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   1 .TH "MEMCACHED_CALLBACK_SET" "3" "January 26, 2012" "1.0.4" "libmemcached"
   2 .SH NAME
   3 memcached_callback_set \- libmemcached Documentation
   4 .
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  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_return_t memcached_callback_set (memcached_st *ptr, memcached_callback_t flag, const void *data);
  41 .UNINDENT
  42 .INDENT 0.0
  43 .TP
  44 .B void * memcached_callback_get (memcached_st *ptr, memcached_callback_t flag, memcached_return_t *error);
  45 .UNINDENT
  46 .sp
  47 Compile and link with \-lmemcached
  48 .SH DESCRIPTION
  49 .sp
  50 libmemcached(3) can have callbacks set key execution points. These either
  51 provide function calls at points in the code, or return pointers to
  52 structures for particular usages.
  53 .sp
  54 \fBmemcached_callback_get()\fP takes a callback flag and returns the
  55 structure or function set by \fBmemcached_callback_set()\fP.
  56 .sp
  57 \fBmemcached_callback_set()\fP changes the function/structure assigned by a
  58 callback flag. No connections are reset.
  59 .sp
  60 You can use \fI\%MEMCACHED_CALLBACK_USER_DATA\fP to provide custom context
  61 if required for any of the callbacks.
  62 .INDENT 0.0
  63 .TP
  64 .B MEMCACHED_CALLBACK_CLEANUP_FUNCTION
  65 .UNINDENT
  66 .sp
  67 When \fBmemcached_delete()\fP is called this function will be excuted. At
  68 the point of its execution all connections are closed.
  69 .INDENT 0.0
  70 .TP
  71 .B MEMCACHED_CALLBACK_CLONE_FUNCTION
  72 .UNINDENT
  73 .sp
  74 When \fBmemcached_delete()\fP is called this function will be excuted.
  75 At the point of its execution all connections are closed.
  76 .INDENT 0.0
  77 .TP
  78 .B MEMCACHED_CALLBACK_PREFIX_KEY
  79 See \fI\%MEMCACHED_CALLBACK_NAMESPACE\fP
  80 .UNINDENT
  81 .INDENT 0.0
  82 .TP
  83 .B MEMCACHED_CALLBACK_NAMESPACE
  84 .UNINDENT
  85 .sp
  86 You can set a value which will be used to create a domain for your keys.
  87 The value specified here will be prefixed to each of your keys. The value can
  88 not be greater then \fBMEMCACHED_PREFIX_KEY_MAX_SIZE \- 1\fP and will
  89 reduce \fBMEMCACHED_MAX_KEY\fP by the value of your key.
  90 .sp
  91 The prefix key is only applied to the primary key, not the master key.
  92 \fBMEMCACHED_FAILURE\fP will be returned if no key is set. In the case of
  93 a key which is too long, \fBMEMCACHED_BAD_KEY_PROVIDED\fP will be returned.
  94 .sp
  95 If you set a value with the value being NULL then the prefix key is disabled.
  96 .INDENT 0.0
  97 .TP
  98 .B MEMCACHED_CALLBACK_USER_DATA
  99 .UNINDENT
 100 .sp
 101 This allows you to store a pointer to a specifc piece of data. This can be
 102 retrieved from inside of \fBmemcached_fetch_execute()\fP. Cloning a
 103 \fBmemcached_st\fP will copy the pointer to the clone.
 104 .INDENT 0.0
 105 .TP
 106 .B MEMCACHED_CALLBACK_MALLOC_FUNCTION
 107 .UNINDENT
 108 .sp
 109 Deprecated since version <0.32: Use \fBmemcached_set_memory_allocators\fP instead.
 110 .INDENT 0.0
 111 .TP
 112 .B MEMCACHED_CALLBACK_REALLOC_FUNCTION
 113 .UNINDENT
 114 .sp
 115 Deprecated since version <0.32: Use \fBmemcached_set_memory_allocators\fP instead.
 116 .INDENT 0.0
 117 .TP
 118 .B MEMCACHED_CALLBACK_FREE_FUNCTION
 119 .UNINDENT
 120 .sp
 121 Deprecated since version <0.32: Use \fBmemcached_set_memory_allocators\fP instead.
 122 .INDENT 0.0
 123 .TP
 124 .B MEMCACHED_CALLBACK_GET_FAILURE
 125 .UNINDENT
 126 .sp
 127 This function implements the read through cache behavior. On failure of retrieval this callback will be called.
 128 .sp
 129 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.
 130 .sp
 131 You must clone the \fBmemcached_st\fP in order to
 132 make use of it. The value will be stored only if you return
 133 \fBMEMCACHED_SUCCESS\fP or \fBMEMCACHED_BUFFERED\fP. Returning
 134 \fBMEMCACHED_BUFFERED\fP will cause the object to be buffered and not sent
 135 immediatly (if this is the default behavior based on your connection setup
 136 this will happen automatically).
 137 .sp
 138 The prototype for this is:
 139 .INDENT 0.0
 140 .TP
 141 .B memcached_return_t (*memcached_trigger_key)(memcached_st *ptr, char *key, size_t key_length, memcached_result_st *result);
 142 .UNINDENT
 143 .INDENT 0.0
 144 .TP
 145 .B MEMCACHED_CALLBACK_DELETE_TRIGGER
 146 .UNINDENT
 147 .sp
 148 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.
 149 .sp
 150 The prototype for this is:
 151 .INDENT 0.0
 152 .TP
 153 .B typedef memcached_return_t (*memcached_trigger_delete_key)(memcached_st *ptr, char *key, size_t key_length);
 154 .UNINDENT
 155 .SH RETURN
 156 .sp
 157 \fBmemcached_callback_get()\fP return the function or structure that was
 158 provided. Upon error, nothing is set, null is returned, and the
 159 \fBmemcached_return_t\fP argument is set to \fBMEMCACHED_FAILURE\fP.
 160 .sp
 161 \fBmemcached_callback_set()\fP returns \fBMEMCACHED_SUCCESS\fP upon
 162 successful setting, otherwise \fBMEMCACHED_FAILURE\fP on error.
 163 .SH HOME
 164 .sp
 165 To find out more information please check:
 166 \fI\%http://libmemcached.org/\fP
 167 .SH AUTHOR
 168 .sp
 169 Brian Aker, <\fI\%brian@tangent.org\fP>
 170 .SH SEE ALSO
 171 .sp
 172 \fImemcached(1)\fP \fIlibmemcached(3)\fP \fImemcached_strerror(3)\fP
 173 .SH AUTHOR
 174 Brian Aker
 175 .SH COPYRIGHT
 176 2011, Brian Aker DataDifferential, http://datadifferential.com/
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