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, Brian Aker DataDifferential, http://datadifferential.com/