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

   1 .TH "MEMCACHED_CALLBACK" "3" "April 11, 2011" "0.47" "libmemcached"
   2 .SH NAME
   3 memcached_callback \- 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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