https://blog.csdn.net/weixin_48916144/article/details/147990723
https://www.cnblogs.com/sexintercourse/p/18824051
public class SnowflakeIdGenerator
{
// 雪花算法的各个参数
private static readonly long Epoch = new DateTime(2022, 1, 1).Ticks / 10000; // 设置纪元时间（单位：毫秒）
private static readonly int MachineIdBits = 10; // 机器ID部分占用的位数
private static readonly int SequenceBits = 12; // 序列号部分占用的位数
private static readonly long MaxMachineId = -1L ^ (-1L << MachineIdBits); // 最大机器ID（1023）
private static readonly long SequenceMask = -1L ^ (-1L << SequenceBits); // 最大序列号（4095）
private long lastTimestamp = -1L; // 上次生成ID的时间戳
private long machineId; // 机器ID
private long sequence = 0L; // 序列号
private readonly object lockObject = new object();
// 构造函数：传入机器ID
public SnowflakeIdGenerator(long machineId)
{
if (machineId > MaxMachineId || machineId < 0)
{
throw new ArgumentException($"Machine ID should be between 0 and {MaxMachineId}");
}
this.machineId = machineId;
}
// 生成下一个唯一的ID
public long NextId()
{
lock (lockObject)
{
long timestamp = GetCurrentTimestamp();
if (timestamp == lastTimestamp)
{
// 同一毫秒内，序列号加1
sequence = (sequence + 1) & SequenceMask;
if (sequence == 0)
{
// 如果序列号溢出，等待下一毫秒
timestamp = WaitNextMillis(lastTimestamp);
}
}
else
{
sequence = 0;
}
lastTimestamp = timestamp;
// 组合成64位的ID
return (timestamp - Epoch) << (MachineIdBits + SequenceBits) // 时间戳部分
| (machineId << SequenceBits) // 机器ID部分
| sequence; // 序列号部分
}
}
// 获取当前时间戳（毫秒）
private long GetCurrentTimestamp()
{
return DateTime.UtcNow.Ticks / 10000 - Epoch; // 获取当前时间的毫秒数
}
// 等待下一毫秒
private long WaitNextMillis(long lastTimestamp)
{
long timestamp = GetCurrentTimestamp();
while (timestamp <= lastTimestamp)
{
timestamp = GetCurrentTimestamp();
}
return timestamp;
}
}