Fabric: Explicit Scheduler creation and destruction management in RCTSurfacePresenter

Summary: Previously, the `_scheduler` method in `RCTSurfacePresenter` was implemented as a lazy getter. The only problem with that is that Scheduler instance might be (re)created in the middle of the hot-reloading process (e.g. external request to relayout some Surface might trigger that). Since it does not make any sense to create an empty Scheduler during the reloading process, now the Scheduler creation only happens in constructor and right after the VM is reloaded.

Reviewed By: JoshuaGross

Differential Revision: D17299441

fbshipit-source-id: 273451bbb03e8cdf532131adfdf3bc60c34e997e

Author: shergin

React/Base/Surface/SurfaceHostingView/RCTSurfaceHostingView.mm

@@ -80,10 +80,8 @@ - (void)setFrame:(CGRect)frame
     &maximumSize
   );
 
-  if (RCTSurfaceStageIsRunning(_stage)) {
     [_surface setMinimumSize:minimumSize
                  maximumSize:maximumSize];
-  }
 }
 
 - (CGSize)intrinsicContentSize

React/Fabric/RCTSurfacePresenter.mm

@@ -51,14 +51,14 @@ @interface RCTSurfacePresenter () <RCTSchedulerDelegate, RCTMountingManagerDeleg
 
 @implementation RCTSurfacePresenter {
   std::mutex _schedulerMutex;
-  std::mutex _contextContainerMutex;
   RCTScheduler
       *_Nullable _scheduler; // Thread-safe. Mutation of the instance variable is protected by `_schedulerMutex`.
   RCTMountingManager *_mountingManager; // Thread-safe.
   RCTSurfaceRegistry *_surfaceRegistry; // Thread-safe.
   RCTBridge *_bridge; // Unsafe. We are moving away from Bridge.
   RCTBridge *_batchedBridge;
   std::shared_ptr<const ReactNativeConfig> _reactNativeConfig;
+  ContextContainer::Shared _contextContainer;
   better::shared_mutex _observerListMutex;
   NSMutableArray<id<RCTSurfacePresenterObserver>> *_observers;
   RCTImageLoader *_imageLoader;
@@ -88,6 +88,8 @@ - (instancetype)initWithBridge:(RCTBridge *_Nullable)bridge
       _reactNativeConfig = std::make_shared<const EmptyReactNativeConfig>();
     }
 
+    _contextContainer = std::make_shared<ContextContainer>();
+
     _observers = [NSMutableArray array];
 
     [[NSNotificationCenter defaultCenter] addObserver:self
@@ -98,6 +100,8 @@ - (instancetype)initWithBridge:(RCTBridge *_Nullable)bridge
                                              selector:@selector(handleJavaScriptDidLoadNotification:)
                                                  name:RCTJavaScriptDidLoadNotification
                                                object:_bridge];
+
+    [self _createScheduler];
   }
 
   return self;
@@ -186,13 +190,15 @@ - (BOOL)synchronouslyUpdateViewOnUIThread:(NSNumber *)reactTag props:(NSDictiona
 
 #pragma mark - Private
 
-- (RCTScheduler *)_scheduler
+- (nullable RCTScheduler *)_scheduler
 {
   std::lock_guard<std::mutex> lock(_schedulerMutex);
+  return _scheduler;
+}
 
-  if (_scheduler) {
-    return _scheduler;
-  }
+- (void)_createScheduler
+{
+  std::lock_guard<std::mutex> lock(_schedulerMutex);
 
   auto componentRegistryFactory = [factory = wrapManagedObject(self.componentViewFactory)](
                                       EventDispatcher::Weak const &eventDispatcher,
@@ -203,6 +209,8 @@ - (RCTScheduler *)_scheduler
 
   auto runtimeExecutor = [self getRuntimeExecutor];
 
+  [self _updateContextContainerIfNeeded_DEPRECATED];
+
   auto toolbox = SchedulerToolbox{};
   toolbox.contextContainer = self.contextContainer;
   toolbox.componentRegistryFactory = componentRegistryFactory;
@@ -218,11 +226,13 @@ - (RCTScheduler *)_scheduler
 
   _scheduler = [[RCTScheduler alloc] initWithToolbox:toolbox];
   _scheduler.delegate = self;
-
-  return _scheduler;
 }
 
-@synthesize contextContainer = _contextContainer;
+- (void)_destroyScheduler
+{
+  std::lock_guard<std::mutex> lock(_schedulerMutex);
+  _scheduler = nil;
+}
 
 - (RuntimeExecutor)getRuntimeExecutor
 {
@@ -250,16 +260,6 @@ - (RuntimeExecutor)getRuntimeExecutor
 
 - (ContextContainer::Shared)contextContainer
 {
-  std::lock_guard<std::mutex> lock(_contextContainerMutex);
-
-  if (_contextContainer) {
-    return _contextContainer;
-  }
-
-  _contextContainer = std::make_shared<ContextContainer>();
-
-  [self _updateContextContainerIfNeeded_DEPRECATED];
-
   return _contextContainer;
 }
 
@@ -409,34 +409,27 @@ - (void)mountingManager:(RCTMountingManager *)mountingManager didMountComponents
 
 - (void)handleBridgeWillReloadNotification:(NSNotification *)notification
 {
-  {
-    std::lock_guard<std::mutex> lock(_schedulerMutex);
-    if (!_scheduler) {
-      // Seems we are already in the realoding process.
-      return;
-    }
+  if (!self._scheduler) {
+    // Seems we are already in the reloading process.
+    return;
   }
 
   [self _stopAllSurfaces];
-
-  {
-    std::lock_guard<std::mutex> lock(_schedulerMutex);
-    _scheduler = nil;
-  }
+  [self _destroyScheduler];
 }
 
 - (void)handleJavaScriptDidLoadNotification:(NSNotification *)notification
 {
   RCTBridge *bridge = notification.userInfo[@"bridge"];
-  if (bridge != _batchedBridge) {
-    _batchedBridge = bridge;
+  if (bridge == _batchedBridge) {
+    // Nothing really changed.
+    return;
+  }
 
-    // Some of the injected dependencies are tight to a particular instance of Bridge,
-    // so they need to be reinjected.
-    [self _updateContextContainerIfNeeded_DEPRECATED];
+  _batchedBridge = bridge;
 
-    [self _startAllSurfaces];
-  }
+  [self _createScheduler];
+  [self _startAllSurfaces];
 }
 
 @end