From 3f3d58fc6763e3df5df7815bd73699215e5fe11e Mon Sep 17 00:00:00 2001
From: int21h <vk@alphacloud.net>
Date: Mon, 16 Sep 2024 12:02:03 -0400
Subject: [PATCH 1/3] Remove memory allocations in GuidCombGenerator under .NET
8+
---
.../IdGen/GuidComb/GuidCombFixture.cs | 32 ++++++++++++++
src/NHibernate/Id/GuidCombGenerator.cs | 43 ++++++++++++++++---
2 files changed, 69 insertions(+), 6 deletions(-)
create mode 100644 src/NHibernate.Test/IdGen/GuidComb/GuidCombFixture.cs
diff --git a/src/NHibernate.Test/IdGen/GuidComb/GuidCombFixture.cs b/src/NHibernate.Test/IdGen/GuidComb/GuidCombFixture.cs
new file mode 100644
index 00000000000..b79bbb807b1
--- /dev/null
+++ b/src/NHibernate.Test/IdGen/GuidComb/GuidCombFixture.cs
@@ -0,0 +1,32 @@
+using System;
+using NHibernate.Id;
+using NUnit.Framework;
+
+namespace NHibernate.Test.IdGen.GuidComb;
+
+[TestFixture]
+public class GuidCombFixture
+{
+ class GuidCombGeneratorEx : GuidCombGenerator
+ {
+ public static Guid Generate(string guid, DateTime utcNow) => GenerateComb(Guid.Parse(guid), utcNow);
+ }
+
+ [Test]
+ public void CanGenerateSequentialGuid()
+ {
+ Assert.AreEqual(Guid.Parse("076a04fa-ef4e-4093-8479-b0e10103cdc5"),
+ GuidCombGeneratorEx.Generate(
+ "076a04fa-ef4e-4093-8479-8599e96f14cf",
+ new DateTime(2023, 12, 23, 15, 45, 55, DateTimeKind.Utc)),
+ "seed: 076a04fa");
+
+ Assert.AreEqual(Guid.Parse("81162ee2-a4cb-4611-9327-d61f0137e5b6"),
+ GuidCombGeneratorEx.Generate(
+ "81162ee2-a4cb-4611-9327-23bbda36176c",
+ new DateTime(2050, 01, 29, 18, 55, 35, DateTimeKind.Utc)),
+ "seed: 81162ee2");
+
+ }
+
+}
diff --git a/src/NHibernate/Id/GuidCombGenerator.cs b/src/NHibernate/Id/GuidCombGenerator.cs
index cb01227c979..076ef8bc1cc 100644
--- a/src/NHibernate/Id/GuidCombGenerator.cs
+++ b/src/NHibernate/Id/GuidCombGenerator.cs
@@ -1,4 +1,5 @@
using System;
+using System.Diagnostics;
using NHibernate.Engine;
namespace NHibernate.Id
@@ -36,21 +37,50 @@ public partial class GuidCombGenerator : IIdentifierGenerator
/// <returns>The new identifier as a <see cref="Guid"/>.</returns>
public object Generate(ISessionImplementor session, object obj)
{
- return GenerateComb();
+ return GenerateComb(Guid.NewGuid(), DateTime.UtcNow);
}
/// <summary>
/// Generate a new <see cref="Guid"/> using the comb algorithm.
/// </summary>
- private Guid GenerateComb()
+ protected static Guid GenerateComb(in Guid guid, DateTime utcNow)
{
- byte[] guidArray = Guid.NewGuid().ToByteArray();
+#if NET8_0_OR_GREATER
+ Span<byte> guidArray = stackalloc byte[16];
+ Span<byte> msecsArray = stackalloc byte[sizeof(long)];
+ Span<byte> daysArray = stackalloc byte[sizeof(int)];
- DateTime now = DateTime.UtcNow;
+ var bytesWritten = guid.TryWriteBytes(guidArray);
+ Debug.Assert(bytesWritten);
// Get the days and milliseconds which will be used to build the byte string
- TimeSpan days = new TimeSpan(now.Ticks - BaseDateTicks);
- TimeSpan msecs = now.TimeOfDay;
+ TimeSpan days = new TimeSpan(utcNow.Ticks - BaseDateTicks);
+ TimeSpan msecs = utcNow.TimeOfDay;
+
+ // Convert to a byte array
+ // Note that SQL Server is accurate to 1/300th of a millisecond so we divide by 3.333333
+
+ bytesWritten = BitConverter.TryWriteBytes(daysArray, days.Days)
+ && BitConverter.TryWriteBytes(msecsArray, (long)(msecs.TotalMilliseconds / 3.333333));
+ Debug.Assert(bytesWritten);
+
+ msecsArray.Reverse();
+
+ // Copy the bytes into the guid
+ //Array.Copy(daysArray, daysArray.Length - 2, guidArray, guidArray.Length - 6, 2);
+ guidArray[10] = daysArray[1];
+ guidArray[11] = daysArray[0];
+
+ //Array.Copy(msecsArray, msecsArray.Length - 4, guidArray, guidArray.Length - 4, 4);
+ msecsArray[^4..].CopyTo(guidArray[^4..]);
+ return new Guid(guidArray);
+#else
+
+ byte[] guidArray = guid.ToByteArray();
+
+ // Get the days and milliseconds which will be used to build the byte string
+ TimeSpan days = new TimeSpan(utcNow.Ticks - BaseDateTicks);
+ TimeSpan msecs = utcNow.TimeOfDay;
// Convert to a byte array
// Note that SQL Server is accurate to 1/300th of a millisecond so we divide by 3.333333
@@ -66,6 +96,7 @@ private Guid GenerateComb()
