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NAME

       memcached_callback_get, memcached_callback_set - Get and set a callback

LIBRARY

       C Client Library for memcached (libmemcached, -lmemcached)

SYNOPSIS

         #include <memcached.h>

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

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

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 have been closed.

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

       MEMCACHED_CALLBACK_PREFIX_KEY
           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.

       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: use memcached_set_memory_allocators instead.

       MEMCACHED_CALLBACK_REALLOC_FUNCTION
           DEPRECATED: use memcached_set_memory_allocators instead.

       MEMCACHED_CALLBACK_FREE_FUNCTION
           DEPRECATED: 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:
       <https://launchpad.net/libmemcached>

AUTHOR

       Brian Aker, <brian@tangent.org>

SEE ALSO

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

                                  2010-01-07     memcached_callback_get.pop(3)