1MEMCACHED_CAS(3)                 libmemcached                 MEMCACHED_CAS(3)
2
3
4

NAME

6       memcached_cas - Working with data on the server in an atomic fashion
7

SYNOPSIS

9       #include <libmemcached/memcached.h>
10
11       memcached_return_t  memcached_cas(memcached_st *ptr,  const  char *key,
12       size_t key_length, const char *value, size_t value_length, time_t expi‐
13       ration, uint32_t flags, uint64_t cas)
14
15       memcached_return_t     memcached_cas_by_key(memcached_st *ptr,    const
16       char *group_key,     size_t group_key_length,     const      char *key,
17       size_t key_length, const char *value, size_t value_length, time_t expi‐
18       ration, uint32_t flags, uint64_t cas)
19
20       Compile and link with -lmemcached
21

DESCRIPTION

23       memcached_cas() overwrites data in the server  as  long  as  the  "cas"
24       value  is  still the same in the server. You can get the cas value of a
25       result by calling memcached_result_cas()  on  a  memcached_result_st(3)
26       structure.  At  the point that this note was written cas is still buggy
27       in memached. Turning on tests for it in  libmemcached(3)  is  optional.
28       Please see memcached_set() for information on how to do this.
29
30       memcached_cas_by_key()  method  behaves  in a similar method as the non
31       key methods. The difference is that it uses the group_key parameter  to
32       map objects to particular servers.
33
34       memcached_cas() is testsed with the MEMCACHED_BEHAVIOR_USE_UDP behavior
35       enabled. However, when using these operations with  this  behavior  on,
36       there  are  limits to the size of the payload being sent to the server.
37       The reason for these limits is that the Memcached Server does not allow
38       multi-datagram  requests  and  the current server implementation sets a
39       datagram size to 1400 bytes. Due to protocol overhead, the actual limit
40       of  the  user  supplied data is less than 1400 bytes and depends on the
41       protocol in use as, well as the operation being executed. When  running
42       with  the binary protocol, MEMCACHED_BEHAVIOR_BINARY_PROTOCOL, the size
43       of the key,value, flags and expiry combined may not exceed 1368  bytes.
44       When  running  with  the  ASCII  protocol,  the  exact limit fluctuates
45       depending on which function is being executed and whether the  function
46       is  a cas operation or not. For non-cas ASCII set operations, there are
47       at least 1335 bytes available to split among the key,  key_prefix,  and
48       value; for cas ASCII operations there are at least 1318 bytes available
49       to split among the key, key_prefix and value. If the total size of  the
50       command,    including    overhead,   exceeds   1400   bytes,   a   MEM‐
51       CACHED_WRITE_FAILURE will be returned.
52

RETURN

54       All methods return a value of type memcached_return_t.  On success  the
55       value will be MEMCACHED_SUCCESS.  Use memcached_strerror() to translate
56       this value to a printable string.
57

HOME

59       To find out more information please check: http://libmemcached.org/
60

SEE ALSO

62       memcached(1) libmemached(3) memcached_strerror(3) memcached_set(3) mem‐
63       cached_append(3)     memcached_add(3)     memcached_prepend(3)     mem‐
64       cached_replace(3)
65

AUTHOR

67       Brian Aker
68

70       2011-2013, Brian Aker DataDifferential, http://datadifferential.com/
71
72
73
74
751.0.16                         January 31, 2013               MEMCACHED_CAS(3)
Impressum