Crash when changes happen to the queue

Hi,

I’ve been trying to use Stylophone on windows but the app keeps on crashing whenever I try to skip a song, or modify a playlist in a way that removes items. I’ve build a debug version to investigate and here is what happens on my system:

1. contrary to the comment at QueueViewModel.cs:209 plchanges does not necessarily give the full list of files. For instance when skipping on my system the response always contains a single song which is the newly playing song. The logic that follows is then invalid.
2. The removal of the chosen songs then crashes the ui. I’m not sure what could be causing this crash since the list of song is still valid from an UI perspective.

Here is the stack of the crash:

 	KernelBase.dll!RaiseFailFastException()	Unknown
 	combase.dll!RoFailFastWithErrorContextInternal2(HRESULT hrError, unsigned long cStowedExceptions, _STOWED_EXCEPTION_INFORMATION_V2 * * aStowedExceptionPointers) Line 1468	C++
 	[Inline Frame] Windows.UI.Xaml.dll!std::vector<float,std::allocator<float>>::_Xrange() Line 1728	C++
 	Windows.UI.Xaml.dll!std::vector<float,std::allocator<float>>::at(const unsigned __int64 _Pos) Line 1494	C++
 	Windows.UI.Xaml.dll!DirectUI::Components::Moco::StackingLayoutStrategyImpl::RegisterSize(int index, bool isHeader, float newSize) Line 758	C++
 	Windows.UI.Xaml.dll!DirectUI::Components::Moco::StackingLayoutStrategyImpl::GetContainerBounds(int indexInItems, int containerDesiredSize, Windows::Foundation::Size referenceInformation, Windows::UI::Xaml::Controls::LayoutReference) Line 804	C++
 	Windows.UI.Xaml.dll!DirectUI::Components::Moco::StackingLayoutStrategyImpl::GetElementBounds(Windows::UI::Xaml::Controls::ElementType elementType, int elementIndex, Windows::Foundation::Size containerDesiredSize, Windows::UI::Xaml::Controls::LayoutReference referenceInformation, Windows::Foundation::Rect pReturnValue, Windows::Foundation::Rect *) Line 105	C++
 	Windows.UI.Xaml.dll!DirectUI::StackingLayoutStrategy::GetElementBoundsImpl(Windows::UI::Xaml::Controls::ElementType elementType, int elementIndex, Windows::Foundation::Size containerDesiredSize, Windows::UI::Xaml::Controls::LayoutReference referenceInformation, Windows::Foundation::Rect pReturnValue, Windows::Foundation::Rect *) Line 79	C++
 	Windows.UI.Xaml.dll!DirectUI::StackingLayoutStrategyGenerated::GetElementBounds(Windows::UI::Xaml::Controls::ElementType elementType, int elementIndex, Windows::Foundation::Size containerDesiredSize, Windows::UI::Xaml::Controls::LayoutReference referenceInformation, Windows::Foundation::Rect windowConstraint, Windows::Foundation::Rect * pResult) Line 177	C++
 	Windows.UI.Xaml.dll!DirectUI::ModernCollectionBasePanel::OnItemRemoved(int nIndex, bool itemRemovedForGroupReset) Line 1662	C++
 	Windows.UI.Xaml.dll!DirectUI::ModernCollectionBasePanel::NotifyOfItemsChangedImpl(Windows::Foundation::Collections::IVectorChangedEventArgs * e) Line 1251	C++
 	Windows.UI.Xaml.dll!DirectUI::ModernCollectionBasePanelGenerated::NotifyOfItemsChanged(Windows::Foundation::Collections::IVectorChangedEventArgs * pE) Line 915	C++
 	Windows.UI.Xaml.dll!DirectUI::ItemsControl::OnItemsChanged(Windows::Foundation::Collections::IVectorChangedEventArgs * pArgs) Line 1111	C++
 	Windows.UI.Xaml.dll!DirectUI::Selector::OnItemsChanged(Windows::Foundation::Collections::IVectorChangedEventArgs * e) Line 1375	C++
 	Windows.UI.Xaml.dll!DirectUI::ListViewBase::OnItemsChanged(Windows::Foundation::Collections::IVectorChangedEventArgs * pArgs) Line 200	C++
 	Windows.UI.Xaml.dll!DirectUI::ItemsControl::OnItemsChangedImpl(IInspectable * e) Line 1125	C++
 	Windows.UI.Xaml.dll!DirectUI::ItemsControlGenerated::OnItemsChanged(IInspectable * pE) Line 683	C++
 	Windows.UI.Xaml.dll!DirectUI::ItemsControlGenerated::OnItemsChangedProtected(IInspectable * pE) Line 704	C++
 	[Inline Frame] Windows.UI.Xaml.dll!std::_Func_class<long,Windows::Foundation::Collections::IObservableVector<Windows::Foundation::DateTime> *,Windows::Foundation::Collections::IVectorChangedEventArgs *>::operator()(Windows::Foundation::Collections::IObservableVector<Windows::Foundation::DateTime> * <_Args_0>, Windows::Foundation::Collections::IVectorChangedEventArgs * <_Args_1>) Line 869	C++
 	Windows.UI.Xaml.dll!ctl::event_handler_base<Windows::Foundation::Collections::VectorChangedEventHandler<Windows::Foundation::DateTime>,Windows::Foundation::Collections::IObservableVector<Windows::Foundation::DateTime>,Windows::Foundation::Collections::IVectorChangedEventArgs,DirectUI::DateTimeVectorChangedTraits>::Invoke(Windows::Foundation::Collections::IObservableVector<Windows::Foundation::DateTime> * pSender, Windows::Foundation::Collections::IVectorChangedEventArgs * pArgs) Line 38	C++
