连续 GUID
GuidHelper.Increment();
GuidHelper.Next();
GuidHelper.Next(SequentialGuidType.AsEnd);
Guid.NetGuid() 产生的 Guid 是混乱无序的，为生成顺序 Guid，需要使用 DateTime.UtcNow.Ticks。
Ticks的值更新取决于系统计时器，介于0.5~15ms之间；太频繁的调用函数，会出现乱序，建议调用间隔1ms。
using System;
using System.Security.Cryptography;
/// <summary>
/// 连续GUID帮助类
/// </summary>
public static class GuidHelper
{
/// <summary>
/// RFC版本,值为 1~5
/// </summary>
private static readonly byte _version = 4;
/// <summary>
/// RFC变体,值为 [8,9,A,B]
/// </summary>
private static readonly byte _variant = 8;
/// <summary>
/// 高位过滤，0b00001111
/// </summary>
private static readonly byte _filterHighBit = 0b00001111;
/// <summary>
/// 低位过滤，0b11110000
/// </summary>
private static readonly byte _filterLowBit = 0b11110000;
private static readonly RandomNumberGenerator _randomNumberGenerator = RandomNumberGenerator.Create();
/// <summary>
/// 生成连续递增的GUID(不符合 RFC 4122 标准)
/// </summary>
/// <param name="sequentialGuidType"></param>
/// <returns></returns>
public static Guid Increment(SequentialGuidType guidType = SequentialGuidType.AsString)
{
var randomBytes = new byte[8];
_randomNumberGenerator.GetBytes(randomBytes);
// 一个Tick是100ns，10_000Tick=1ms
var timestamp = DateTime.UtcNow.Ticks;
var timestampBytes = BitConverter.GetBytes(timestamp);
if (BitConverter.IsLittleEndian)
{
Array.Reverse(timestampBytes);
}
var rslt = new byte[16];
switch (guidType)
{
case SequentialGuidType.AsString:
case SequentialGuidType.AsBinary:
{
// 16位数组：前8位为时间戳，后8位为随机数
Buffer.BlockCopy(timestampBytes, 0, rslt, 0, 8);
Buffer.BlockCopy(randomBytes, 0, rslt, 8, 8);
// 小端系统需要翻转
if (guidType == SequentialGuidType.AsString && BitConverter.IsLittleEndian)
{
Array.Reverse(rslt, 0, 4);
Array.Reverse(rslt, 4, 2);
Array.Reverse(rslt, 6, 2);
}
}
break;
case SequentialGuidType.AsEnd:
{
// 16位数组：前8位为随机数，后8位为时间戳
Buffer.BlockCopy(randomBytes, 0, rslt, 0, 8);
Buffer.BlockCopy(timestampBytes, 6, rslt, 8, 2);
Buffer.BlockCopy(timestampBytes, 0, rslt, 10, 6);
}
break;
default:
break;
}
return new Guid(rslt);
}
/// <summary>
/// 生成连续GUID
/// <para>符合 RFC 4122 标准</para>
/// </summary>
/// <param name="sequentialGuidType"></param>
/// <returns></returns>
public static Guid Next(SequentialGuidType guidType = SequentialGuidType.AsString)
{
/* RFC 4122
* dddddddd-dddd-Mddd-Ndrr-rrrrrrrrrrrr
* M，RFC版本（version），这里值为4
* N，RFC变体（variant），这里固定值为8
* d，从0001-1-1 0时至今的时钟周期数（DateTime.UtcNow.Ticks）
* r，随机数（random bytes）
*/
var randomBytes = new byte[8];
_randomNumberGenerator.GetBytes(randomBytes);
var timestamp = DateTime.UtcNow.Ticks;
var timestampBytes = BitConverter.GetBytes(timestamp);
