Implement .NET 8 Blazor state management

[rockfordlhotka]

Closes #3596

[ossendorf-at-hoelscher]

Hi. Would you mind comments and questions from me to this pr changes?

[rockfordlhotka]

I love feedback!

@ossendorf-at-hoelscher if you'd like to be able to use the PR feedback tools in GitHub, please send me a signed contributor agreement and I'll add you.

[ossendorf-at-hoelscher]

I love feedback!

@ossendorf-at-hoelscher if you'd like to be able to use the PR feedback tools in GitHub, please send me a signed contributor agreement and I'll add you.

I'll discuss this with my superior if I can get some worktime for such things. Otherwise I'll send one from my private account 😄

[rockfordlhotka]

@ossendorf-at-hoelscher I made quite a few changes - some based on your feedback.

I had it working, and then did something that broke the transition from wasm back to server. And I don't know what I did to break it 😢

Some observations.

1. I can't use ConcurrentDictionary because that appears to do a lock that blocks wasm->server transition
2. Using a tcs also seemed to block the wasm->server transition
3. Of course, 1 and 2 are now suspect, because it is currently broken anyway!
4. I'd forgotten that the initial landing page must initialize the cookie, and so state is unavailable for the site's initial landing page. I've now added properties that can be used to determine whether the state is actually available (via StateManager)

I don't know how deeply you (or anyone else) wants to invest in helping to get this working, but just in case, I have pushed my test project to GitHub:

https://github.com/rockfordlhotka/CslaBlazorApp

The solution directly references the Csla, Csla.AspNetCore, Csla.Blazor, and Csla.Blazor.WebAssembly projects. To help load the solution, here's my relative directory structure:

s:\src\CslaBlazorApp
s:\src\rdl\csla

If you clone those two repos into that folder structure, the solution should just load and run.

Unfortunately, right now, navigating from the Counter page (once it reloads as wasm) back to either server-rendered page will result in a timeout because the Counter page's Dispose method isn't invoking asynchronously like it should. It is being blocked by the initialize process of the server pages.

I can't figure out why right now. My Blazor8State app is implemented basically the same exact way, and it works fine (as did the CslaBlazorApp at one point in here).

[StefanOssendorf]

@rockfordlhotka A short analysis shows that your session.IsCheckedOut does not transition from true (used in WASM) to false (used on Server) when you have such a switch between pages. Is this bool really necessary?

[StefanOssendorf]

I suppose I should have read your comment more carefully 😅.

The Counters Dispose method is invoked when navigating from Counter -> Weather. But the updated session (on server) is never(?) updated on the client side. So you run into the timeout. Furthermore it's not a deadlock. It's just that no state change comes back after updating it on the server.

On that regard: You should change the Blazor StateManager from void SaveState to Task SaveState and await the Task of SendSession(). Otherwise you get timing problems which will be hard to track down.

[rockfordlhotka]

The goal is to support LocalContext, and the developer can change those values as they choose. So any changes made in wasm should be available on the server (and visa versa).

With my Blazor8State app I was able to make this work using the ischeckedout flag and the Dispose in the wasm page.

I momentarily had it working in CSLA as well, and really wish I'd done a git commit at that point!

[rockfordlhotka]

Furthermore it's not a deadlock

Sadly it really is. The wasm page isn't disposed because the server page is blocking the transition.

If the server page doesn't block, then dispose is called, the state is updated on the server, and the while loop exits.

[StefanOssendorf]

Do we have different before? Just to make sure: when I start your app with F5 and navigate away from counter. I get always the timeout exception. The WASM page gets disposed after the exception happens. So the spinlock is executing and not blocked/dead. Btw: happy new year 😄 Rockford Lhotka ***@***.***> schrieb am Mo., 1. Jan. 2024, 22:46:

…

Furthermore it's not a deadlock Sadly it really is. The wasm page isn't disposed because the server page is blocking the transition. If the server page doesn't block, then dispose is called, the state is updated on the server, and the while loop exits. — Reply to this email directly, view it on GitHub <#3641 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABJCZOPXXLHUIMROKOZW64TYMMVERAVCNFSM6AAAAABBE2FUTOVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTQNZTGQ4TEOJVGM> . You are receiving this because you commented.Message ID: ***@***.***>

[rockfordlhotka]

Now you see why I added the timeout, otherwise the browser is permanently locked.

Run the Blazor8State app to see how it works, and why I'm puzzled that the csla app fails.

[rockfordlhotka]

I figured it out! Finally!

I was meticulously comparing my working Blazor8State code to the not working CslaBlazorApp code. Line by line, undoing all sorts of nice improvements, etc.

Finally realized that the server-static page in the working code is streaming. That's the key, is to have the server-static page be streaming, so it starts rendering and thus releases the wasm page to dispose.

[StefanOssendorf]

Great. So back to implementing the nice improvments :D

[StefanOssendorf]

Since the ConcurrentDictionary/ TaskCompletionSource wasn't the problem wouldn't it be better to try them now (with a working solution)?