 	Windows.UI.Xaml.dll!DirectUI::CEventSourceBase<DirectUI::IUntypedEventSource,Windows::Foundation::Collections::VectorChangedEventHandler<IInspectable *>,Windows::Foundation::Collections::IObservableVector<IInspectable *>,Windows::Foundation::Collections::IVectorChangedEventArgs>::Raise(Windows::Foundation::Collections::IObservableVector<IInspectable *> * pSource, Windows::Foundation::Collections::IVectorChangedEventArgs * pArgs) Line 307	C++
 	Windows.UI.Xaml.dll!DirectUI::ItemCollection::OnCollectionChanged(Windows::Foundation::Collections::IObservableVector<IInspectable *> * pSender, Windows::Foundation::Collections::IVectorChangedEventArgs * e) Line 410	C++
 	[Inline Frame] Windows.UI.Xaml.dll!DirectUI::ItemCollection::UpdateItemsSourceList::__l23::<lambda_333c454cfd67f0d9d59f18ca318bd614>::operator()(IInspectable * sender, Windows::Foundation::Collections::IVectorChangedEventArgs * args) Line 368	C++
 	[Inline Frame] Windows.UI.Xaml.dll!std::invoke(DirectUI::ItemCollection::UpdateItemsSourceList::__l23::<lambda_333c454cfd67f0d9d59f18ca318bd614> &) Line 1488	C++
 	[Inline Frame] Windows.UI.Xaml.dll!std::_Invoker_ret<long,0>::_Call(DirectUI::ItemCollection::UpdateItemsSourceList::__l23::<lambda_333c454cfd67f0d9d59f18ca318bd614> &) Line 660	C++
 	Windows.UI.Xaml.dll!std::_Func_impl_no_alloc<<lambda_333c454cfd67f0d9d59f18ca318bd614>,long,Windows::Foundation::Collections::IObservableVector<IInspectable *> *,Windows::Foundation::Collections::IVectorChangedEventArgs *>::_Do_call(Windows::Foundation::Collections::IObservableVector<IInspectable *> * && <_Args_0>, Windows::Foundation::Collections::IVectorChangedEventArgs * && <_Args_1>) Line 822	C++
 	[Inline Frame] Windows.UI.Xaml.dll!std::_Func_class<long,Windows::Foundation::Collections::IObservableVector<Windows::Foundation::DateTime> *,Windows::Foundation::Collections::IVectorChangedEventArgs *>::operator()(Windows::Foundation::Collections::IObservableVector<Windows::Foundation::DateTime> * <_Args_0>, Windows::Foundation::Collections::IVectorChangedEventArgs * <_Args_1>) Line 869	C++
 	Windows.UI.Xaml.dll!ctl::event_handler_base<Windows::Foundation::Collections::VectorChangedEventHandler<Windows::Foundation::DateTime>,Windows::Foundation::Collections::IObservableVector<Windows::Foundation::DateTime>,Windows::Foundation::Collections::IVectorChangedEventArgs,DirectUI::DateTimeVectorChangedTraits>::Invoke(Windows::Foundation::Collections::IObservableVector<Windows::Foundation::DateTime> * pSender, Windows::Foundation::Collections::IVectorChangedEventArgs * pArgs) Line 38	C++
 	Windows.UI.Xaml.dll!DirectUI::TrackerEventSource<Windows::Foundation::Collections::VectorChangedEventHandler<IInspectable *>,Windows::Foundation::Collections::IObservableVector<IInspectable *>,Windows::Foundation::Collections::IVectorChangedEventArgs>::Raise(Windows::Foundation::Collections::IObservableVector<IInspectable *> * pSource, Windows::Foundation::Collections::IVectorChangedEventArgs * pArgs) Line 572	C++
 	[Inline Frame] Windows.UI.Xaml.dll!DirectUI::BindableObservableVectorWrapper::RaiseVectorChanged(Windows::Foundation::Collections::IVectorChangedEventArgs *) Line 286	C++
 	Windows.UI.Xaml.dll!DirectUI::BindableObservableVectorWrapper::RaiseVectorChanged(Windows::Foundation::Collections::CollectionChange action, unsigned int index) Line 274	C++
 	Windows.UI.Xaml.dll!DirectUI::BindableObservableVectorWrapper::ProcessCollectionChange(Windows::UI::Xaml::Interop::INotifyCollectionChangedEventArgs * pArgs) Line 225	C++
 	[Inline Frame] Windows.UI.Xaml.dll!std::_Func_class<long,IInspectable *,Windows::UI::Xaml::Interop::INotifyCollectionChangedEventArgs *>::operator()(IInspectable * <_Args_0>, Windows::UI::Xaml::Interop::INotifyCollectionChangedEventArgs * <_Args_1>) Line 869	C++
 	Windows.UI.Xaml.dll!ctl::event_handler_base<Windows::UI::Xaml::Interop::INotifyCollectionChangedEventHandler,IInspectable,Windows::UI::Xaml::Interop::INotifyCollectionChangedEventArgs,DirectUI::CollectionChangedTraits>::Invoke(IInspectable * pSender, Windows::UI::Xaml::Interop::INotifyCollectionChangedEventArgs * pArgs) Line 38	C++
 	Windows.UI.Xaml.dll!ctl::event_handler_base<Windows::UI::Xaml::Interop::INotifyCollectionChangedEventHandler,IInspectable,Windows::UI::Xaml::Interop::INotifyCollectionChangedEventArgs,DirectUI::CollectionChangedTraits>::Invoke(IInspectable * pSender, Windows::UI::Xaml::Interop::INotifyCollectionChangedEventArgs * pArgs) Line 27	C++
 	[External Code]	
>	Stylophone.Common.dll!Stylophone.Common.ViewModels.QueueViewModel.MPDConnectionService_QueueChanged.AnonymousMethod__2() Line 217	C#

