[Fusion] Perfomance Optimizations

src/HotChocolate/Fusion/src/Fusion.Execution/Execution/ExecutionState.cs

@@ -152,7 +152,11 @@ public void Reset()
         ResetNodeStates();
         ResetRemainingDependencies();
 
-        _completedResults.Clear();
+        while (_completedResults.TryDequeue(out _))
+        {
+            // do nothing, just clear the queue
+        }
+
         ClearPendingMerges();
         _mergeFailures?.Clear();
         _activeNodes = 0;

src/HotChocolate/Fusion/src/Fusion.Execution/HotChocolate.Fusion.Execution.csproj

@@ -5,6 +5,7 @@
     <RootNamespace>HotChocolate.Fusion</RootNamespace>
     <LangVersion>preview</LangVersion>
     <DefineConstants>$(DefineConstants);FUSION</DefineConstants>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 
   <ItemGroup>

src/HotChocolate/Fusion/src/Fusion.Execution/Text/Json/CompositeResultDocument.MetaDb.cs

@@ -415,7 +415,7 @@ internal readonly DbRow Get(Cursor cursor)
         {
             AssertValidCursor(cursor);
 
-            return MemoryMarshal.Read<DbRow>(RowSpan(cursor));
+            return Unsafe.ReadUnaligned<DbRow>(ref RowRef(cursor));
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
@@ -437,16 +437,16 @@ internal readonly (Cursor, ElementTokenType) GetStartCursor(Cursor cursor)
         {
             AssertValidCursor(cursor);
 
-            var span = RowSpan(cursor);
-            var sourceAndType = MemoryMarshal.Read<int>(span[DbRow.SourceAndTypeOffset..]);
+            ref var row = ref RowRef(cursor);
+            var sourceAndType = Unsafe.ReadUnaligned<int>(ref Unsafe.Add(ref row, DbRow.SourceAndTypeOffset));
             var tokenType = (ElementTokenType)((sourceAndType >>> 15) & 0x0F);
 
             if (tokenType is ElementTokenType.Reference)
             {
-                var value = MemoryMarshal.Read<int>(span[DbRow.LocationOrRowsOffset..]) & 0x1FFFFFFF;
+                var value = Unsafe.ReadUnaligned<int>(ref Unsafe.Add(ref row, DbRow.LocationOrRowsOffset)) & 0x1FFFFFFF;
                 cursor = new Cursor(value);
-                span = RowSpan(cursor);
-                sourceAndType = MemoryMarshal.Read<int>(span[DbRow.SourceAndTypeOffset..]);
+                row = ref RowRef(cursor);
+                sourceAndType = Unsafe.ReadUnaligned<int>(ref Unsafe.Add(ref row, DbRow.SourceAndTypeOffset));
                 tokenType = (ElementTokenType)((sourceAndType >>> 15) & 0x0F);
             }
 
@@ -458,7 +458,7 @@ internal readonly int GetLocation(Cursor cursor)
         {
             AssertValidCursor(cursor);
 
-            var locationOrRows = MemoryMarshal.Read<int>(RowSpan(cursor)[DbRow.LocationOrRowsOffset..]);
+            var locationOrRows = Unsafe.ReadUnaligned<int>(ref Unsafe.Add(ref RowRef(cursor), DbRow.LocationOrRowsOffset));
             return locationOrRows & 0x1FFFFFFF;
         }
 
@@ -467,7 +467,7 @@ internal readonly Cursor GetLocationCursor(Cursor cursor)
         {
             AssertValidCursor(cursor);
 
-            var locationOrRows = MemoryMarshal.Read<int>(RowSpan(cursor)[DbRow.LocationOrRowsOffset..]);
+            var locationOrRows = Unsafe.ReadUnaligned<int>(ref Unsafe.Add(ref RowRef(cursor), DbRow.LocationOrRowsOffset));
             return new Cursor(locationOrRows & 0x1FFFFFFF);
         }
 
@@ -476,7 +476,7 @@ internal readonly int GetParent(Cursor cursor)
         {
             AssertValidCursor(cursor);
 
-            var parent = MemoryMarshal.Read<int>(RowSpan(cursor));
+            var parent = Unsafe.ReadUnaligned<int>(ref RowRef(cursor));
             return parent & 0x1FFFFFFF;
         }
 
