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   1 .TH "MEMCACHED_CALLBACK_SET" "3" "July 05, 2012" "1.0.9" "libmemcached"
   2 .SH NAME
   3 memcached_callback_set \- libmemcached Documentation
   4 .
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  32 .
  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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