Replacing the RemoveRange with a for loop of RemoveAt seems to solve the crash.

I’ve not seen this issue reported so maybe there’s something on my setup that triggers both weird behaviors. The mpd server protocol version is 0.23.5 and it’s the android version of the app.

[hlbstd]

I think I’ve found the cause of those additional notifications, it’s the proxy database plugin, aka “satellite mode”. I’ve switched to a local db and the application now works as expected.

This issue is solved as far as I’m concerned, I’ll leave it open in case you want to handle this particular setup in app.

[hlbstd]

Skipping a song always trigger this event for me, with consume enabled or not. With consume enabled the behaviour actually matches the comment (I receive the songs remaining in the playlist). I think this is not the only instance of me receiving this event more often than intended by the app. I have another issue when playing an album for instance, the callback is triggered at least twice and is run in parallel which also messes with the list.

An easy fix on my side is to use the playlistinfo command and run ReplaceRange on the whole queue each time but it makes the ui refresh a lot more than it should I think.

Putting aside the what triggers the callback, shouldn’t the result of plchanges be handled a bit differently anyway ? Since the command gives the new offsets of the modified elements, couldn’t they be used to find out which elements have actually been removed/added/shuffled without presuming of the result and with minimal modification to the list ? I don’t know much about xaml/winui so maybe this wouldn’t be beneficial to minimizes changes to the UI.