Serialization problem

[imperugo]

Hi folks,
I'm getting an error during RunCompilemethod.

For a reason that I don't know the lasted version or RazorEngine is trying to serialize a class used into my project. That class is not serializable for tha reason the app crashes.
The weird part is that the previous version of RazorEngine was working, so probably is something related to the new version.

Here the error message:

Type 'Owin.OwinRequestScopeContext' in assembly 'OwinRequestScopeContext, Version=1.0.1.0, Culture=neutral, PublicKeyToken=null' is not marked as serializable.

and here the stack

at System.AppDomain.InternalCreateInstanceFromWithNoSecurity(String assemblyName, String typeName) at RazorEngine.Compilation.CrossAppDomainCleanUp..ctor(AppDomain toWatch, IPrinter printer) at RazorEngine.Compilation.CrossAppDomainCleanUp.CreateInitial() at System.Lazy`1.CreateValue() --- End of stack trace from previous location where exception was thrown --- at System.Lazy`1.get_Value() at RazorEngine.Compilation.CrossAppDomainCleanUp.RegisterCleanup(String item, Boolean throwOnDefault) at RazorEngine.Templating.DefaultCachingProvider.CacheTemplate(ICompiledTemplate template, ITemplateKey templateKey) at RazorEngine.Templating.RazorEngineService.CompileAndCacheInternal(ITemplateKey key, Type modelType) at RazorEngine.Templating.RazorEngineService.GetCompiledTemplate(ITemplateKey key, Type modelType, Boolean compileOnCacheMiss) at RazorEngine.Templating.RazorEngineService.GetTemplate(ITemplateKey key, Type modelType, Object model, DynamicViewBag viewbag) at RazorEngine.Templating.TemplateService.GetTemplate(String razorTemplate, Object model, String cacheName) at RazorEngine.Templating.TemplateService.Parse(String razorTemplate, Object model, DynamicViewBag viewBag, String cacheName) at RazorEngine.Razor.Parse[T](String razorTemplate, T model, String cacheName) at 

Any hint?

[matthid]

Can you tell me more about your environment? This has to do with the cleanup code, which ensures that temporary files are deleted once the AppDomain has been unloaded.

If you are fine with temporary files remaining on disk you can use:

config.CachingProvider = new DefaultCachingProvider(t => { 
    /*TODO: Delete t after the application has been closed */ })

But this needs further investigation why it wants to serialize your class...

[matthid]

Can you try to spin up a new Thread dedicated for RazorEngine only and see if that fixes the problem?

[imperugo]

Hi @matthid
your fix works!!!
About the environment I'm on Windows 8.1, IIS, MVC/WebApi/Owin and I'm using RazorEngine into IdentityServer3.

All packages are up to date from nuget.
Do you need more info?

[matthid]

Well it's not really a fix as you now need to cleanup your temp files regularly ...
I think I now know what the issue is (even I have no repro). The info provided in #268 helped. Thanks @impworks.

Can you test the Thread method as well (ie just wrapping RazorEngine calls to a new Thread)
and if it doesn't work:

using (var flow = System.Threading.ExecutionContext.SuppressFlow()) {
  // Call RazorEngine here
  flow.Undo()
}

And if that doesn't work a combination of those (spin up a new thread while the flow is suppressed).

If that works I can integrate a fix in RazorEngine.

[imperugo]

Doing this

using (var flow = System.Threading.ExecutionContext.SuppressFlow()) 
{
    parsedHtml = Engine.Razor.RunCompile(template, cacheKey, model.GetType(), model);

    // Call RazorEngine here
    flow.Undo();
}

I still have the error.

[imperugo]

btw I'm on async method, so another thread, maybe could be useful to know

[matthid]

And with

using (var flow = System.Threading.ExecutionContext.SuppressFlow()) 
{
    var t = new System.Threading.Thread(() =>
    {
          parsedHtml = Engine.Razor.RunCompile(template, cacheKey, model.GetType(), model);
    });
    t.Start();
    t.Join();
    flow.Undo();
}

?

[imperugo]

In this case parsedHtml is not available out or that thread. I should wait right?

[matthid]

yeah wait for the thread to finish. It's just for testing I don't recommend using this code ...

[imperugo]

I'm getting AsyncFlowControl object can be used only once to call Undo().

with that

using (var flow = System.Threading.ExecutionContext.SuppressFlow())
{
    var t = new System.Threading.Thread(() =>
    {
        parsedHtml = Engine.Razor.RunCompile(template, cacheKey, model.GetType(), model);
    });
    t.Start();
    t.Join();
    flow.Undo();

    return Task.FromResult(StringToStream(parsedHtml));
}

[matthid]

I think you can remove the Undo call. But it removes the other Exception which looks good.

[imperugo]

Ok works.
So what's the best workaround? New thread or Caching Provider?