using System; using System.Diagnostics; using System.Threading; using NewLife.Common; namespace NewLife.Data { /// <summary>流式Id</summary> [Obsolete("=>SnowFlake")] public class FlowId : Snowflake { } /// <summary>雪花算法。分布式Id</summary> /// <remarks> /// 文档 https://www.yuque.com/smartstone/nx/snow_flake /// /// 使用一个 64 bit 的 long 型的数字作为全局唯一 id。在分布式系统中的应用十分广泛,且ID 引入了时间戳,基本上保持自增。 /// 1bit保留 + 41bit时间戳 + 10bit机器 + 12bit序列号 /// </remarks> public class Snowflake { #region 属性 /// <summary>开始时间戳。首次使用前设置,否则无效,默认1970-1-1</summary> public DateTime StartTimestamp { get; set; } = new DateTime(1970, 1, 1); /// <summary>机器Id,取10位</summary> public Int32 WorkerId { get; set; } private Int32 _Sequence; /// <summary>序列号,取12位</summary> public Int32 Sequence { get => _Sequence; set => _Sequence = value; } private Int64 _msStart; private Stopwatch _watch; private Int64 _lastTime; #endregion #region 核心方法 private void Init() { // 初始化WorkerId,取5位实例加上5位进程,确保同一台机器的WorkerId不同 if (WorkerId <= 0) { var nodeId = SysConfig.Current.Instance; var pid = Process.GetCurrentProcess().Id; var tid = Thread.CurrentThread.ManagedThreadId; //WorkerId = ((nodeId & 0x1F) << 5) | (pid & 0x1F); //WorkerId = (nodeId ^ pid ^ tid) & 0x3FF; WorkerId = ((nodeId & 0x1F) << 5) | ((pid ^ tid) & 0x1F); } // 记录此时距离起点的毫秒数以及开机嘀嗒数 if (_watch == null) { _msStart = (Int64)(DateTime.Now - StartTimestamp).TotalMilliseconds; _watch = Stopwatch.StartNew(); } } /// <summary>获取下一个Id</summary> /// <returns></returns> public virtual Int64 NewId() { Init(); // 此时嘀嗒数减去起点嘀嗒数,加上七点毫秒数 //var ms = (Int64)(DateTime.Now - StartTimestamp).TotalMilliseconds; var ms = _watch.ElapsedMilliseconds + _msStart; var wid = WorkerId & 0x3FF; var seq = Interlocked.Increment(ref _Sequence) & 0x0FFF; //!!! 避免时间倒退 if (ms < _lastTime) ms = _lastTime; // 相同毫秒内,如果序列号用尽,则可能超过4096,导致生成重复Id // 睡眠1毫秒,抢占它的位置 @656092719(广西-风吹面) if (_lastTime == ms && seq == 0) { //ms++; // spin等1000次耗时141us,10000次耗时397us,100000次耗时3231us。@i9-10900k //Thread.SpinWait(1000); while (_lastTime == ms) ms = _watch.ElapsedMilliseconds + _msStart; } _lastTime = ms; /* * 每个毫秒内_Sequence没有归零,主要是为了安全,避免被人猜测得到前后Id。 * 而毫秒内的顺序,重要性不大。 */ return (ms << (10 + 12)) | (Int64)(wid << 12) | (Int64)seq; } /// <summary>获取指定时间的Id,带上节点和序列号。可用于根据业务时间构造插入Id</summary> /// <param name="time">时间</param> /// <returns></returns> public virtual Int64 NewId(DateTime time) { Init(); var ms = (Int64)(time - StartTimestamp).TotalMilliseconds; var wid = WorkerId & 0x3FF; var seq = Interlocked.Increment(ref _Sequence) & 0x0FFF; return (ms << (10 + 12)) | (Int64)(wid << 12) | (Int64)seq; } /// <summary>时间转为Id,不带节点和序列号。可用于构建时间片段查询</summary> /// <param name="time">时间</param> /// <returns></returns> public virtual Int64 GetId(DateTime time) { var t = (Int64)(time - StartTimestamp).TotalMilliseconds; return t << (10 + 12); } /// <summary>尝试分析</summary> /// <param name="id"></param> /// <param name="time">时间</param> /// <param name="workerId">节点</param> /// <param name="sequence">序列号</param> /// <returns></returns> public virtual Boolean TryParse(Int64 id, out DateTime time, out Int32 workerId, out Int32 sequence) { time = StartTimestamp.AddMilliseconds(id >> (10 + 12)); workerId = (Int32)((id >> 12) & 0x3FF); sequence = (Int32)(id & 0x0FFF); return true; } #endregion } }
代码地址:https://github.com/NewLifeX/X/blob/master/NewLife.Core/Data/Snowflake.cs