3 memcached_get, memcached_mget, memcached_fetch
7 C Client Library for memcached (libmemcached, -lmemcached)
11 #include <memcached.h>
14 memcached_fetch_result(memcached_st *ptr,
15 memcached_result_st *result,
16 memcached_return *error);
18 char *memcached_get (memcached_st *ptr,
19 char *key, size_t key_length,
22 memcached_return *error);
25 memcached_mget (memcached_st *ptr,
26 char **keys, size_t *key_length,
27 unsigned int number_of_keys);
29 memcached_get_by_key(memcached_st *ptr,
30 char *master_key, size_t master_key_length,
31 char *key, size_t key_length,
34 memcached_return *error);
37 memcached_mget_by_key(memcached_st *ptr,
38 char *master_key, size_t master_key_length,
39 char **keys, size_t *key_length,
40 unsigned int number_of_keys);
42 char *memcached_fetch (memcached_st *ptr,
43 char *key, size_t *key_length,
46 memcached_return *error);
48 memcached_fetch_execute(memcached_st *ptr,
49 unsigned int (*callback[])(memcached_st *ptr, memcached_result_st *result, void *context),
51 unsigned int number_of_callbacks);
55 memcached_get() is used to fetch an individual value from the server. You
56 must pass in a key and its length to fetch the object. You must supply
57 three pointer variables which will give you the state of the returned
58 object. A uint32_t pointer to contain whatever flags you stored with the value,
59 a size_t pointer which will be filled with size of of the object, and a
60 memcached_return pointer to hold any error. The object will be returned
61 upon success and NULL will be returned on failure.
63 memcached_mget() is used to select multiple keys at once. For multiple key
64 operations it is always faster to use this function. This function always
65 works asynchronously. memcached_fetch() is then used to retrieve any keys
66 found. No error is given on keys that are not found. You must call either
67 memcached_fetch() or memcached_fetch_result() after a successful call to
68 memcached_mget(). You should continue to call these functions until they
69 return NULL (aka no more values). If you need to quit in the middle of a
70 memcached_get() call, execute a memcached_quit(). After you do this, you can
71 issue new queries against the server.
73 memcached_fetch() is used to fetch an individual value from the server.
74 memcached_mget() must always be called before using this method. You
75 must pass in a key and its length to fetch the object. You must supply
76 three pointer variables which will give you the state of the returned
77 object. A uint32_t pointer to contain whatever flags you stored with the value,
78 a size_t pointer which will be filled with size of of the object, and a
79 memcached_return pointer to hold any error. The object will be returned
80 upon success and NULL will be returned on failure.
82 memcached_fetch_result() is used to return a memcached_result_st(3) structure
83 from a memcached server. The result object is forward compatible with changes
84 to the server. For more information please refer to the memcached_result_st(3)
85 help. This function will dynamically allocate a result structure for you
86 if you do not pass one to the function.
88 memcached_fetch_execute() is a callback function for result sets. Instead
89 of returning the results to you for processing, it passes each of the
90 result sets to the list of functions you provide. It passes to the function
91 a memcached_st that can be cloned for use in the called function (it can not
92 be used directly). It also passes a result set which does not need to be freed.
93 Finally it passes a "context". This is just a pointer to a memory reference
94 you supply the calling function. Currently only one value is being passed
95 to each function call. In the future there will be an option to allow this
98 memcached_get_by_key() and memcached_mget_by_key() behave in a similar nature
99 as memcached_get() and memcached_mget(). The difference is that they take
100 a master key that is used for determining which server an object was stored
101 if key partitioning was used for storage.
105 All objects returned must be freed by the calling application.
106 memcached_get() and memcached_fetch() will return NULL on error. You must
107 look at the value of error to determine what the actual error was.
111 To find out more information please check:
112 L<http://tangent.org/552/libmemcached.html>
116 Brian Aker, E<lt>brian@tangent.orgE<gt>
120 memcached(1) libmemcached(3) memcached_strerror(3)