feat(nostr): relay liveness watchdog for silent-dead sockets (#291) - #324
feat(nostr): relay liveness watchdog for silent-dead sockets (#291)#324codaMW wants to merge 4 commits into
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…2P#291) The SDK can report a relay as Connected while its websocket has silently died — no events flow, yet no disconnect is detected. On Android this happens routinely when the app is backgrounded, and has caused a live trade to miss its hold-invoice turn during a ~22-minute silence. Add a pool-owned liveness observer that bumps a last_event_at timestamp on every event or message, and a silence watchdog that every 30s forces a disconnect/reconnect when the pool is Online yet has seen no traffic for longer than SILENCE_TIMEOUT_SECS (210s — above the ~60s Android drop cycle, well under the observed failure window). The forced reconnect drives the existing Online→resubscribe path, which rebuilds order and chat subscriptions. The decision is a pure should_force_reconnect() with unit tests covering the online/offline, threshold-boundary, and never-seen-traffic cases. Device-verified on Android: backgrounding the app produced repeated silences (237s, 217s) while the SDK still reported Online; the watchdog fired each time, reconnected, resubscribed, and orders completed end-to-end through the recovered connection.
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Important
This repository does not receive automatic reviews because it has fewer than 10 stars. ⚙️ Run configurationConfiguration used: Organization UI Review profile: CHILL Plan: Pro Plus Run ID: WalkthroughRelayPool now records the latest relay activity, observes pool notifications, and runs a silence watchdog. An online pool reconnects when silence exceeds 210 seconds. Tests cover activity, thresholds, startup, and non-online states. ChangesRelay liveness recovery
Estimated code review effort: 4 (Complex) | ~45 minutes Merge Risk: 🟡 Moderate · up to The watchdog can fail to recover a silently dead connection during startup and can repeatedly reconnect a quiet pool after recovery, potentially leaving messages or subscriptions unavailable and causing reconnect churn. The baseline should be initialized and rearmed before this change is considered merge-ready. Sequence Diagram(s)sequenceDiagram
participant RelayPool
participant PoolNotifications
participant Client
PoolNotifications-->>RelayPool: relay event or message
RelayPool->>RelayPool: update last_event_at
RelayPool->>RelayPool: check silence threshold
RelayPool->>Client: disconnect and reconnect when online silence exceeds 210 seconds
Suggested reviewers: Poem
🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
Full details: Linked Issues checkExplanation The PR implements the core requirements in issue Full details: Out of Scope Changes checkExplanation The code changes are limited to RelayPool liveness tracking, watchdog reconnection logic, and related tests. These changes directly support issue ✨ Finishing Touches🧪 Generate unit tests (beta)
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In `@rust/src/nostr/relay_pool.rs`:
- Around line 287-289: Update the Online transition and forced reconnect flow
around client.disconnect, client.connect, and last_event_at to initialize a
liveness baseline when entering Online and rearm it when reconnect begins, while
preserving last_event_at as event-only if needed by adding a separate reconnect
timestamp. Ensure watchdog recovery remains active during initial startup
silence and waits the intended post-reconnect interval instead of immediately
reconnecting again; replace zero-last-event coverage with tests for both
scenarios.
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rust/src/nostr/relay_pool.rs
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…view) Addresses the CodeRabbit review on MostroP2P#324: - Seed last_event_at at connect time in the constructor, so a socket that is silent from startup (never delivers a first event) is measured against SILENCE_TIMEOUT_SECS instead of being ignored while last_event_at stays 0. - Rearm last_event_at right after a forced reconnect, so the watchdog waits a full interval before considering another reconnect rather than firing on every 30s poll against a stale timestamp. Tests: renamed zero_last_event_is_never_a_basis to zero_last_event_guards_pre_connect_window (it documents the pre-first-connect guard), and added baseline_set_at_connect_triggers_on_startup_silence and fresh_baseline_after_reconnect_does_not_retrigger. 7 watchdog tests pass.
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Strict review of current head 6c47f5e81efd1b3d20ce9d359ec3da18968b3006.
Blocking issue
The watchdog is pool-wide: it records one last_event_at for traffic from any relay and only runs when the aggregate pool state is Online. The default configuration has two relays (relay.mostro.network and nos.lol). If one relay's websocket becomes silently dead while the other continues delivering events/messages, last_event_at remains fresh and the pool remains Online, so this watchdog never reconnects the dead relay. Subscriptions assigned to that relay can remain dead indefinitely, which is the failure mode this PR claims to fix.
Please track liveness per relay (or otherwise prove that any traffic from one relay guarantees the health of every subscribed relay), and reconnect/resubscribe only the affected relay or the complete pool as appropriate. Add a multi-relay regression test where relay A is silent while relay B continues producing traffic; the watchdog must still detect and recover A.
