fix(moq-mux): let an importer own its catalog rendition from reservation - #2869
fix(moq-mux): let an importer own its catalog rendition from reservation#2869kixelated wants to merge 2 commits into
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A `Rendition` claimed its name only when `set` published a config, but a
lazily-configured importer resolves that config much later: an avc3/annexb
H.264 track has no rendition until its first SPS arrives. In that gap an
outside write (`moq_publish_video_config` in libmoq) landed successfully,
was silently overwritten when the importer finally called `set`, and was
then deleted by the importer's `Drop` on `moq_publish_media_finish`,
taking the caller's entry with it.
The two write paths disagreed on purpose and by accident. `Rendition::set`
goes through `RenditionConfig::insert`, a bare `BTreeMap::insert` that
overwrites because the rendition owns the name; `hang::catalog::Video::insert`
takes a vacant entry and otherwise errors. Nothing connected the two, so
"owned by an importer" was unrepresentable.
Claim the name when the rendition is reserved instead. The claim lives for
the rendition's lifetime, so `set` can't clobber a caller's entry and `Drop`
can't delete one. Outside writes go through new checked `Guard` methods
(`insert_video`, `insert_audio`, `remove_video`, `remove_audio`) that refuse
a claimed name, and only mark the catalog updated on success, so a refused
write no longer republishes an unchanged catalog.
libmoq's doc comments claimed `moq_publish_{video,audio}_config` replace an
existing rendition. They never did; they error. Corrected to describe what
the code does, and `moq_publish_{video,audio}_remove` now says it refuses a
rendition an importer owns.
moq-audio's encode producer hand-rolls the same insert/remove-on-drop
lifecycle, so it could author into a name an importer had reserved but not
yet resolved. Routed through the checked methods too.
`libmoq::Error` flattens `moq_mux::Error::Hang`, so a catalog duplicate
still reports -18 whether it surfaced directly or through a moq-mux call.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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WalkthroughThe catalog now reserves rendition names for live media tracks before configuration resolves. Caller insert and remove APIs reject names claimed by media tracks, reject duplicate insertions, and treat absent removals as no-ops. Audio and video producers use these APIs. Mux error conversion maps hang errors separately. Documentation and tests cover ownership, release, and 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
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In `@rs/moq-mux/src/catalog/producer.rs`:
- Around line 52-60: Change claimed and its claim/release logic from set
membership to per-name reference counts, so duplicate live Rendition handles
keep the name claimed until the last handle drops. Update the relevant claim and
release methods, including release_claim, to increment and decrement counts and
remove the entry only at zero; add a regression test covering two same-name
renditions and ensuring the claim persists after either one is dropped.
In `@rs/moq-mux/src/error.rs`:
- Around line 102-104: The public Error enum must not gain a new exhaustive
variant in this release. Update the Error representation to preserve downstream
exhaustive matches, either by applying #[non_exhaustive] only in the appropriate
breaking-version release or by replacing RenditionClaimed with a nonbreaking
representation for the current release.
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rs/libmoq/src/api.rsrs/libmoq/src/error.rsrs/libmoq/src/publish.rsrs/libmoq/src/test.rsrs/moq-audio/src/encode/producer.rsrs/moq-mux/src/catalog/producer.rsrs/moq-mux/src/catalog/tracks.rsrs/moq-mux/src/error.rs
| /// A caller tried to write a catalog rendition an importer owns. | ||
| #[error("rendition owned by an importer: {0}")] | ||
| RenditionClaimed(String), |
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Do not add a variant to an exhaustive public enum.
Error has no #[non_exhaustive]. Adding RenditionClaimed makes downstream exhaustive matches fail to compile. Use #[non_exhaustive] in the appropriate breaking-version release, or use a nonbreaking error representation for this release.
As per coding guidelines, "Public enums that may gain variants: add #[non_exhaustive] so external matches keep compiling."
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In `@rs/moq-mux/src/error.rs` around lines 102 - 104, The public Error enum must
not gain a new exhaustive variant in this release. Update the Error
representation to preserve downstream exhaustive matches, either by applying
#[non_exhaustive] only in the appropriate breaking-version release or by
replacing RenditionClaimed with a nonbreaking representation for the current
release.
