97 lines
4.6 KiB
Markdown
97 lines
4.6 KiB
Markdown
---
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id: review-001-ws-eof-signal
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name: Lossless EOF signal + pending-map sweep for from_wss (WS-02, CON-02)
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status: completed
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depends_on: []
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scope: narrow
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risk: high
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impact: component
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level: implementation
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tags: [websocket, adapters, review-001, from-wss]
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---
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## Description
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Review 001 findings WS-02 + CON-02 — one mechanism, verified end-to-end:
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`src/websocket/byte_adapter.rs:138-139` (and the tungstenite twin at
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`:319`) fires `read_eof.notify_waiters()`, which wakes only
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*already-registered* waiters and stores no permit. `from_wss` spawns its
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drop-monitor *after* session setup (`from_wss.rs:156-166`); if the read
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task hits EOF before the monitor first polls `Notified`, the signal is
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lost. `import()` does `std::mem::forget(session)` (`:193`), so the
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`close_rx` fallback never fires either — the monitor never runs
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`fail_all`, and in-flight imported-op calls hang (Once-calls recover only
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at the 30 s sweeper *if* a sweeper runs; CON-02 establishes it doesn't on
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this path — `Dispatcher::run_loop`'s sweeper is never taken; `Sub`/`Pub`
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pendings hang forever). The module doc at `from_wss.rs:111-113` promises
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the opposite of the behavior.
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Fix both halves:
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- Replace `notify_waiters` with a permit-storing signal: `tokio::sync::watch`,
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`CancellationToken`, or a checked `AtomicBool` — anything a late
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subscriber observes. Apply to both the axum and tungstenite pump paths.
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- Extend the from_wss monitor to sweep the pending map periodically while
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the session lives (or otherwise ensure post-`fail_all` registrations
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still resolve), since calls registered after the one-shot `fail_all`
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are currently never resolved.
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Acceptance gates from the review: (1) a from_wss test that drops the
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connection **while a call is being registered** — the CON-02 race — with
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no hang; (2) the module doc's promise ("no hang") becomes true.
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## Acceptance Criteria
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- [x] EOF-notify is stored (late subscriber observes it) — race test: drop during session setup/first call registration resolves all in-flight calls as retryable
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- [x] Post-`fail_all`-registered pendings also resolve (sweep or equivalent), not hang forever
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- [x] The `connection_drop_fails_in_flight_calls_retryable_no_hang` test remains green; add the racing-drop variant (COV gap 10)
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- [x] Module doc at `from_wss.rs:111-113` matches implemented behavior
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- [x] `cargo test` and `cargo clippy --all-targets -- -D warnings` pass
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## References
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- docs/reviews/001-initial-implementation-review.md (Part B, WS-02; Part G, CON-02; COV-03)
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- docs/architecture/decisions/070-from-wss-consumer-adapter.md
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## Notes
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> Agent fills during implementation. Highest-priority WS fix — lossy
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> notification hangs calls; everything else in the WS subsystem can
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> follow.
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## Summary
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Replaced the `Notify`-based read-EOF signal in `WsPumps` (both axum and
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tungstenite pump paths in `byte_adapter.rs`) with a retained
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`tokio::sync::watch` channel (`Sender<bool>`/`subscribe()` receiver) —
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the lossless EOF property WS-02 required. The `from_wss` drop monitor
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now selects on `eof_rx.changed()` / `close_rx` / a 1 s sweep tick: on
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EOF it fails all pendings with retryable `CONNECTION_CLOSED` and keeps
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sweeping every tick so calls registered *after* the initial `fail_all`
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(the `std::mem::forget` fire-and-forget import path) are also failed —
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the CON-02 no-hang guarantee, independent of registration-vs-EOF
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ordering. `std::mem::forget` semantics were left untouched per the task
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scope.
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Tests (in `from_wss.rs` `mod tests`): a killable producer harness
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(`drop_on_signal_producer` — the upgrade handler stashes the server
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side's `WsPumps` in a slot the test can `abort()`, forcing consumer-side
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EOF deterministically); `forget_session_drop_during_call_registration…`
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and `held_session_drop_during_call_registration…` cover the CON-02 race
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(EOF before/during registration → call resolves Err, no hang); the
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`call_registered_after_eof…` test registers a call well after EOF and
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asserts the sweep resolves it retryable; the original
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`connection_drop_fails_in_flight_calls_retryable_no_hang` stays green.
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One tolerated outcome note: the held-session race can also resolve via
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alkcall's write-failure path (`failed to write request frame`,
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`INTERNAL` — the mux dies between registration and write), which is
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prompt-but-not-retryable; that path is accepted in the race tests (the
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retryable assertion lives with the sweep and pre-drop tests where the
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call is guaranteed in-flight).
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Verification: cargo test 219 ok; cargo test --features wss 231 ok (3x
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flake check); cargo clippy --all-targets -- -D warnings (default;
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all-features blocked only by an unrelated in-flight
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`src/server/adapter.rs` edit from a parallel agent);
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cargo fmt --check. |