implement NativeFinalizers in Realm

ffigen/config.yaml

@@ -18,8 +18,6 @@ compiler-opts:
   - '-DFFI_GEN'
   - '-I../src/realm-core/src'
   - '-I../src/dart-dl'
-typedef-map:
-  'size_t' : 'IntPtr'
 sort: true
 functions:
   exclude:

lib/src/native/realm_bindings.dart

@@ -1846,6 +1846,25 @@ class RealmLibrary {
           .asFunction<
               void Function(ffi.Pointer<realm_async_open_task_t>, int)>();
 
+  ffi.Pointer<ffi.Void> realm_attach_finalizer(
+    Object handle,
+    ffi.Pointer<ffi.Void> realmPtr,
+    int size,
+  ) {
+    return _realm_attach_finalizer(
+      handle,
+      realmPtr,
+      size,
+    );
+  }
+
+  late final _realm_attach_finalizerPtr = _lookup<
+      ffi.NativeFunction<
+          ffi.Pointer<ffi.Void> Function(ffi.Handle, ffi.Pointer<ffi.Void>,
+              ffi.Int)>>('realm_attach_finalizer');
+  late final _realm_attach_finalizer = _realm_attach_finalizerPtr.asFunction<
+      ffi.Pointer<ffi.Void> Function(Object, ffi.Pointer<ffi.Void>, int)>();
+
   int realm_auth_credentials_get_provider(
     ffi.Pointer<realm_app_credentials_t> arg0,
   ) {
@@ -3462,6 +3481,23 @@ class RealmLibrary {
   late final _realm_delete_files = _realm_delete_filesPtr.asFunction<
       bool Function(ffi.Pointer<ffi.Char>, ffi.Pointer<ffi.Bool>)>();
 
+  void realm_dettach_finalizer(
+    ffi.Pointer<ffi.Void> finalizableHandle,
+    Object handle,
+  ) {
+    return _realm_dettach_finalizer(
+      finalizableHandle,
+      handle,
+    );
+  }
+
+  late final _realm_dettach_finalizerPtr = _lookup<
+      ffi.NativeFunction<
+          ffi.Void Function(
+              ffi.Pointer<ffi.Void>, ffi.Handle)>>('realm_dettach_finalizer');
+  late final _realm_dettach_finalizer = _realm_dettach_finalizerPtr
+      .asFunction<void Function(ffi.Pointer<ffi.Void>, Object)>();
+
   /// Subscribe to notifications for this object.
   ///
   /// @return A non-null pointer if no exception occurred.

lib/src/native/realm_core.dart

@@ -86,6 +86,11 @@ class _RealmCore {
   static const libraryVersion = '0.8.0+rc';
   late String nativeLibraryVersion = _realmLib.realm_dart_library_version().cast<Utf8>().toDartString();
 
+  // for debugging only. Enable in realm_dart.cpp
+  // void invokeGC() {
+  //   _realmLib.realm_dart_gc();
+  // }
+
   LastError? getLastError(Allocator allocator) {
     final error = allocator<realm_error_t>();
     final success = _realmLib.realm_get_last_error(error);
@@ -2312,9 +2317,8 @@ void _tearDownFinalizationTrace(Object value, Object finalizationToken) {
   _traceFinalization(finalizationToken);
 }
 
-final _nativeFinalizer = NativeFinalizer(_realmLib.addresses.realm_release);
-
 abstract class HandleBase<T extends NativeType> implements Finalizable {
+  late Pointer<Void> _finalizableHandle;
   Pointer<T> _pointer;
   bool get released => _pointer == nullptr;
   final bool isUnowned;
@@ -2323,7 +2327,8 @@ abstract class HandleBase<T extends NativeType> implements Finalizable {
   void keepAlive() {}
 
   HandleBase(this._pointer, int size) : isUnowned = false {
-    _nativeFinalizer.attach(this, _pointer.cast(), detach: this, externalSize: size);
+    _finalizableHandle = _realmLib.realm_attach_finalizer(this, _pointer.cast(), size);
+
     if (_enableFinalizerTrace) {
       _setupFinalizationTrace(this, _pointer);
     }
@@ -2347,7 +2352,8 @@ abstract class HandleBase<T extends NativeType> implements Finalizable {
     _releaseCore();
 
     if (!isUnowned) {
-      _nativeFinalizer.detach(this);
+      _realmLib.realm_dettach_finalizer(_finalizableHandle, this);
+
       _realmLib.realm_release(_pointer.cast());
     }
 

lib/src/realm_class.dart

@@ -483,6 +483,9 @@ class Realm implements Finalizable {
   /// This is a workaround of a Dart VM bug and will be removed in a future version of the SDK.
   static void shutdown() => scheduler.stop();
 
+  // For debugging only. Enable in realm_dart.cpp
+  // static void gc() => realmCore.invokeGC();
+
   void _ensureManagedByThis(RealmEntity entity, String operation) {
     if (entity.realm != this) {
       if (entity.isFrozen) {

src/realm_dart.cpp

@@ -93,5 +93,25 @@ RLM_API void realm_dart_invoke_unlock_callback(bool success, void* unlockFunc)
     (*castFunc)(success);
 }
 
-// stamped into the library by the build system (see prepare-release.yml)
+// Stamped into the library by the build system (see prepare-release.yml)
+// Keep this method as it is written and do not format it. 
+// We have a github workflow that looks for and replaces this string as it is written here.
 RLM_API const char* realm_dart_library_version() { return "0.8.0+rc"; }
+
+//for debugging only
+// RLM_API void realm_dart_gc() { 
+//     Dart_ExecuteInternalCommand_DL("gc-now", nullptr);
+// }
+
+void handle_finalizer(void* isolate_callback_data, void* realmPtr) {
+  realm_release(realmPtr);
+}
+
+RLM_API void* realm_attach_finalizer(Dart_Handle handle, void* realmPtr, int size) {
+  return Dart_NewFinalizableHandle_DL(handle, realmPtr, size, handle_finalizer);
+}
+
+RLM_API void realm_dettach_finalizer(void* finalizableHandle, Dart_Handle handle) {
+  Dart_FinalizableHandle finalHandle = reinterpret_cast<Dart_FinalizableHandle>(finalizableHandle);
+  return Dart_DeleteFinalizableHandle_DL(finalHandle, handle);
+}

src/realm_dart.h

@@ -43,4 +43,11 @@ RLM_API void realm_dart_invoke_unlock_callback(bool success, void* unlockFunc);
 
 RLM_API const char* realm_dart_library_version();
 
+// for debugging only. Enable in realm_dart.cpp
+// RLM_API void realm_dart_gc();
+
+RLM_API void* realm_attach_finalizer(Dart_Handle handle, void* realmPtr, int size);
+RLM_API void realm_dettach_finalizer(void* finalizableHandle, Dart_Handle handle);
+
+
 #endif // REALM_DART_H