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 executed. At the point of its execution all
           connections have been closed.

       MEMCACHED_CALLBACK_CLONE_FUNCTION
           When memcached_delete() is called this function will be executed. 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
           immediately (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)