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fix(moq-net): a subscriber reads only the frames its ranges cover - #6129
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The cursor filtered whole groups, so a range starting or ending inside a cached group handed out every frame of it. Each handed-out group is now positioned to the frames its covering ranges name, on the arrival, re-offer, and ordered paths, and the datagram path judges object IDs against the same per-group bounds. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
# Conflicts: # quest/m1/subscribe-ranges/README.md # rs/moq-net/src/model/track.rs
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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| hull = Some(match hull { | ||
| None => (start, end), | ||
| Some((low, high)) => (start.min(low), end.zip(high).map(|(end, high)| end.max(high))), | ||
| }); |
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When two requested ranges cover disjoint portions of the same group, collapsing them to their hull returns frames that neither range requested. For example, ranges [group 4 frame 1, frame 2) and [group 4 frame 5, frame 6) produce bounds 1..6, leaking frames 2 through 4 through both arrival and ordered reads. Preserve the disjoint intervals or filter individual frame reads instead of widening them to a hull.
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Declining. A group is handed out once, as one run of frames, so a reader can't skip frames 2 through 4 inside it without a per-frame filter on group::Consumer that nothing else needs. The wire has the same shape: a lite group stream is one contiguous run, so a relay serving these two ranges sends the hull too, and the model matches what a remote subscriber would get. Two ranges splitting one group with a hole is also not a decodable request for media, where frames depend on earlier ones. The frames doc now says why it reads the hull. Datagrams, which carry their own Object ID, are now judged per range (see the other thread), so they do honor the hole.
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| let (start, end) = self.filter.window.frames(sequence); | ||
| let object = datagram.wire.as_ref().and_then(|wire| wire.object_id).unwrap_or(0); | ||
| let framed = object >= start && end.is_none_or(|end| object < end); | ||
| if sequence >= self.floor() && admits && framed { |
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With mixed time and absolute ranges, admits and framed can be satisfied by different ranges, allowing a datagram that no individual range covers. For example, an absolute range starting at object 1 admits group 5 but excludes object 0, while a time-started range whose resolved span includes group 5 contributes frame 0 even if the datagram's own timestamp precedes that range; object 0 then passes both aggregate checks. Evaluate sequence, timestamp, and object ID together per range before taking their union.
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Fixed: Window::admits_datagram now takes the Object ID and checks the sequence, timestamp, and Object ID against one range at a time, so different ranges can no longer each pass one condition. a_datagram_is_judged_against_one_range_at_a_time covers your example (an absolute start at 5/1 plus a time range starting after the datagram's timestamp) and an untimed group split by two ranges.
(Written by Claude Opus 5.5)
WalkthroughSubscription windows now calculate frame bounds for each group. Subscriber delivery applies those bounds to non-relayed groups and datagrams, while relayed groups remain whole for object-ID filtering. Tests cover frame-limited reads, unavailable starting frames, and datagram filtering. The frame-bounds documentation and its README link were removed. Priority: ⬇️ Low Merge Risk: 🟡 Moderate · up to
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| Check name | Status | Explanation | Resolution |
|---|---|---|---|
| Docstring Coverage |  |
Docstring coverage is 66.67% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 12 functions across 3 files. (1 skipped: … | Write docstrings for the functions missing them to satisfy the coverage threshold. |
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Check name Status Explanation Title check The title clearly and concisely describes the main change: subscribers now read only the frames covered by their ranges. Linked Issues check Check skipped because no linked issues were found for this pull request. Out of Scope Changes check Check skipped because no linked issues were found for this pull request. Description check The pull request description directly explains the frame-bound subscription changes, affected paths, design decisions, tests, and expected API and wire behavior.
Full details: Docstring Coverage
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Explanation
Docstring coverage is 66.67% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 12 functions across 3 files. (1 skipped: 1 too large.)
Resolution
Write docstrings for the functions missing them to satisfy the coverage threshold.
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Actionable comments posted: 1
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Inline comments:
Review comments at @rs/moq-net/src/model/track.rs:
- Around line 5782-5785: The admission logic around admits_datagram and
filter.window.frames must evaluate timestamp, sequence, and Object ID using the
same subscription range. Replace the independent checks with per-range
evaluation, preserving the floor constraint and ensuring an object ID of 0 is
admitted only when that same range covers it.
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📒 Files selected for processing: 6
quest/m1/subscribe-ranges/README.mdquest/m1/subscribe-ranges/frame-bounds.mdrs/moq-net/src/model/group.rsrs/moq-net/src/model/subscription.rsrs/moq-net/src/model/subscription/window.rsrs/moq-net/src/model/track.rs
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- quest/m1/subscribe-ranges/README.md
- quest/m1/subscribe-ranges/frame-bounds.md
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Sequence, timestamp, and Object ID were checked against the window as a whole, so two ranges could each pass one condition and admit a datagram neither covers. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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| self.advance_arrival(peeked.group.sequence, peeked.index); | ||
| peeked.group.cache_refresh(); | ||
| return Poll::Ready(Ok(Some(self.with_expiry(peeked.group)))); | ||
| return Poll::Ready(Ok(Some(self.deliver(peeked.group)))); |
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When a nested/resuming reader has reserved this group and another task calls Control::update with new frame bounds before the group is consumed, this fast path bypasses sync() and deliver consults the old filter.window. The group is therefore positioned using the previous range and can return frames excluded by the current subscription. Sync and revalidate the reserved group before handing it out.
