C# guid optimizations with stackalloc and Span<byte>

Author: chronoxor

projects/CSharp/Proto/com.chronoxor.fbe.cs

@@ -76,17 +76,20 @@ public static Guid Sequential()
             }
 
             long ticks = (now - GregorianEpoch).Ticks;
-            byte[] guid = new byte[16];
+            Span<byte> guid = stackalloc byte[16];
             byte[] timestamp = BitConverter.GetBytes(ticks);
 
             // Copy node
-            Array.Copy(NodeBytes, 0, guid, 10, Math.Min(6, NodeBytes.Length));
+            for (int i = 0; i < Math.Min(6, NodeBytes.Length); i++)
+                guid[10 + i] = NodeBytes[i];
 
             // Copy clock sequence
-            Array.Copy(ClockSequenceBytes, 0, guid, 8, Math.Min(2, ClockSequenceBytes.Length));
+            for (int i = 0; i < Math.Min(2, ClockSequenceBytes.Length); i++)
+                guid[8 + i] = ClockSequenceBytes[i];
 
             // Copy timestamp
-            Array.Copy(timestamp, 0, guid, 0, Math.Min(8, timestamp.Length));
+            for (int i = 0; i < Math.Min(8, timestamp.Length); i++)
+                guid[i] = timestamp[i];
 
             // Set the variant
             guid[8] &= 0x3F;

projects/CSharp/Tests/Tests.csproj

@@ -5,7 +5,7 @@
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.2.0" />
-    <PackageReference Include="xunit" Version="2.4.1" />
+    <PackageReference Include="xunit" Version="2.4.2" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.5">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>

source/generator_csharp.cpp

@@ -133,17 +133,20 @@ void GeneratorCSharp::GenerateFBEUuidGenerator()
             }
 
             long ticks = (now - GregorianEpoch).Ticks;
-            byte[] guid = new byte[16];
+            Span<byte> guid = stackalloc byte[16];
             byte[] timestamp = BitConverter.GetBytes(ticks);
 
             // Copy node
-            Array.Copy(NodeBytes, 0, guid, 10, Math.Min(6, NodeBytes.Length));
+            for (int i = 0; i < Math.Min(6, NodeBytes.Length); i++)
+                guid[10 + i] = NodeBytes[i];
 
             // Copy clock sequence
-            Array.Copy(ClockSequenceBytes, 0, guid, 8, Math.Min(2, ClockSequenceBytes.Length));
+            for (int i = 0; i < Math.Min(2, ClockSequenceBytes.Length); i++)
+                guid[8 + i] = ClockSequenceBytes[i];
 
             // Copy timestamp
-            Array.Copy(timestamp, 0, guid, 0, Math.Min(8, timestamp.Length));
+            for (int i = 0; i < Math.Min(8, timestamp.Length); i++)
+                guid[i] = timestamp[i];
 
             // Set the variant
             guid[8] &= 0x3F;