if (BitConverter.IsLittleEndian)
{
Array.Reverse(timestampBytes);
}
var rslt = new byte[16];
switch (guidType)
{
case SequentialGuidType.AsString:
case SequentialGuidType.AsBinary:
{
/* 时间戳 + 随机数
* 0 1 2 3 4 5 6 7 8 9 10
* dddddddd-dddd-Mddd-Ndrr-rrrrrrrrrrrr
* Block1 2 3 4 5
* Data1 2 3 4
*/
// 时间戳前6个字节
Buffer.BlockCopy(timestampBytes, 0, rslt, 0, 6);
// 高4位为版本 | 低4位是时间戳元素[6]的高4位
rslt[6] = (byte)((_version << 4) | ((timestampBytes[6] & _filterLowBit) >> 4));
// 高4位：[6]低4位 | 低4位：[7]高4位
rslt[7] = (byte)(((timestampBytes[6] & _filterHighBit) << 4) | ((timestampBytes[7] & _filterLowBit) >> 4));
// 高4位：变体 | 低4位：[7]低4位
rslt[8] = (byte)((_variant << 4) | (timestampBytes[7] & _filterHighBit));
// 剩余7个字节由随机数组填充
Buffer.BlockCopy(randomBytes, 0, rslt, 9, 7);
// 小端系统需要翻转
if (guidType == SequentialGuidType.AsString && BitConverter.IsLittleEndian)
{
Array.Reverse(rslt, 0, 4);
Array.Reverse(rslt, 4, 2);
Array.Reverse(rslt, 6, 2);
}
}
break;
case SequentialGuidType.AsEnd:
{
/* 随机数 + 时间戳
* rrrrrrrr-rrrr-Mxdr-Nddd-dddddddddddd
* Block1 2 3 4 5
* Data4 = Block4 + Block5
* 排序顺序：Block5 > Block4 > Block3 > Block2 > Block1
* Data3 = Block3，被认为是 uint16，排序并不是从左往右，为消除影响，x位取固定值
*/
Buffer.BlockCopy(randomBytes, 0, rslt, 0, 6);
// Mx 高4位为版本 | 低4位：0
rslt[6] = (byte)(_version << 4);
// dr 高4位：[7]低4位 | 低4位：随机数
rslt[7] = (byte)(((timestampBytes[7] & _filterHighBit) << 4) | (randomBytes[7] & _filterHighBit));
// Nd 高4位：变体 | 低4位：[6]高4位
rslt[8] = (byte)((_variant << 4) | ((timestampBytes[6] & _filterLowBit) >> 4));
// dd 高4位：[6]低4位 | 低4位：[7]高4位
rslt[9] = (byte)(((timestampBytes[6] & _filterHighBit) << 4) | ((timestampBytes[7] & _filterLowBit) >> 4));
// 剩余6个字节是时间戳的前6个字节
Buffer.BlockCopy(timestampBytes, 0, rslt, 10, 6);
if (BitConverter.IsLittleEndian)
{
// 包含版本数的 Data3 需要翻转
Array.Reverse(rslt, 6, 2);
}
}
break;
default:
break;
}
return new Guid(rslt);
}
}
/// <summary>
/// GUID类型
/// </summary>
public enum SequentialGuidType
{
/// <summary>
/// <para>dddddddd-dddd-Mddd-Ndrr-rrrrrrrrrrrr</para>
/// <para>用于MySql和PostgreSql</para>
/// <para>当使用<see cref="Guid.ToString()"/>方法进行格式化时连续</para>
/// <para>顺序体现在第8个字节</para>
/// </summary>
AsString,
/// <summary>
/// <para>dddddddd-dddd-Mddd-Ndrr-rrrrrrrrrrrr</para>
/// <para>用于Oracle</para>
/// <para>当使用<see cref="Guid.ToByteArray()"/>方法进行格式化时连续</para>
/// <para>顺序体现在第8个字节，连续递增</para>
/// </summary>
AsBinary,
/// <summary>
/// <para>rrrrrrrr-rrrr-Mxdr-Nddd-dddddddddddd</para>
/// <para>用于SqlServer</para>
/// <para>连续性体现于GUID的第4块（Data4）</para>
/// <para>顺序比较Block5 > Block4 > Block3 > Block2 > Block1</para>
/// </summary>
AsEnd,
}
