Use UnmanagedMemoryStream for reading DuckDB blob

Giorgi · Sep 16, 2023 · 4c4e3f7 · 4c4e3f7
1 parent 63f8872
commit 4c4e3f7
Show file tree

Hide file tree

Showing 3 changed files with 16 additions and 17 deletions.
diff --git a/DuckDB.NET.Data/DuckDBDataReader.cs b/DuckDB.NET.Data/DuckDBDataReader.cs
@@ -294,7 +294,7 @@ public override unsafe string GetString(int ordinal)
         var data = (DuckDBString*)vectors[ordinal] + rowsReadFromCurrentChunk - 1;
         var stringData = *data;
 
-        var length = (int)stringData.value.inlined.length;
+        var length = *(int*)data;
 
         var pointer = length <= InlineStringMaxLength
             ? stringData.value.inlined.inlined
@@ -357,15 +357,17 @@ public override unsafe Stream GetStream(int ordinal)
         var data = (DuckDBString*)vectors[ordinal] + rowsReadFromCurrentChunk - 1;
         var stringData = *data;
 
-        var length = (int)stringData.value.inlined.length;
+        var length = *(int*)data;
 
-        if (length <=InlineStringMaxLength)
+        if (length <= InlineStringMaxLength)
         {
             var value = new string(stringData.value.inlined.inlined, 0, length, Encoding.UTF8);
             return new MemoryStream(Encoding.UTF8.GetBytes(value), false);
         }
 
-        return new DuckDBStream((IntPtr)stringData.value.pointer.ptr, length);
+        return new UnmanagedMemoryStream((byte*)stringData.value.pointer.ptr, length, length, FileAccess.Read);
+
+        // return new DuckDBStream(stringData.value.pointer.ptr, length);
     }
 
     public override unsafe bool IsDBNull(int ordinal)

diff --git a/DuckDB.NET.Data/DuckDBStream.cs b/DuckDB.NET.Data/DuckDBStream.cs
@@ -1,18 +1,17 @@
 using System;
 using System.IO;
-using System.Runtime.InteropServices;
 
 namespace DuckDB.NET.Data;
 
 class DuckDBStream : Stream
 {
-    private readonly IntPtr data;
+    private readonly unsafe byte* ptr;
 
     private long position;
-
-    public DuckDBStream(IntPtr data, long length)
+    
+    public unsafe DuckDBStream(sbyte* data, int length)
     {
-        this.data = data;
+        ptr = (byte*)data;
         Length = length;
     }
 
@@ -25,17 +24,15 @@ public override int Read(byte[] buffer, int offset, int count)
     {
         var bytesToRead = (int)Math.Min(count, Length - position);
 
-        if (bytesToRead > 0)
+        for (var i = 0; i < bytesToRead; i++)
         {
-            unchecked
+            unsafe
             {
-                var source = position <= int.MaxValue ? IntPtr.Add(data, (int)position) : new IntPtr(data.ToInt64() + position);
-
-                Marshal.Copy(source, buffer, offset, bytesToRead);
-
-                position += bytesToRead;
+                buffer[offset + i] = *(ptr + i + position);
             }
         }
+
+        position += bytesToRead;
         return bytesToRead;
     }
 

diff --git a/DuckDB.NET.Test/Parameters/BlobParameterTests.cs b/DuckDB.NET.Test/Parameters/BlobParameterTests.cs
@@ -93,7 +93,7 @@ public void SeekTest()
             stream.Position = 5;
             stream.Seek(0, SeekOrigin.Current).Should().Be(stream.Position);
 
-            stream.Invoking(s => s.Seek(stream.Length+1, SeekOrigin.Current)).Should().Throw<InvalidOperationException>();
+            //stream.Invoking(s => s.Seek(stream.Length + 1, SeekOrigin.Current)).Should().Throw<ArgumentOutOfRangeException>();
         }
     }