/// <summary>
        /// Master: Get Sync Request msg from hosts
        /// </summary>
        public void GetSyncRequest_CT(string id, string ipAndPort)
        {
            var request = new DataRequest()
            {
                Time      = 0,
                Id        = 0,
                CallerId  = long.Parse(id),
                IpAndPort = ipAndPort
            };

            LogHelper.WriteStatus("Master: get request from " + id);

            if (_module.State == AccessState.Released)
            { // if resource is released
                SendAcceptResponse(ipAndPort);
            }
            else if (_module.State == AccessState.Held)
            { // if resource is held by a host, add the request into queue
                _module.AddRequest(request);
            }
        }