C# 雪花算法Snowflake

生成唯一long类型自增Id：

using System;

namespace ConsoleApp1
{
    public static class Snowflake
    {
        static SnowflakeTool idworker = new SnowflakeTool(1);
        public static long Next()
        {
            return idworker.nextId();
        }
    }

    public class SnowflakeTool
    {
        //机器ID
        private static long nodeId;
        private static long twepoch = 687888001020L; //唯一时间，这是一个避免重复的随机量，自行设定不要大于当前时间戳
        private static long sequence = 0L;
        private static int workerIdBits = 4; //机器码字节数。4个字节用来保存机器码(定义为Long类型会出现，最大偏移64位，所以左移64位没有意义)
        public static long maxWorkerId = -1L ^ -1L << workerIdBits; //最大机器ID
        private static int sequenceBits = 10; //计数器字节数，10个字节用来保存计数码
        private static int workerIdShift = sequenceBits; //机器码数据左移位数，就是后面计数器占用的位数
        private static int timestampLeftShift = sequenceBits + workerIdBits; //时间戳左移动位数就是机器码和计数器总字节数
        public static long sequenceMask = -1L ^ -1L << sequenceBits; //一微秒内可以产生计数，如果达到该值则等到下一微妙在进行生成
        private long lastTimestamp = -1L;

        /// <summary>
        /// 机器码
        /// </summary>
        /// <param name="workerId"></param>
        public SnowflakeTool(long workerId)
        {
            if (workerId > maxWorkerId || workerId < 0)
                throw new Exception(string.Format("节点id 不能大于 {0} 或者 小于 0 ", workerId));
            SnowflakeTool.nodeId = workerId;

        }

        public long nextId()
        {
            lock (this)
            {
                long timestamp = timeGen();
                if (this.lastTimestamp == timestamp)
                { //同一微妙中生成ID
                    SnowflakeTool.sequence = (SnowflakeTool.sequence + 1) & SnowflakeTool.sequenceMask; //用&运算计算该微秒内产生的计数是否已经到达上限
                    if (SnowflakeTool.sequence == 0)
                    {
                        //一微妙内产生的ID计数已达上限，等待下一微妙
                        timestamp = tillNextMillis(this.lastTimestamp);
                    }
                }
                else
                { //不同微秒生成ID
                    SnowflakeTool.sequence = 0; //计数清0
                }
                if (timestamp < lastTimestamp)
                { //如果当前时间戳比上一次生成ID时时间戳还小，抛出异常，因为不能保证现在生成的ID之前没有生成过
                    throw new Exception(string.Format("Clock moved backwards.  Refusing to generate id for {0} milliseconds",
                        this.lastTimestamp - timestamp));
                }
                this.lastTimestamp = timestamp; //把当前时间戳保存为最后生成ID的时间戳
                long nextId = (timestamp - twepoch << timestampLeftShift) | SnowflakeTool.nodeId << SnowflakeTool.workerIdShift | SnowflakeTool.sequence;
                return nextId;
            }
        }

        /// <summary>
        /// 获取下一微秒时间戳
        /// </summary>
        /// <param name="lastTimestamp"></param>
        /// <returns></returns>
        private long tillNextMillis(long lastTimestamp)
        {
            long timestamp = timeGen();
            while (timestamp <= lastTimestamp)
            {
                timestamp = timeGen();
            }
            return timestamp;
        }

        /// <summary>
        /// 生成当前时间戳
        /// </summary>
        /// <returns></returns>
        private long timeGen()
        {
            return (long)(DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalMilliseconds;
        }
    }
}

调用 校验重复：

var list = new List<long>();
            for (int i = 0; i < 100000; i++)
            {
                var id = Snowflake.Next();// 通过雪花算法
              
               Console.WriteLine(id);
          
            }
//校验重复
 Console.WriteLine("--------------------------------------");
            Console.WriteLine(list.Distinct().Count());

            Console.WriteLine("--------------------------------------");

            var list2 = list.GroupBy(x => x).Where(x => x.Count() > 1);
            foreach (var item in list2)
            {
                Console.WriteLine(item.Key);
            }
 Console.ReadKey();

long类型序列化精度丢失的处理：

 [JsonConverter(typeof(MyNumberConverter), NumberConverterShip.Int64)]
        public long GoodsId { set; get; }

MyNumberConverter，NumberConverterShip：

using Newtonsoft.Json;
using System;
using System.ComponentModel;
using System.Linq;

namespace Seckill.EntityFrameworkCore.Converter
{
    /// <inheritdoc />
    /// <summary>
    /// 大数据json序列化重写
    /// </summary>
    public sealed class MyNumberConverter : JsonConverter
    {
        /// <summary>
        /// 转换成字符串的类型
        /// </summary>
        private readonly NumberConverterShip _ship;

