C#1FriendlyDoge

✅ Run code in main thread after Task.Run completed?

Hello, I have a long running void function that I execute in a separate thread by calling Task.Run(MyFunction). Now how could I run another function in the main thread when this one ends? Do I need to make an event or something? What are the common approaches to this?

Kouhai ／人◕ ‿‿ ◕人＼•412d ago

You'll need a way to schedule a method to be invoked on the main thread the same way BeginInvoke works

1FriendlyDoge•412d ago

Cant use BeginInvoke because I use AvaloniaUI instead of winforms :(

Kouhai ／人◕ ‿‿ ◕人＼•412d ago

You can use Dispatcher.BeginInvoke

1FriendlyDoge•412d ago

also not defined (probably because it isnt cross platform)

Kouhai ／人◕ ‿‿ ◕人＼•412d ago

Ah, it's called InvokeAsync in Avalonia

1FriendlyDoge•412d ago

Do I just run that in my Task?

Kouhai ／人◕ ‿‿ ◕人＼•412d ago

Yes, InvokeAsync will schedule a function to be called on the main thread

1FriendlyDoge•412d ago

Seems to have zero effect

if(_auth.ResolveIdentifier() && Storage.DiscordUser != null)
{
    Dispatcher.UIThread.InvokeAsync(() =>
    {
        AuthStatus = "Authenticated as " + Storage.DiscordUser.username + "#" + Storage.DiscordUser.discriminator;
    }).Start();
    return;
}

if(_auth.ResolveIdentifier() && Storage.DiscordUser != null)
{
    Dispatcher.UIThread.InvokeAsync(() =>
    {
        AuthStatus = "Authenticated as " + Storage.DiscordUser.username + "#" + Storage.DiscordUser.discriminator;
    }).Start();
    return;
}

AuthStatus is just an ObservableProperty that is bound to a textblock in my UI Every component on its own works, just when I combine them nothing happens, the function ends without the UI being modified

Kouhai ／人◕ ‿‿ ◕人＼•412d ago

Don't call .Start

1FriendlyDoge•412d ago

Same effect sadly

Kouhai ／人◕ ‿‿ ◕人＼•412d ago

Have you checked whether the passed method gets called or not?

1FriendlyDoge•412d ago

yup, put Environment.Exit(0); right after for debugging, got called

Kouhai ／人◕ ‿‿ ◕人＼•412d ago

So the method is getting called... Also in Avalonia's docs they say it's better to use Post if you don't need to wait for a result to return

1FriendlyDoge•412d ago

The weird thing is, it even calls the Environment.Exit when I put it in the dispatch body

if(_auth.ResolveIdentifier() && Storage.DiscordUser != null)
{
    Dispatcher.UIThread.Post(() =>
    {
        AuthStatus = "Authenticated as " + Storage.DiscordUser.username + "#" + Storage.DiscordUser.discriminator;
        Environment.Exit(0);
    });
    return;
}

if(_auth.ResolveIdentifier() && Storage.DiscordUser != null)
{
    Dispatcher.UIThread.Post(() =>
    {
        AuthStatus = "Authenticated as " + Storage.DiscordUser.username + "#" + Storage.DiscordUser.discriminator;
        Environment.Exit(0);
    });
    return;
}

This is so weird And updating AuthStatus in sync works like normal

jcotton42•412d ago

is there any reason you can't just do

await Task.Run(...);
OtherFunctionYouWantToRun();

await Task.Run(...);
OtherFunctionYouWantToRun();

1FriendlyDoge•412d ago

My UI would freeze doing that

jcotton42•412d ago

no it won't await doesn't block the calling thread or at least, it shouldn't unless you've done something wrong

1FriendlyDoge•412d ago

Is there any way to make a constructor async, or what is the best way to make it call an async function that runs this?

jcotton42•412d ago

constructors cannot be async what is this constructor for? A window or page? (or something similar)

1FriendlyDoge•412d ago

ViewModel of a page

jcotton42•412d ago

does the Page have like a loaded event?

1FriendlyDoge•412d ago

Pretty sure no Viewmodel constructor is pretty much that

jcotton42•412d ago

can you link the control you're using? I can't seem to find one called Page

1FriendlyDoge•412d ago

I am using https://avaloniaui.net and this is just a viewmodel of a usercontrol I use as page

jcotton42•412d ago

ah hm I found this https://github.com/AvaloniaUI/Avalonia/issues/1049

GitHub

How to bind command to loaded event? · Issue #1049 · AvaloniaUI/Ava...

Has Avalonia any api similar with this?

jcotton42•412d ago

but otherwise you might need to use the dispatcher I guess

1FriendlyDoge•412d ago

The thing is just that the dispatcher doesnt seem to work It can dispatch everything I tried so far, just not UI changes for some reason

jcotton42•412d ago

if AuthStatus is being bound to, you might not even need the dispatcher

1FriendlyDoge•412d ago

<TextBlock
                FontFamily="Open Sans"
                FontSize="20"
                Text="{Binding AuthStatus}"
                TextAlignment="Center">
</TextBlock>

<TextBlock
                FontFamily="Open Sans"
                FontSize="20"
                Text="{Binding AuthStatus}"
                TextAlignment="Center">
</TextBlock>

jcotton42•412d ago

also, found this https://docs.avaloniaui.net/guides/basics/accessing-the-ui-thread

You can access the current UI thread via Dispatcher.UIThread. You can either use Post or InvokeAsync, if you want to run a job on the UI thread. Use Post when you just want to start a job, but you don't need to wait for the job to be finished and you don't need the result. If you need to wait for the result, then use InvokeAsync instead.

it looks you should be using Post, or using InvokeAsync, but also awaiting it

1FriendlyDoge•412d ago

Already tried both of those, both dont work

jcotton42•412d ago

I also see nothing about Start need to dip, have a work meeting starting

1FriendlyDoge•411d ago

I copied 1:1 from that page, both approaches do nothing Alright, thank you for your help (Bump) $close

MODiX•411d ago

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