feat(driver,net)!: more nonempty

[Berrysoft]

A new trait PollFirst is added to make compio-net simpler.

Also add poll_first for Accept.

[Copilot]

Pull request overview

This PR refactors socket non-empty/poll-first handling so compio-net can work against a new compio_driver::PollFirst trait, and extends the optimization to Accept on Linux/io-uring. It mainly centralizes poll-first state handling in compio-net while wiring the new trait through driver socket operations.

Changes:

• Add a new public PollFirst trait in compio-driver and migrate receive/managed socket ops from inherent poll_first() methods to trait impls.
• Extend io-uring poll-first support to Accept, including Linux kernel gating and listener-side state tracking in compio-net.
• Replace the non-Linux inline socket-state stub with a dedicated stub.rs module and split Linux socket state into separate recv/accept tracking.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
compio-net/src/socket/stub.rs	Adds the non-Linux no-op SocketState stub used outside Linux.
compio-net/src/socket/mod.rs	Refactors socket recv/accept paths to use trait-based poll-first hooks and accept-side extra state.
compio-net/src/socket/linux.rs	Reworks Linux socket state into packed recv/accept non-empty tracking with poll-first helpers.
compio-driver/src/sys/pal/iour/mod.rs	Extends poll-first SQE flag gating so Accept uses a newer kernel threshold.
compio-driver/src/sys/op/socket/unix.rs	Adds poll-first state to Unix Accept and implements the new trait.
compio-driver/src/sys/op/socket/mod.rs	Replaces inherent poll_first() methods on socket receive ops with PollFirst trait impls.
compio-driver/src/sys/op/socket/iour.rs	Applies poll-first SQE flag handling to io-uring Accept.
compio-driver/src/sys/op/managed/iour.rs	Converts managed io-uring recv ops to the shared PollFirst trait.
compio-driver/src/sys/op/managed/fusion.rs	Forwards PollFirst through fused managed recv ops.
compio-driver/src/sys/op/managed/fallback.rs	Forwards PollFirst through fallback managed recv ops.
compio-driver/src/sys/driver/mod.rs	Introduces the new public PollFirst trait.

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[abh1nav10]

The try_update and update APIs landed in the standard library in 1.95. Maybe we can add it to synchrony, make a minor version bump, and then use it here as well, since fetch_update is getting deprecated in 1.99.
Happy to make a PR to synchrony!

[Berrysoft]

PRs are welcome :) , for synchrony.

[AsakuraMizu]

The try_update and update APIs landed in the standard library in 1.95.

@Berrysoft I want to ask that question again: Do we have a MSRV?

[Berrysoft]

Do we have a MSRV?

Again, no.