CTS timeout and linked cancellation tokens

[pepone]

    I don't know.

CreateLinkedTokenSource + CancelAfter creates one less disposable object and doesn't involve UnsafeRegister... so it looks cleaner.

Originally posted by @bernardnormier in #2396 (comment)

[pepone]

We should sort this out we use both patterns, and the reason to pick one or the other is not clear

The deadline interceptor and middleware use UnsafeRegister

https://github.com/zeroc-ice/icerpc-csharp/blob/1574c9ec419b5fac88a5c24eb07c170a92f0a075/src/IceRpc.Deadline/DeadlineInterceptor.cs#L79-L82

Using CreateLinkedTokenSource and CancelAfter seems simpler, the implementation of CreateLinkedTokenSource hides this UnsafeRegister call and the CanBeCanceled check

https://github.com/dotnet/runtime/blob/5b8ebeabb32f7f4118d0cc8b8db28705b62469ee/src/libraries/System.Private.CoreLib/src/System/Threading/CancellationTokenSource.cs#L747-L748

https://github.com/dotnet/runtime/blob/5b8ebeabb32f7f4118d0cc8b8db28705b62469ee/src/libraries/System.Private.CoreLib/src/System/Threading/CancellationTokenSource.cs#L773-L792

On the other hand, it makes sense to use UnsafeRegister to avoid allocating an additional TCS like in

https://github.com/zeroc-ice/icerpc-csharp/blob/1574c9ec419b5fac88a5c24eb07c170a92f0a075/src/IceRpc/Transports/Internal/SlicPipeWriter.cs#L82-L84

Here using UsafeRegister avoids allocating a CTS, but other than that the CreateLinkedTokenSource is similar under the hood it uses UnsafeRegister we are not paying for the synchronization context stuff

Related:

dotnet/runtime#27238