Timeout behavior support

[zachpainter77]

This PR adds support for creating a timeout behavior.

This PR is in direct response to #1056 , and the long discussion of #592. This was an older issue turned to discussion. I have solved the issue with the below implementation.

The below implementation modifies the RequestHandlerDelegate to take an optional CancellationToken. I also modify the RequestHandlerWrapperImpl to match the delegate so the casting still works. Then I modify the Aggregation to pass the token into the handle method for the next handler.

Usage:

 public class TimeoutBehavior<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse>
     where TRequest : notnull
 {
     public async Task<TResponse> Handle(TRequest request, RequestHandlerDelegate<TResponse> next, CancellationToken cancellationToken)
     {
         using (var cts = new CancellationTokenSource(someTimeoutDuration))
         {
             return await next(cts.Token);
         }
     }
 }

Test Handler:

 public class TimeoutRequestHandler : IRequestHandler<TimeoutRequest>
 {
     private readonly Dependency _dependency;

     public TimeoutRequestHandler(Dependency dependency) => _dependency = dependency;

     public async Task Handle(TimeoutRequest request, CancellationToken cancellationToken)
     {
         await Task.Delay(someTimeThatIsLongerThanTheTimeoutDuration, cancellationToken);

         _dependency.Called = true;
     }
 }

Unit Test:

 [Fact]
 public async Task TimeoutBehavior_Void_Should_Cancel_Long_Running_Task_And_Throw_Exception()
 {
     var request = new TimeoutRequest();

     var exception = await Should.ThrowAsync<TaskCanceledException>(() => _mediator.Send(request));

     exception.ShouldNotBeNull();
     exception.ShouldBeAssignableTo<TaskCanceledException>();
     _dependency.Called.ShouldBeFalse();
 }

[github-actions]

This PR is stale because it has been open 28 days with no activity. Remove stale label or comment or this will be closed in 14 days.

[dazinator]

not stale.. still waiting for feedback and hopeful merge..