Clean up managed dependencies for Mono's domain/loader context (#46323)

Co-authored-by: Aleksey Kliger (λgeek) <akliger@gmail.com>

src/libraries/System.Private.CoreLib/src/System/Runtime/Loader/AssemblyLoadContext.cs

@@ -39,10 +39,14 @@ private enum InternalState
             s_allContexts;
 
 #region private data members
-        // If you modify any of these fields, you must also update the
+        // If you modify this field, you must also update the
         // AssemblyLoadContextBaseObject structure in object.h
         // and MonoManagedAssemblyLoadContext in object-internals.h
 
+        // Contains the reference to VM's representation of the AssemblyLoadContext
+        private readonly IntPtr _nativeAssemblyLoadContext;
+#endregion
+
         // synchronization primitive to protect against usage of this instance while unloading
         private readonly object _unloadLock;
 
@@ -54,17 +58,13 @@ private enum InternalState
 
         private readonly string? _name;
 
-        // Contains the reference to VM's representation of the AssemblyLoadContext
-        private readonly IntPtr _nativeAssemblyLoadContext;
-
         // Id used by s_allContexts
         private readonly long _id;
 
         // Indicates the state of this ALC (Alive or in Unloading state)
         private InternalState _state;
 
         private readonly bool _isCollectible;
-#endregion
 
         protected AssemblyLoadContext() : this(false, false, null)
         {
@@ -180,6 +180,9 @@ public IEnumerable<Assembly> Assemblies
         // Returns: A handle to the loaded native library
         public event Func<Assembly, string, IntPtr>? ResolvingUnmanagedDll
         {
+#if MONO
+            [DynamicDependency(nameof(MonoResolveUnmanagedDllUsingEvent))]
+#endif
             add
             {
                 _resolvingUnmanagedDll += value;
@@ -198,6 +201,9 @@ public event Func<Assembly, string, IntPtr>? ResolvingUnmanagedDll
         // Returns: The Loaded assembly object.
         public event Func<AssemblyLoadContext, AssemblyName, Assembly?>? Resolving
         {
+#if MONO
+            [DynamicDependency(nameof(MonoResolveUsingResolvingEvent))]
+#endif
             add
             {
                 _resolving += value;
@@ -222,16 +228,28 @@ public event Action<AssemblyLoadContext>? Unloading
 
 #region AppDomainEvents
         // Occurs when an Assembly is loaded
+#if MONO
+        [method: DynamicDependency(nameof(OnAssemblyLoad))]
+#endif
         internal static event AssemblyLoadEventHandler? AssemblyLoad;
 
         // Occurs when resolution of type fails
+#if MONO
+        [method: DynamicDependency(nameof(OnTypeResolve))]
+#endif
         internal static event ResolveEventHandler? TypeResolve;
 
         // Occurs when resolution of resource fails
+#if MONO
+        [method: DynamicDependency(nameof(OnResourceResolve))]
+#endif
         internal static event ResolveEventHandler? ResourceResolve;
 
         // Occurs when resolution of assembly fails
         // This event is fired after resolve events of AssemblyLoadContext fails
+#if MONO
+        [method: DynamicDependency(nameof(OnAssemblyResolve))]
+#endif
         internal static event ResolveEventHandler? AssemblyResolve;
 #endregion
 

src/mono/mono/metadata/appdomain.c

@@ -142,12 +142,15 @@ add_assembly_to_alc (MonoAssemblyLoadContext *alc, MonoAssembly *ass);
 
 #endif
 
+#ifndef ENABLE_NETCORE
+
 static MonoAppDomainHandle
 mono_domain_create_appdomain_internal (char *friendly_name, MonoAppDomainSetupHandle setup, MonoError *error);
 
 static MonoDomain *
 mono_domain_create_appdomain_checked (char *friendly_name, char *configuration_file, MonoError *error);
 
+#endif
 
 static void
 mono_context_set_default_context (MonoDomain *domain);
@@ -596,6 +599,8 @@ mono_runtime_quit_internal (void)
 		quit_function (mono_get_root_domain (), NULL);
 }
 
+#ifndef ENABLE_NETCORE
+
 /**
  * mono_domain_create_appdomain:
  * \param friendly_name The friendly name of the appdomain to create
@@ -651,6 +656,8 @@ mono_domain_create_appdomain_checked (char *friendly_name, char *configuration_f
 	HANDLE_FUNCTION_RETURN_VAL (result);
 }
 
