemcached/memcached.h>

       memcached_callback_t

       memcached_return_t memcached_callback_set(memcached_st *ptr, memcached_callback_t flag, const void *data)

       void * memcached_callback_get(memcached_st *ptr, memcached_callback_t flag, memcached_return_t *error)

       Compile and link with -lmemcached

DESCRIPTION

       libmemcached(3)  can  have  callbacks  set  key  execution points. These either provide function calls at
       points in the code, or return pointers to structures for particular usages.

       memcached_callback_get()  takes  a  callback  flag  and  returns  the  structure  or  function   set   by
       memcached_callback_set().

       memcached_callback_set()  changes  the function/structure assigned by a callback flag. No connections are
       reset.

       You can use MEMCACHED_CALLBACK_USER_DATA to provide custom context if required for any of the callbacks.

       MEMCACHED_CALLBACK_CLEANUP_FUNCTION

       When memcached_delete() is called this function will be excuted.  At  the  point  of  its  execution  all
       connections are closed.

       MEMCACHED_CALLBACK_CLONE_FUNCTION

       When  memcached_delete()  is  called  this  function  will be excuted.  At the point of its execution all
       connections are closed.

       MEMCACHED_CALLBACK_PREFIX_KEY
              See MEMCACHED_CALLBACK_NAMESPACE

       MEMCACHED_CALLBACK_NAMESPACE

       You can set a value which will be used to create a domain for your keys.  The value specified  here  will
       be prefixed to each of your keys. The value can not be greater then MEMCACHED_PREFIX_KEY_MAX_SIZE - 1 and
       will reduce MEMCACHED_MAX_KEY by the value of your key.

       The prefix key is only applied to the primary  key,  not  the  master  key.   MEMCACHED_FAILURE  will  be
       returned  if  no  key  is set. In the case of a key which is too long, MEMCACHED_BAD_KEY_PROVIDED will be
       returned.

       If you set a value with the value being NULL then the prefix key is disabled.

       MEMCACHED_CALLBACK_USER_DATA

       This allows you to store a pointer to a specifc piece of data. This  can  be  retrieved  from  inside  of
       memcached_fetch_execute(). Cloning a memcached_st will copy the pointer to the clone.

       MEMCACHED_CALLBACK_MALLOC_FUNCTION

       Deprecated since version <0.32: Use memcached_set_memory_allocators instead.

       MEMCACHED_CALLBACK_REALLOC_FUNCTION

       Deprecated since version <0.32: Use memcached_set_memory_allocators instead.

       MEMCACHED_CALLBACK_FREE_FUNCTION

       Deprecated since version <0.32: Use memcached_set_memory_allocators instead.

       MEMCACHED_CALLBACK_GET_FAILURE

       This  function  implements the read through cache behavior. On failure of retrieval this callback will be
       called.

       You are responsible for populating the result object provided. This result object will then be stored  in
       the server and returned to the calling process.

       You  must  clone the memcached_st in order to make use of it. The value will be stored only if you return
       MEMCACHED_SUCCESS or MEMCACHED_BUFFERED.  Returning  MEMCACHED_BUFFERED  will  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).

       The prototype for this is:

       memcached_return_t   (*memcached_trigger_key)(memcached_st   *ptr,   char   *key,   size_t    key_length,
       memcached_result_st *result);

       MEMCACHED_CALLBACK_DELETE_TRIGGER

       This  function  implements  a  trigger upon successful deletion of a key. The memcached_st structure will
       need to be cloned in order to make use of it.

       The prototype for this is:

       typedef  memcached_return_t  (*memcached_trigger_delete_key)(memcached_st   *ptr,   char   *key,   size_t
       key_length);

RETURN

       memcached_callback_get()  return the function or structure that was provided. Upon error, nothing is set,
       null is returned, and the memcached_return_t argument is set to MEMCACHED_FAILURE.

       memcached_callback_set() returns MEMCACHED_SUCCESS upon successful setting,  otherwise  MEMCACHED_FAILURE
       on error.

HOME

       To find out more information please check: http://libmemcached.org/

AUTHOR

       Brian Aker, <brian@tangent.org>

SEE ALSO

       memcached(1) libmemcached(3) memcached_strerror(3)

AUTHOR

       Brian Aker

COPYRIGHT

       2011-2013, Brian Aker DataDifferential, http://datadifferential.com/