bionic (3) memcached_cas.3.gz

NAME

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

SYNOPSIS

       #include <libmemcached/memcached.h>

       memcached_return_t    memcached_cas(memcached_st *ptr,    const   char *key,   size_t key_length,   const
       char *value, size_t value_length, time_t expiration, uint32_t flags, uint64_t cas)

       memcached_return_t         memcached_cas_by_key(memcached_st *ptr,         const         char *group_key,
       size_t group_key_length,  const  char *key,  size_t key_length,  const  char *value, size_t value_length,
       time_t expiration, uint32_t flags, uint64_t cas)

       Compile and link with -lmemcached

DESCRIPTION

       memcached_cas() overwrites data in the server as long as the "cas" value is still the same in the server.
       You  can  get  the  cas  value  of a result by calling memcached_result_cas() on a memcached_result_st(3)
       structure. At the point that this note was written cas is still buggy in memached. Turning on  tests  for
       it in libmemcached(3) is optional. Please see memcached_set() for information on how to do this.

       memcached_cas_by_key()  method behaves in a similar method as the non key methods. The difference is that
       it uses the group_key parameter to map objects to particular servers.

       memcached_cas() is testsed with the MEMCACHED_BEHAVIOR_USE_UDP  behavior  enabled.  However,  when  using
       these  operations  with  this  behavior on, there are limits to the size of the payload being sent to the
       server.  The reason for these limits is that the Memcached Server does not allow multi-datagram  requests
       and  the  current server implementation sets a datagram size to 1400 bytes. Due to protocol overhead, the
       actual limit of the user supplied data is less than 1400 bytes and depends on the  protocol  in  use  as,
       well    as    the    operation    being    executed.    When    running   with   the   binary   protocol,
       MEMCACHED_BEHAVIOR_BINARY_PROTOCOL, the size of the key,value, flags and expiry combined may  not  exceed
       1368  bytes. When running with the ASCII protocol, the exact limit fluctuates depending on which function
       is being executed and whether the function is a cas operation or not. For non-cas ASCII  set  operations,
       there  are  at  least  1335  bytes available to split among the key, key_prefix, and value; for cas ASCII
       operations there are at least 1318 bytes available to split among the key, key_prefix and value.  If  the
       total  size  of  the  command,  including overhead, exceeds 1400 bytes, a MEMCACHED_WRITE_FAILURE will be
       returned.

RETURN

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

HOME

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

SEE ALSO

       memcached(1)  libmemached(3)  memcached_strerror(3) memcached_set(3) memcached_append(3) memcached_add(3)
       memcached_prepend(3) memcached_replace(3)

AUTHOR

       Brian Aker

COPYRIGHT

       2011-2013, Brian Aker DataDifferential, http://datadifferential.com/