git.m6w6.name Git - awesomized/libmemcached/blob - docs/memcached_set.rst

   1 .. highlight:: perl
   2
   3
   4 memcached_set, memcached_add, memcached_replace
   5 ***********************************************
   6
   7
   8 Store value on server
   9
  10
  11 *******
  12 LIBRARY
  13 *******
  14
  15
  16 C Client Library for memcached (libmemcached, -lmemcached)
  17
  18
  19 ********
  20 SYNOPSIS
  21 ********
  22
  23
  24
  25 .. code-block:: perl
  26
  27    #include <libmemcached/memcached.h>
  28
  29    memcached_return_t
  30      memcached_set (memcached_st *ptr,
  31                     const char *key, size_t key_length,
  32                     const char *value, size_t value_length,
  33                     time_t expiration,
  34                     uint32_t flags);
  35
  36    memcached_return_t
  37      memcached_add (memcached_st *ptr,
  38                     const char *key, size_t key_length,
  39                     const char *value, size_t value_length,
  40                     time_t expiration,
  41                     uint32_t flags);
  42
  43    memcached_return_t
  44      memcached_replace (memcached_st *ptr,
  45                         const char *key, size_t key_length,
  46                         const char *value, size_t value_length,
  47                         time_t expiration,
  48                         uint32_t flags);
  49
  50    memcached_return_t
  51      memcached_prepend(memcached_st *ptr,
  52                        const char *key, size_t key_length,
  53                        const char *value, size_t value_length,
  54                        time_t expiration,
  55                        uint32_t flags)
  56
  57    memcached_return_t
  58      memcached_append(memcached_st *ptr,
  59                       const char *key, size_t key_length,
  60                        const char *value, size_t value_length,
  61                        time_t expiration,
  62                        uint32_t flags)
  63    memcached_return_t
  64      memcached_cas(memcached_st *ptr,
  65                    const char *key, size_t key_length,
  66                    const char *value, size_t value_length,
  67                    time_t expiration,
  68                    uint32_t flags,
  69                    uint64_t cas);
  70
  71    memcached_return_t
  72      memcached_set_by_key(memcached_st *ptr,
  73                           const char *master_key, size_t master_key_length,
  74                           const char *key, size_t key_length,
  75                           const char *value, size_t value_length,
  76                           time_t expiration,
  77                           uint32_t flags);
  78
  79    memcached_return_t
  80      memcached_add_by_key(memcached_st *ptr,
  81                           const char *master_key, size_t master_key_length,
  82                           const char *key, size_t key_length,
  83                           const char *value, size_t value_length,
  84                           time_t expiration,
  85                           uint32_t flags);
  86
  87    memcached_return_t
  88      memcached_replace_by_key(memcached_st *ptr,
  89                               const char *master_key, size_t master_key_length,
  90                               const char *key, size_t key_length,
  91                               const char *value, size_t value_length,
  92                               time_t expiration,
  93                               uint32_t flags);
  94
  95    memcached_return_t
  96      memcached_prepend_by_key(memcached_st *ptr,
  97                               const char *master_key, size_t master_key_length,
  98                               const char *key, size_t key_length,
  99                               const char *value, size_t value_length,
 100                               time_t expiration,
 101                               uint32_t flags);
 102
 103    memcached_return_t
 104      memcached_append_by_key(memcached_st *ptr,
 105                              const char *master_key, size_t master_key_length,
 106                              const char *key, size_t key_length,
 107                              const char *value, size_t value_length,
 108                              time_t expiration,
 109                              uint32_t flags);
 110
 111    memcached_return_t
 112      memcached_cas_by_key(memcached_st *ptr,
 113                           const char *master_key, size_t master_key_length,
 114                           const char *key, size_t key_length,
 115                           const char *value, size_t value_length,
 116                           time_t expiration,
 117                           uint32_t flags,
 118                           uint64_t cas);
 119
 120
 121
 122 ***********
 123 DESCRIPTION
 124 ***********
 125
 126
 127 memcached_set(), memcached_add(), and memcached_replace() are all used to
 128 store information on the server. All methods take a key, and its length to
 129 store the object. Keys are currently limited to 250 characters by the
 130 memcached(1) server. You must also supply a value and a length. Optionally you
 131 may support an expiration time for the object and a 16 byte value (it is
 132 meant to be used as a bitmap).
