9 memcached_callback_get, memcached_callback_set - Get and set a callback
17 C Client Library for memcached (libmemcached, -lmemcached)
28 #include <memcached.h>
31 memcached_callback_set (memcached_st *ptr,
32 memcached_callback_t flag,
36 memcached_callback_get (memcached_st *ptr,
37 memcached_callback_t flag,
38 memcached_return_t *error);
47 libmemcached(3) can have callbacks set key execution points. These either
48 provide function calls at points in the code, or return pointers to
49 structures for particular usages.
51 memcached_callback_get() takes a callback flag and returns the structure or
52 function set by memcached_callback_set().
54 memcached_callback_set() changes the function/structure assigned by a
55 callback flag. No connections are reset.
57 You can use MEMCACHED_CALLBACK_USER_DATA to provide custom context if required for any
61 MEMCACHED_CALLBACK_CLEANUP_FUNCTION
63 When memcached_delete() is called this function will be excuted. At the
64 point of its execution all connections have been closed.
68 MEMCACHED_CALLBACK_CLONE_FUNCTION
70 When memcached_delete() is called this function will be excuted. At the
71 point of its execution all connections have been closed.
75 MEMCACHED_CALLBACK_PREFIX_KEY
77 You can set a value which will be used to create a domain for your keys.
78 The value specified here will be prefixed to each of your keys. The value can not
79 be greater then MEMCACHED_PREFIX_KEY_MAX_SIZE - 1 and will reduce MEMCACHED_MAX_KEY by
80 the value of your key. The prefix key is only applied to the primary key,
81 not the master key. MEMCACHED_FAILURE will be returned if no key is set. In the case
82 of a key which is too long MEMCACHED_BAD_KEY_PROVIDED will be returned.
84 If you set a value with the value being NULL then the prefix key is disabled.
87 MEMCACHED_CALLBACK_USER_DATA
89 This allows you to store a pointer to a specifc piece of data. This can be
90 retrieved from inside of memcached_fetch_execute(). Cloning a memcached_st
91 will copy the pointer to the clone.
95 MEMCACHED_CALLBACK_MALLOC_FUNCTION
97 DEPRECATED: use memcached_set_memory_allocators instead.
101 MEMCACHED_CALLBACK_REALLOC_FUNCTION
103 DEPRECATED: use memcached_set_memory_allocators instead.
107 MEMCACHED_CALLBACK_FREE_FUNCTION
109 DEPRECATED: use memcached_set_memory_allocators instead.
113 MEMCACHED_CALLBACK_GET_FAILURE
115 This function implements the read through cache behavior. On failure of retrieval this callback will be called.
116 You are responsible for populating the result object provided. This result object will then be stored in the server and
117 returned to the calling process. You must clone the memcached_st in order to
118 make use of it. The value will be stored only if you return
119 MEMCACHED_SUCCESS or MEMCACHED_BUFFERED. Returning MEMCACHED_BUFFERED will
120 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).
122 The prototype for this is:
123 memcached_return_t (\*memcached_trigger_key)(memcached_st \*ptr, char \*key, size_t key_length, memcached_result_st \*result);
127 MEMCACHED_CALLBACK_DELETE_TRIGGER
129 This function implements a trigger upon successful deletion of a key. The memcached_st structure will need to be cloned
130 in order to make use of it.
132 The prototype for this is:
133 typedef memcached_return_t (\*memcached_trigger_delete_key)(memcached_st \*ptr, char \*key, size_t key_length);
143 memcached_callback_get() return the function or structure that was provided.
144 Upon error, nothing is set, null is returned, and the memcached_return_t
145 argument is set to MEMCACHED_FAILURE.
147 memcached_callback_set() returns MEMCACHED_SUCCESS upon successful setting,
148 otherwise MEMCACHED_FAILURE on error.
156 To find out more information please check:
157 `https://launchpad.net/libmemcached <https://launchpad.net/libmemcached>`_
165 Brian Aker, <brian@tangent.org>
173 memcached(1) libmemcached(3) memcached_strerror(3)