Properly Deal with Timeouts Inside device::maintain

[cwfitzgerald]

Connections

Closes #4589
Closes #3601

Description

We were not properly dealing with polls which timed out. This exposed the concept of timeouts to the user so that they can properly deal with polls which time out.

This doesn't fix anything with timeouts inside surface.configure.

Testing

Added timeout test.

Checklist

• Run cargo fmt.
• Run cargo clippy. If applicable, add:
  • --target wasm32-unknown-unknown
  • --target wasm32-unknown-emscripten
• Run cargo xtask test to run tests.
• Add change to CHANGELOG.md. See simple instructions inside file.

[cwfitzgerald]

Pulled this into draft as it breaks all of our WebGL2 tests.

tl;dr: the whole reason device.poll(Wait) worked on WebGL2 is because of a the very logic bug that this fixes. WebGL2 is always treated as a timeout, so it always treats the wait as finished. Which is completely UB on other backends, but on WebGL2 it doesn't matter as there's no way to observe the lack of it actually finishing.

Going to need to:

• Add a feature to make poll(Wait) fail validation.
• Add an async helper function for a cross platform poll(Wait)
• Switch all existing polls to that function.

[cwfitzgerald]

I still want to deal with this, it was just a much larger task than I initially thought.

[teoxoy]

This should also include the removal of the expected failure on MoltenVK (f38bdd8).

[thalisvilela]

My first time working with WebGPU today, trying to implement heavy slow compute shader workload, as i set up and tested everything, as soon i started throwing real work at it, stumbled upon this issue immediately... Not my lucky day...

[Wumpf]

@thalisvilela fwiw this issue does not affect WebGPU but all native backends + WebGL, but that's probably what you meant :)

[thalisvilela]

@Wumpf thank you very much for the tip! I would have probably give a shot at these other methods, you just saved me from a lot of frustration! It's the first time i'm working directly with "shaders", i've mostly used CUDA before. I'm glad this issue surfaced immediately to be honest.