78 lines
3.8 KiB
Markdown
78 lines
3.8 KiB
Markdown
---
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id: review-002-fwd15-stream-timeout
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name: Subscriptions must not inherit the 30s total request timeout (FWD-15) + stream byte cap (FWD-14)
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status: completed
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depends_on: []
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scope: moderate
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risk: medium
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impact: component
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level: implementation
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tags: [client, review-002, adapters]
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---
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## Description
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Review 002 FWD-15 [major] + FWD-14. Two streaming-path defects, same
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code region (`src/adapters/forward.rs:824-934`):
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1. **FWD-15**: `forward_stream` sends through the shared client whose
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`DEFAULT_REQUEST_TIMEOUT` is 30 s — verified against reqwest 0.13.4
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that the total-timeout sleep rides into the response body stream.
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A healthy subscription dies at 30 s with `SSE stream error:
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operation timed out` — even keep-alive-emitting sources (the
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gateway deliberately runs subscriptions unbounded per ADR-021;
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dispatch.rs:28). The outbound half of the same subscription is
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mortally capped.
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2. **FWD-14**: the streaming branch has no size accounting — the 1 MiB
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cap bounds a single SSE *line*, not the stream. A hostile upstream
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emits well-formed 1-MiB-line events forever: 30 s of those is
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~GB/s into envelope allocation (mitigated only by the timeout —
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which FWD-15's fix then removes, so **both must land together or
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the fix makes FWD-14 worse**).
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## Acceptance Criteria
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- [ ] FWD-15: `HandlerKind::Stream` forwards send with
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`request_timeout: None` while keeping connect + read timeouts
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(implementer's choice: per-request extension override verified
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against reqwest 0.13, or a second derived client built from the
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same config minus the total timeout) — a >30 s healthy
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subscription survives
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- [ ] FWD-15 wire test: responder trickling `: keepalive` comments past
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30 s (scaled: use a configurable short client timeout in the
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test) → stream still delivering events after the old deadline
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- [ ] FWD-14: a total byte cap on the streaming path (accumulate
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across `feed`; per-subscription total, default documented) and
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the line-cap check moved to *before* `extend_from_slice` so the
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overshoot cannot exceed cap + one chunk
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- [ ] FWD-14 test: a stream exceeding the total cap terminates with a
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single terminal error envelope (the stream-ends semantics)
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- [ ] Cap value + no-timeout decision documented in the module doc and
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http-server.md (ADR-049/021 note: unbounded *time* by design for
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subscriptions, bounded *bytes* per subscription)
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- [ ] `cargo test`, `cargo clippy --all-targets -- -D warnings`,
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`cargo fmt --check` pass
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## References
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- docs/reviews/002-post-remediation-review.md (Part D', FWD-14, FWD-15; Unit 2 rationale)
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- src/adapters/forward.rs:824-934 (send + streaming branch), :969-1082 (SSE parser), http_client.rs:69-95/:149-150/:164-178 (timeout config + read-timeout doc claim)
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- docs/architecture/decisions/049-streaming-handler-for-subscriptions.md
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- tasks/client/review-001-client-timeout-retry.md (the timeout defaults this revises)
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## Notes
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Order matters **within** this task: land FWD-15 with FWD-14 in the same
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commit-series — removing the total timeout without the byte cap opens
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an unbounded-memory window. The read-timeout (10/30 s stall guard)
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stays: it bounds upstream *staleness*; the doc at http_client.rs:149-150
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already correctly describes read-timeout as the stall guard (the total
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timeout's "stalled upstream" claim there is the thing being fixed).
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Coordinate with review-002-cli01-retry-after-budget (same file) and
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review-002-client-policy-wire-tests (which should follow this to test
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the new behavior) — sequence those.
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## Summary
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Derived timeout-less stream client (reqwest 0.13 cannot clear a client total timeout per-request, verified against source) + 1GiB total-bytes cap with pre-extend buffer check; over-cap streams end with one HTTP_413 terminal envelope. Wire tests for both arms.
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