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

   1 .TH "MEMCACHED_CAS_BY_KEY" "3" "May 23, 2011" "0.47" "libmemcached"
   2 .SH NAME
   3 memcached_cas_by_key \- Storing and Replacing Data
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  32 .
  33 .SH SYNOPSIS
  34 .sp
  35 #include <libmemcached/memcached.h>
  36 .INDENT 0.0
  37 .TP
  38 .B 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);
  39 .UNINDENT
  40 .INDENT 0.0
  41 .TP
  42 .B 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);
  43 .UNINDENT
  44 .sp
  45 Compile and link with \-lmemcached
  46 .SH DESCRIPTION
  47 .sp
  48 memcached_cas() overwrites data in the server as long as the "cas" value is
  49 still the same in the server. You can get the cas value of a result by
  50 calling memcached_result_cas() on a memcached_result_st(3) structure. At the point
  51 that this note was written cas is still buggy in memached. Turning on tests
  52 for it in libmemcached(3) is optional. Please see memcached_set() for
  53 information on how to do this.
  54 .sp
  55 memcached_cas_by_key() method behaves in a similar method as the non key
  56 methods. The difference is that it uses the group_key parameter to map
  57 objects to particular servers.
  58 .sp
  59 memcached_cas() is testsed with the \fBMEMCACHED_BEHAVIOR_USE_UDP\fPbehavior enabled. However, when using these operations with this behavior on, there
  60 are limits to the size of the payload being sent to the server.  The reason for
  61 these limits is that the Memcached Server does not allow multi\-datagram requests
  62 and the current server implementation sets a datagram size to 1400 bytes. Due
  63 to protocol overhead, the actual limit of the user supplied data is less than
  64 1400 bytes and depends on the protocol in use as, well as the operation being
  65 executed. When running with the binary protocol, \(ga\(ga MEMCACHED_BEHAVIOR_BINARY_PROTOCOL\(ga\(ga,
  66 the size of the key,value, flags and expiry combined may not exceed 1368 bytes.
  67 When running with the ASCII protocol, the exact limit fluctuates depending on
  68 which function is being executed and whether the function is a cas operation
  69 or not. For non\-cas ASCII set operations, there are at least 1335 bytes available
  70 to split among the key, key_prefix, and value; for cas ASCII operations there are
  71 at least 1318 bytes available to split among the key, key_prefix and value. If the
  72 total size of the command, including overhead, exceeds 1400 bytes, a \fBMEMCACHED_WRITE_FAILURE\fPwill be returned.
  73 .SH RETURN
  74 .sp
  75 All methods return a value of type \fBmemcached_return_t\fP.
  76 On success the value will be \fBMEMCACHED_SUCCESS\fP.
  77 Use memcached_strerror() to translate this value to a printable string.
  78 .SH HOME
  79 .sp
  80 To find out more information please check:
  81 \fI\%http://libmemcached.org/\fP
  82 .SH SEE ALSO
  83 .sp
  84 memcached(1) libmemached(3) memcached_strerror(3) memcached_set(3) memcached_append(3) memcached_add(3) memcached_prepend(3) memcached_replace(3)
  85 .SH AUTHOR
  86 Brian Aker
  87 .SH COPYRIGHT
  88 2011, Brian Aker DataDifferential, http://datadifferential.com/
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