Save memory allocations when reading Guid or BitString

Author: Giorgi

DuckDB.NET.Data/Data.csproj

@@ -22,6 +22,7 @@ Added support for writing to List and Array columns when using managed Appender.
   </ItemGroup>
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
     <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="6.0.0" />
+    <PackageReference Include="System.Memory" Version="4.5.5" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\DuckDB.NET.Bindings\Bindings.csproj" />

DuckDB.NET.Data/Extensions/GuidConverter.cs

@@ -6,56 +6,59 @@ namespace DuckDB.NET.Data.Extensions;
 
 internal static class GuidConverter
 {
+    private const string GuidFormat = "D";
     private static readonly char[] HexDigits = "0123456789abcdef".ToCharArray();
 
     //Ported from duckdb source code UUID::ToString
     //https://github.com/duckdb/duckdb/blob/9c91b3a329073ea1767b0aaff94b51da98dd03e2/src/common/types/uuid.cpp#L56
     public static Guid ConvertToGuid(this DuckDBHugeInt input)
     {
-        var buffer = new char[36];
-
-        var upper = input.Upper ^ (((long)1) << 63);
+        Span<char> buffer = stackalloc char[36];
+        var num = input.Upper ^ long.MinValue;
         var position = 0;
-
-        ByteToHex((ulong)(upper >> 56 & 0xFF));
-        ByteToHex((ulong)(upper >> 48 & 0xFF));
-        ByteToHex((ulong)(upper >> 40 & 0xFF));
-        ByteToHex((ulong)(upper >> 32 & 0xFF));
-
+        
+        ByteToHex(buffer, ref position, (ulong)((num >> 56) & 0xFF));
+        ByteToHex(buffer, ref position, (ulong)((num >> 48) & 0xFF));
+        ByteToHex(buffer, ref position, (ulong)((num >> 40) & 0xFF));
+        ByteToHex(buffer, ref position, (ulong)((num >> 32) & 0xFF));
+        
         buffer[position++] = '-';
-
-        ByteToHex((ulong)(upper >> 24 & 0xFF));
-        ByteToHex((ulong)(upper >> 16 & 0xFF));
-
+        
+        ByteToHex(buffer, ref position, (ulong)((num >> 24) & 0xFF));
+        ByteToHex(buffer, ref position, (ulong)((num >> 16) & 0xFF));
+        
         buffer[position++] = '-';
-
-        ByteToHex((ulong)(upper >> 8 & 0xFF));
-        ByteToHex((ulong)(upper & 0xFF));
-
+        
+        ByteToHex(buffer, ref position, (ulong)((num >> 8) & 0xFF));
+        ByteToHex(buffer, ref position, (ulong)(num & 0xFF));
+        
         buffer[position++] = '-';
-
-        ByteToHex(input.Lower >> 56 & 0xFF);
-        ByteToHex(input.Lower >> 48 & 0xFF);
-
+        
+        ByteToHex(buffer, ref position, (input.Lower >> 56) & 0xFF);
+        ByteToHex(buffer, ref position, (input.Lower >> 48) & 0xFF);
+        
         buffer[position++] = '-';
-
-        ByteToHex(input.Lower >> 40 & 0xFF);
-        ByteToHex(input.Lower >> 32 & 0xFF);
-        ByteToHex(input.Lower >> 24 & 0xFF);
-        ByteToHex(input.Lower >> 16 & 0xFF);
-        ByteToHex(input.Lower >> 8 & 0xFF);
-        ByteToHex(input.Lower & 0xFF);
-
-        return new Guid(new string(buffer));
-
-        void ByteToHex(ulong value)
+        
+        ByteToHex(buffer, ref position, (input.Lower >> 40) & 0xFF);
+        ByteToHex(buffer, ref position, (input.Lower >> 32) & 0xFF);
+        ByteToHex(buffer, ref position, (input.Lower >> 24) & 0xFF);
+        ByteToHex(buffer, ref position, (input.Lower >> 16) & 0xFF);
+        ByteToHex(buffer, ref position, (input.Lower >> 8) & 0xFF);
+        ByteToHex(buffer, ref position, input.Lower & 0xFF);
+
+#if NET6_0_OR_GREATER
+        return Guid.ParseExact(buffer, GuidFormat);
+#else
+        return Guid.ParseExact(new string(buffer.ToArray()), GuidFormat);
+#endif
+
+        static void ByteToHex(Span<char> buffer, ref int position, ulong value)
         {
-            buffer[position++] = HexDigits[(value >> 4) & 0xf];
-            buffer[position++] = HexDigits[value & 0xf];
+            buffer[position++] = HexDigits[(value >> 4) & 0xF];
+            buffer[position++] = HexDigits[value & 0xF];
         }
     }
 
-
     //https://github.com/duckdb/duckdb/blob/9c91b3a329073ea1767b0aaff94b51da98dd03e2/src/common/types/uuid.cpp#L6
     public static DuckDBHugeInt ToHugeInt(this Guid guid)
     {

DuckDB.NET.Data/Internal/Reader/StringVectorDataReader.cs

@@ -1,8 +1,8 @@
-using System;
+using DuckDB.NET.Native;
+using System;
 using System.Collections;
 using System.IO;
 using System.Text;
-using DuckDB.NET.Native;
 
 namespace DuckDB.NET.Data.Internal.Reader;
 
@@ -53,6 +53,15 @@ private string GetBitString(ulong offset)
     {
         var bitArray = GetBitStringAsBitArray(offset);
 
+#if NET6_0_OR_GREATER
+        return string.Create(bitArray.Length, bitArray, (chars, array) =>
+        {
+            for (int index = 0; index < array.Length; index++)
+            {
+                chars[index] = array[index] ? '1' : '0';
+            }
+        });
+#else
         var output = new char[bitArray.Length];
 
         for (var index = 0; index < bitArray.Count; index++)
@@ -61,6 +70,7 @@ private string GetBitString(ulong offset)
         }
 
         return new string(output);
+#endif
     }
 
     //Copied from https://github.com/duckdb/duckdb/blob/8a17511028d306561d88da9425f9e0e88dedd70c/src/common/types/bit.cpp#L63