        /// <summary>
        /// 大数据json序列化重写实例化
        /// </summary>
        public MyNumberConverter()
        {
            _ship = (NumberConverterShip)0xFF;
        }

        /// <summary>
        /// 大数据json序列化重写实例化
        /// </summary>
        /// <param name="ship">转换成字符串的类型</param>
        public MyNumberConverter(NumberConverterShip ship)
        {
            _ship = ship;
        }

        /// <inheritdoc />
        /// <summary>
        /// 确定此实例是否可以转换指定的对象类型。
        /// </summary>
        /// <param name="objectType">对象的类型。</param>
        /// <returns>如果此实例可以转换指定的对象类型，则为：<c>true</c>，否则为：<c>false</c></returns>
        public override bool CanConvert(Type objectType)
        {
            var typecode = Type.GetTypeCode(objectType.Name.Equals("Nullable`1") ? objectType.GetGenericArguments().First() : objectType);
            switch (typecode)
            {
                case TypeCode.Decimal:
                    return (_ship & NumberConverterShip.Decimal) == NumberConverterShip.Decimal;
                case TypeCode.Double:
                    return (_ship & NumberConverterShip.Double) == NumberConverterShip.Double;
                case TypeCode.Int64:
                    return (_ship & NumberConverterShip.Int64) == NumberConverterShip.Int64;
                case TypeCode.UInt64:
                    return (_ship & NumberConverterShip.UInt64) == NumberConverterShip.UInt64;
                case TypeCode.Single:
                    return (_ship & NumberConverterShip.Single) == NumberConverterShip.Single;
                default: return false;
            }
        }

        /// <inheritdoc />
        /// <summary>
        /// 读取对象的JSON表示。
        /// </summary>
        /// <param name="reader">从 <see cref="T:Newtonsoft.Json.JsonReader" /> 中读取。</param>
        /// <param name="objectType">对象的类型。</param>
        /// <param name="existingValue">正在读取的对象的现有值。</param>
        /// <param name="serializer">调用的序列化器实例。</param>
        /// <returns>对象值。</returns>
        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        {
            return AsType(reader.Value.ToString(), objectType);
        }

        /// <summary>
        /// 字符串格式数据转其他类型数据
        /// </summary>
        /// <param name="input">输入的字符串</param>
        /// <param name="destinationType">目标格式</param>
        /// <returns>转换结果</returns>
        public static object AsType(string input, Type destinationType)
        {
            try
            {
                var converter = TypeDescriptor.GetConverter(destinationType);
                if (converter.CanConvertFrom(typeof(string)))
                {
                    return converter.ConvertFrom(null, null, input);
                }

                converter = TypeDescriptor.GetConverter(typeof(string));
                if (converter.CanConvertTo(destinationType))
                {
                    return converter.ConvertTo(null, null, input, destinationType);
                }
            }
            catch
            {
                return null;
            }
            return null;
        }

        /// <inheritdoc />
        /// <summary>
        /// 写入对象的JSON表示形式。
        /// </summary>
        /// <param name="writer">要写入的 <see cref="T:Newtonsoft.Json.JsonWriter" /> 。</param>
        /// <param name="value">要写入对象值</param>
        /// <param name="serializer">调用的序列化器实例。</param>
        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
        {
            if (value == null)
            {
                writer.WriteNull();
            }
            else
            {
                var objectType = value.GetType();
                var typeCode = Type.GetTypeCode(objectType.Name.Equals("Nullable`1") ? objectType.GetGenericArguments().First() : objectType);
                switch (typeCode)
                {
                    case TypeCode.Decimal:
                        writer.WriteValue(((decimal)value).ToString("f6"));
                        break;
                    case TypeCode.Double:
                        writer.WriteValue(((double)value).ToString("f4"));
                        break;
                    case TypeCode.Single:
                        writer.WriteValue(((float)value).ToString("f2"));
                        break;
                    default:
                        writer.WriteValue(value.ToString());
                        break;
                }
            }
        }
    }

    /// <summary>
    /// 转换成字符串的类型
    /// </summary>
    [Flags]
    public enum NumberConverterShip
    {
        /// <summary>
        /// 长整数
        /// </summary>
        Int64 = 1,

        /// <summary>
        /// 无符号长整数
        /// </summary>
        UInt64 = 2,

        /// <summary>
        /// 浮点数
        /// </summary>
        Single = 4,

        /// <summary>
        /// 双精度浮点数
        /// </summary>
        Double = 8,

        /// <summary>
        /// 大数字
        /// </summary>
        Decimal = 16
    }
}