[Windows] Fix EGL surface destruction race

shell/platform/windows/flutter_windows_view.cc

@@ -7,7 +7,9 @@
 #include <chrono>
 
 #include "flutter/common/constants.h"
+#include "flutter/fml/make_copyable.h"
 #include "flutter/fml/platform/win/wstring_conversion.h"
+#include "flutter/fml/synchronization/waitable_event.h"
 #include "flutter/shell/platform/common/accessibility_bridge.h"
 #include "flutter/shell/platform/windows/keyboard_key_channel_handler.h"
 #include "flutter/shell/platform/windows/text_input_plugin.h"
@@ -81,6 +83,22 @@ void UpdateVsync(const FlutterWindowsEngine& engine,
   }
 }
 
+/// Destroys a rendering surface that backs a Flutter view.
+void DestroyWindowSurface(const FlutterWindowsEngine& engine,
+                          std::unique_ptr<egl::WindowSurface> surface) {
+  // EGL surfaces are used on the raster thread if the engine is running.
+  // There may be pending raster tasks that use this surface. Destroy the
+  // surface on the raster thread to avoid concurrent uses.
+  if (engine.running()) {
+    engine.PostRasterThreadTask(fml::MakeCopyable(
+        [surface = std::move(surface)] { surface->Destroy(); }));
+  } else {
+    // There's no raster thread if engine isn't running. The surface can be
+    // destroyed on the platform thread.
+    surface->Destroy();
+  }
+}
+
 }  // namespace
 
 FlutterWindowsView::FlutterWindowsView(
@@ -105,7 +123,9 @@ FlutterWindowsView::~FlutterWindowsView() {
   // Notify the engine the view's child window will no longer be visible.
   engine_->OnWindowStateEvent(GetWindowHandle(), WindowStateEvent::kHide);
 
-  DestroyRenderSurface();
+  if (surface_) {
+    DestroyWindowSurface(*engine_, std::move(surface_));
+  }
 }
 
 bool FlutterWindowsView::OnEmptyFrameGenerated() {
@@ -706,12 +726,6 @@ bool FlutterWindowsView::ResizeRenderSurface(size_t width, size_t height) {
   return true;
 }
 
-void FlutterWindowsView::DestroyRenderSurface() {
-  if (surface_) {
-    surface_->Destroy();
-  }
-}
-
 egl::WindowSurface* FlutterWindowsView::surface() const {
   return surface_.get();
 }

shell/platform/windows/flutter_windows_view.h

@@ -50,9 +50,6 @@ class FlutterWindowsView : public WindowBindingHandlerDelegate {
   // Should be called before calling FlutterEngineRun using this view.
   void CreateRenderSurface();
 
-  // Destroys current rendering surface if one has been allocated.
-  void DestroyRenderSurface();
-
   // Get the EGL surface that backs the Flutter view.
   //
   // This might be nullptr or an invalid surface.

shell/platform/windows/flutter_windows_view_unittests.cc

@@ -264,6 +264,12 @@ TEST(FlutterWindowsViewTest, Shutdown) {
     InSequence s;
     EXPECT_CALL(*engine_ptr, running).WillOnce(Return(true));
     EXPECT_CALL(*engine_ptr, RemoveView(view_id)).Times(1);
+    EXPECT_CALL(*engine_ptr, running).WillOnce(Return(true));
+    EXPECT_CALL(*engine_ptr, PostRasterThreadTask)
+        .WillOnce([](fml::closure callback) {
+          callback();
+          return true;
+        });
     EXPECT_CALL(*surface_ptr, Destroy).Times(1);
   }
 }
@@ -825,7 +831,14 @@ TEST(FlutterWindowsViewTest, WindowResizeTests) {
   auto windows_proc_table = std::make_shared<NiceMock<MockWindowsProcTable>>();
   std::unique_ptr<FlutterWindowsEngine> engine =
       GetTestEngine(windows_proc_table);
+
   EngineModifier engine_modifier{engine.get()};
+  engine_modifier.embedder_api().PostRenderThreadTask = MOCK_ENGINE_PROC(
+      PostRenderThreadTask,
+      ([](auto engine, VoidCallback callback, void* user_data) {
+        callback(user_data);
+        return kSuccess;
+      }));
 
