C#实现SQLSERVER数据库中有序GUID生成（NewSequentialId）

GUID作为数据库主键由于其无序性所以性能不怎么好，SQL Server中有个函数NewSequentialId可以生成有序的GUID，由于在程序中需要用到，就用C#实现了一下，生成的GUID格式基本和SQL Server一致。

程序代码参考了rpcrt4.dll中UuidCreateSequential的实现。

     public class GuidHelper
     {
         private static bool initialised;
         private static int count;

         private static long time;
         private static long timelast;
         private static ushort sequence;

         private static byte[] address; //网卡MAC
         private static readonly object locker = new object();
         public static Guid NewSequentialId()
         {
             lock(locker)
             {
                 if (!initialised)
                 {
                     timelast = UuidGetSystemTime();
                     count = TICKS_PER_CLOCK_TICK;
                     Random rand = new Random();
                     sequence = (ushort)(((rand.Next(, ) & 0xFF) << ) + rand.Next(, ) & 0xFF);
                     sequence &= 0x1FFF;
                     address = GetAddressBytes();
                     initialised = true;
                 }
                 while (true)
                 {
                     time = UuidGetSystemTime();
                     if (time > timelast)
                     {
                         count = ;
                         break;
                     }
                     if (time < timelast)
                     {
                         sequence = (ushort)((sequence + ) & 0x1FFF);
                         count = ;
                         break;
                     }
                     if (count < TICKS_PER_CLOCK_TICK)
                     {
                         count++;
                         break;
                     }
                 }

                 timelast = time;
                 time += count;

                 byte[] guidArray = new byte[];

                 uint data1 = (uint)(time & 0xffffffff);
                 ushort data2 = (ushort)((time >> ) & 0xffff);
                 ushort data3 = (ushort)((time >> ) & 0x0fff);
                 /* This is a version 1 UUID */
                 data3 |= ( << );

                 guidArray[] = (byte)data1;
                 guidArray[] = (byte)(data1 >> );
                 guidArray[] = (byte)(data1 >> );
                 guidArray[] = (byte)(data1 >> );
                 guidArray[] = (byte)data2;
                 guidArray[] = (byte)(data2 >> );
                 guidArray[] = (byte)data3;
                 guidArray[] = (byte)(data3 >> );
                 guidArray[] = (byte)(sequence & 0xff);
                 guidArray[] = (byte)((sequence & 0x3f00) >> );
                 guidArray[] |= 0x80;
                 Array.Copy(address, , guidArray, , );

                 return new Guid(guidArray);
             }//locker
         }//UuidCreateSequential

         private static readonly int TICKS_PER_CLOCK_TICK = ;
         private static readonly int SECSPERDAY = ;
         private static readonly int TICKSPERSEC = ;
         private static readonly long SECS_15_OCT_1582_TO_1601 = ( +  +  +  *  + ) * SECSPERDAY;
         private static readonly long TICKS_15_OCT_1582_TO_1601 = SECS_15_OCT_1582_TO_1601 * TICKSPERSEC;
         private static long UuidGetSystemTime()
         {
             DateTime dt = DateTime.Now;
             var ft = dt.ToFileTime();
             ft += TICKS_15_OCT_1582_TO_1601;
             return ft;
         }

         private static byte[] GetAddressBytes()
         {
             byte[] bytes;
             NetworkInterface[] nic = NetworkInterface.GetAllNetworkInterfaces();
             if (nic == null || nic.Length < )
             {
                 bytes = new byte[];
                 bytes[] = 0x01;
                 return bytes;
             }
             bytes = nic[].GetPhysicalAddress().GetAddressBytes();
             return bytes;
         }
     }

代码写的比较粗糙，不过功能已经实现，有需要的朋友可以自行优化！