feat: MemoryPackSerializer.ResetState, ResetReaderState, ResetWriterState

src/MemoryPack.Core/MemoryPackSerializer.StateBackup.cs

@@ -0,0 +1,64 @@
+using System.Runtime.CompilerServices;
+
+namespace MemoryPack;
+
+public static partial class MemoryPackSerializer
+{
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static StateSnapshot ResetState(bool resetReaderState = true, bool resetWriterState = true)
+        => new(resetReaderState, resetWriterState);
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static StateSnapshot ResetReaderState()
+        => new(true, false);
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static StateSnapshot ResetWriterState()
+        => new(false, true);
+
+    // Nested types
+
+    public readonly struct StateSnapshot : IDisposable
+    {
+        readonly bool _resetReaderState;
+        readonly bool _resetWriterState;
+        readonly SerializerWriterThreadStaticState? _threadStaticState;
+        readonly MemoryPackWriterOptionalState? _threadStaticWriterOptionalState;
+        readonly MemoryPackReaderOptionalState? _threadStaticReaderOptionalState;
+
+        internal StateSnapshot(bool resetReaderState, bool resetWriterState)
+        {
+            _resetReaderState = resetReaderState;
+            _resetWriterState = resetWriterState;
+
+            if (resetReaderState)
+            {
+                _threadStaticReaderOptionalState = threadStaticReaderOptionalState;
+                threadStaticReaderOptionalState = null;
+
+            }
+
+            if (resetWriterState)
+            {
+                _threadStaticState = threadStaticState;
+                threadStaticState = null;
+                _threadStaticWriterOptionalState = threadStaticWriterOptionalState;
+                threadStaticWriterOptionalState = null;
+            }
+        }
+
+        public void Dispose()
+        {
+            if (_resetReaderState)
+            {
+                threadStaticReaderOptionalState = _threadStaticReaderOptionalState;
+            }
+
+            if (_resetWriterState)
+            {
+                threadStaticState = _threadStaticState;
+                threadStaticWriterOptionalState = _threadStaticWriterOptionalState;
+            }
+        }
+    }
+}