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[WiP] Fix leak on Command Element #26044

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[WiP] Fix leak on Command Element #26044

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647a176
fix leak on Commandelement
pictos Nov 21, 2024
24f2e77
enable fix
pictos Nov 21, 2024
c7d8dbe
add DeviceTests
pictos Nov 21, 2024
ecb9dd6
revert RefreshViewTests to main
pictos Nov 21, 2024
426bc70
adjust rebase
pictos Dec 14, 2024
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24 changes: 23 additions & 1 deletion src/Controls/src/Core/CommandElement.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -18,8 +18,13 @@ public static void OnCommandChanged(BindableObject bo, object o, object n)
{
var commandElement = (ICommandElement)bo;
if (n is ICommand newCommand)
{
newCommand.CanExecuteChanged += commandElement.CanExecuteChanged;
commandElement.CanExecuteChanged(bo, EventArgs.Empty);

HandleTearDown(commandElement);

commandElement.CanExecuteChanged(bo, EventArgs.Empty);
}
}

public static void OnCommandParameterChanged(BindableObject bo, object o, object n)
Expand All @@ -35,5 +40,22 @@ public static bool GetCanExecute(ICommandElement commandElement)

return commandElement.Command.CanExecute(commandElement.CommandParameter);
}

static void HandleTearDown(ICommandElement commandElement)
{
if (commandElement is not VisualElement ve)
return;

ve.Unloaded -= OnUnloaded;
ve.Unloaded += OnUnloaded;
Comment on lines +49 to +50
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What is the idea behind this?

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safe code to avoid the same control to subscribe the same event more than once. But this will be reworked, this approach will not be used


static void OnUnloaded(object? sender, EventArgs e)
{
if (sender is ICommandElement element && element.Command is not null)
{
element.Command.CanExecuteChanged -= element.CanExecuteChanged;
}
}
}
}
}
56 changes: 54 additions & 2 deletions src/Controls/tests/DeviceTests/Memory/MemoryTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
using System.Collections.ObjectModel;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Input;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Maui.Controls;
using Microsoft.Maui.Controls.Handlers;
Expand All @@ -29,18 +30,21 @@ void SetupBuilder()
handlers.AddHandler<ActivityIndicator, ActivityIndicatorHandler>();
handlers.AddHandler<Border, BorderHandler>();
handlers.AddHandler<BoxView, BoxViewHandler>();
handlers.AddHandler<Button, ButtonHandler>();

handlers.AddHandler<CarouselView, CarouselViewHandler>();
handlers.AddHandler<CollectionView, CollectionViewHandler>();
handlers.AddHandler<CheckBox, CheckBoxHandler>();
handlers.AddHandler<DatePicker, DatePickerHandler>();
handlers.AddHandler<Shape, ShapeViewHandler>();

handlers.AddHandler<Entry, EntryHandler>();
handlers.AddHandler<EntryCell, EntryCellRenderer>();
handlers.AddHandler<Editor, EditorHandler>();
#pragma warning disable CS0618 // Type or member is obsolete
handlers.AddHandler<Frame, FrameRenderer>();
#pragma warning restore CS0618 // Type or member is obsolete
handlers.AddHandler<GraphicsView, GraphicsViewHandler>();
handlers.AddHandler<Grid, LayoutHandler>();
handlers.AddHandler<HybridWebView, HybridWebViewHandler>();
handlers.AddHandler<Label, LabelHandler>();
handlers.AddHandler<ListView, ListViewRenderer>();
Expand All @@ -57,6 +61,7 @@ void SetupBuilder()
handlers.AddHandler<RefreshView, RefreshViewHandler>();
handlers.AddHandler<IScrollView, ScrollViewHandler>();
handlers.AddHandler<SearchBar, SearchBarHandler>();
handlers.AddHandler<Shape, ShapeViewHandler>();
handlers.AddHandler<Slider, SliderHandler>();
handlers.AddHandler<Stepper, StepperHandler>();
handlers.AddHandler<SwipeView, SwipeViewHandler>();
Expand Down Expand Up @@ -177,7 +182,7 @@ public async Task HandlerDoesNotLeak(Type type)
#if ANDROID
// NOTE: skip certain controls on older Android devices
if ((type == typeof(DatePicker) || type == typeof(ListView)) && !OperatingSystem.IsAndroidVersionAtLeast(30))
return;
return;

if (type == typeof(HybridWebView) && !OperatingSystem.IsAndroidVersionAtLeast(24))
{
Expand Down Expand Up @@ -559,6 +564,45 @@ await InvokeOnMainThreadAsync(() =>
}
#endif

[Fact("CommandElement, as Button, doesn't leak")]
public async Task DoesNotLeak()
{
SetupBuilder();

// Long-lived ICommand, like a Singleton ViewModel
var command = new MyCommand();
WeakReference reference = null;
var navPage = new NavigationPage(new ContentPage());
// Several GCs required on iOS

await CreateHandlerAndAddToWindow<WindowHandlerStub>(new Window(navPage), async window =>
{
var layout = new Grid();

var btn = new Button
{
Command = command
};

var label = new Label();
layout.Add(btn);

var page2 = new ContentPage
{
Content = layout
};

reference = new(btn);
await navPage.PushAsync(page2);
await OnLoadedAsync(btn);
await navPage.PopAsync();
await OnUnloadedAsync(page2);
});
Assert.NotNull(reference);

await AssertionExtensions.WaitForGC(reference);
}

[Fact]
public async Task TweenersWillNotLeakDuringInfiniteAnimation()
{
Expand Down Expand Up @@ -587,6 +631,14 @@ await CreateHandlerAndAddToWindow(new Window(page), async () =>
}
}

class MyCommand : ICommand
{
public event EventHandler CanExecuteChanged;
public bool CanExecute(object parameter) => true;
public void Execute(object parameter) { }
public void FireCanExecuteChanged() => CanExecuteChanged?.Invoke(this, EventArgs.Empty);
}

sealed class AnimationPage : ContentPage
{
Button CounterBtn { get; } = new();
Expand Down
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