Merge branch '21-dart-finalizer-api'

objectbox/lib/src/native/admin.dart

@@ -21,9 +21,14 @@ import 'store.dart';
 /// Note: ObjectBox Admin is currently supported for Android apps only.
 /// [Additional configuration](https://docs.objectbox.io/data-browser) is
 /// required.
-class Admin {
+class Admin implements Finalizable {
   late Pointer<OBX_admin> _cAdmin;
-  late final Pointer<OBX_dart_finalizer> _cFinalizer;
+
+  /// Runs native close function on [_cAdmin] if this is garbage collected.
+  ///
+  /// Keeps the finalizer itself reachable (static), otherwise it might be
+  /// disposed of before the finalizer callback gets a chance to run.
+  static final _finalizer = NativeFinalizer(C.addresses.admin_close.cast());
 
   @pragma('vm:prefer-inline')
   Pointer<OBX_admin> get _ptr =>
@@ -53,26 +58,19 @@ class Admin {
 
     _cAdmin = C.admin(opt);
 
-    // Keep the finalizer so we can detach it when close() is called manually.
-    _cFinalizer = C.dartc_attach_finalizer(
-        this, native_admin_close, _cAdmin.cast(), 1024 * 1024);
-    if (_cFinalizer == nullptr) {
-      close();
-      throwLatestNativeError();
-    }
+    _finalizer.attach(this, _cAdmin.cast(),
+        detach: this, externalSize: 1024 * 1024);
   }
 
   /// Closes and cleans up all resources used by this Admin.
   void close() {
-    if (!isClosed()) {
-      final errors = List.filled(2, 0);
-      if (_cFinalizer != nullptr) {
-        errors[0] = C.dartc_detach_finalizer(_cFinalizer, this);
-      }
-      errors[1] = C.admin_close(_cAdmin);
-      _cAdmin = nullptr;
-      errors.forEach(checkObx);
+    if (isClosed()) {
+      return;
     }
+    _finalizer.detach(this);
+    final error = C.admin_close(_cAdmin);
+    _cAdmin = nullptr;
+    checkObx(error);
   }
 
   /// Returns if the admin is already closed and can no longer be used.
@@ -82,7 +80,6 @@ class Admin {
   /// assigned automatically (a "0" port was used in the [bindUri]).
   late final int port = () {
     final result = C.admin_port(_ptr);
-    reachabilityFence(this);
     if (result == 0) throwLatestNativeError();
     return result;
   }();

objectbox/lib/src/native/bindings/bindings.dart

@@ -148,27 +148,3 @@ void initializeDartAPI() {
 // -1 => failed to initialize - incompatible Dart version
 int _dartAPIInitialized = 0;
 Object? _dartAPIInitException;
-
-/// A couple of native functions we need as callbacks to pass back to native.
-/// Unfortunately, ffigen keeps those private.
-typedef _NativeClose = Int Function(Pointer<Void> ptr);
-
-final native_store_close =
-    _lib!.lookup<NativeFunction<_NativeClose>>('obx_store_close');
-final native_query_close =
-    _lib!.lookup<NativeFunction<_NativeClose>>('obx_query_close');
-final native_query_prop_close =
-    _lib!.lookup<NativeFunction<_NativeClose>>('obx_query_prop_close');
-final native_admin_close =
-    _lib!.lookup<NativeFunction<_NativeClose>>('obx_admin_close');
-final weak_store_free = _lib!
-    .lookup<NativeFunction<Void Function(Pointer<OBX_weak_store>)>>(
-        'obx_weak_store_free');
-
-/// Keeps `this` alive until this call, preventing finalizers to run.
-/// Necessary for objects with a finalizer attached because the optimizer may
-/// mark the object as unused (-> GCed -> finalized) even before it's method
-/// finished executing.
-/// See https://github.com/dart-lang/sdk/issues/35770#issuecomment-840398463
-@pragma('vm:never-inline')
-Object reachabilityFence(Object obj) => obj;

objectbox/lib/src/native/bindings/objectbox_c.dart

@@ -8115,6 +8115,21 @@ class ObjectBoxC {
               ffi.Handle)>>('obx_dart_detach_finalizer');
   late final _dartc_detach_finalizer = _dartc_detach_finalizerPtr
       .asFunction<int Function(ffi.Pointer<OBX_dart_finalizer>, Object)>();
+
+  late final addresses = _SymbolAddresses(this);
+}
+
+class _SymbolAddresses {
+  final ObjectBoxC _library;
+  _SymbolAddresses(this._library);
+  ffi.Pointer<ffi.NativeFunction<obx_err Function(ffi.Pointer<OBX_store>)>>
+      get store_close => _library._store_closePtr;
+  ffi.Pointer<ffi.NativeFunction<obx_err Function(ffi.Pointer<OBX_query>)>>
+      get query_close => _library._query_closePtr;
+  ffi.Pointer<ffi.NativeFunction<obx_err Function(ffi.Pointer<OBX_query_prop>)>>
+      get query_prop_close => _library._query_prop_closePtr;
+  ffi.Pointer<ffi.NativeFunction<obx_err Function(ffi.Pointer<OBX_admin>)>>
+      get admin_close => _library._admin_closePtr;
 }
 
 abstract class OBXFeature {

objectbox/lib/src/native/observable.dart

@@ -85,7 +85,6 @@ extension ObservableStore on Store {
       observer.cObserver =
           C.dartc_observe_single_type(_ptr, entityId, observer.nativePort);
     });
-    reachabilityFence(this);
 
     return observer.stream;
   }
@@ -126,7 +125,6 @@ extension ObservableStore on Store {
     observer.init(() {
       observer.cObserver = C.dartc_observe(_ptr, observer.nativePort);
     }, broadcast: broadcast);
-    reachabilityFence(this);
 
     if (broadcast) {
       _onClose[observer] = observer.close;

objectbox/lib/src/native/query/property.dart

@@ -1,25 +1,27 @@
 part of query;
 
