def cas(key, expiry=0, raw=false)
raise MemCacheError, "Update of readonly cache" if @readonly
raise MemCacheError, "A block is required" unless block_given?
(value, token) = gets(key, raw)
return nil unless value
updated = yield value
with_server(key) do |server, cache_key|
value = Marshal.dump updated unless raw
logger.debug { "cas #{key} to #{server.inspect}: #{value.to_s.size}" } if logger
command = "cas #{cache_key} 0 #{expiry} #{value.to_s.size} #{token}#{noreply}\r\n#{value}\r\n"
with_socket_management(server) do |socket|
socket.write command
break nil if @no_reply
result = socket.gets
raise_on_error_response! result
if result.nil?
server.close
raise MemCacheError, "lost connection to #{server.host}:#{server.port}"
end
result
end
end
end