pgsql/mysql/sqlserver适配

FreeSql/FreeUtil.cs

@@ -0,0 +1,34 @@
+using NpgsqlTypes;
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Text;
+using System.Threading;
+
+public static class FreeUtil {
+
+	private static DateTime dt1970 = new DateTime(1970, 1, 1);
+	private static ThreadLocal<Random> rnd = new ThreadLocal<Random>();
+	private static readonly int __staticMachine = ((0x00ffffff & Environment.MachineName.GetHashCode()) +
+#if NETSTANDARD1_5 || NETSTANDARD1_6
+			1
+#else
+			AppDomain.CurrentDomain.Id
+#endif
+			) & 0x00ffffff;
+	private static readonly int __staticPid = Process.GetCurrentProcess().Id;
+	private static int __staticIncrement = rnd.Value.Next();
+	/// <summary>
+	/// 生成类似Mongodb的ObjectId有序、不重复Guid
+	/// </summary>
+	/// <returns></returns>
+	public static Guid NewMongodbId() {
+		var now = DateTime.Now;
+		var uninxtime = (int)now.Subtract(dt1970).TotalSeconds;
+		int increment = Interlocked.Increment(ref __staticIncrement) & 0x00ffffff;
+		var rand = rnd.Value.Next(0, int.MaxValue);
+		var guid = $"{uninxtime.ToString("x8").PadLeft(8, '0')}{__staticMachine.ToString("x8").PadLeft(8, '0').Substring(2, 6)}{__staticPid.ToString("x8").PadLeft(8, '0').Substring(6, 2)}{increment.ToString("x8").PadLeft(8, '0')}{rand.ToString("x8").PadLeft(8, '0')}";
+		return Guid.Parse(guid);
+	}
+}