Source: Coding guidelines
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| fn check_claim(&self, name: &str) -> crate::Result<()> { | ||
| match self.claimed.lock().unwrap().contains(name) { | ||
| true => Err(crate::Error::RenditionClaimed(name.to_string())), | ||
| false => Ok(()), | ||
| } |
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When cloned producers are used concurrently, a thread can pass check_claim, release the claimed mutex, and then be descheduled before inserting; another thread can reserve the same rendition during that gap, after which the first insertion succeeds and is later overwritten and removed by the importer. The claim transition and the guarded catalog mutation need to be synchronized under one lock so the original corruption cannot recur under concurrent use. (Written by GPT-5.6 Sol)
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| /// waiting for its first SPS) leaves the name absent long enough for an external insert to | ||
| /// land, which the importer then overwrites and removes on drop, taking the caller's entry | ||
| /// with it. See [`Guard::insert_video`]. | ||
| claimed: Arc<Mutex<std::collections::BTreeSet<String>>>, |
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A bare-name BTreeSet conflates claims belonging to different catalog sections and cannot count multiple owners. For example, a video rendition and a custom Reserved::init rendition may both use v because their RenditionConfig implementations mutate disjoint maps; this stores one set element, and dropping the custom rendition removes the video rendition's claim, allowing remove_video("v") to delete the still-live video. It also rejects unrelated audio/custom operations while the shared string is claimed, so claims need a section/owner identity or reference count rather than only the name. (Written by GPT-5.6 Sol)
AGENTS.md reference: AGENTS.md:L143-L148
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| fn drop(&mut self) { | ||
| self.catalog.lock().audio.remove(&self.name); | ||
| // Refused only if an importer owns the name, in which case the entry isn't ours to delete. | ||
| let _ = self.catalog.lock().remove_audio(&self.name); |
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If another unresolved rendition claims this name after Producer::new inserts the audio config, this checked removal returns RenditionClaimed and the error is discarded, leaving the catalog advertising the encoder's dead track indefinitely. Claim creation does not reject an existing catalog entry, so this ordering is possible; the encoder should hold the same Rendition ownership primitive used by importers, or otherwise acquire ownership atomically with insertion and guarantee removal. (Written by GPT-5.6 Sol)
AGENTS.md reference: AGENTS.md:L129-L131
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| pub fn audio_config(&mut self, broadcast: Id, name: &str, config: hang::catalog::AudioConfig) -> Result<(), Error> { | ||
| let (_, catalog) = self.broadcasts.get_mut(broadcast).ok_or(Error::BroadcastNotFound)?; | ||
| catalog.lock().audio.insert(name, config).map_err(Error::Hang)?; | ||
| catalog.lock().insert_audio(name, config)?; |
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Is there some way to avoid this API change? I don't like stuff in the root if it could be scoped.
| /// waiting for its first SPS) leaves the name absent long enough for an external insert to | ||
| /// land, which the importer then overwrites and removes on drop, taking the caller's entry | ||
| /// with it. See [`Guard::insert_video`]. | ||
| claimed: Arc<Mutex<std::collections::BTreeSet<String>>>, |
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We should combine the multiple Arc<Mutex state.
| } | ||
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| /// Refuse a name a live [`Rendition`](super::Rendition) owns. | ||
| fn check_claim(&self, name: &str) -> crate::Result<()> { |
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Yeah this seems racey, we need to keep the lock held.
Review follow-up on the claim mechanism, which had three holes of its own. The claim lived in its own mutex, so a check told you nothing: a caller could pass `check_claim`, an importer could reserve the same name, and the caller's write then landed in a slot the importer would overwrite and delete. The original corruption, one layer up. `Rendition`'s Drop had the mirror of it, releasing the claim before taking the lock to remove the entry. Claims now live beside the catalog under one lock, so a check and the mutation it guards can't interleave, and Drop removes the entry and releases the claim in a single critical section, entry first. Claims are also keyed by section and reference counted. A bare name conflated `video["v"]` with `audio["v"]`, which are disjoint maps and unrelated renditions, so a video claim wrongly refused an audio write and dropping either released the other's claim. The section is the `RenditionConfig` type. The count covers two renditions sharing a name, where the first to drop must not release the second's claim. The four checked `Guard` methods collapse to two generic over `RenditionConfig`: `insert` (section inferred from the config) and `remove::<C>`. Fewer new symbols, and custom extension renditions get the same protection as video and audio. The libmoq hang flattening was too broad. Mapping every `moq_mux::Error::Hang` to -18 also caught errors from the consume path (`container::legacy` and `container::loc` both raise `hang::Error`), changing codes that had nothing to do with the catalog. It is now applied at the four catalog call sites only, so a duplicate rendition stays -18 and everything else stays -29. Reverted the moq-audio change. Routing it through the checked methods let its Drop-time removal be refused and discarded, leaving a dead rendition advertised for the life of the broadcast. It needs the real ownership guard, which is its own change. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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| impl<E: CatalogExt> DerefMut for Guard<'_, E> { | ||
