git.m6w6.name Git - m6w6/libmemcached/blob - docs/man/memcached_callback_get.3

   1 .TH "MEMCACHED_CALLBACK_GET" "3" "April 08, 2011" "0.47" "libmemcached"
   2 .SH NAME
   3 memcached_callback_get \- libmemcached Documentation
   4 .
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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 .nf
  41 .ft C
  42 #include <libmemcached/memcached.h>
  43
  44 memcached_return_t
  45   memcached_callback_set (memcached_st *ptr,
  46                           memcached_callback_t flag,
  47                           void *data);
  48
  49 void *
  50   memcached_callback_get (memcached_st *ptr,
  51                           memcached_callback_t flag,
  52                           memcached_return_t *error);
  53 .ft P
  54 .fi
  55 .SH DESCRIPTION
  56 .sp
  57 libmemcached(3) can have callbacks set key execution points. These either
  58 provide function calls at points in the code, or return pointers to
  59 structures for particular usages.
  60 .sp
  61 memcached_callback_get() takes a callback flag and returns the structure or
  62 function set by memcached_callback_set().
  63 .sp
  64 memcached_callback_set() changes the function/structure assigned by a
  65 callback flag. No connections are reset.
  66 .sp
  67 You can use MEMCACHED_CALLBACK_USER_DATA to provide custom context if required for any
  68 of the callbacks
  69 .sp
  70 MEMCACHED_CALLBACK_CLEANUP_FUNCTION
  71 .INDENT 0.0
  72 .INDENT 3.5
  73 .sp
  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 .UNINDENT
  78 .sp
  79 MEMCACHED_CALLBACK_CLONE_FUNCTION
  80 .INDENT 0.0
  81 .INDENT 3.5
  82 .sp
  83 When memcached_delete() is called this function will be excuted. At the
  84 point of its execution all connections have been closed.
  85 .UNINDENT
  86 .UNINDENT
  87 .sp
  88 MEMCACHED_CALLBACK_PREFIX_KEY
  89 .INDENT 0.0
  90 .INDENT 3.5
  91 .sp
  92 You can set a value which will be used to create a domain for your keys.
  93 The value specified here will be prefixed to each of your keys. The value can not
  94 be greater then MEMCACHED_PREFIX_KEY_MAX_SIZE \- 1 and will reduce MEMCACHED_MAX_KEY by
  95 the value of your key. The prefix key is only applied to the primary key,
  96 not the master key. MEMCACHED_FAILURE will be returned if no key is set. In the case
  97 of a key which is too long MEMCACHED_BAD_KEY_PROVIDED will be returned.
  98 .sp
  99 If you set a value with the value being NULL then the prefix key is disabled.
 100 .UNINDENT
 101 .UNINDENT
 102 .sp
 103 MEMCACHED_CALLBACK_USER_DATA
 104 .INDENT 0.0
 105 .INDENT 3.5
 106 .sp
 107 This allows you to store a pointer to a specifc piece of data. This can be
 108 retrieved from inside of memcached_fetch_execute(). Cloning a memcached_st
 109 will copy the pointer to the clone.
 110 .UNINDENT
 111 .UNINDENT
 112 .sp
 113 MEMCACHED_CALLBACK_MALLOC_FUNCTION
 114 .INDENT 0.0
 115 .INDENT 3.5
 116 .sp
 117 DEPRECATED: use memcached_set_memory_allocators instead.
 118 .UNINDENT
 119 .UNINDENT
 120 .sp
 121 MEMCACHED_CALLBACK_REALLOC_FUNCTION
 122 .INDENT 0.0
 123 .INDENT 3.5
 124 .sp
 125 DEPRECATED: use memcached_set_memory_allocators instead.
 126 .UNINDENT
 127 .UNINDENT
 128 .sp
 129 MEMCACHED_CALLBACK_FREE_FUNCTION
 130 .INDENT 0.0
 131 .INDENT 3.5
 132 .sp
 133 DEPRECATED: use memcached_set_memory_allocators instead.
 134 .UNINDENT
 135 .UNINDENT
 136 .sp
 137 MEMCACHED_CALLBACK_GET_FAILURE
 138 .INDENT 0.0
 139 .INDENT 3.5
 140 .sp
 141 This function implements the read through cache behavior. On failure of retrieval this callback will be called.
 142 You are responsible for populating the result object provided. This result object will then be stored in the server and
 143 returned to the calling process. You must clone the memcached_st in order to
 144 make use of it. The value will be stored only if you return
 145 MEMCACHED_SUCCESS or MEMCACHED_BUFFERED. Returning MEMCACHED_BUFFERED will
 146 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).
 147 .sp
 148 The prototype for this is:
 149 memcached_return_t (*memcached_trigger_key)(memcached_st *ptr, char *key, size_t key_length, memcached_result_st *result);
 150 .UNINDENT
 151 .UNINDENT
 152 .sp
 153 MEMCACHED_CALLBACK_DELETE_TRIGGER
 154 .INDENT 0.0
 155 .INDENT 3.5
 156 .sp
 157 This function implements a trigger upon successful deletion of a key. The memcached_st structure will need to be cloned
 158 in order to make use of it.
 159 .sp
 160 The prototype for this is:
 161 typedef memcached_return_t (*memcached_trigger_delete_key)(memcached_st *ptr, char *key, size_t key_length);
 162 .UNINDENT
 163 .UNINDENT
 164 .SH RETURN
 165 .sp
 166 memcached_callback_get() return the function or structure that was provided.
 167 Upon error, nothing is set, null is returned, and the memcached_return_t
 168 argument is set to MEMCACHED_FAILURE.
 169 .sp
 170 memcached_callback_set() returns MEMCACHED_SUCCESS upon successful setting,
 171 otherwise MEMCACHED_FAILURE on error.
 172 .SH HOME
 173 .sp
 174 To find out more information please check:
 175 \fI\%https://launchpad.net/libmemcached\fP
 176 .SH AUTHOR
 177 .sp
 178 Brian Aker, <\fI\%brian@tangent.org\fP>
 179 .SH SEE ALSO
 180 .sp
 181 memcached(1) libmemcached(3) memcached_strerror(3)
 182 .SH AUTHOR
 183 Brian Aker
 184 .SH COPYRIGHT
 185 2011, Brian Aker
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