jenkins-promote-staging-trunk-libmemcached-15
[awesomized/libmemcached] / docs / man / memcached_callback_get.3
1 .TH "MEMCACHED_CALLBACK_GET" "3" "April 28, 2012" "1.0.7" "libmemcached"
2 .SH NAME
3 memcached_callback_get \- libmemcached Documentation
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33 .sp
34 Get and set a callback
35 .SH SYNOPSIS
36 .sp
37 #include <libmemcached/memcached.h>
38 .INDENT 0.0
39 .TP
40 .B memcached_callback_t
41 .UNINDENT
42 .INDENT 0.0
43 .TP
44 .B memcached_return_t memcached_callback_set(memcached_st\fI\ *ptr\fP, \fI\%memcached_callback_t\fP\fI\ flag\fP, const void\fI\ *data\fP)
45 .UNINDENT
46 .INDENT 0.0
47 .TP
48 .B void * memcached_callback_get(memcached_st\fI\ *ptr\fP, \fI\%memcached_callback_t\fP\fI\ flag\fP, memcached_return_t\fI\ *error\fP)
49 .UNINDENT
50 .sp
51 Compile and link with \-lmemcached
52 .SH DESCRIPTION
53 .sp
54 libmemcached(3) can have callbacks set key execution points. These either
55 provide function calls at points in the code, or return pointers to
56 structures for particular usages.
57 .sp
58 \fI\%memcached_callback_get()\fP takes a callback flag and returns the
59 structure or function set by \fI\%memcached_callback_set()\fP.
60 .sp
61 \fI\%memcached_callback_set()\fP changes the function/structure assigned by a
62 callback flag. No connections are reset.
63 .sp
64 You can use \fI\%MEMCACHED_CALLBACK_USER_DATA\fP to provide custom context
65 if required for any of the callbacks.
66 .INDENT 0.0
67 .TP
68 .B MEMCACHED_CALLBACK_CLEANUP_FUNCTION
69 .UNINDENT
70 .sp
71 When \fBmemcached_delete()\fP is called this function will be excuted. At
72 the point of its execution all connections are closed.
73 .INDENT 0.0
74 .TP
75 .B MEMCACHED_CALLBACK_CLONE_FUNCTION
76 .UNINDENT
77 .sp
78 When \fBmemcached_delete()\fP is called this function will be excuted.
79 At the point of its execution all connections are closed.
80 .INDENT 0.0
81 .TP
82 .B MEMCACHED_CALLBACK_PREFIX_KEY
83 See \fI\%MEMCACHED_CALLBACK_NAMESPACE\fP
84 .UNINDENT
85 .INDENT 0.0
86 .TP
87 .B MEMCACHED_CALLBACK_NAMESPACE
88 .UNINDENT
89 .sp
90 You can set a value which will be used to create a domain for your keys.
91 The value specified here will be prefixed to each of your keys. The value can
92 not be greater then \fBMEMCACHED_PREFIX_KEY_MAX_SIZE\fP \- 1 and will
93 reduce \fBMEMCACHED_MAX_KEY\fP by the value of your key.
94 .sp
95 The prefix key is only applied to the primary key, not the master key.
96 \fBMEMCACHED_FAILURE\fP will be returned if no key is set. In the case of
97 a key which is too long, \fBMEMCACHED_BAD_KEY_PROVIDED\fP will be returned.
98 .sp
99 If you set a value with the value being NULL then the prefix key is disabled.
100 .INDENT 0.0
101 .TP
102 .B MEMCACHED_CALLBACK_USER_DATA
103 .UNINDENT
104 .sp
105 This allows you to store a pointer to a specifc piece of data. This can be
106 retrieved from inside of \fBmemcached_fetch_execute()\fP. Cloning a
107 \fBmemcached_st\fP will copy the pointer to the clone.
108 .INDENT 0.0
109 .TP
110 .B MEMCACHED_CALLBACK_MALLOC_FUNCTION
111 .UNINDENT
112 .sp
113 Deprecated since version <0.32: Use \fBmemcached_set_memory_allocators\fP instead.
114 .INDENT 0.0
115 .TP
116 .B MEMCACHED_CALLBACK_REALLOC_FUNCTION
117 .UNINDENT
118 .sp
119 Deprecated since version <0.32: Use \fBmemcached_set_memory_allocators\fP instead.
120 .INDENT 0.0
121 .TP
122 .B MEMCACHED_CALLBACK_FREE_FUNCTION
123 .UNINDENT
124 .sp
125 Deprecated since version <0.32: Use \fBmemcached_set_memory_allocators\fP instead.
126 .INDENT 0.0
127 .TP
128 .B MEMCACHED_CALLBACK_GET_FAILURE
129 .UNINDENT
130 .sp
131 This function implements the read through cache behavior. On failure of retrieval this callback will be called.
132 .sp
133 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.
134 .sp
135 You must clone the \fBmemcached_st\fP in order to
136 make use of it. The value will be stored only if you return
137 \fBMEMCACHED_SUCCESS\fP or \fBMEMCACHED_BUFFERED\fP. Returning
138 \fBMEMCACHED_BUFFERED\fP will cause the object to be buffered and not sent
139 immediatly (if this is the default behavior based on your connection setup
140 this will happen automatically).
141 .sp
142 The prototype for this is:
143 .INDENT 0.0
144 .TP
145 .B memcached_return_t (*memcached_trigger_key)(memcached_st *ptr, char *key, size_t key_length, memcached_result_st *result);
146 .UNINDENT
147 .INDENT 0.0
148 .TP
149 .B MEMCACHED_CALLBACK_DELETE_TRIGGER
150 .UNINDENT
151 .sp
152 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.
153 .sp
154 The prototype for this is:
155 .INDENT 0.0
156 .TP
157 .B typedef memcached_return_t (*memcached_trigger_delete_key)(memcached_st *ptr, char *key, size_t key_length);
158 .UNINDENT
159 .SH RETURN
160 .sp
161 \fI\%memcached_callback_get()\fP return the function or structure that was
162 provided. Upon error, nothing is set, null is returned, and the
163 \fBmemcached_return_t\fP argument is set to \fBMEMCACHED_FAILURE\fP.
164 .sp
165 \fI\%memcached_callback_set()\fP returns \fBMEMCACHED_SUCCESS\fP upon
166 successful setting, otherwise \fBMEMCACHED_FAILURE\fP on error.
167 .SH HOME
168 .sp
169 To find out more information please check:
170 \fI\%http://libmemcached.org/\fP
171 .SH AUTHOR
172 .sp
173 Brian Aker, <\fI\%brian@tangent.org\fP>
174 .SH SEE ALSO
175 .sp
176 \fImemcached(1)\fP \fIlibmemcached(3)\fP \fImemcached_strerror(3)\fP
177 .SH AUTHOR
178 Brian Aker
179 .SH COPYRIGHT
180 2011, Brian Aker DataDifferential, http://datadifferential.com/
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