_gchandle string intern

Source/Engine/Engine/NativeInterop.Managed.cs

@@ -139,7 +139,7 @@ namespace FlaxEngine.Interop
 
         private ManagedArray(IntPtr ptr, int length, Type arrayType, Type elementType)
         {
-            Assert.IsTrue(arrayType.IsArray);
+            //Assert.IsTrue(arrayType.IsArray);
             _elementType = elementType;
             _elementSize = NativeInterop.GetTypeSize(elementType);
             _unmanagedData = ptr;
@@ -313,7 +313,7 @@ namespace FlaxEngine.Interop
                 return IntPtr.Zero;
             else if (str == string.Empty)
                 return ManagedHandle.ToIntPtr(EmptyStringHandle);
-            Assert.IsTrue(str.Length > 0);
+            //Assert.IsTrue(str.Length > 0);
             return ManagedHandle.ToIntPtr(str);
         }
 
@@ -324,7 +324,7 @@ namespace FlaxEngine.Interop
                 return IntPtr.Zero;
             else if (str == string.Empty)
                 return ManagedHandle.ToIntPtr(EmptyStringHandle);
-            Assert.IsTrue(str.Length > 0);
+            //Assert.IsTrue(str.Length > 0);
             return ManagedHandle.ToIntPtr(str, GCHandleType.Weak);
         }
 
@@ -336,6 +336,25 @@ namespace FlaxEngine.Interop
             return Unsafe.As<string>(ManagedHandle.FromIntPtr(ptr).Target);
         }
 
+        internal static Dictionary<string, ManagedHandle> strHandles = new(512);
+
+        //[System.Diagnostics.DebuggerStepThrough]
+        public static unsafe IntPtr ToNativeIntern(string str)
+        {
+            if (str == null)
+                return IntPtr.Zero;
+            else if (string.IsInterned(str) == null && str.Length > 128)
+                return ManagedHandle.ToIntPtr(str, GCHandleType.Weak);
+
+            // Allocate normal handle for interned strings as those should never change
+            if (!strHandles.TryGetValue(str, out ManagedHandle handle))
+            {
+                handle = ManagedHandle.Alloc(str, GCHandleType.Normal);
+                strHandles.Add(str, handle);
+            }
+            return ((IntPtr)handle);
+        }
+
         [System.Diagnostics.DebuggerStepThrough]
         public static void Free(IntPtr ptr)
         {

Source/Engine/Engine/NativeInterop.Marshallers.cs

@@ -613,7 +613,12 @@ namespace FlaxEngine.Interop
         public static class ManagedToNative
         {
             public static string ConvertToManaged(IntPtr unmanaged) => ManagedString.ToManaged(unmanaged);
+#if true
+            // TODO: interned string pool
+            public static unsafe IntPtr ConvertToUnmanaged(string managed) => ManagedString.ToNativeIntern(managed);
+#else
             public static unsafe IntPtr ConvertToUnmanaged(string managed) => managed == null ? IntPtr.Zero : ManagedHandle.ToIntPtr(managed, GCHandleType.Weak);
+#endif
             public static void Free(IntPtr unmanaged)
             {
                 //ManagedString.Free(unmanaged); // No need to free weak handles