Examples for Sync/Send leave too many open questions about comprehensive-rust HOT 2 OPEN

Hi @proski!

Possibly extraneous:

These types are thread-safe, but they cannot be moved to another thread:

• MutexGuard<T: Sync>: Uses OS level primitives which must be deallocated on the thread which created them.

It feels like a zoo with exotic animals. I'd rather see an exact definition of "thread-safe".

Yeah, this slide is tough... I normally have to add a lot of context around it when teaching. So we should start by adding the missing information to the notes at the bottom of the page.

If you like, you could send us a PR with any information you've found useful yourself.

from comprehensive-rust.

These types are thread-safe, but they cannot be moved to another thread:

• MutexGuard<T: Sync>: Uses OS level primitives which must be deallocated on the thread which created them.

It feels like a zoo with exotic animals. I'd rather see an exact definition of "thread-safe".

I would say that in this context "thread-safe" is trying to convey that these are types whose values can be safely accessed from multiple threads concurrently. This means, of course, having a reference to them in multiple threads, AKA Sync. This makes sense for MutexGuard, as its most useful attribute is its Deref::deref method which takes &self.

It would be good to clarify this in the slide content itself.

from comprehensive-rust.