GH-41349: [C#] Optimize DecimalUtility.GetBytes(SqlDecimal) on .NET 7+ (

#42150) ### What changes are included in this PR? Adds code to avoid an allocation when converting from SqlDecimal to Decimal128. Adds a .NET 8 target to Apache.Arrow.csproj to enable the optimization. Makes a small source change to build successfully with latest C# version. ### Are these changes tested? Yes. ### Are there any user-facing changes? No. Closes #41349 * GitHub Issue: #41349 Authored-by: Curt Hagenlocher <[email protected]> Signed-off-by: Curt Hagenlocher <[email protected]>
apache · Jun 14, 2024 · a7a46b2 · a7a46b2
1 parent 3333648
commit a7a46b2
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Showing 3 changed files with 9 additions and 6 deletions.
diff --git a/csharp/src/Apache.Arrow/Apache.Arrow.csproj b/csharp/src/Apache.Arrow/Apache.Arrow.csproj
@@ -8,10 +8,10 @@
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(IsWindows)'=='true'">
-    <TargetFrameworks>netstandard2.0;net6.0;net462</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;net6.0;net8.0;net462</TargetFrameworks>
   </PropertyGroup>
   <PropertyGroup Condition="'$(IsWindows)'!='true'">
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;net6.0;net8.0</TargetFrameworks>
   </PropertyGroup>
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETStandard' or '$(TargetFramework)' == 'net462'">

diff --git a/csharp/src/Apache.Arrow/DecimalUtility.cs b/csharp/src/Apache.Arrow/DecimalUtility.cs
@@ -431,9 +431,12 @@ internal static void GetBytes(SqlDecimal value, int precision, int scale, Span<b
                 value = SqlDecimal.ConvertToPrecScale(value, precision, scale);
             }
 
-            // TODO: Consider groveling in the internals to avoid the probable allocation
-            Span<int> span = bytes.CastTo<int>();
-            value.Data.AsSpan().CopyTo(span);
+#if NET7_0_OR_GREATER
+            value.WriteTdsValue(bytes.CastTo<uint>());
+#else
+            value.Data.AsSpan().CopyTo(bytes.CastTo<int>());
+#endif
+
             if (!value.IsPositive)
             {
                 Span<long> longSpan = bytes.CastTo<long>();

diff --git a/csharp/src/Apache.Arrow/Scalars/BinaryView.cs b/csharp/src/Apache.Arrow/Scalars/BinaryView.cs
@@ -83,7 +83,7 @@ private BinaryView(int length, int prefix, int bufferIndex, int offset)
         public bool IsInline => Length <= MaxInlineLength;
 
 #if NET5_0_OR_GREATER
-        public ReadOnlySpan<byte> Bytes => MemoryMarshal.CreateReadOnlySpan<byte>(ref Unsafe.AsRef(_inline[0]), IsInline ? Length : PrefixLength);
+        public ReadOnlySpan<byte> Bytes => MemoryMarshal.CreateReadOnlySpan<byte>(ref Unsafe.AsRef(in _inline[0]), IsInline ? Length : PrefixLength);
 #else
         public unsafe ReadOnlySpan<byte> Bytes => new ReadOnlySpan<byte>(Unsafe.AsPointer(ref _inline[0]), IsInline ? Length : PrefixLength);
 #endif