+#endif
+
 /**
  * mono_domain_set_config:
  * \param domain \c MonoDomain initialized with the appdomain we want to change
@@ -913,13 +920,21 @@ mono_domain_try_type_resolve_name (MonoDomain *domain, MonoAssembly *assembly, M
 
 	MONO_STATIC_POINTER_INIT (MonoMethod, method)
 
-		MonoClass *alc_class = mono_class_get_assembly_load_context_class ();
-		g_assert (alc_class);
-		method = mono_class_get_method_from_name_checked (alc_class, "OnTypeResolve", -1, 0, error);
+		static gboolean inited;
+		// avoid repeatedly calling mono_class_get_method_from_name_checked
+		if (!inited) {
+			ERROR_DECL (local_error);
+			MonoClass *alc_class = mono_class_get_assembly_load_context_class ();
+			g_assert (alc_class);
+			method = mono_class_get_method_from_name_checked (alc_class, "OnTypeResolve", -1, 0, local_error);
+			mono_error_cleanup (local_error);
+			inited = TRUE;
+		}
 
 	MONO_STATIC_POINTER_INIT_END (MonoMethod, method)
 
-	goto_if_nok (error, return_null);
+	if (!method)
+		goto return_null;
 
 	g_assert (domain);
 	g_assert (MONO_HANDLE_BOOL (name));
@@ -1489,14 +1504,21 @@ mono_try_assembly_resolve_handle (MonoAssemblyLoadContext *alc, MonoStringHandle
 	MONO_STATIC_POINTER_INIT (MonoMethod, method)
 
 		ERROR_DECL (local_error);
-		MonoClass *alc_class = mono_class_get_assembly_load_context_class ();
-		g_assert (alc_class);
-		method = mono_class_get_method_from_name_checked (alc_class, "OnAssemblyResolve", -1, 0, local_error);
-		mono_error_assert_ok (local_error);
+		static gboolean inited;
+		if (!inited) {
+			MonoClass *alc_class = mono_class_get_assembly_load_context_class ();
+			g_assert (alc_class);
+			method = mono_class_get_method_from_name_checked (alc_class, "OnAssemblyResolve", -1, 0, local_error);
+			inited = TRUE;
+		}
+		mono_error_cleanup (local_error);
 
 	MONO_STATIC_POINTER_INIT_END (MonoMethod, method)
 
-	g_assert (method);
+	if (!method) {
+		ret = NULL;
+		goto leave;
+	}
 
 	MonoReflectionAssemblyHandle requesting_handle;
 	if (requesting) {
@@ -1626,12 +1648,19 @@ mono_domain_fire_assembly_load_event (MonoDomain *domain, MonoAssembly *assembly
 #ifdef ENABLE_NETCORE
 	MONO_STATIC_POINTER_INIT (MonoMethod, method)
 
-		MonoClass *alc_class = mono_class_get_assembly_load_context_class ();
-		g_assert (alc_class);
-		method = mono_class_get_method_from_name_checked (alc_class, "OnAssemblyLoad", -1, 0, error);
+		static gboolean inited;
+		if (!inited) {
+			ERROR_DECL (local_error);
+			MonoClass *alc_class = mono_class_get_assembly_load_context_class ();
+			g_assert (alc_class);
+			method = mono_class_get_method_from_name_checked (alc_class, "OnAssemblyLoad", -1, 0, local_error);
+			mono_error_cleanup (local_error);
+			inited = TRUE;
+		}
 
 	MONO_STATIC_POINTER_INIT_END (MonoMethod, method)
-	goto_if_nok (error, exit);
+	if (!method)
+		goto exit;
 
 	MonoReflectionAssemblyHandle assembly_handle;
 	assembly_handle = mono_assembly_get_object_handle (domain, assembly, error);
@@ -3524,4 +3553,3 @@ mono_runtime_install_appctx_properties (void)
 }
 
 #endif
-

src/mono/mono/metadata/assembly-load-context.c

@@ -346,14 +346,19 @@ mono_alc_invoke_resolve_using_resolving_event (MonoAssemblyLoadContext *alc, Mon
 	MONO_STATIC_POINTER_INIT (MonoMethod, resolve)
 
 		ERROR_DECL (local_error);
-		MonoClass *alc_class = mono_class_get_assembly_load_context_class ();
-		g_assert (alc_class);
-		resolve = mono_class_get_method_from_name_checked (alc_class, "MonoResolveUsingResolvingEvent", -1, 0, local_error);
-		mono_error_assert_ok (local_error);
+		static gboolean inited;
+		if (!inited) {
+			MonoClass *alc_class = mono_class_get_assembly_load_context_class ();
+			g_assert (alc_class);
+			resolve = mono_class_get_method_from_name_checked (alc_class, "MonoResolveUsingResolvingEvent", -1, 0, local_error);
+			inited = TRUE;
+		}
+		mono_error_cleanup (local_error);
 
