关于分布式环境下的id生成

public class IdWorker
    {
        //基准时间
        public const long Twepoch = 1288834974657L;

        //机器标识位数
        private const int WorkerIdBits = 6;

        //数据标志位数
        private const int DatacenterIdBits = 6;

        //序列号识位数
        private const int SequenceBits = 10;

        //机器ID最大值
        private const long MaxWorkerId = -1L ^ (-1L << WorkerIdBits);

        //数据标志ID最大值
        private const long MaxDatacenterId = -1L ^ (-1L << DatacenterIdBits);

        //序列号ID最大值
        private const long SequenceMask = -1L ^ (-1L << SequenceBits);

        //机器ID偏左移10位
        private const int WorkerIdShift = SequenceBits;

        //数据ID偏左移15位
        private const int DatacenterIdShift = SequenceBits + WorkerIdBits;

        //时间毫秒左移20位
        public const int TimestampLeftShift = SequenceBits + WorkerIdBits + DatacenterIdBits;

        private static readonly DateTime Jan1St1970 = new DateTime
            (1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);

        private readonly object _lock = new object();
        private long _lastTimestamp = -1L;

        public IdWorker(long workerId, long datacenterId, long sequence = 0L)
        {
            // 如果超出范围就抛出异常
            if (workerId > MaxWorkerId || workerId < 0)
                throw new ArgumentException(string.Format("worker Id 必须大于0，且不能大于MaxWorkerId： {0}", MaxWorkerId));

            if (datacenterId > MaxDatacenterId || datacenterId < 0)
                throw new ArgumentException(string.Format("datacenterId Id 必须大于0，且不能大于MaxWorkerId： {0}",
                    MaxDatacenterId));

            //先检验再赋值
            WorkerId = workerId;
            DatacenterId = datacenterId;
            Sequence = sequence;
        }

        public long WorkerId { get; protected set; }
        public long DatacenterId { get; protected set; }

        public long Sequence { get; internal set; }

        public virtual long NextId(long dataNode=0)
        {
            lock (_lock)
            {
                if (dataNode > MaxDatacenterId || dataNode < 0)
                    throw new ArgumentException($"dataNode 必须大于0，且不能大于MaxWorkerId： {MaxDatacenterId}");
                if (dataNode == 0)
                    dataNode = DatacenterId;
                var timestamp = TimeGen();
                if (timestamp < _lastTimestamp)
                    throw new Exception($"时间戳必须大于上一次生成ID的时间戳.  拒绝为{_lastTimestamp - timestamp}毫秒生成id");

                //如果上次生成时间和当前时间相同,在同一毫秒内
                if (_lastTimestamp == timestamp)
                {
                    //sequence自增，和sequenceMask相与一下，去掉高位
                    Sequence = (Sequence + 1) & SequenceMask;
                    //判断是否溢出,也就是每毫秒内超过1024，当为1024时，与sequenceMask相与，sequence就等于0
                    if (Sequence == 0)
                        timestamp = TilNextMillis(_lastTimestamp);
                }
                else
                {
                    //如果和上次生成时间不同,重置sequence，就是下一毫秒开始，sequence计数重新从0开始累加,
                    //为了保证尾数随机性更大一些,最后一位可以设置一个随机数
                    Sequence = 0; //new Random().Next(10);
                }

                _lastTimestamp = timestamp;
                return ((timestamp - Twepoch) << TimestampLeftShift) | (dataNode << DatacenterIdShift) |
                       (WorkerId << WorkerIdShift) | Sequence;
            }
        }

        /// <summary>
        /// 防止产生的时间比之前的时间还要小（由于NTP回拨等问题）,保持增量的趋势.
        /// </summary>
        /// <param name="lastTimestamp"></param>
        /// <returns></returns>
        protected virtual long TilNextMillis(long lastTimestamp)
        {
            var timestamp = TimeGen();
            while (timestamp <= lastTimestamp)
                timestamp = TimeGen();
            return timestamp;
        }

        /// <summary>
        /// 获取当前的时间戳
        /// </summary>
        /// <returns></returns>
        protected virtual long TimeGen()
        {
            return (long) (DateTime.UtcNow - Jan1St1970).TotalMilliseconds;
        }
    }

public void GetId()
{
  new IdWorker(1, 1).NextId();          
}