Flowtable concurrent fuzz

[daniel-noland]

This is a temp placeholder while I discuss with @sergeymatov. Ignore for now if you aren't @sergeymatov

This PR is a temporary placeholder while the author discusses changes with @sergeymatov; reviewers other than @sergeymatov are asked to ignore it for now. It adds a FlowTable concurrency fuzz test and supporting concurrency-harness adjustments, and removes a FlowTable API incompatible with shuttle-based testing.

Summary

• New bolero-driven concurrent fuzz test for FlowTable (cfg(test) and cfg(not(feature = "loom"))):

  • Adds flow-entry/src/flow_table/concurrent_fuzz.rs: generates Scenario { seed_key, ops: [Vec; 3] } via bolero, normalizes generation so at least two worker streams include Insert, and implements bolero::TypeGenerator for Scenario.
  • Runs three concurrent worker threads via concurrency::thread::scope (one per op stream). Uses a shared Arc stored in a StubItem inside flow nat_state to exercise racing updates and asserts per-entry status after workers finish.
  • Selects either a current-thread Tokio runtime for the std backend or no runtime when running under shuttle.
  • Adds a test function stress_test_concurrency_model() that drives generation through concurrency::stress.

• Concurrency harness changes and exports:

  • concurrency/src/stress.rs: adds a public helper pub fn shuttle_config() -> shuttle::Config (cfg(all(not(feature = "loom"), feature = "shuttle"))) returning a Config with 4 MiB stack size; refactors the shuttle branch of stress to use shuttle_config().
  • concurrency/src/lib.rs: documents and publicly re-exports stress::stress (removed #[doc(hidden)]), and conditionally re-exports stress::shuttle_config when shuttle is enabled and loom is not.
  • concurrency/tests/quiescent_shuttle.rs: replaces shuttle::check_random / check_pct helper calls with explicit shuttle::Runner construction (RandomScheduler / PctScheduler) and runner.run, using the shared shuttle_config where applicable.

• FlowTable API and tests:

  • flow-entry/src/flow_table/table.rs: removes the public pub fn drain_stale(&self) -> usize method; related concurrent test assertions were tightened to assert_eq! where appropriate.

• Bolero test utilities for FlowInfo:

  • net/src/flows/flow_info.rs: under cfg(any(test, feature = "bolero")), adds pub fn new_with_status(...) to construct FlowInfo with an explicit FlowStatus, and a bolero::TypeGenerator for FlowStatus that maps sampled u8 % 8 into Active/Cancelled/Expired/Detached with Active weighted higher.

Notes, testing, and metadata

• The PR is explicitly a discussion placeholder; author notes enabling the [bolero] feature in a non-dev context was accidental (IDE assistance) and should be treated as a test/dev-only concern.
• The new fuzz test is excluded from loom builds (FlowTable uses DashMap-like concurrency not suitable for loom).
• Backends supported by the stress harness: std (current-thread Tokio runtime) and shuttle (portfolio runners with Random / PCT schedulers).
• Lines changed: large additions in flow-entry/src/flow_table/concurrent_fuzz.rs (+~322), medium changes in concurrency and flow_info files; estimated review effort: Medium–High.

Conventional commits

• Commits follow conventional-style messages; no merge commits present.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 26ccd14c-80b5-4f26-a1fe-cbf3ea6d361a

📥 Commits

Reviewing files that changed from the base of the PR and between c13f66f and 97eeb5f.

📒 Files selected for processing (1)

• flow-entry/src/flow_table/concurrent_fuzz.rs

🚧 Files skipped from review as they are similar to previous changes (1)

• flow-entry/src/flow_table/concurrent_fuzz.rs

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📝 Walkthrough

Walkthrough

Exposes concurrency::stress (with module docs) and a shuttle_config helper; updates shuttle tests to use explicit shuttle::Runner; adds bolero generators and FlowInfo test constructor; introduces a bolero-driven concurrent FlowTable fuzz test; removes FlowTable::drain_stale.

