private long GetTimestampAndSetSeq()
{
var timestamp = NumUtil.TimeMilliNum();
if (timestamp < lastTimestamp)
{
//如果当前时间小于上一次ID生成的时间戳，说明系统时钟回退过这个时候应当抛出异常
throw new ArgumentException(
$"Clock moved backwards. Refusing to generate id for {lastTimestamp - timestamp} milliseconds");
}
// 如果是同一时间生成的，则进行毫秒内序列
if (lastTimestamp == timestamp)
{
sequence = (sequence + 1) & maxSequence;
//毫秒内序列溢出
//阻塞到下一个毫秒,获得新的时间戳
if (sequence == 0)
{
timestamp = WaitNextMillis();
}
}
//时间戳改变，毫秒内序列重置
else
{
sequence = 0L;
}
//上次生成ID的时间截
lastTimestamp = timestamp;
return(timestamp);
}
/// <summary>
/// 当前毫秒内序列使用完，等待下一毫秒
/// </summary>
/// <returns></returns>
protected long WaitNextMillis()
{
long timeTicks;
do
{
timeTicks = NumUtil.TimeMilliNum();
} while (timeTicks <= lastTimestamp);
return(timeTicks);
}