@@ -485,7 +485,7 @@ internal readonly Cursor GetParentCursor(Cursor cursor)
         {
             AssertValidCursor(cursor);
 
-            var parent = MemoryMarshal.Read<int>(RowSpan(cursor)) & 0x1FFFFFFF;
+            var parent = Unsafe.ReadUnaligned<int>(ref RowRef(cursor)) & 0x1FFFFFFF;
 
             return new Cursor(parent);
         }
@@ -496,7 +496,7 @@ internal readonly int GetNumberOfRows(Cursor cursor)
             AssertValidCursor(cursor);
 
             // NumberOfRows shares storage with Location in int 3.
-            var value = MemoryMarshal.Read<int>(RowSpan(cursor)[DbRow.LocationOrRowsOffset..]);
+            var value = Unsafe.ReadUnaligned<int>(ref Unsafe.Add(ref RowRef(cursor), DbRow.LocationOrRowsOffset));
             return value & 0x1FFFFFFF;
         }
 
@@ -505,7 +505,7 @@ internal readonly ElementFlags GetFlags(Cursor cursor)
         {
             AssertValidCursor(cursor);
 
-            var selectionAndFlags = MemoryMarshal.Read<int>(RowSpan(cursor)[DbRow.SelectionAndFlagsOffset..]);
+            var selectionAndFlags = Unsafe.ReadUnaligned<int>(ref Unsafe.Add(ref RowRef(cursor), DbRow.SelectionAndFlagsOffset));
             return (ElementFlags)((selectionAndFlags >> 17) & 0x7F);
         }
 
@@ -530,7 +530,7 @@ internal readonly int GetSizeOrLength(Cursor cursor)
         {
             AssertValidCursor(cursor);
 
-            var value = MemoryMarshal.Read<int>(RowSpan(cursor)[DbRow.SizeOffset..]);
+            var value = Unsafe.ReadUnaligned<int>(ref Unsafe.Add(ref RowRef(cursor), DbRow.SizeOffset));
 
             return value & int.MaxValue;
         }
@@ -573,20 +573,31 @@ internal readonly ElementTokenType GetElementTokenType(Cursor cursor, bool resol
         {
             AssertValidCursor(cursor);
 
-            var sourceAndType = MemoryMarshal.Read<int>(RowSpan(cursor)[DbRow.SourceAndTypeOffset..]);
+            var sourceAndType = Unsafe.ReadUnaligned<int>(ref Unsafe.Add(ref RowRef(cursor), DbRow.SourceAndTypeOffset));
             var tokenType = (ElementTokenType)((sourceAndType >>> 15) & 0x0F);
 
             if (resolveReferences && tokenType == ElementTokenType.Reference)
             {
                 var value = GetLocation(cursor);
                 var resolved = new Cursor(value);
-                sourceAndType = MemoryMarshal.Read<int>(RowSpan(resolved)[DbRow.SourceAndTypeOffset..]);
+                sourceAndType = Unsafe.ReadUnaligned<int>(ref Unsafe.Add(ref RowRef(resolved), DbRow.SourceAndTypeOffset));
                 tokenType = (ElementTokenType)((sourceAndType >>> 15) & 0x0F);
             }
 
             return tokenType;
         }
 
+        /// <summary>
+        /// Returns a reference to the first byte of the row the cursor points to.
+        /// </summary>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private readonly ref byte RowRef(Cursor cursor)
+        {
+            var chunk = _chunks[cursor.Chunk];
+            ref var data = ref MemoryMarshal.GetArrayDataReference(chunk.Buffer);
+            return ref Unsafe.Add(ref data, chunk.Offset + cursor.ByteOffset);
+        }
+
         /// <summary>
         /// Returns the span that begins at the start of the row the cursor points to.
         /// </summary>

src/HotChocolate/Fusion/src/Fusion.Execution/Text/Json/CompositeResultDocument.cs

@@ -132,6 +132,7 @@ internal int GetPropertyCount(Cursor current)
         return row.SizeOrLength;
     }
 
+    [SkipLocalsInit]
     internal CompactPath CreateCompactPath(Cursor current)
     {
         var firstRow = _metaDb.Get(current);