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Fixed in 64e789f: both peek fast paths (arrival and ordered) now sync() before handing the reserved group out, so it is still the reserved group but positioned by the ranges in force at the take. a_peeked_group_is_bounded_by_the_ranges_at_handout peeks group 4, replaces the ranges through Control::update to start at 4/5, and checks the taken group starts at frame 5 in both orders; it fails without the fix.
(Written by Claude Opus 5.5)
A Control update between a peek and the take left the cursor's window stale, so the reserved group was positioned by the old ranges. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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| if !group.relayed() { | ||
| let (start, end) = self.filter.window.frames(group.sequence); |
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When a group arrived through IETF/moq-transport, relayed() is true even for ordinary sequential Object IDs, so this branch skips all frame positioning. If another subscriber widened the relay's aggregate request, a frame-bounded local reader such as moq-ffi, moq-mux, or an in-process consumer therefore receives the entire cached group; unlike a downstream wire publisher, group::Consumer performs no later Object-ID filtering. Apply Object-ID-aware bounds, limiting the passthrough exception to the mid-group case it actually requires.
AGENTS.md reference: rs/moq-net/AGENTS.md:L11-L11
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Declining: handing relayed moq-transport groups out whole is decision 2 in the PR description, which the maintainer accepted. A relayed group's Object IDs are only known to match its frame ordinals until Wire::sparse turns on, which can happen mid-group after handout, so positioning by ordinal could cut frames the IETF publisher still needs (it filters by Object ID itself, under the same wire().is_none() rule). Positioning by Object ID would need the model to map IDs to ordinals for frames that may not have arrived yet. The local-reader gap you describe is real and is listed as the follow-up, to do once a consumer needs mid-group bounds on a relayed track.
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|
Ready to merge.
(Written by Claude Opus 5.5) |
# Conflicts: # rs/moq-net/src/model/group.rs
Completes
quest/m1/subscribe-ranges/frame-bounds.md(deleted here).Summary
track::Subscriberfiltered whole groups, so a range starting at group 4 frame 5, or ending at group 6 frame 3, handed local readers (moq-ffi, moq-mux, in-process apps) every cached frame of those groups. Now:Window::frames(sequence)returns the frames a group's covering ranges name: the start frame where an absolute start falls inside it, the exclusive end where an absolute end does, whole groups otherwise. Overlapping ranges in one group read the hull.Cursor::deliver, which replaceswith_expiryon the arrival, re-offer, peeked, and ordered paths), usingskip_to+end_at. Positioning happens when the group is taken, not when it is peeked, and the peek fast paths sync first, so a reserved group is bounded by the ranges in force at handout even after aControl::update(review finding).Span::coversreads a span up to an unsettled time end's cap, the groups it reads meanwhile, so a time range covering a group whole widens another range's frame bounds there.Window::admits_datagram), rather than the subscription's lowest start, so a mid-group start behind an earlier disjoint range no longer leaks its group's datagram, a mid-group end applies too, and two ranges can't each pass one condition (review finding).Regression tests:
a_range_reads_only_its_frames(start at 4/5, end at 6/3, read throughrecv_groupandordered(), with a wider subscriber widening the aggregate),a_group_missing_its_asked_head_lags,frames_bound_only_the_groups_an_anchor_falls_inside,a_datagram_is_judged_against_one_range_at_a_time,a_peeked_group_is_bounded_by_the_ranges_at_handout, and an extra case ina_mid_group_start_drops_the_start_groups_datagram. The first two fail without the fix.Public API and wire impact
No signature changes and no wire changes. Behavior: a local subscriber's groups now start and stop at its range's frame bounds. The lite and IETF publishers already positioned served groups themselves, so what they send is unchanged.
Decisions
Settled by the maintainer on 2026-10-20, each on the recommended option:
Error::Lagged. The lite publisher'sposition_groupstill skips and DROPs such groups at the wire.position_groupdoes"). Rejected: it breaks route takeover recovery (a_takeover_serves_the_open_group_head_to_later_readers, where a reader'sLaggedread gets the head from another copy) and fetch-filled heads (fetch_fills_the_head_of_a_live_group).group.wire().is_some()) are handed out whole.Position.frame(ServeRange::apply), and a relayed group's IDs may not be its frame ordinals (Wire::sparsecan turn on mid-group), so positioning by ordinal would cut frames the IETF publisher needs, for example on a Next Object join over sparse IDs. This matches the IETF publisher's ownwire().is_none()rule.position_group.Fetch as a range
quest/m1/subscribe-ranges/fetch-range.md(merged) requires this quest for head fills: a one-range subscription for a cached live group missing its range's head. Decision 1 is what makes that possible, since the group is still handed out for a fill to complete, where skipping it would turn the fill into a miss. The one tension: today onlyfetch_grouprequests a head fill, and a subscription reading that group getsError::Laggedat the missing head (unless a route copy holds it), so fetch-range has to make the one-range read request the fill rather than letLaggedreach the caller. This PR records that in fetch-range's Plan, drops itsRequiredlink to this deleted quest, and updates the matching line indynamic.md.JS
@moq/net'sSubscriptiononly has group bounds (groups.start/groups.end), with no frame positions, so it can't express this case and there is nothing to mirror. Frame-precise ranges there belong to JS ranges.Checks
origin/main(time anchors, moq-dev/moq#6074); conflicts intrack.rs's datagram path (main's time-awareadmits_datagramkept, the per-group frame check replacesmid_group) and the epic README.cargo test -p moq-net --all-features(2344 lib tests plus integration) andcargo clippy -p moq-net --all-features --lib --tests -D warningspass after the merge and the review fixes.just checkstops early here onbench/relay.test.py(the gh module), which times out inside it and passes on its own; unrelated to this diff, so CI is the full gate.Follow-ups
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