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[m6w6/libmemcached] / docs / memcached_callback.pod
1 =head1 NAME
2
3 memcached_callback_get memcached_callback_set
4
5 =head1 LIBRARY
6
7 C Client Library for memcached (libmemcached, -lmemcached)
8
9 =head1 SYNOPSIS
10
11 #include <memcached.h>
12
13 memcached_return
14 memcached_callback_set (memcached_st *ptr,
15 memcached_callback flag,
16 void *data);
17
18 void *
19 memcached_callback_get (memcached_st *ptr,
20 memcached_callback flag,
21 memcached_return *error);
22
23 =head1 DESCRIPTION
24
25 libmemcached(3) can have callbacks set key execution points. These either
26 provide function calls at points in the code, or return pointers to
27 structures for particular usages.
28
29 memcached_callback_get() takes a callback flag and returns the structure or
30 function set by memcached_callback_set().
31
32 memcached_callback_set() changes the function/structure assigned by a
33 callback flag. No connections are reset.
34
35 You can use MEMCACHED_CALLBACK_USER_DATA to provide custom context if required for any
36 of the callbacks
37
38 =over 4
39
40 =item MEMCACHED_CALLBACK_CLEANUP_FUNCTION
41
42 When memcached_delete() is called this function will be excuted. At the
43 point of its execution all connections have been closed.
44
45 =item MEMCACHED_CALLBACK_CLONE_FUNCTION
46
47 When memcached_delete() is called this function will be excuted. At the
48 point of its execution all connections have been closed.
49
50 =item MEMCACHED_CALLBACK_USER_DATA
51
52 This allows you to store a pointer to a specifc piece of data. This can be
53 retrieved from inside of memcached_fetch_execute(). Cloning a memcached_st
54 will copy the pointer to the clone.
55
56 =item MEMCACHED_CALLBACK_MALLOC_FUNCTION,
57
58 This alllows yout to pass in a customized version of malloc that will be used instead of the builtin malloc(3) call.
59 The prototype for this is:
60
61 void *(*memcached_malloc_function)(memcached_st *ptr, const size_t size);
62
63 =item MEMCACHED_CALLBACK_REALLOC_FUNCTION,
64
65 This alllows yout to pass in a customized version of realloc that will be used instead of the builtin realloc(3) call.
66 The prototype for this is:
67
68 void *(*memcached_realloc_function)(memcached_st *ptr, void *mem, const size_t size);
69
70 =item MEMCACHED_CALLBACK_FREE_FUNCTION,
71
72 This alllows yout to pass in a customized version of realloc that will be used instead of the builtin free(3) call.
73 The prototype for this is:
74
75 typedef void (*memcached_free_function)(memcached_st *ptr, void *mem);
76
77 =item MEMCACHED_CALLBACK_GET_FAILURE,
78
79 This function implements the read through cache behavior. On failure of retrieval this callback will be called.
80 You are responsible for populating the result object provided. This result object will then be stored in the server and
81 returned to the calling process. You must clone the memcached_st in order to
82 make use of it. The value will be stored only if you return
83 MEMCACHED_SUCCESS or MEMCACHED_BUFFERED. Returning MEMCACHED_BUFFERED will
84 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).
85
86 The prototype for this is:
87 memcached_return (*memcached_trigger_key)(memcached_st *ptr, char *key, size_t key_length, memcached_result_st *result);
88
89 =back
90
91 =head1 RETURN
92
93 memcached_callback_get() return the function or structure that was provided.
94 Upon error, nothing is set, null is returned, and the memcached_return
95 argument is set to MEMCACHED_FAILURE.
96
97 memcached_callback_set() returns MEMCACHED_SUCCESS upon successful setting,
98 otherwise MEMCACHED_FAILURE on error.
99
100 =head1 HOME
101
102 To find out more information please check:
103 L<http://tangent.org/552/libmemcached.html>
104
105 =head1 AUTHOR
106
107 Brian Aker, E<lt>brian@tangent.orgE<gt>
108
109 =head1 SEE ALSO
110
111 memcached(1) libmemcached(3) memcached_strerror(3)
112
113 =cut
114