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[awesomized/libmemcached] / docs / man / memcached_callback_set.3
1 .TH "MEMCACHED_CALLBACK_SET" "3" "April 12, 2011" "0.47" "libmemcached"
2 .SH NAME
3 memcached_callback_set \- libmemcached Documentation
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32 .
33 .sp
34 Get and set a callback
35 .SH LIBRARY
36 .sp
37 C Client Library for memcached (libmemcached, \-lmemcached)
38 .SH SYNOPSIS
39 .sp
40 #include <libmemcached/memcached.h>
41 .INDENT 0.0
42 .TP
43 .B memcached_return_t memcached_callback_set (memcached_st *ptr, memcached_callback_t flag, void *data);
44 .UNINDENT
45 .INDENT 0.0
46 .TP
47 .B void * memcached_callback_get (memcached_st *ptr, memcached_callback_t flag, memcached_return_t *error);
48 .UNINDENT
49 .SH DESCRIPTION
50 .sp
51 libmemcached(3) can have callbacks set key execution points. These either
52 provide function calls at points in the code, or return pointers to
53 structures for particular usages.
54 .sp
55 memcached_callback_get() takes a callback flag and returns the structure or
56 function set by memcached_callback_set().
57 .sp
58 memcached_callback_set() changes the function/structure assigned by a
59 callback flag. No connections are reset.
60 .sp
61 You can use MEMCACHED_CALLBACK_USER_DATA to provide custom context if required for any
62 of the callbacks
63 .INDENT 0.0
64 .TP
65 .B MEMCACHED_CALLBACK_CLEANUP_FUNCTION
66 .
67 When memcached_delete() is called this function will be excuted. At the
68 point of its execution all connections have been closed.
69 .UNINDENT
70 .INDENT 0.0
71 .TP
72 .B MEMCACHED_CALLBACK_CLONE_FUNCTION
73 .
74 When memcached_delete() is called this function will be excuted. At the
75 point of its execution all connections have been closed.
76 .UNINDENT
77 .INDENT 0.0
78 .TP
79 .B MEMCACHED_CALLBACK_PREFIX_KEY
80 .
81 You can set a value which will be used to create a domain for your keys.
82 The value specified here will be prefixed to each of your keys. The value can not
83 be greater then MEMCACHED_PREFIX_KEY_MAX_SIZE \- 1 and will reduce MEMCACHED_MAX_KEY by
84 the value of your key. The prefix key is only applied to the primary key,
85 not the master key. MEMCACHED_FAILURE will be returned if no key is set. In the case
86 of a key which is too long MEMCACHED_BAD_KEY_PROVIDED will be returned.
87 .sp
88 If you set a value with the value being NULL then the prefix key is disabled.
89 .UNINDENT
90 .INDENT 0.0
91 .TP
92 .B MEMCACHED_CALLBACK_USER_DATA
93 .
94 This allows you to store a pointer to a specifc piece of data. This can be
95 retrieved from inside of memcached_fetch_execute(). Cloning a memcached_st
96 will copy the pointer to the clone.
97 .UNINDENT
98 .INDENT 0.0
99 .TP
100 .B MEMCACHED_CALLBACK_MALLOC_FUNCTION
101 .
102 DEPRECATED: use memcached_set_memory_allocators instead.
103 .UNINDENT
104 .INDENT 0.0
105 .TP
106 .B MEMCACHED_CALLBACK_REALLOC_FUNCTION
107 .
108 DEPRECATED: use memcached_set_memory_allocators instead.
109 .UNINDENT
110 .INDENT 0.0
111 .TP
112 .B MEMCACHED_CALLBACK_FREE_FUNCTION
113 .
114 DEPRECATED: use memcached_set_memory_allocators instead.
115 .UNINDENT
116 .INDENT 0.0
117 .TP
118 .B MEMCACHED_CALLBACK_GET_FAILURE
119 .
120 This function implements the read through cache behavior. On failure of retrieval this callback will be called.
121 You are responsible for populating the result object provided. This result object will then be stored in the server and
122 returned to the calling process. You must clone the memcached_st in order to
123 make use of it. The value will be stored only if you return
124 MEMCACHED_SUCCESS or MEMCACHED_BUFFERED. Returning MEMCACHED_BUFFERED will
125 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).
126 .sp
127 The prototype for this is:
128 memcached_return_t (*memcached_trigger_key)(memcached_st *ptr, char *key, size_t key_length, memcached_result_st *result);
129 .UNINDENT
130 .INDENT 0.0
131 .TP
132 .B MEMCACHED_CALLBACK_DELETE_TRIGGER
133 .UNINDENT
134 .sp
135 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.
136 .sp
137 The prototype for this is: typedef memcached_return_t (*memcached_trigger_delete_key)(memcached_st *ptr, char *key, size_t key_length);
138 .SH RETURN
139 .sp
140 memcached_callback_get() return the function or structure that was provided.
141 Upon error, nothing is set, null is returned, and the memcached_return_t
142 argument is set to MEMCACHED_FAILURE.
143 .sp
144 memcached_callback_set() returns MEMCACHED_SUCCESS upon successful setting,
145 otherwise MEMCACHED_FAILURE on error.
146 .SH HOME
147 .sp
148 To find out more information please check:
149 \fI\%https://launchpad.net/libmemcached\fP
150 .SH AUTHOR
151 .sp
152 Brian Aker, <\fI\%brian@tangent.org\fP>
153 .SH SEE ALSO
154 .sp
155 \fImemcached(1)\fP \fIlibmemcached(3)\fP \fImemcached_strerror(3)\fP
156 .SH AUTHOR
157 Brian Aker
158 .SH COPYRIGHT
159 2011, Brian Aker DataDifferential, http://datadifferential.com/
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