Remove .Result inside Client.MaybeClose method

[iuribrindeiro]

I'm facing the following error when trying to close a connection:

Unhandled exception. System.AggregateException: One or more errors occurred. (Operation is not valid due to the current state of the object.)
 ---> System.InvalidOperationException: Operation is not valid due to the current state of the object.
   at System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore`1.SignalCompletion()
   at System.Threading.Tasks.Sources.ManualResetValueTaskSourceCore`1.SetException(Exception error)
   at RabbitMQ.Stream.Client.ManualResetValueTaskSource`1.SetException(Exception error)
   at RabbitMQ.Stream.Client.Client.<>c__54`2.<Request>b__54_0(Object valueTaskSource)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.CancellationTokenSource.ExecuteCallbackHandlers(Boolean throwOnFirstException)
   --- End of inner exception stack trace ---
   at System.Threading.CancellationTokenSource.ExecuteCallbackHandlers(Boolean throwOnFirstException)
   at System.Threading.TimerQueueTimer.Fire(Boolean isThreadPool)
   at System.Threading.TimerQueue.FireNextTimers()
   at System.Threading.ThreadPoolWorkQueue.Dispatch()
   at System.Threading.PortableThreadPool.WorkerThread.WorkerThreadStart()

See this issue #25 for historical discussion

After cloning and debugging the source code of this library, I figured out that there is a Task.Result under the Client.MaybeClose method. I don't really understand why we couldn't just make MaybeClose return type async Task<CloseResponse> and await on that particular task there. Not sure if there is a reason for that. But I would like to mention that I can't even create a connection when the current SynchronizationContext runs on the main thread because there is no .ConfigureAwait(false) under StreamSystem.Create, for example. Is there a reason why we don't use ConfigureAwait(false) very often? According to this microsoft blog post libraries should use this to prevent getting the current application SynchronizationContext and cause a deadlock (like what is happening to Client.MaybeClose).

Here is a repo that reproduces this issue by implementing a custom single thread SynchronizationContext: https://github.com/iuribrindeiro/RabbitMQThreadIssue

I'm up to raise a PR to fix this, if that is the case.

[Gsantomaggio]

Thank you.
The link https://github.com/iuribrindeiro/RabbitMQThreadIssue does not work!

[iuribrindeiro]

Thank you. The link https://github.com/iuribrindeiro/RabbitMQThreadIssue does not work!

I'm so sorry, I think that I made it private by mistake. Please try again.

[Gsantomaggio]

you are right. We have to add ConfigureAwait(false)

We are working on 1.2.0 version. Feel free to propose a PR. thank you

[Gsantomaggio]

@iuribrindeiro do you have a chance to test #230 ? it should solve the problem

[iuribrindeiro]

Oh, this is great! Will try it till next Monday.