Returns a list of all cluster stats from the cache provider
        :type pattern: str
        :return: a list of Stats

def get_stats(self, pattern):
        """
        Returns a list of all cluster stats from the cache provider
        :type pattern: str
        :return: a list of Stats
        """
        if not self.cache:
            return
        key_list = self.cache.get(Conf.Q_STAT)
        if not key_list or len(key_list) == 0:
            return []
        stats = []
        for key in key_list:
            stat = self.cache.get(key)
            if stat:
                stats.append(stat)
            else:
                key_list.remove(key)
        self.cache.set(Conf.Q_STAT, key_list)
        return stats