Changes

Concurrency Testing & FlowTable Fuzz Coverage

Layer / File(s)	Summary
Shuttle configuration extraction and re-export concurrency/src/stress.rs, concurrency/src/lib.rs	New shuttle_config() helper sets 4 MiB stack size; stress dispatcher uses it; public re-export with documentation exposes stress and shuttle_config (shuttle-only).
Bolero property generators for test data net/src/flows/flow_info.rs	Adds FlowInfo::new_with_status() constructor and FlowStatus bolero generator that biases toward Active while producing terminal states.
Migrate quiescent_shuttle tests to explicit Runner API concurrency/tests/quiescent_shuttle.rs	Both protocol_under_shuttle and protocol_under_shuttle_pct construct shuttle::Runner explicitly with RandomScheduler / PctScheduler and call runner.run instead of helper functions.
Comprehensive concurrent fuzz test for FlowTable flow-entry/src/flow_table/concurrent_fuzz.rs, flow-entry/src/flow_table/mod.rs	Bolero-driven scenario generator creates three concurrent workers performing Insert/Lookup/Invalidate/Extend on derived key sets with a shared Arc<AtomicU8> in locked nat_state; scenarios run via concurrency::stress with runtime selection based on backend.
FlowTable API cleanup and test assertions flow-entry/src/flow_table/table.rs	Removes public drain_stale() method; updates test_flow_table_reshard assertions to use assert_eq!.

🎯 3 (Moderate) | ⏱️ ~25 minutes

"🐰 I hop through stacks and configs bright,
Bolero seeds tumble into concurrent night,
Three workers race, atoms blink and spin,
Stress runs the plan — let the fuzzing begin,
A carrot for tests, chaos trimmed thin."

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Flowtable concurrent fuzz' is clear and directly describes the main change: adding a concurrent fuzzing test for FlowTable using bolero and the concurrency module.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

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🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch flowtable-concurrent-fuzz

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[Copilot]

Pull request overview

This PR adds bolero-driven concurrent fuzz coverage for FlowTable and refactors shuttle runner configuration so bolero+shuttle suites can share the same “standard” shuttle Config (notably the increased stack size).

Changes:

• Add a new concurrent bolero stress test module for FlowTable (flow-entry/src/flow_table/concurrent_fuzz.rs) and wire it into the test build.
• Add bolero::TypeGenerator support for net::flows::FlowStatus behind cfg(test) / feature = "bolero".
• Introduce and re-export concurrency::shuttle_config() and update an existing shuttle fuzz test to use it.

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
net/src/flows/flow_info.rs	Adds a bolero TypeGenerator impl for FlowStatus under test/feature gating.
net/Cargo.toml	Changes dataplane-net default features to include bolero.
flow-entry/src/flow_table/table.rs	Removes drain_stale and tweaks assertions in a concurrency test.
flow-entry/src/flow_table/mod.rs	Registers the new concurrent_fuzz test module.
flow-entry/src/flow_table/concurrent_fuzz.rs	Adds a new bolero + concurrency::stress concurrent fuzz/stress test for FlowTable.
concurrency/tests/quiescent_shuttle.rs	Switches shuttle fuzz tests to use an explicit Runner with shared config.
concurrency/src/stress.rs	Adds shuttle_config() and reuses it inside stress()’s shuttle backend.
concurrency/src/lib.rs	Re-exports stress as supported API and exposes shuttle_config() under shuttle cfg.
Cargo.lock	Dependency lockfile updates (crate version bumps).

Comments suppressed due to low confidence (1)

flow-entry/src/flow_table/table.rs:262

confidence: 8
tags: [docs]

`drain_stale` was removed, but `insert_common` still documents a safety argument in terms of “drain_stale’s stale condition …” (see the comment around `table.insert(...)`). That reference is now misleading and should be updated to describe the behavior without mentioning the deleted method.

/// Lookup a flow in the table.
///
/// # Panics
///
/// Panics if this thread already holds the read lock on the table.
pub fn lookup<Q>(&self, flow_key: &Q) -> Option<Arc<FlowInfo>>

</details>

[sergeymatov]

For me LGTM, we need to address [bolero] as non-dev dependency

[daniel-noland]

For me LGTM, we need to address [bolero] as non-dev dependency

yup, that was just me committing by accident. I only enabled it to help my IDE and never intended that for merge