如何使用 Async 和 Await 技术编写函数？

Question

I want to run a void function that writes to a textblock in WPF

private async Task<int> TASK_ClickthroughBuild(string server, int frame, int click)
{
    if (server == "value")
    {
        CreativeCode.Inlines.Add(openScript + newLine);
        CreativeCode.Inlines.Add("var " + click + " = '%%CLICK_URL_ESC%%%%DEST_URL%%';" + newLine);
        CreativeCode.Inlines.Add("var " + frame + " = document.getElementById('" + frame + "');" + newLine);
        CreativeCode.Inlines.Add(frame + ".href = " + click + ";" + newLine);
        CreativeCode.Inlines.Add(closeScript);
        PASSBACKframeINT = frame;              
    }
    return PASSBACKframeINT;
}

The above function returns an integer value and writes code to a textblock.

This is the second function.

private async Task clickElementBuild()
{
    CreativeCode.Inlines.Add("<a href='#' id='" + PASSBACKframeINT + "' target='_blank' class='" + PASSBACKwrapINT + "' >" + newLine);
    CreativeCode.Inlines.Add("<div class='" + PASSBACKblockINT + "' id='" + overlayINT + "'></div>" + newLine);
}

The second function, the code needs to write the textblock code ABOVE the first function, but depends on the returned value of first function to write properly.

So I need to write this in an Asynchronous format. Can I have pointers or a better way of doing this?

Thanks

Answer 1

I'm assuming you're using .NET 4.5 or else you'd have chosen a Threading-Solution.

Calling an async Function is basically telling the Mainthread to pass everything to a Backgroundthread.

As asynchronous functions are called there's the "risk of soft data consistency". Like in your case or in simpler words the analogy of Forms.show() and Forms.showDialog().

There are several ways to bypass this. Threading solves this with JOIN() OR WAITALL() and async with System.Threading.Thread.Sleep(x) or some prefer Application.DoEvents()

You can place an Await-For-Background-Task-Clause above your Code which is in risk of "soft data consistency" or place the code it in the Mainthread.

If you're new to async functions. I recommend this tutorial to use it.

https://visualstudiomagazine.com/articles/2014/06/01/how-to-simplify-asynchronous-programming.aspx

Answer 2

Sorted. Basically, return the value and used Async to await the returned value in the first place.