Feature/1077 component registration activating properties autowired

[weelink]

No description provided.

[weelink]

When a registration is added during the lookup of a ServiceRegistrationInfo, the Registered and RegistrationSourceAdded events aren't raised. In order to raise these events, a reference to a IComponentRegistryBuilder is required.

This introduces a nasty design issue. ComponentRegistryBuilder depends on a IRegisteredServicesTracker and DefaultRegisteredServicesTracker depends on a ComponentRegistryBuilder, but only when raising these events.

The two failed tests (WhenRegistrationIsMade_ComponentRegisteredEventFired and WhenASourceIsAddedToTheRegistry_TheSourceAddedEventIsRaised) also indicate that there is some design problem.

The underlying problem that needs to be fixed is how to raise these events from DefaultRegisteredServicesTracker?

[weelink]

The failing test is WhenSeveralThreadsResolveNotAlreadyRegisteredType_DoesNotThrow. This PR doesn't touch any code related to this test as far as I can tell.

This may be an unrelated bug. @tillig any thoughts?

[tillig]

Entirely from the top of my head, because unfortunately I'm super swamped with the old day job at the moment and all my "free time" was used up by the Autofac 5 release and ensuing set of other releases, bugs, etc...

The test in question:

        [Fact]
        public void WhenSeveralThreadsResolveNotAlreadyRegisteredType_DoesNotThrow()
        {
            for (var i = 0; i < 20_000; i++)
            {
                var builder = new ContainerBuilder();
                builder.RegisterSource(new AnyConcreteTypeNotAlreadyRegisteredSource());
                var container = builder.Build();
                Parallel.Invoke(() => container.Resolve<A>(), () => container.Resolve<A>());
            }
        }

And the failed test error stack trace:

  Error Message:
   System.AggregateException : One or more errors occurred.
---- System.InvalidOperationException : Collection was modified; enumeration operation may not execute.
  Stack Trace:
     at System.Threading.Tasks.Task.FastWaitAll(Task[] tasks)
   at System.Threading.Tasks.Parallel.Invoke(ParallelOptions parallelOptions, Action[] actions)
   at System.Threading.Tasks.Parallel.Invoke(Action[] actions)
   at Autofac.Test.Concurrency.ConcurrencyTests.WhenSeveralThreadsResolveNotAlreadyRegisteredType_DoesNotThrow() in C:\projects\autofac\test\Autofac.Test\Concurrency\ConcurrencyTests.cs:line 144
----- Inner Stack Trace -----
   at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Collections.Generic.List`1.Enumerator.MoveNextRare()
   at System.Collections.Generic.List`1.Enumerator.MoveNext()
   at System.Linq.Enumerable.<ConcatIterator>d__59`1.MoveNext()
   at System.Linq.Enumerable.Any[TSource](IEnumerable`1 source)
   at Autofac.Core.Registration.DefaultRegisteredServicesTracker.TryGetRegistration(Service service, IComponentRegistration& registration) in C:\projects\autofac\src\Autofac\Core\Registration\DefaultRegisteredServicesTracker.cs:line 147
   at Autofac.Core.Registration.ComponentRegistry.TryGetRegistration(Service service, IComponentRegistration& registration) in C:\projects\autofac\src\Autofac\Core\Registration\ComponentRegistry.cs:line 92
   at Autofac.ResolutionExtensions.TryResolveService(IComponentContext context, Service service, IEnumerable`1 parameters, Object& instance) in C:\projects\autofac\src\Autofac\ResolutionExtensions.cs:line 1064
   at Autofac.ResolutionExtensions.ResolveService(IComponentContext context, Service service, IEnumerable`1 parameters) in C:\projects\autofac\src\Autofac\ResolutionExtensions.cs:line 892
   at Autofac.ResolutionExtensions.Resolve[TService](IComponentContext context, IEnumerable`1 parameters) in C:\projects\autofac\src\Autofac\ResolutionExtensions.cs:line 314
   at Autofac.Test.Concurrency.ConcurrencyTests.<>c__DisplayClass5_0.<WhenSeveralThreadsResolveNotAlreadyRegisteredType_DoesNotThrow>b__1() in C:\projects\autofac\test\Autofac.Test\Concurrency\ConcurrencyTests.cs:line 144
   at System.Threading.Tasks.Task.InnerInvoke()
   at System.Threading.Tasks.Task.Execute()

This is potentially related to a recent change @alexmg worked on to try to solve a threading issue where ACTNARS was being problematic (#1073).

After inlining, it appears the problem is when it's looking at the Any call here to see if there are any existing implementations. That was inlined from the call on line 147.

That code:

if (_serviceInfo.TryGetValue(service, out var existing) && existing.IsInitialized && existing.Implementations.Any())
    return existing;

My gut feel is that potentially the fix for #1073 without the locking may have been passing... coincidentally? That is, before your changes the ACTNARS register-the-type-on-the-fly was happening fast enough that it would do the whole registration on one thread before the other thread could do its check for Any(). However, with the new changes where the Registered event is getting raised as things are added on the fly, there's enough delay that the thread is switching. So it's like...

• A: Get pretty far into the registration process so it's about to add the registration on the fly.
• B: Start into the registration process. Get into that line above, dereference existing.Implementations, and switch threads.
• A: Finish the registration process, raise the event (adding a delay), switch threads.
• B: existing.Implementations starts enumerating Any() and sees thread A changed the collection. Explode.

Roughly.

I don't know off the top of my head how to fix that. Is there a need for a concurrent collection for the implementations set? How will that affect perf? Is there a better call than Any() to make? I'm stabbing in the dark, brainstorming, not recommending any of these things. That's my off-the-cuff hypothesis with the small amount of time that I can look at this right now....

...which, unfortunately, just hit like half an hour so I'm toooootally out on this for now. Perhaps @alexmg, @alistairjevans, @alsami, or one of the other members of the @autofac/autofac org can help.