 	MONO_STATIC_POINTER_INIT_END (MonoMethod, resolve)
 
-	g_assert (resolve);
+	if (!resolve)
+		return NULL;
 
 	return invoke_resolve_method (resolve, alc, aname, error);
 }

src/mono/mono/metadata/class-internals.h

@@ -1003,7 +1003,9 @@ typedef struct {
 	MonoClass *iremotingtypeinfo_class;
 #endif
 	MonoClass *mono_method_message_class;
+#ifndef ENABLE_NETCORE
 	MonoClass *appdomain_class;
+#endif
 	MonoClass *field_info_class;
 	MonoClass *method_info_class;
 	MonoClass *stack_frame_class;

src/mono/mono/metadata/domain.c

@@ -735,9 +735,7 @@ mono_init_internal (const char *filename, const char *exe_filename, const char *
                 mono_defaults.corlib, "System.Threading", "ThreadAbortException");
 #endif
 
-#ifdef ENABLE_NETCORE
-	mono_defaults.appdomain_class = mono_defaults.object_class;
-#else
+#ifndef ENABLE_NETCORE
 	mono_defaults.appdomain_class = mono_class_get_appdomain_class ();
 #endif
 

src/mono/mono/metadata/icall.c

@@ -5566,13 +5566,20 @@ try_resource_resolve_name (MonoReflectionAssemblyHandle assembly_handle, MonoStr
 
 	MONO_STATIC_POINTER_INIT (MonoMethod, resolve_method)
 
-		MonoClass *alc_class = mono_class_get_assembly_load_context_class ();
-		g_assert (alc_class);
-		resolve_method = mono_class_get_method_from_name_checked (alc_class, "OnResourceResolve", -1, 0, error);
+		static gboolean inited;
+		if (!inited) {
+			MonoClass *alc_class = mono_class_get_assembly_load_context_class ();
+			g_assert (alc_class);
+			resolve_method = mono_class_get_method_from_name_checked (alc_class, "OnResourceResolve", -1, 0, error);
+			inited = TRUE;
+		}
+		mono_error_cleanup (error);
+		error_init_reuse (error);
 
 	MONO_STATIC_POINTER_INIT_END (MonoMethod, resolve_method)
 
-	goto_if_nok (error, return_null);
+	if (!resolve_method)
+		goto return_null;
 
 	gpointer args [2];
 	args [0] = MONO_HANDLE_RAW (assembly_handle);

src/mono/mono/metadata/native-library.c

@@ -568,13 +568,19 @@ netcore_resolve_with_dll_import_resolver (MonoAssemblyLoadContext *alc, MonoAsse
 	MONO_STATIC_POINTER_INIT (MonoMethod, resolve)
 
 		ERROR_DECL (local_error);
-		MonoClass *native_lib_class = mono_class_get_native_library_class ();
-		g_assert (native_lib_class);
-		resolve = mono_class_get_method_from_name_checked (native_lib_class, "MonoLoadLibraryCallbackStub", -1, 0, local_error);
-		mono_error_assert_ok (local_error);
+		static gboolean inited;
+		if (!inited) {
+			MonoClass *native_lib_class = mono_class_get_native_library_class ();
+			g_assert (native_lib_class);
+			resolve = mono_class_get_method_from_name_checked (native_lib_class, "MonoLoadLibraryCallbackStub", -1, 0, local_error);
+			inited = TRUE;
+		}
+		mono_error_cleanup (local_error);
 
 	MONO_STATIC_POINTER_INIT_END (MonoMethod, resolve)
-	g_assert (resolve);
+
+	if (!resolve)
+		return NULL;
 
 	if (mono_runtime_get_no_exec ())
 		return NULL;

src/mono/mono/metadata/object-internals.h

@@ -1660,15 +1660,7 @@ typedef enum {
 // Keep in sync with System.Runtime.Loader.AssemblyLoadContext
 typedef struct {
 	MonoObject object;
-	MonoObject *unload_lock;
-	MonoEvent *resolving_unmaned_dll;
-	MonoEvent *resolving;
-	MonoEvent *unloading;
-	MonoString *name;
 	MonoAssemblyLoadContext *native_assembly_load_context;
-	gint64 id;
-	gint32 internal_state;
-	MonoBoolean is_collectible;
 } MonoManagedAssemblyLoadContext;
 
