twitter的snowflake算法(C#版本)

以下是 C# 版本的 Twitter Snowflake 算法实现：

public class Snowflake
{
    private static readonly DateTime Twepoch = new DateTime(2021, 1, 1, 0, 0, 0, DateTimeKind.Utc);
    private const int WorkerIdBits = 5;
    private const int DatacenterIdBits = 5;
    private const int SequenceBits = 12;
    private const long MaxWorkerId = -1L ^ (-1L << WorkerIdBits);
    private const long MaxDatacenterId = -1L ^ (-1L << DatacenterIdBits);
    private const long SequenceMask = -1L ^ (-1L << SequenceBits);
    private const int WorkerIdShift = SequenceBits;
    private const int DatacenterIdShift = SequenceBits + WorkerIdBits;
    private const int TimestampLeftShift = SequenceBits + WorkerIdBits + DatacenterIdBits;
    private readonly object _lock = new object();
    private readonly long _workerId;
    private readonly long _datacenterId;
    private long _sequence = 0L;
    private long _lastTimestamp = -1L;

    public Snowflake(long workerId, long datacenterId)
    {
        if (workerId > MaxWorkerId || workerId < 0)
        {
            throw new ArgumentException($"worker Id can't be greater than {MaxWorkerId} or less than 0");
        }

        if (datacenterId > MaxDatacenterId || datacenterId < 0)
        {
            throw new ArgumentException($"datacenter Id can't be greater than {MaxDatacenterId} or less than 0");
        }

        _workerId = workerId;
        _datacenterId = datacenterId;
    }

    public long NextId()
    {
        lock (_lock)
        {
            var timestamp = TimeGen();

            if (_lastTimestamp == timestamp)
            {
                _sequence = (_sequence + 1) & SequenceMask;

                if (_sequence == 0)
                {
                    timestamp = TilNextMillis(_lastTimestamp);
                }
            }
            else
            {
                _sequence = 0L;
            }

            if (timestamp < _lastTimestamp)
            {
                throw new Exception($"Clock moved backwards. Refusing to generate id for {_lastTimestamp - timestamp} milliseconds");
            }

            _lastTimestamp = timestamp;

            return ((timestamp - Twepoch.Ticks) << TimestampLeftShift) |
                   (_datacenterId << DatacenterIdShift) |
                   (_workerId << WorkerIdShift) |
                   _sequence;
        }
    }

    private static long TilNextMillis(long lastTimestamp)
    {
        var timestamp = TimeGen();

        while (timestamp <= lastTimestamp)
        {
            timestamp = TimeGen();
        }

        return timestamp;
    }

    private static long TimeGen() => DateTime.UtcNow.Ticks;
}

使用示例：

var snowflake = new Snowflake(workerId: 1, datacenterId: 1);
var id = snowflake.NextId();

在上面的示例中，`workerId` 和 `datacenterId` 分别表示工作节点 ID 和数据中心 ID，这两个参数需要根据实际情况进行配置。调用 `NextId()` 方法即可生成一个唯一的 Snowflake ID。