fix(price): bound Nostr-sourced price staleness at 1.5x TTL, not 2x - #886
fix(price): bound Nostr-sourced price staleness at 1.5x TTL, not 2x#886ToRyVand wants to merge 2 commits into
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rank_candidates accepted a trusted-node rate event up to the full max_price_staleness_seconds old, then the store stamped it as_of=now and served it for another full max_price_staleness_seconds before refusing it — total age up to ~2x the configured TTL. Threading a per-source timestamp through Quote/AggregateResult/store for every provider would be a real architecture change to the pure, clockless aggregation core (aggregate.rs). But Nostr is already fallback-only (restrict_nostr_to_fallback in manager.rs): its quote for a currency only survives to aggregation when it's the sole contributor that tick, so the double-staleness bug only manifests there — every HTTP-sourced as_of is already accurate. Adds [price].nostr_ingestion_budget_pct (default 0.5): the Nostr provider's acceptance window becomes max_price_staleness_seconds * nostr_ingestion_budget_pct instead of the full TTL, bounding total age at (1 + nostr_ingestion_budget_pct) x TTL -- 1.5x at the default, tunable tighter per operator. Closes MostroP2P#860.
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Included review availability: Your plan includes up to 2 reviews per rolling hour; 0 remain after this review. WalkthroughThe change adds a validated ChangesNostr ingestion freshness budget
Estimated code review effort: 3 (Moderate) | ~20 minutes Merge Risk: ⚪ Minimal · up to This PR narrows the maximum age of accepted Nostr price events through a validated setting, reducing possible price staleness without changing the broader price-storage flow. No actionable merge-blocking risk remains beyond normal checks and review. Sequence Diagram(s)sequenceDiagram
participant PriceSettings
participant PriceManager
participant NostrProvider
PriceSettings->>PriceManager: provide nostr_ingestion_budget_pct
PriceManager->>NostrProvider: construct with budget percentage
NostrProvider->>NostrProvider: calculate max_age and apply one-second minimum
NostrProvider->>NostrProvider: reject events older than scaled max_age
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Inline comments:
In `@src/price/providers/nostr.rs`:
- Around line 121-127: Choose and enforce one documented contract for sub-second
ingestion windows: either reject configurations where
max_price_staleness_seconds multiplied by nostr_ingestion_budget_pct is below
one, or retain the one-second minimum and document the effective max(1 second,
floor(TTL × budget)) behavior. Apply the selected contract in
src/price/providers/nostr.rs lines 121-127 around the max_age calculation; if
retaining the minimum, update the corresponding configuration documentation in
src/price/config.rs lines 23-31, settings.tpl.toml lines 151-154, and
docs/PRICE_PROVIDERS.md lines 896-911.
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docs/PRICE_PROVIDERS.mdsettings.tpl.tomlsrc/price/config.rssrc/price/manager.rssrc/price/providers/nostr.rs
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Great job @ToRyVand i will be looking into this asap...sorry with lnp2p bot closure work is exploding for a small team like us! |
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@arkanoider really sorry to hear about lnp2pBot — that's a hard loss, especially for a project so many people relied on. If Mostro's team capacity is stretched right now, I'm glad to help with whatever's most useful — more reviews, more PRs. |
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Request changes — on the design, not the implementation. The bug is real, the
code is clean, 146 price tests pass, clippy and fmt are clean, and the
restrict_nostr_to_fallback blast-radius analysis is correct. My problem is
with the premise and the knob.
The 2× case isn't the general one. rank_candidates already filters
!e.is_expired_at(now) (nostr.rs:194), and this same manager stamps
expiration = now + min(update_interval_seconds * 2, 3600) on the events it
publishes (manager.rs:537-538) — 600s at the defaults. So for a trusted node
running this code the binding gate was already 600s, not 1800: real exposure
was 600 + 1800 = 1.33×TTL. The 2× case needs a third-party publisher that
omits the expiration tag (the filter is "if any"). That's a legitimate case to
fix, but neither the PR body nor the new docs mention the expiration filter,
and the regression test uses signed_event, which carries no expiration tag —
so it's measuring exactly that third-party case without saying so. This
changes what the right default is.
The repo already has a canonical answer for "how old may a rate event be",
and it isn't a fraction of the TTL. It's the expiration this node stamps on
its own events: 2 × update_interval_seconds. Deriving the ingestion window
from that — or refusing an event with no expiration tag — gives 600s at the
defaults, tighter than the 900s here (1.33× vs 1.5×), self-tunes with the
poll cadence, and adds no configuration. A knob whose meaning to the operator
is "pick how far past your own TTL you'd like to go" is a strange thing to
expose permanently.
And 1.0× is closer than the body suggests. Threading a timestamp through
Quote → aggregate_tick → AggregateResult → store for every provider would
indeed be an architecture change, but both pieces needed for the narrow case
already exist: AggregateResult.contributors (aggregate.rs:29) gives
per-currency provenance, and store.update() takes an arbitrary now, so it
can be called twice:
let (nostr_only, rest) = aggregates.clone().into_iter()
.partition(|(_, a)| a.contributors == [ProviderId::Nostr]);
self.store.update(rest, now);
self.store.update(nostr_only, now - nostr_event_age);The only genuinely new plumbing is the provider exposing the age of the event
it used. That closes #860 at an exact 1.0×, also without new config. Worth
ruling out explicitly before a permanent setting goes in.
