code: private static void logRpcFly(JSONObject msgJson, ChannelHandlerContext ctx) {
          try {
              String ssid = msgJson.getString("$ssid");
              String from = msgJson.getString("$LOCAL_NODE_ID");
              String msgType = msgJson.getString("$msgType");
              if (ssid != null) {
                  long start = (long) msgJson.remove("$timestampMs");//目前是用完删掉,避免传递到业务层
                  LOG.debug(new JSONObject() {{
                      put("cost", System.currentTimeMillis() - start);
                      put("type", "rpcFly");
                      put("ssid", ssid);
                      put("from", from);
                      /*put("length", msgStr.length());*/
                      /*put("fullMsg", msgStr);*/
                      put("msgType", msgType);
                      put("client", ctx.channel().localAddress());
                      put("server", ctx.channel().remoteAddress());
                  }});
              }
          } catch (Throwable e) {
              LOG.error(e);
          }
      }
docs: 打印rpc消息传输耗时等信息:术语rpcFly