 /// Property query base.
-class PropertyQuery<T> {
+class PropertyQuery<T> implements Finalizable {
   final Query<dynamic> _query;
 
   /// Pointer to the native instance. Use [_ptr] for safe access instead.
   final Pointer<OBX_query_prop> _cProp;
-  late final Pointer<OBX_dart_finalizer> _cFinalizer;
+
+  /// Runs native close function on [_cProp] if this is garbage collected.
+  ///
+  /// Keeps the finalizer itself reachable (static), otherwise it might be
+  /// disposed of before the finalizer callback gets a chance to run.
+  static final _finalizer =
+      NativeFinalizer(C.addresses.query_prop_close.cast());
+
   bool _closed = false;
   final int _type;
   bool _distinct = false;
   bool _caseSensitive = false;
 
   PropertyQuery._(this._query, this._cProp, this._type) {
     checkObxPtr(_cProp, 'property query');
-    _cFinalizer = C.dartc_attach_finalizer(
-        this, native_query_prop_close, _cProp.cast(), 64);
-    if (_cFinalizer == nullptr) {
-      close();
-      throwLatestNativeError();
-    }
+    _finalizer.attach(this, _cProp.cast(), detach: this, externalSize: 64);
   }
 
   @pragma("vm:prefer-inline")
@@ -36,20 +38,15 @@ class PropertyQuery<T> {
   void close() {
     if (!_closed) {
       _closed = true;
-      var err = 0;
-      if (_cFinalizer != nullptr) {
-        err = C.dartc_detach_finalizer(_cFinalizer, this);
-      }
+      _finalizer.detach(this);
       checkObx(C.query_prop_close(_cProp));
-      checkObx(err);
     }
   }
 
   int _count() {
     final ptr = malloc<Uint64>();
     try {
       checkObx(C.query_prop_count(_ptr, ptr));
-      reachabilityFence(this);
       return ptr.value;
     } finally {
       malloc.free(ptr);
@@ -65,7 +62,6 @@ class PropertyQuery<T> {
     try {
       cItems = checkObxPtr(
           findFn(_ptr, cDefault ?? nullptr), 'Property query failed');
-      reachabilityFence(this);
       return listReadFn(cItems);
     } finally {
       if (cDefault != null) malloc.free(cDefault);
@@ -77,7 +73,6 @@ class PropertyQuery<T> {
     final ptr = malloc<Double>();
     try {
       checkObx(C.query_prop_avg(_ptr, ptr, nullptr));
-      reachabilityFence(this);
       return ptr.value;
     } finally {
       malloc.free(ptr);
@@ -93,7 +88,6 @@ extension IntegerPropertyQuery on PropertyQuery<int> {
     final ptr = malloc<Int64>();
     try {
       checkObx(fn(_ptr, ptr, nullptr));
-      reachabilityFence(this);
       return ptr.value;
     } finally {
       malloc.free(ptr);
@@ -116,7 +110,6 @@ extension IntegerPropertyQuery on PropertyQuery<int> {
   set distinct(bool d) {
     _distinct = d;
     checkObx(C.query_prop_distinct(_ptr, d));
-    reachabilityFence(this);
   }
 
   /// Minimum value of the property over all objects matching the query.
@@ -191,7 +184,6 @@ extension DoublePropertyQuery on PropertyQuery<double> {
     final ptr = malloc<Double>();
     try {
       checkObx(fn(_ptr, ptr, nullptr));
-      reachabilityFence(this);
       return ptr.value;
     } finally {
       malloc.free(ptr);
@@ -214,7 +206,6 @@ extension DoublePropertyQuery on PropertyQuery<double> {
   set distinct(bool d) {
     _distinct = d;
     checkObx(C.query_prop_distinct(_ptr, d));
-    reachabilityFence(this);
   }
 
   /// Minimum value of the property over all objects matching the query.
@@ -266,7 +257,6 @@ extension StringPropertyQuery on PropertyQuery<String> {
   set caseSensitive(bool caseSensitive) {
     _caseSensitive = caseSensitive;
     checkObx(C.query_prop_distinct_case(_ptr, _distinct, _caseSensitive));
-    reachabilityFence(this);
   }
 
   /// Get status of the case-sensitive configuration.
@@ -282,7 +272,6 @@ extension StringPropertyQuery on PropertyQuery<String> {
   set distinct(bool d) {
     _distinct = d;
     checkObx(C.query_prop_distinct_case(_ptr, d, _caseSensitive));
-    reachabilityFence(this);
   }
 
   /// Returns the count of non-null values.