rate

type Limiter struct {
	RedisClient RedisClient
	Decay       time.Duration
	Limit       int
}

type RedisClient interface {
	ZAdd(key string, members ...redis.Z) (int64, error)
	ZRemRangeByScore(key, min, max string) (int64, error)
	Expire(key string, expiration time.Duration) (bool, error)
	ZCard(key string) (int64, error)
}