code: function dispatch_signals()
      {
          if (empty($this->signals))
              return;
  
          $signalsExported = join(" ", array_map(function($signal) {
              return isset($this->signalNames[$signal]) ? $this->signalNames[$signal] : $signal;
          }, $this->signals));
          $this->logger->debug("dispatch signals $signalsExported");
          while ($signalNumber = array_shift($this->signals)) {
              $handleFunction = $this->signalMappingToMethod[$signalNumber];
              call_user_func([&$this, $handleFunction], [$signalNumber]);
          }
      }
docs: 执行信号队列
  
  @return void