Test with loom

[jonhoo]

@carllerche recently published loom which does correctness checking for concurrent algorithms. It'd be neat to try to get that working for evmap's tests!

[jonhoo]

cc @novacrazy

[aDotInTheVoid]

I've started work on this here

[aDotInTheVoid]

Currently, this is blocked on loom only supporting Aquire fences.

[jonhoo]

Hmm, my guess here is that you can just test with Acquire fences, and it should be fine. Or at least you should be able to make progress. You can see what I did to deal with this in crossbeam: https://github.com/crossbeam-rs/crossbeam/blob/03e04ba4426e47f6b76d9e9da551c81157f9cbb0/crossbeam-epoch/src/lib.rs#L81-L92

[jonhoo]

@aDotInTheVoid Did you have a change to try out using a stronger fence for testing?

[jonhoo]

Now that evmap is split up into left-right and evmap, it should be easier to at least get loom testing for left-right itself!