ci: Run loom test in tokio-util

[pepedinho]

Added a dedicated CI task to run sync_cancellation_token tests in Loom.

Note:
I was unable to apply the --cfg loom flag to this test because it generated compilation conflicts. Therefore, the test runs without it in this task.

fixes #7271

[Darksonn]

Can you clarify what you mean about not being able to apply --cfg loom? I see it right here.

[pepedinho]

my bad, I removed it in my local tests, but I forgot to remove it in the CI, I will send a commit to fix that

[ADD-SP]

Here are some suggestions in case you are unfamiliar with the tokio project.

You could add loom as dev-dependency gated by cfg(loom), here is an example.

tokio/tokio/Cargo.toml

Lines 159 to 160 in dd74c7c

	[target.'cfg(loom)'.dev-dependencies]
	loom = { version = "0.7", features = ["futures", "checkpoint"] }

Then, enter the tokio-util directory, an run the following command.

LOOM_MAX_PREEMPTIONS=1 LOOM_MAX_BRANCHES=10000 \
RUSTFLAGS="-C debug_assertions --cfg tokio_unstable --cfg loom" \
 cargo test --features full cancellation_token -- --test-threads=1 --nocapture

You will see several compilation errors, including some use import statements are failed, this is because some module is gated by #![cfg(not(loom))] but tokio-util doesn't has relevant gate. this can be fixed by adding #![cfg(not(loom))] in a proper place.

Once you have finished all compilation errors, you could read the document of loom to understand its usage, and also read existing loom tests as example.

You might also need to mock the std's import by loom, just like what tokio did.

Finally, you can run tests, write tests, and fix tests.

[pepedinho]

Thank you very much for your help and your time. I’ve added the guards everywhere they were needed, and now the tests run without any issues using the --cfg loom flag.
Now i run this in ci job :

LOOM_MAX_PREEMPTIONS=1 LOOM_MAX_BRANCHES=10000 \
          RUSTFLAGS="-C debug_assertions --cfg tokio_unstable --cfg loom" \
          cargo test --features full --test sync_cancellation_token -- --test-threads=1 --nocapture

[ADD-SP]

Please add the loom as optional dev-dependency of tokio-util, we also need to enable tokio-util/src/sync/tests/loom_cancellation_token.rs as this test is currently ignored.

[ADD-SP]

Suggested change

	working-directory: tokio
	working-directory: tokio-util

[ADD-SP]

Suggested change

	cargo test --features full --test sync_cancellation_token -- --test-threads=1 --nocapture
	cargo test --lib --release --features full -- --test-threads=1 --nocapture loom_cancellation_token