code: func InitAppStatus() error {
  	LogAccess.Debug("Init App Status Engine as ", PushConf.Stat.Engine)
  	switch PushConf.Stat.Engine {
  	case "memory":
  		StatStorage = memory.New()
  	case "redis":
  		StatStorage = redis.New(PushConf)
  	case "boltdb":
  		StatStorage = boltdb.New(PushConf)
  	case "buntdb":
  		StatStorage = buntdb.New(PushConf)
  	case "leveldb":
  		StatStorage = leveldb.New(PushConf)
  	case "badger":
  		StatStorage = badger.New(PushConf)
  	default:
  		LogError.Error("storage error: can't find storage driver")
  		return errors.New("can't find storage driver")
  	}
  
  	if err := StatStorage.Init(); err != nil {
  		LogError.Error("storage error: " + err.Error())
  
  		return err
  	}
  
  	return nil
  }
docs: // InitAppStatus for initialize app status