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/

1.0.18                                          February 09, 2014                      MEMCACHED_CALLBACK_GET(3)