Merge branch 'alc_reload_fix' of https://github.com/GoaLitiuM/FlaxEngine into GoaLitiuM-alc_reload_fix

Source/Engine/Engine/NativeInterop.Unmanaged.cs

@@ -903,11 +903,25 @@ namespace FlaxEngine.Interop
 
             AssemblyLocations.Remove(assembly.FullName);
 
-            // Clear all caches which might hold references to closing assembly
+            // Unload native library handles associated for this assembly
+            string nativeLibraryName = assemblyOwnedNativeLibraries.GetValueOrDefault(assembly);
+            if (nativeLibraryName != null && loadedNativeLibraries.TryGetValue(nativeLibraryName, out IntPtr nativeLibrary))
+            {
+                NativeLibrary.Free(nativeLibrary);
+                loadedNativeLibraries.Remove(nativeLibraryName);
+            }
+            if (nativeLibraryName != null)
+                nativeLibraryPaths.Remove(nativeLibraryName);
+        }
+
+        [UnmanagedCallersOnly]
+        internal static void ReloadScriptingAssemblyLoadContext()
+        {
+#if FLAX_EDITOR
+            // Clear all caches which might hold references to assemblies in collectible ALC
             typeCache.Clear();
 
             // Release all references in collectible ALC
-#if FLAX_EDITOR
             cachedDelegatesCollectible.Clear();
             foreach (var pair in typeHandleCacheCollectible)
                 pair.Value.Free();
@@ -918,23 +932,13 @@ namespace FlaxEngine.Interop
             foreach (var handle in fieldHandleCacheCollectible)
                 handle.Free();
             fieldHandleCacheCollectible.Clear();
-#endif
+
             _typeSizeCache.Clear();
 
             foreach (var pair in classAttributesCacheCollectible)
                 pair.Value.Free();
             classAttributesCacheCollectible.Clear();
 
-            // Unload native library handles associated for this assembly
-            string nativeLibraryName = assemblyOwnedNativeLibraries.GetValueOrDefault(assembly);
-            if (nativeLibraryName != null && loadedNativeLibraries.TryGetValue(nativeLibraryName, out IntPtr nativeLibrary))
-            {
-                NativeLibrary.Free(nativeLibrary);
-                loadedNativeLibraries.Remove(nativeLibraryName);
-            }
-            if (nativeLibraryName != null)
-                nativeLibraryPaths.Remove(nativeLibraryName);
-
             // Unload the ALC
             bool unloading = true;
             scriptingAssemblyLoadContext.Unloading += (alc) => { unloading = false; };
@@ -945,6 +949,7 @@ namespace FlaxEngine.Interop
 
             InitScriptingAssemblyLoadContext();
             DelegateHelpers.InitMethods();
+#endif
         }
 
         [UnmanagedCallersOnly]

Source/Engine/Scripting/ManagedCLR/MCore.h

@@ -47,7 +47,7 @@ public:
 
 #if USE_EDITOR
     // Called by Scripting in a middle of hot-reload (after unloading modules but before loading them again).
-    static void OnMidHotReload();
+    static void ReloadScriptingAssemblyLoadContext();
 #endif
 
 public:

Source/Engine/Scripting/Runtime/DotNet.cpp

@@ -160,6 +160,7 @@ DECLARE_ENUM_OPERATORS(MTypeAttributes);
 DECLARE_ENUM_OPERATORS(MMethodAttributes);
 DECLARE_ENUM_OPERATORS(MFieldAttributes);
 
+// Multiple AppDomains are superseded by AssemblyLoadContext in .NET
 extern MDomain* MRootDomain;
 extern MDomain* MActiveDomain;
 extern Array<MDomain*, FixedAllocation<4>> MDomains;
@@ -301,11 +302,14 @@ void MCore::UnloadEngine()
 
 #if USE_EDITOR
 
-void MCore::OnMidHotReload()
+void MCore::ReloadScriptingAssemblyLoadContext()
 {
     // Clear any cached class attributes (see https://github.com/FlaxEngine/FlaxEngine/issues/1108)
     for (auto e : CachedClassHandles)
         e.Value->_attributes.Clear();
+
+    static void* ReloadScriptingAssemblyLoadContextPtr = GetStaticMethodPointer(TEXT("ReloadScriptingAssemblyLoadContext"));
+    CallStaticMethod<void>(ReloadScriptingAssemblyLoadContextPtr);
 }
 
 #endif
@@ -723,16 +727,12 @@ bool MAssembly::LoadImage(const String& assemblyPath, const StringView& nativePa
 
 bool MAssembly::UnloadImage(bool isReloading)
 {
-    if (_handle)
+    if (_handle && isReloading)
     {
-        // TODO: closing assembly on reload only is copy-paste from mono, do we need do this on .NET too?
-        if (isReloading)
-        {
-            LOG(Info, "Unloading managed assembly \'{0}\' (is reloading)", String(_name));
+        LOG(Info, "Unloading managed assembly \'{0}\' (is reloading)", String(_name));
 
-            static void* CloseAssemblyPtr = GetStaticMethodPointer(TEXT("CloseAssembly"));
-            CallStaticMethod<void, const void*>(CloseAssemblyPtr, _handle);
-        }
+        static void* CloseAssemblyPtr = GetStaticMethodPointer(TEXT("CloseAssembly"));
+        CallStaticMethod<void, const void*>(CloseAssemblyPtr, _handle);
 
         CachedAssemblyHandles.Remove(_handle);
         _handle = nullptr;

Source/Engine/Scripting/Runtime/Mono.cpp

@@ -716,7 +716,7 @@ void MCore::UnloadEngine()
 
 #if USE_EDITOR
 
-void MCore::OnMidHotReload()
+void MCore::ReloadScriptingAssemblyLoadContext()
 {
 }
 

Source/Engine/Scripting/Runtime/None.cpp

@@ -61,7 +61,7 @@ void MCore::UnloadEngine()
 
 #if USE_EDITOR
 
-void MCore::OnMidHotReload()
+void MCore::ReloadScriptingAssemblyLoadContext()
 {
 }
 

Source/Engine/Scripting/Scripting.cpp

@@ -706,7 +706,9 @@ void Scripting::Reload(bool canTriggerSceneReload)
     modules.Clear();
     _nonNativeModules.ClearDelete();
     _hasGameModulesLoaded = false;
-    MCore::OnMidHotReload();
+
+    // Release and create a new assembly load context for user assemblies
+    MCore::ReloadScriptingAssemblyLoadContext();
 
     // Give GC a try to cleanup old user objects and the other mess
     MCore::GC::Collect();