docs: private void permitSem() {
          if (channelStatus.isStart()) {
              channelMutex.set(true);
              logger.debug("channel status is ok!");
          } else {
              channelMutex.set(false);
              logger.debug("channel status is fail!");
          }
  
          boolean permit = isPermit(false);
          if (permit == false) {
              if (logger.isDebugEnabled()) {
                  logger.debug("Permit is fail!");
              }
              // 如果未授权，则设置信号量为0
              permitMutex.set(false);
          } else {
              // 信号量+1
              if (logger.isDebugEnabled()) {
                  logger.debug("Permit is Ok!");
              }
              permitMutex.set(true);
          }
  
          processChanged(permit);// 通知下变化
      }