Running SignalR self-host samples throws exception with latest mono dev branch - linux

Question

Using Mono on Linux, the sample Microsoft.AspNet.SignalR.Mono found at https://github.com/SignalR/SignalR seems to work using the stable release of mono but not with the latest development branch (3.99). Anyone encounter this? I get the following exception:
Unhandled Exception:
System.Reflection.TargetInvocationException: Exception has been thrown by the
target of an invocation. ---> System.InvalidProgramException: Invalid IL code
in (wrapper delegate-invoke)
<Module>:invoke_callvirt_CancellationTokenRegistration_CancellationToken&_Action`1<object>_object
(System.Threading.CancellationToken&,System.Action`1<object>,object): IL_004f:
castclass 0x00000007
at
Microsoft.AspNet.SignalR.Infrastructure.CancellationTokenExtensions.SafeRegister
(CancellationToken cancellationToken, System.Action`1 callback, System.Object
state) [0x00000] in <filename unknown>:0
at
Microsoft.AspNet.SignalR.Hosting.HostDependencyResolverExtensions.InitializeResolverDispose
(IDependencyResolver resolver, CancellationToken hostShutdownToken) [0x00000]
in <filename unknown>:0
at
Microsoft.AspNet.SignalR.Hosting.HostDependencyResolverExtensions.InitializeHost
(IDependencyResolver resolver, System.String instanceName, CancellationToken
hostShutdownToken) [0x00000] in <filename unknown>:0
at Owin.OwinExtensions.UseSignalRMiddleware[PersistentConnectionMiddleware]
(IAppBuilder builder, System.Object[] args) [0x00000] in <filename unknown>:0
at Owin.OwinExtensions.RunSignalR (IAppBuilder builder, System.Type
connectionType, Microsoft.AspNet.SignalR.ConnectionConfiguration configuration)
[0x00000] in <filename unknown>:0
at Owin.OwinExtensions.RunSignalR[RawConnection] (IAppBuilder builder,
Microsoft.AspNet.SignalR.ConnectionConfiguration configuration) [0x00000] in
<filename unknown>:0
at Owin.OwinExtensions.RunSignalR[RawConnection] (IAppBuilder builder)
[0x00000] in <filename unknown>:0
at Microsoft.AspNet.SelfHost.Samples.Startup.<Configuration>b__0 (IAppBuilder
map) [0x00000] in <filename unknown>:0
at Owin.MapExtensions.Map (IAppBuilder app, PathString pathMatch,
System.Action`1 configuration) [0x00000] in <filename unknown>:0
at Owin.MapExtensions.Map (IAppBuilder app, System.String pathMatch,
System.Action`1 configuration) [0x00000] in <filename unknown>:0
at Microsoft.AspNet.SelfHost.Samples.Startup.Configuration (IAppBuilder app)
[0x00000] in <filename unknown>:0
at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke
(System.Reflection.MonoMethod,object,object[],System.Exception&)
at System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags
invokeAttr, System.Reflection.Binder binder, System.Object[] parameters,
System.Globalization.CultureInfo culture) [0x00000] in <filename unknown>:0
--- End of inner exception stack trace ---
at System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags
invokeAttr, System.Reflection.Binder binder, System.Object[] parameters,
System.Globalization.CultureInfo culture) [0x00000] in <filename unknown>:0
at System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[]
parameters) [0x00000] in <filename unknown>:0
at Owin.Loader.DefaultLoader+<>c__DisplayClass12.<MakeDelegate>b__b
(IAppBuilder builder) [0x00000] in <filename unknown>:0
at Owin.Loader.DefaultLoader+<>c__DisplayClass1.<LoadImplementation>b__0
(IAppBuilder builder) [0x00000] in <filename unknown>:0
at Microsoft.Owin.Hosting.Engine.HostingEngine.ResolveApp
(Microsoft.Owin.Hosting.Engine.StartContext context) [0x00000] in <filename
unknown>:0
at Microsoft.Owin.Hosting.Engine.HostingEngine.Start
(Microsoft.Owin.Hosting.Engine.StartContext context) [0x00000] in <filename
unknown>:0
at Microsoft.Owin.Hosting.Starter.DirectHostingStarter.Start
(Microsoft.Owin.Hosting.StartOptions options) [0x00000] in <filename unknown>:0
at Microsoft.Owin.Hosting.Starter.HostingStarter.Start
(Microsoft.Owin.Hosting.StartOptions options) [0x00000] in <filename unknown>:0
at Microsoft.Owin.Hosting.WebApp.StartImplementation (IServiceProvider
services, Microsoft.Owin.Hosting.StartOptions options) [0x00000] in <filename
unknown>:0
at Microsoft.Owin.Hosting.WebApp.Start (Microsoft.Owin.Hosting.StartOptions
options) [0x00000] in <filename unknown>:0
at Microsoft.Owin.Hosting.WebApp.Start[Startup]
(Microsoft.Owin.Hosting.StartOptions options) [0x00000] in <filename unknown>:0
at Microsoft.Owin.Hosting.WebApp.Start[Startup] (System.String url) [0x00000]
in <filename unknown>:0
at Microsoft.AspNet.SelfHost.Samples.Program.Main (System.String[] args)
[0x00000] in <filename unknown>:0
[ERROR] FATAL UNHANDLED EXCEPTION: System.Reflection.TargetInvocationException:
Exception has been thrown by the target of an invocation. --->
System.InvalidProgramException: Invalid IL code in (wrapper delegate-invoke)
<Module>:invoke_callvirt_CancellationTokenRegistration_CancellationToken&_Action`1<object>_object
(System.Threading.CancellationToken&,System.Action`1<object>,object): IL_004f:
castclass 0x00000007

Answer 1

This looks like a bug in later versions of Mono. I reported this on Friday: http://bugzilla.xamarin.com/show_bug.cgi?id=29665

Answer 2

That issue is already reported on SignalIR repo. Try pulling the latest version of the dev branch, ASP.NET team have commented out the code throwing that exception as a workaround for now.

Answer 3

What I eventually went with was to return the fallback register in ResolveRegisterDelegate() if IsRunningMono is true:
if (MonoUtility.IsRunningMono)
return fallback;
try
{
methodInfo = typeof(CancellationToken).GetMethod("InternalRegisterWithoutEC",
BindingFlags.NonPublic | BindingFlags.Instance,
binder: null,
types: new[] { typeof(Action<object>), typeof(object) },
modifiers: null);
}
catch
{
// Swallow this exception. Being extra paranoid, we don't want anything to break in case this dirty
// reflection hack fails for any reason
}
I noticed that this was happening in the earlier stable release of mono because the GetMethod("InternalRegisterWithoutEC") was returning null and did NOT return null with the latest dev branch of mono.