Minor, if the setting survives:
- _pct names a fraction here (0.5 = 50%) while its immediate neighbour
outlier_threshold_pct = 5.0 means 5%. Someone following the local
convention writes 50 and gets a startup error — validation catches it, but
the name invites the mistake. ..._fraction, or keep _pct and take 50.0. - 1.0 is accepted and documented as "wasteful but not itself invalid" — it
is precisely the pre-#860 behaviour. Exclude it, or say that plainly. - The 1-second floor edge case (a 1s TTL with a 0.001 budget) is spelled out
in five places for a config nobody will ever write. One line covers it.
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Thanks @Catrya — you're right, and the problem is upstream of this PR. Closing it. The premise was wrong in the issue, not just here. #860 quotes the age Which makes this PR a no-op at the defaults — 900s ingestion window against Two notes, both from the source: Your 1.0x sketch is more complete than you argued. I went looking for the The gap is one field over:
Minor points all correct ( On the process note from #842: it applies here too. #860 is also my own issue, |
3 participants
Closes #860. Thanks @arkanoider for the ping — took it as requested.
The bug
NostrProvider::rank_candidates(src/price/providers/nostr.rs) accepted a trusted-node rate event up to the fullmax_price_staleness_secondsold.PriceManager::update_allthen stamped every currency in the tick's aggregate withas_of = nowregardless of source, and the store (PriceStore::get) allows serving an entry for another fullmax_price_staleness_secondsbefore refusing it. Net: a Nostr-sourced price could be served for close to 2x the configured TTL — against a setting whose name implies one TTL.Why not "carry
created_atthrough toas_of" (the issue's own original suggestion)That framing was written against an older shape of this code. Today,
Quote(src/price/provider.rs) andAggregateResult(src/price/aggregate.rs) carry no timestamp at all —aggregate.rsis explicitly documented as a pure, clockless transform, andstore.update()takes onenow: i64for the whole tick's aggregate, not per-source. Threading a real per-source timestamp throughQuote→aggregate_tick→AggregateResult→storefor every provider would be a real architecture change.It also turns out to be more than the bug needs: Nostr is already restricted to fallback-only (
restrict_nostr_to_fallbackinmanager.rs) — for any currency a non-Nostr provider can cover this tick, Nostr's quote for that currency is dropped before aggregation ever sees it. Nostr's quote only survives to affectas_ofwhen it's the sole contributor for that currency this tick. Every HTTP-sourcedas_ofis already accurate (ingestion ≈ observation for an HTTP fetch), so the double-staleness bug is real only in the Nostr-exclusive case.The fix
Given that narrower blast radius, this closes it entirely inside the Nostr provider's own acceptance gate — no changes to
Quote,AggregateResult,aggregate_tick, orPriceStore.New
[price]settingnostr_ingestion_budget_pct: f64(default0.5). The Nostr provider'smax_agebecomesmax_price_staleness_seconds × nostr_ingestion_budget_pctinstead of the full TTL — the setting's "how old may an event be when accepted" and "how long may we serve what we accepted" roles get split instead of double-counted. Worst case total age:0.5×TTL(ingestion)+ 1.0×TTL(store's own unchanged window)= 1.5×TTL. Not an exact 1.0x bound (that would need the full timestamp-threading refactor above), but it directly closes the issue's own framing ("served for ~2x") and gives operators a knob to tighten further (e.g.0.2→ 1.2x) without more code changes.0.5as the default balances that against the Nostr provider's purpose as a fallback-of-last-resort — a too-small ingestion window would reject more still-useful, merely-lagging events, worst in exactly the case (Nostr-exclusive currency) where losing the source is worst.nostr_anchor_dependent(fiat-cross-via-Nostr-anchor) currencies are out of scope here — that flag protects a different thing (republication provenance, PR #841). They benefit transitively from a fresher anchor without needing separate handling; noted in the docs rather than silently left unaddressed.Changes
src/price/config.rs:PriceSettings.nostr_ingestion_budget_pct(default0.5), validated to(0, 1].src/price/providers/nostr.rs:NostrProvider::newtakes the new param;max_ageis scaled before the existing zero-floor.src/price/manager.rs:build_provider/from_settingsthread the new setting through.settings.tpl.toml,docs/PRICE_PROVIDERS.md: documented.Test plan
0.25 × 2000 = 500) and the zero-floor edge case (a budget that would round to 0s) both covered.<= 0,> 1.0rejected;1.0and0.5accepted.price::*tests updated for the newNostrProvider::newsignature and passing (146 tests in the module).cargo build,cargo clippy --all-targets -- -D warnings,cargo fmt --check,cargo test --bin mostrod(1190 passed),markdownlint-cli2on the touched doc — all clean.Summary by CodeRabbit
New Features
Bug Fixes
Validation