Saves a cluster statistic to the cache provider
        :type key: str
        :type value: str
        :type timeout: int

def set_stat(self, key, value, timeout):
        """
        Saves a cluster statistic to the cache provider
        :type key: str
        :type value: str
        :type timeout: int
        """
        if not self.cache:
            return
        key_list = self.cache.get(Conf.Q_STAT, [])
        if key not in key_list:
            key_list.append(key)
        self.cache.set(Conf.Q_STAT, key_list)
        return self.cache.set(key, value, timeout)