| fn deref_mut(&mut self) -> &mut Self::Target { | ||
| self.updated = true; | ||
| &mut self.catalog | ||
| &mut self.state.catalog | ||
| } |
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Because Guard still publicly dereferences to &mut Catalog, Rust callers can continue using documented mutations such as catalog.lock().video.renditions.insert(...), which never call check_claim. If an importer has reserved the same slot, that path can overwrite its entry and the importer's later Drop will delete the replacement, reproducing the corruption this change is intended to prevent. The ownership boundary needs to prevent or validate direct mutable access rather than relying on callers to select the new checked methods. (Written by GPT-5.6 Sol)
AGENTS.md reference: AGENTS.md:L135-L143
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| pub(super) fn release_claim<C: super::RenditionConfig<E>>(&mut self, name: &str, present: bool) { | ||
| if present { | ||
| C::remove(&mut self.state.catalog, name); | ||
| self.updated = true; |
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When two same-section renditions claim one name, as the new counter and test explicitly allow, both can call set; dropping either one unconditionally removes the shared catalog entry here even though the counter remains nonzero. The surviving rendition then cannot update the absent entry, while outside code is still refused by its remaining claim, so the track disappears until that handle also drops. The new per-slot count is fresh evidence that claim release and entry removal must account for the last owner, or duplicate ownership must be rejected. (Written by GPT-5.6 Sol)
AGENTS.md reference: AGENTS.md:L143-L148
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Root cause
A
moq_mux::catalog::Renditionclaimed its name only oncesetpublished a config. A lazily-configured importer resolves that config much later: an avc3/annexb H.264 track has no rendition at all until its first SPS arrives.In that window an outside write succeeded, and then quietly lost:
moq_publish_media(format="avc3")reserves track0.avc3. No catalog rendition yet.moq_publish_video_config(name="0.avc3")succeeds, since the name is vacant.Rendition::setoverwrites the caller's entry.moq_publish_media_finishdrops the rendition, whoseDropremoves0.avc3, deleting what the caller published.The two write paths disagreed, half on purpose.
Rendition::setgoes throughRenditionConfig::insert, a bareBTreeMap::insertthat overwrites because the rendition owns the name;hang::catalog::Video::inserttakes aVacantentry and otherwise returnsDuplicate. Nothing connected them, so "this name belongs to an importer" was unrepresentable.Publish::{video,audio}_removehad the mirror of the same hole: a rawBTreeMap::removethat would delete an importer-owned rendition out from under it.Fix
Claim the name when the rendition is reserved, not when it's set. The claim spans the rendition's lifetime, so
setcan't clobber a caller's entry andDropcan't delete one.Outside writes go through new checked
Guardmethods, which refuse a claimed name:insert_video/insert_audioremove_video/remove_audioThese also mark the catalog updated only on success. Previously
Guard'sDerefMutsetupdated = truebefore the insert ran, so a failed insert republished an unchanged catalog as a spurious group.Also in scope, same class of bug:
moq_publish_{video,audio}_config"replaces" an existing rendition. They never did, they error. Corrected, and the_removedocs now state they refuse an importer-owned name.libmoq::Errornow flattensmoq_mux::Error::Hang, so a catalog duplicate still reports -18 whether it surfaced directly or through a moq-mux call rather than silently becoming -29.Public API changes
Additive only, so this targets
main:moq_mux::catalog::Guard::{insert_video, insert_audio, remove_video, remove_audio}.moq_mux::Error::RenditionClaimed(the enum is#[non_exhaustive]).Tests
Five new tests. The two that encode the root cause were verified to fail without the fix (by reverting just the
claimcall):moq-mux:an_unresolved_rendition_still_owns_its_name,an_owned_rendition_survives_an_outside_remove(both fail without the claim), plusdropping_a_rendition_frees_its_nameandremoving_an_absent_rendition_succeedsas the complements.libmoq:publish_media_owns_its_rendition_before_the_first_keyframedrives the exact avc3 sequence above through the C ABI.just checkandjust testpass (1199 tests).just checkdoesn't compile libmoq, socargo test -p libmoqwas run separately: 64 passed.Cross-package sync
rs/libmoqC ABI: no signature changed, somoq.h,cpp/obs/src, anddoc/bin/obs.mdneed no update. Doc comments inapi.rswere corrected in place.(written by Opus 5)