Fabric: Automatic removing outstanding Surface on Scheduler destructi…

…on; gated.

Summary:
This is an addition to an automatic emergency clean-up algorithm that we have in Scheduler. In addition to committing empty surfaces, we also remove those surfaces from the registry making calling stuff on them impossible. Removing surfaces waits for all commits in flight to be finished, so it theoretically can deadlock (so we gated that).

If we won't face deadlocks in a coming couple of weeks, I would remove gating.

Changelog: [Internal] Fabric-specific internal change.

Reviewed By: mdvacca

Differential Revision: D21610683

fbshipit-source-id: 71feeaa0ee4521a0180cdfba6e3a271e7f7d9401

ReactCommon/fabric/scheduler/Scheduler.cpp

@@ -93,9 +93,13 @@ Scheduler::Scheduler(
 #ifdef ANDROID
   enableNewStateReconciliation_ = reactNativeConfig_->getBool(
       "react_fabric:enable_new_state_reconciliation_android");
+  removeOutstandingSurfacesOnDestruction_ = reactNativeConfig_->getBool(
+      "react_fabric:remove_outstanding_surfaces_on_destruction_android");
 #else
   enableNewStateReconciliation_ = reactNativeConfig_->getBool(
       "react_fabric:enable_new_state_reconciliation_ios");
+  removeOutstandingSurfacesOnDestruction_ = reactNativeConfig_->getBool(
+      "react_fabric:remove_outstanding_surfaces_on_destruction_ios");
 #endif
 }
 
@@ -140,6 +144,12 @@ Scheduler::~Scheduler() {
     uiManager_->getShadowTreeRegistry().visit(
         surfaceId,
         [](ShadowTree const &shadowTree) { shadowTree.commitEmptyTree(); });
+
+    // Removing surfaces is gated because it acquires mutex waiting for commits
+    // in flight; in theory, it can deadlock.
+    if (removeOutstandingSurfacesOnDestruction_) {
+      uiManager_->getShadowTreeRegistry().remove(surfaceId);
+    }
   }
 }
 

ReactCommon/fabric/scheduler/Scheduler.h

@@ -121,7 +121,11 @@ class Scheduler final : public UIManagerDelegate {
    */
   std::shared_ptr<better::optional<EventDispatcher const>> eventDispatcher_;
 
+  /*
+   * Temporary flags.
+   */
   bool enableNewStateReconciliation_{false};
+  bool removeOutstandingSurfacesOnDestruction_{false};
 };
 
 } // namespace react