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using System;
using System.Threading;
using Xamarin.Forms.CustomAttributes;
using Xamarin.Forms.Internals;
#if UITEST
using Xamarin.UITest;
using NUnit.Framework;
#endif
namespace Xamarin.Forms.Controls.Issues
{
[Preserve(AllMembers = true)]
[Issue(IssueTracker.Bugzilla, 45926, "MessagingCenter prevents subscriber from being collected", PlatformAffected.All)]
public class Bugzilla45926 : TestNavigationPage
{
protected override void Init()
{
Button createPage, sendMessage, doGC;
Label instanceCount = new Label();
Label messageCount = new Label();
instanceCount.Text = $"Instances: {_45926SecondPage.InstanceCounter.ToString()}";
messageCount.Text = $"Messages: {_45926SecondPage.MessageCounter.ToString()}";
var content = new ContentPage {
Title = "Test",
Content = new StackLayout {
VerticalOptions = LayoutOptions.Center,
Children = {
(createPage = new Button { Text = "New Page" }),
(sendMessage = new Button { Text = "Send Message" }),
(doGC = new Button { Text = "Do GC" }),
instanceCount, messageCount
}
}
};
createPage.Clicked += (s, e) =>
{
PushAsync(new _45926IntermediatePage());
PushAsync(new _45926SecondPage());
};
sendMessage.Clicked += (s, e) =>
{
MessagingCenter.Send (this, "Test");
};
doGC.Clicked += (sender, e) => {
GC.Collect ();
GC.WaitForPendingFinalizers();
instanceCount.Text = $"Instances: {_45926SecondPage.InstanceCounter.ToString()}";
messageCount.Text = $"Messages: {_45926SecondPage.MessageCounter.ToString()}";
};
PushAsync(content);
}
#if UITEST
[Test]
public void Issue45926Test ()
{
RunningApp.WaitForElement (q => q.Marked ("New Page"));
RunningApp.Tap (q => q.Marked ("New Page"));
RunningApp.Back();
RunningApp.Back();
RunningApp.Tap(q => q.Marked("Do GC"));
RunningApp.Tap(q => q.Marked("Send Message"));
RunningApp.Tap(q => q.Marked("Do GC"));
RunningApp.WaitForElement (q => q.Marked ("Instances: 0"));
RunningApp.WaitForElement (q => q.Marked ("Messages: 0"));
}
#endif
}
[Preserve(AllMembers = true)]
public class _45926IntermediatePage : ContentPage
{
}
[Preserve(AllMembers = true)]
public class _45926SecondPage : ContentPage
{
public static int InstanceCounter = 0;
public static int MessageCounter = 0;
public _45926SecondPage ()
{
Interlocked.Increment(ref InstanceCounter);
Content = new Label {
HorizontalOptions = LayoutOptions.Center,
VerticalOptions = LayoutOptions.Center,
Text = "Second Page #" + (InstanceCounter)
};
MessagingCenter.Subscribe<Bugzilla45926> (this, "Test", OnMessage);
}
protected override void OnDisappearing ()
{
base.OnDisappearing ();
}
void OnMessage (Bugzilla45926 app)
{
System.Diagnostics.Debug.WriteLine ("Got Test message!");
Interlocked.Increment(ref MessageCounter);
}
~_45926SecondPage ()
{
Interlocked.Decrement(ref InstanceCounter);
System.Diagnostics.Debug.WriteLine ("~SecondPage: {0}", GetHashCode ());
}
}
}
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