 133
 134 memcached_set() will write an object to the server. If an object already
 135 exists it will overwrite what is in the server. If the object does not exist
 136 it will be written. If you are using the non-blocking mode this function
 137 will always return true unless a network error occurs.
 138
 139 memcached_replace() replaces an object on the server. If the object is not
 140 found on the server an error occurs.
 141
 142 memcached_add() adds an object to the server. If the object is found on the
 143 server an error occurs, otherwise the value is stored.
 144
 145 memcached_prepend() places a segment of data before the last piece of data
 146 stored. Currently expiration and key are not used in the server.
 147
 148 memcached_append() places a segment of data at the end of the last piece of
 149 data stored. Currently expiration and key are not used in the server.
 150
 151 memcached_cas() overwrites data in the server as long as the "cas" value is
 152 still the same in the server. You can get the cas value of a result by
 153 calling memcached_result_cas() on a memcached_result_st(3) structure. At the point
 154 that this note was written cas is still buggy in memached. Turning on support
 155 for it in libmemcached(3) is optional. Please see memcached_set() for
 156 information on how to do this.
 157
 158 memcached_set_by_key(), memcached_add_by_key(), memcached_replace_by_key(),
 159 memcached_prepend_by_key(), memcached_append_by_key_by_key(),
 160 memcached_cas_by_key() methods all behave in a similar method as the non key
 161 methods. The difference is that they use their master_key parameter to map
 162 objects to particular servers.
 163
 164 If you are looking for performance, memcached_set() with non-blocking IO is
 165 the fastest way to store data on the server.
 166
 167 All of the above functions are supported with the \ ``MEMCACHED_BEHAVIOR_USE_UDP``\
 168 behavior enabled. But when using these operations with this behavior on, there
 169 are limits to the size of the payload being sent to the server.  The reason for
 170 these limits is that the Memcahed Server does not allow multi-datagram requests
 171 and the current server implementation sets a datagram size to 1400 bytes. Due
 172 to protocol overhead, the actual limit of the user supplied data is less than
 173 1400 bytes and depends on the protocol in use as well as the operation being
 174 executed. When running with the binary protocol, \ `` MEMCACHED_BEHAVIOR_BINARY_PROTOCOL``\ ,
 175 the size of the key,value, flags and expiry combined may not exceed 1368 bytes.
 176 When running with the ASCII protocol, the exact limit fluctuates depending on
 177 which function is being executed and whether the function is a cas operation
 178 or not. For non-cas ASCII set operations, there are at least 1335 bytes available
 179 to split among the key, key_prefix, and value; for cas ASCII operations there are
 180 at least 1318 bytes available to split among the key, key_prefix and value. If the
 181 total size of the command, including overhead, exceeds 1400 bytes, a \ ``MEMCACHED_WRITE_FAILURE``\
 182 will be returned.
 183
 184
 185 ******
 186 RETURN
 187 ******
 188
 189
 190 All methods return a value of type \ ``memcached_return_t``\ .
 191 On success the value will be \ ``MEMCACHED_SUCCESS``\ .
 192 Use memcached_strerror() to translate this value to a printable string.
 193
 194 For memcached_replace() and memcached_add(), \ ``MEMCACHED_NOTSTORED``\  is a
 195 legitmate error in the case of a collision.
 196
 197
 198 ****
 199 HOME
 200 ****
 201
 202
 203 To find out more information please check:
 204 `https://launchpad.net/libmemcached <https://launchpad.net/libmemcached>`_
 205
 206
 207 ******
 208 AUTHOR
 209 ******
 210
 211
 212 Brian Aker, <brian@tangent.org>
 213
 214
 215 ********
 216 SEE ALSO
 217 ********
 218
 219
 220 memcached(1) libmemached(3) memcached_strerror(3)
 221