TemplateRenderer should use ThrowIfFaulted when waiting for faulted task

[yishaigalatzer]

Html.EditorFor and Html.DisplayFor are synchronous today. When rendering a view for the editor \ display template, it calls Wait(). Instead we should have both a sync and async pipeline (add Html.EditorForAsync, Html.DisplayForAsync) and have the synchronous version make the blocking call.

Original discussion:

See: https://github.com/aspnet/Mvc/blob/dev/src/Microsoft.AspNet.Mvc.Core/Rendering/Html/TemplateRenderer.cs#L103

Looks like the pipeline needs to accommodation async and we shouldn't be making blocking calls.

[yishaigalatzer]

@davidfowl @lodejard - We are thinking that editor templates should just be sync only.
But if you have other thoughts lets chat about it.

[pranavkm]

Spoke to @loudej and he thinks we should have an async rendering pipeline for Html.EditorFor \ DisplayFor. The synchronous calls will end up doing blocking calls (.Wait()) like they do now.

cc @dougbu

[yishaigalatzer]

I was under the impression that wait calls can end up being deadlocks, and its generally frowned upon.

Can we instead say that editor templates are sync only?

[pranavkm]

Spoke to @GrabYourPitchforks about this today and his opinion was that in the absence of a sync context, we shouldn't have the same sort of issues calling Wait(). His only suggestion was to change the actual Wait() call to task.GetAwaiter().GetResult(). This preserves the stack trace in the event the Task throws.

[yishaigalatzer]

Should we have an extension method to do that?

-----Original Message-----
From: "Pranav K" notifications@github.com
Sent: ‎8/‎14/‎2014 3:42 PM
To: "aspnet/Mvc" Mvc@noreply.github.com
Cc: "Yishai Galatzer" yishai_galatzer@yahoo.com
Subject: Re: [Mvc] TemplateRenderer should not call renderasync().Wait()(#782)

Spoke to @GrabYourPitchforks about this today and his opinion was that in the absence of a sync context, we shouldn't have the same sort of issues calling Wait(). His only suggestion was to change the actual Wait() call to task.GetAwaiter().GetResult(). This preserves the stack trace in the event the Task throws.
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Reply to this email directly or view it on GitHub.

[pranavkm]

We decided to reduce the scope of this bug and address the issue with calling Task.Wait().

[davidfowl]

Was this done? If so why is it still working? /cc @yishaigalatzer @danroth27