   auto egl_manager = std::make_unique<egl::MockManager>();
   auto surface = std::make_unique<egl::MockWindowSurface>();
@@ -883,7 +896,14 @@ TEST(FlutterWindowsViewTest, TestEmptyFrameResizes) {
   auto windows_proc_table = std::make_shared<NiceMock<MockWindowsProcTable>>();
   std::unique_ptr<FlutterWindowsEngine> engine =
       GetTestEngine(windows_proc_table);
+
   EngineModifier engine_modifier{engine.get()};
+  engine_modifier.embedder_api().PostRenderThreadTask = MOCK_ENGINE_PROC(
+      PostRenderThreadTask,
+      ([](auto engine, VoidCallback callback, void* user_data) {
+        callback(user_data);
+        return kSuccess;
+      }));
 
   auto egl_manager = std::make_unique<egl::MockManager>();
   auto surface = std::make_unique<egl::MockWindowSurface>();
@@ -940,7 +960,14 @@ TEST(FlutterWindowsViewTest, TestEmptyFrameResizes) {
 // https://github.com/flutter/flutter/issues/141855
 TEST(FlutterWindowsViewTest, WindowResizeRace) {
   std::unique_ptr<FlutterWindowsEngine> engine = GetTestEngine();
+
   EngineModifier engine_modifier(engine.get());
+  engine_modifier.embedder_api().PostRenderThreadTask = MOCK_ENGINE_PROC(
+      PostRenderThreadTask,
+      ([](auto engine, VoidCallback callback, void* user_data) {
+        callback(user_data);
+        return kSuccess;
+      }));
 
   auto egl_manager = std::make_unique<egl::MockManager>();
   auto surface = std::make_unique<egl::MockWindowSurface>();
@@ -980,7 +1007,14 @@ TEST(FlutterWindowsViewTest, WindowResizeRace) {
 // even though EGL initialized successfully.
 TEST(FlutterWindowsViewTest, WindowResizeInvalidSurface) {
   std::unique_ptr<FlutterWindowsEngine> engine = GetTestEngine();
+
   EngineModifier engine_modifier(engine.get());
+  engine_modifier.embedder_api().PostRenderThreadTask = MOCK_ENGINE_PROC(
+      PostRenderThreadTask,
+      ([](auto engine, VoidCallback callback, void* user_data) {
+        callback(user_data);
+        return kSuccess;
+      }));
 
   auto egl_manager = std::make_unique<egl::MockManager>();
   auto surface = std::make_unique<egl::MockWindowSurface>();
@@ -1477,6 +1511,11 @@ TEST(FlutterWindowsViewTest, DisablesVSyncAfterStartup) {
   EXPECT_CALL(*surface_ptr, MakeCurrent).WillOnce(Return(true));
   EXPECT_CALL(*surface_ptr, SetVSyncEnabled(false)).WillOnce(Return(true));
   EXPECT_CALL(render_context, ClearCurrent).WillOnce(Return(true));
+  EXPECT_CALL(*engine.get(), PostRasterThreadTask)
+      .WillOnce([](fml::closure callback) {
+        callback();
+        return true;
+      });
   EXPECT_CALL(*surface_ptr, Destroy).Times(1);
 
   EngineModifier modifier{engine.get()};
@@ -1519,6 +1558,12 @@ TEST(FlutterWindowsViewTest, EnablesVSyncAfterStartup) {
   EXPECT_CALL(*surface_ptr, MakeCurrent).WillOnce(Return(true));
   EXPECT_CALL(*surface_ptr, SetVSyncEnabled(true)).WillOnce(Return(true));
   EXPECT_CALL(render_context, ClearCurrent).WillOnce(Return(true));
+
+  EXPECT_CALL(*engine.get(), PostRasterThreadTask)
+      .WillOnce([](fml::closure callback) {
+        callback();
+        return true;
+      });
   EXPECT_CALL(*surface_ptr, Destroy).Times(1);
 
   EngineModifier modifier{engine.get()};