Async locking

[MarkCiliaVincenti]

No description provided.

[NotOfficer]

Hey, thanks for the PR but i think this isn't beneficial here. I'd rather not use async locking when the scope itself isn't async to reduce overload, especially in a progress callback.

[MarkCiliaVincenti]

Hi, first off apologies for the indentation mess.
I see what you mean, but I wasn't sure if that callback call could take its time.
In essence the proposed code helps reduce mixing of synchronous code in async methods and the lock observes the cancellation token.

[NotOfficer]

Yeah no problem, i diffed it on a local tool with tabs replaced. Its an user-callback/event with the intention to just update a progress component's state. But i also see the pros of using the async lock if it might take longer. But then again you dont want a progress callback to take long, otherwise it will slowdown the download.