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

   1 .TH "MEMCACHED_REPLACE" "3" "April 07, 2011" "0.47" "libmemcached"
   2 .SH NAME
   3 memcached_replace \- libmemcached Documentation
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  32 .
  33 .sp
  34 Store value on server
  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_set (memcached_st *ptr,
  46                  const char *key, size_t key_length,
  47                  const char *value, size_t value_length,
  48                  time_t expiration,
  49                  uint32_t flags);
  50
  51 memcached_return_t
  52   memcached_add (memcached_st *ptr,
  53                  const char *key, size_t key_length,
  54                  const char *value, size_t value_length,
  55                  time_t expiration,
  56                  uint32_t flags);
  57
  58 memcached_return_t
  59   memcached_replace (memcached_st *ptr,
  60                      const char *key, size_t key_length,
  61                      const char *value, size_t value_length,
  62                      time_t expiration,
  63                      uint32_t flags);
  64
  65 memcached_return_t
  66   memcached_prepend(memcached_st *ptr,
  67                     const char *key, size_t key_length,
  68                     const char *value, size_t value_length,
  69                     time_t expiration,
  70                     uint32_t flags)
  71
  72 memcached_return_t
  73   memcached_append(memcached_st *ptr,
  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 memcached_return_t
  79   memcached_cas(memcached_st *ptr,
  80                 const char *key, size_t key_length,
  81                 const char *value, size_t value_length,
  82                 time_t expiration,
  83                 uint32_t flags,
  84                 uint64_t cas);
  85
  86 memcached_return_t
  87   memcached_set_by_key(memcached_st *ptr,
  88                        const char *master_key, size_t master_key_length,
  89                        const char *key, size_t key_length,
  90                        const char *value, size_t value_length,
  91                        time_t expiration,
  92                        uint32_t flags);
  93
  94 memcached_return_t
  95   memcached_add_by_key(memcached_st *ptr,
  96                        const char *master_key, size_t master_key_length,
  97                        const char *key, size_t key_length,
  98                        const char *value, size_t value_length,
  99                        time_t expiration,
 100                        uint32_t flags);
 101
 102 memcached_return_t
 103   memcached_replace_by_key(memcached_st *ptr,
 104                            const char *master_key, size_t master_key_length,
 105                            const char *key, size_t key_length,
 106                            const char *value, size_t value_length,
 107                            time_t expiration,
 108                            uint32_t flags);
 109
 110 memcached_return_t
 111   memcached_prepend_by_key(memcached_st *ptr,
 112                            const char *master_key, size_t master_key_length,
 113                            const char *key, size_t key_length,
 114                            const char *value, size_t value_length,
 115                            time_t expiration,
 116                            uint32_t flags);
 117
 118 memcached_return_t
 119   memcached_append_by_key(memcached_st *ptr,
 120                           const char *master_key, size_t master_key_length,
 121                           const char *key, size_t key_length,
 122                           const char *value, size_t value_length,
 123                           time_t expiration,
 124                           uint32_t flags);
 125
 126 memcached_return_t
 127   memcached_cas_by_key(memcached_st *ptr,
 128                        const char *master_key, size_t master_key_length,
 129                        const char *key, size_t key_length,
 130                        const char *value, size_t value_length,
 131                        time_t expiration,
 132                        uint32_t flags,
 133                        uint64_t cas);
 134 .ft P
 135 .fi
 136 .SH DESCRIPTION
 137 .sp
 138 memcached_set(), memcached_add(), and memcached_replace() are all used to
 139 store information on the server. All methods take a key, and its length to
 140 store the object. Keys are currently limited to 250 characters by the
 141 memcached(1) server. You must also supply a value and a length. Optionally you
 142 may support an expiration time for the object and a 16 byte value (it is
 143 meant to be used as a bitmap).
 144 .sp
 145 memcached_set() will write an object to the server. If an object already
 146 exists it will overwrite what is in the server. If the object does not exist
 147 it will be written. If you are using the non\-blocking mode this function
 148 will always return true unless a network error occurs.
 149 .sp
 150 memcached_replace() replaces an object on the server. If the object is not
 151 found on the server an error occurs.
 152 .sp
 153 memcached_add() adds an object to the server. If the object is found on the
 154 server an error occurs, otherwise the value is stored.
 155 .sp
 156 memcached_prepend() places a segment of data before the last piece of data
 157 stored. Currently expiration and key are not used in the server.
 158 .sp
 159 memcached_append() places a segment of data at the end of the last piece of
 160 data stored. Currently expiration and key are not used in the server.
 161 .sp
 162 memcached_cas() overwrites data in the server as long as the "cas" value is
 163 still the same in the server. You can get the cas value of a result by
 164 calling memcached_result_cas() on a memcached_result_st(3) structure. At the point
 165 that this note was written cas is still buggy in memached. Turning on support
 166 for it in libmemcached(3) is optional. Please see memcached_set() for
 167 information on how to do this.
 168 .sp
 169 memcached_set_by_key(), memcached_add_by_key(), memcached_replace_by_key(),
 170 memcached_prepend_by_key(), memcached_append_by_key_by_key(),
 171 memcached_cas_by_key() methods all behave in a similar method as the non key
 172 methods. The difference is that they use their master_key parameter to map
 173 objects to particular servers.
 174 .sp
 175 If you are looking for performance, memcached_set() with non\-blocking IO is
 176 the fastest way to store data on the server.
 177 .sp
 178 All of the above functions are supported with the \fBMEMCACHED_BEHAVIOR_USE_UDP\fPbehavior enabled. But when using these operations with this behavior on, there
 179 are limits to the size of the payload being sent to the server.  The reason for
 180 these limits is that the Memcahed Server does not allow multi\-datagram requests
 181 and the current server implementation sets a datagram size to 1400 bytes. Due
 182 to protocol overhead, the actual limit of the user supplied data is less than
 183 1400 bytes and depends on the protocol in use as well as the operation being
 184 executed. When running with the binary protocol, \(ga\(ga MEMCACHED_BEHAVIOR_BINARY_PROTOCOL\(ga\(ga,
 185 the size of the key,value, flags and expiry combined may not exceed 1368 bytes.
 186 When running with the ASCII protocol, the exact limit fluctuates depending on
 187 which function is being executed and whether the function is a cas operation
 188 or not. For non\-cas ASCII set operations, there are at least 1335 bytes available
 189 to split among the key, key_prefix, and value; for cas ASCII operations there are
 190 at least 1318 bytes available to split among the key, key_prefix and value. If the
 191 total size of the command, including overhead, exceeds 1400 bytes, a \fBMEMCACHED_WRITE_FAILURE\fPwill be returned.
 192 .SH RETURN
 193 .sp
 194 All methods return a value of type \fBmemcached_return_t\fP.
 195 On success the value will be \fBMEMCACHED_SUCCESS\fP.
 196 Use memcached_strerror() to translate this value to a printable string.
 197 .sp
 198 For memcached_replace() and memcached_add(), \fBMEMCACHED_NOTSTORED\fP is a
 199 legitmate error in the case of a collision.
 200 .SH HOME
 201 .sp
 202 To find out more information please check:
 203 \fI\%https://launchpad.net/libmemcached\fP
 204 .SH AUTHOR
 205 .sp
 206 Brian Aker, <\fI\%brian@tangent.org\fP>
 207 .SH SEE ALSO
 208 .sp
 209 memcached(1) libmemached(3) memcached_strerror(3)
 210 .SH AUTHOR
 211 Brian Aker
 212 .SH COPYRIGHT
 213 2011, Brian Aker
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