 TYPED_HANDLE_DECL (MonoManagedAssemblyLoadContext);

src/mono/mono/metadata/object.c

@@ -5080,11 +5080,17 @@ mono_first_chance_exception_checked (MonoObjectHandle exc, MonoError *error)
 
 	MONO_STATIC_POINTER_INIT (MonoClassField, field)
 
-		field = mono_class_get_field_from_name_full (mono_defaults.appcontext_class, "FirstChanceException", NULL);
-		g_assert (field);
+		static gboolean inited;
+		if (!inited) {
+			field = mono_class_get_field_from_name_full (mono_defaults.appcontext_class, "FirstChanceException", NULL);
+			inited = TRUE;
+		}
 
 	MONO_STATIC_POINTER_INIT_END (MonoClassField, field)
 
+	if (!field)
+		return;
+
 	MonoVTable *vt = mono_class_vtable_checked (domain, mono_defaults.appcontext_class, error);
 	return_if_nok (error);
 
@@ -5141,13 +5147,18 @@ mono_unhandled_exception_checked (MonoObjectHandle exc, MonoError *error)
 #ifndef ENABLE_NETCORE
 		field = mono_class_get_field_from_name_full (mono_defaults.appdomain_class, "UnhandledException", NULL);
 #else
-		field = mono_class_get_field_from_name_full (mono_defaults.appcontext_class, "UnhandledException", NULL);
+		static gboolean inited;
+		if (!inited) {
+			field = mono_class_get_field_from_name_full (mono_defaults.appcontext_class, "UnhandledException", NULL);
+			inited = TRUE;
+		}
 #endif
-		g_assert (field);
 
 	MONO_STATIC_POINTER_INIT_END (MonoClassField, field)
 
 #ifndef ENABLE_NETCORE
+	g_assert (field);
+
 	MonoDomain *root_domain;
 	MonoObjectHandle current_appdomain_delegate = MONO_HANDLE_NEW (MonoObject, NULL);
 
@@ -5172,6 +5183,9 @@ mono_unhandled_exception_checked (MonoObjectHandle exc, MonoError *error)
 		mono_threads_end_abort_protected_block ();
 	}
 #else
+	if (!field)
+		goto leave;
+
 	MonoObject *delegate = NULL;
 	MonoObjectHandle delegate_handle;
 	MonoVTable *vt = mono_class_vtable_checked (current_domain, mono_defaults.appcontext_class, error);

src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.Descriptors.xml

@@ -9,25 +9,13 @@
 
 		<!-- assembly-load-context.c: -->
 		<!-- object-internals.h: MonoManagedAssemblyLoadContext -->
-		<type fullname="System.Runtime.Loader.AssemblyLoadContext" preserve="fields">
+		<type fullname="System.Runtime.Loader.AssemblyLoadContext">
 			<!-- assembly-load-context.c: mono_alc_invoke_resolve_using_load -->
 			<method name="MonoResolveUsingLoad" />
-			<!-- assembly-load-context.c: mono_alc_invoke_resolve_using_resolving_event -->
-			<method name="MonoResolveUsingResolvingEvent" />
 			<!-- assembly-load-context.c: mono_alc_invoke_resolve_using_resolve_satellite -->
 			<method name="MonoResolveUsingResolveSatelliteAssembly" />
 			<!-- native-library.c: netcore_resolve_with_load () -->
 			<method name="MonoResolveUnmanagedDll" />
-			<!-- native-library.c: netcore_resolve_with_resolving_event () -->
-			<method name="MonoResolveUnmanagedDllUsingEvent" />
-			<!-- appdomain.c: mono_domain_fire_assembly_load_event -->
-			<method name="OnAssemblyLoad" />
-			<!-- appdomain.c: mono_try_assembly_resolve_handle () -->
-			<method name="OnAssemblyResolve" />
-			<!-- appdomain.c: mono_domain_try_type_resolve_name -->
-			<method name="OnTypeResolve" />
-			<!-- icall.c: try_resource_resolve_name -->
-			<method name="OnResourceResolve" />
 		</type>
 
 		<!-- exception.c (mono_get_exception_argument) -->
@@ -643,10 +631,6 @@
 			<method name="OnProcessExit"/>
 			<!-- appdomain.c: get_app_context_base_directory -->
 			<method name="get_BaseDirectory"/>
-			<!-- object.c: mono_unhandled_exception_checked -->
-			<field name="UnhandledException"/>
-			<!-- object.c: mono_first_chance_exception_checked -->
-			<field name="FirstChanceException"/>
 		</type>
 
 		<!-- mono_method_has_unmanaged_callers_only_attribute () -->