[ios_platform_view] crash due to race when disposing platform views. #125223
Description
b/277154520
Actual Behavior
App crashes randomly when PlatformView is disposed while still in the composition order.
Expected behavior:
Engine needs to be resilient about this and not crash.
Reason:
It happens because views_to_dispose_ is populated on the ui thread but composition order is built on the main thread.
DisposeView happens before compositing the view tree. If a view is disposed but still in the composition_order, a NPE would happen during composition.
One solution could be to remove the disposed view from the composition order.
Exception Type: EXC_CRASH (SIGABRT)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Triggered by Thread: 0
Application Specific Information:
abort() called
Last Exception Backtrace:
0 CoreFoundation 0x19e0a7a84 __exceptionPreprocess +
1 libobjc.A.dylib 0x19c4f9958 objc_exception_throw +
2 CoreFoundation 0x19e235554 -[__NSCFString characterAtIndex:].cold.1 +
3 CoreFoundation 0x19e232388 -[__NSArrayM insertObject:atIndex:].cold.2 +
4 CoreFoundation 0x19e0b19d4 -[__NSArrayM insertObject:atIndex:] +
5 Flutter 0x10cbe5498 flutter::IOSExternalViewEmbedder::SubmitFrame(GrDirectContext*, std::_LIBCPP_ABI_NAMESPACE::unique_ptr<flutter::SurfaceFrame, std::_LIBCPP_ABI_NAMESPACE::default_delete<flutter::SurfaceFrame>>) +
6 Flutter 0x10cf8a918 flutter::Rasterizer::DrawToSurfaceUnsafe(flutter::FrameTimingsRecorder&, flutter::LayerTree&) +
7 Flutter 0x10cf8ab70 std::_LIBCPP_ABI_NAMESPACE::__function::__func<flutter::Rasterizer::DrawToSurface(flutter::FrameTimingsRecorder&, flutter::LayerTree&)::$_1, std::_LIBCPP_ABI_NAMESPACE::allocator<flutter::Rasterizer::DrawToSurface(flutter::FrameTimingsRecorder&, flutter::LayerTree&)::$_1>, void ()>::operator()() +
8 Flutter 0x10ce9218c fml::SyncSwitch::Execute(fml::SyncSwitch::Handlers const&) const +
9 Flutter 0x10cf8a2a8 flutter::Rasterizer::DrawToSurface(flutter::FrameTimingsRecorder&, flutter::LayerTree&) +