Array.Copy(msecsArray, msecsArray.Length - 4, guidArray, guidArray.Length - 4, 4);
return new Guid(guidArray);
+#endif
}
#endregion
From 9b5714a86ea0bff5d109817e4561b017111b784f Mon Sep 17 00:00:00 2001
From: "github-actions[bot]" <github-actions[bot]@users.noreply.github.com>
Date: Wed, 25 Sep 2024 14:26:34 +0000
Subject: [PATCH 2/3] Generate async files
---
src/NHibernate/Async/Id/GuidCombGenerator.cs | 1 +
1 file changed, 1 insertion(+)
diff --git a/src/NHibernate/Async/Id/GuidCombGenerator.cs b/src/NHibernate/Async/Id/GuidCombGenerator.cs
index 59540f3d2ca..eb4ef6c7c63 100644
--- a/src/NHibernate/Async/Id/GuidCombGenerator.cs
+++ b/src/NHibernate/Async/Id/GuidCombGenerator.cs
@@ -9,6 +9,7 @@
using System;
+using System.Diagnostics;
using NHibernate.Engine;
namespace NHibernate.Id
From b19ca2809c92d23ca6f1b5453e83ceb855eb42d0 Mon Sep 17 00:00:00 2001
From: Alex Zaytsev <hazzik@gmail.com>
Date: Tue, 11 Feb 2025 10:51:43 +1000
Subject: [PATCH 3/3] apply suggestion from comments
---
src/NHibernate/Id/GuidCombGenerator.cs | 62 +++++++-------------------
1 file changed, 15 insertions(+), 47 deletions(-)
diff --git a/src/NHibernate/Id/GuidCombGenerator.cs b/src/NHibernate/Id/GuidCombGenerator.cs
index 076ef8bc1cc..adbbd78196d 100644
--- a/src/NHibernate/Id/GuidCombGenerator.cs
+++ b/src/NHibernate/Id/GuidCombGenerator.cs
@@ -43,60 +43,28 @@ public object Generate(ISessionImplementor session, object obj)
/// <summary>
/// Generate a new <see cref="Guid"/> using the comb algorithm.
/// </summary>
- protected static Guid GenerateComb(in Guid guid, DateTime utcNow)
+ protected static Guid GenerateComb(Guid guid, DateTime utcNow)
{
-#if NET8_0_OR_GREATER
+#if NETSTANDARD2_1_OR_GREATER || NETCOREAPP2_1_OR_GREATER
Span<byte> guidArray = stackalloc byte[16];
- Span<byte> msecsArray = stackalloc byte[sizeof(long)];
- Span<byte> daysArray = stackalloc byte[sizeof(int)];
-
- var bytesWritten = guid.TryWriteBytes(guidArray);
- Debug.Assert(bytesWritten);
-
- // Get the days and milliseconds which will be used to build the byte string
- TimeSpan days = new TimeSpan(utcNow.Ticks - BaseDateTicks);
- TimeSpan msecs = utcNow.TimeOfDay;
-
- // Convert to a byte array
- // Note that SQL Server is accurate to 1/300th of a millisecond so we divide by 3.333333
-
- bytesWritten = BitConverter.TryWriteBytes(daysArray, days.Days)
- && BitConverter.TryWriteBytes(msecsArray, (long)(msecs.TotalMilliseconds / 3.333333));
- Debug.Assert(bytesWritten);
-
- msecsArray.Reverse();
-
- // Copy the bytes into the guid
- //Array.Copy(daysArray, daysArray.Length - 2, guidArray, guidArray.Length - 6, 2);
- guidArray[10] = daysArray[1];
- guidArray[11] = daysArray[0];
-
- //Array.Copy(msecsArray, msecsArray.Length - 4, guidArray, guidArray.Length - 4, 4);
- msecsArray[^4..].CopyTo(guidArray[^4..]);
- return new Guid(guidArray);
+ guid.TryWriteBytes(guidArray);
#else
-
- byte[] guidArray = guid.ToByteArray();
-
+ var guidArray = guid.ToByteArray();
+#endif
// Get the days and milliseconds which will be used to build the byte string
- TimeSpan days = new TimeSpan(utcNow.Ticks - BaseDateTicks);
- TimeSpan msecs = utcNow.TimeOfDay;
-
- // Convert to a byte array
+ var ts = new TimeSpan(utcNow.Ticks - BaseDateTicks);
+ var days = ts.Days;
+ guidArray[10] = (byte) (days >> 8);
+ guidArray[11] = (byte) days;
+
// Note that SQL Server is accurate to 1/300th of a millisecond so we divide by 3.333333
- byte[] daysArray = BitConverter.GetBytes(days.Days);
- byte[] msecsArray = BitConverter.GetBytes((long) (msecs.TotalMilliseconds / 3.333333));
-
- // Reverse the bytes to match SQL Servers ordering
- Array.Reverse(daysArray);
- Array.Reverse(msecsArray);
-
- // Copy the bytes into the guid
- Array.Copy(daysArray, daysArray.Length - 2, guidArray, guidArray.Length - 6, 2);
- Array.Copy(msecsArray, msecsArray.Length - 4, guidArray, guidArray.Length - 4, 4);
+ var msecs = (long) (utcNow.TimeOfDay.TotalMilliseconds / 3.333333);
+ guidArray[12] = (byte) (msecs >> 24);
+ guidArray[13] = (byte) (msecs >> 16);
+ guidArray[14] = (byte) (msecs >> 8);
+ guidArray[15] = (byte) msecs;
return new Guid(guidArray);
-#endif
}
#endregion