The connect-time baseline and post-reconnect rearm fixes from the existing thread are present. The focused watchdog tests pass locally, and the current CI checks are green.
review) ermeme's review: the watchdog kept one last_event_at for the whole pool and only ran on aggregate Online, so a single silently-dead relay was masked whenever any other relay kept delivering — the exact failure MostroP2P#291 targets. - last_event_at is now a per-relay map (URL -> last-event secs), bumped from the relay_url the SDK already carries on its Event/Message notifications. - The silence watchdog checks each relay independently and reconnects only the silent one via disconnect_relay/connect_relay, leaving live relays untouched. - should_force_reconnect now takes a per-relay RelayStatus; each relay seeds its baseline at connect and rearms after its own reconnect, so startup silence is caught and a fresh reconnect does not immediately retrigger. - Added a_silent_relay_is_flagged_even_while_another_stays_live, the multi-relay regression ermeme asked for (A silent past threshold reconnects while B, with fresh traffic, is left alone). 8 watchdog tests pass; cargo test --lib (298) and clippy --locked -- -D warnings clean.
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Reviewed at 3ad8a24, merged locally against current main (0 behind, merges clean): 298 tests pass, cargo clippy --locked -- -D warnings and cargo check --locked --target wasm32-unknown-unknown are clean.
The per-relay reconnect is well built and the decision is correctly isolated as a pure function. The problem is the signal it uses to decide a socket is dead.
Blocking: "no traffic" is not a liveness signal
Tested against relay.mostro.network, subscribing with a filter equivalent to the app's order-book feed:
[probe] notifications=377 max_gap=240s over 250s (watchdog fires at 210s)
377 notifications in the opening burst, then 240 seconds of complete silence on a perfectly healthy connection. The watchdog fires at 210.
So on a quiet node — a regtest daemon, or any low-traffic Mostro — the watchdog will bounce every relay roughly every four minutes, indefinitely. Each bounce tears down and re-establishes every subscription: a REQ storm plus a window in which events can be missed. That is the failure it exists to prevent.
The cause is that RelayPoolNotification::Message carries NIP-01 messages — EVENT, OK, EOSE, CLOSED, NOTICE, AUTH. WebSocket ping/pong frames never appear there, so a healthy idle socket produces nothing to bump the timestamp.
On native, the SDK already does this, and faster
Default relay flags are READ | WRITE | PING, and the app calls client.add_relay(url) with default options, so ping is on. PING_INTERVAL is 55 s, and when the previous ping went unanswered the connection loop returns:
if ping.last_nonce() != 0 && !ping.replied() {
return Err(Error::NotRepliedToPing);
}That marks the relay disconnected, and reconnect: true — the default — reconnects it. A genuinely dead socket is detected in ≤110 s, against this watchdog's 210 s plus up to 30 s of polling.
The device evidence in the description doesn't separate the two cases: silences of 237 s and 217 s with the SDK reporting Online is exactly what an idle connection looks like. A failed ping would have surfaced as a disconnect in the logs.
Where this is the right layer: web
PingTracker is #[cfg(not(target_arch = "wasm32"))] — on wasm it is an empty struct and the ping branch is compiled out. On web there is no liveness detection at all, so this watchdog is the only thing that could provide it. The PR frames this as an Android fix; its strongest justification is the platform it doesn't mention.
What I'd like changed
- Stop using application-level silence as the trigger on native. Either scope the watchdog to wasm, or replace the trigger with an active check: send a cheap REQ — a filter that matches nothing,
limit(0)— and require an EOSE within N seconds. That measures the transport rather than the traffic. (One to save you the detour:verify_subscriptionsin the SDK's relay options sounds relevant but isn't — it only validates that received events match the filter.) - If it stays on native as a backstop, the threshold has to sit above the SDK's own detection window, and the trigger still can't be silence.
What holds up
- The per-relay reconnect works.
disconnect_relay/connect_relaymake the SDK re-send that relay's long-lived REQs in the new websocket session. Note this means the description's "drives the existingOnline→ resubscribe path" is no longer accurate for a single-relay bounce — the pool may never leaveOnline. It works, through the SDK's own resubscribe rather than that path. should_force_reconnectas a pure function with five tests is the right shape, and it makes changing the trigger cheap.- One pool-level observer rather than instrumenting each consumer: the signal survives any individual subscription being dropped and rebuilt.
- The
Laggedbranch refreshes every timestamp instead of risking a false positive from dropped notifications. Correct call.
2 participants
Closes #291.
Problem
The SDK can report a relay as
Connectedwhile its websocket has silently died no events flow, yet no disconnect is ever detected, so the SDK's own auto-reconnect never triggers. On Android this happens routinely when the app is backgrounded. In the incident behind #291 a live trade sat through a ~22-minute silence and missed its hold-invoice turn, cancelling the order.Approach
Following the issue's steer to investigate the SDK first: nostr-sdk 0.44 auto-reconnects detected drops but has no mechanism for a socket that stays nominally
Connectedwhile silent. This PR adds that missing layer, entirely withinRelayPool:spawn_liveness_observera single pool-ownednotifications()receiver that bumps alast_event_attimestamp on everyEvent/Message. One pool-level observer (rather than instrumenting each transient consumer) means the signal survives any individual subscription being dropped and rebuilt.spawn_silence_watchdogevery 30s, if the pool isOnlineyetlast_event_atis older thanSILENCE_TIMEOUT_SECS, it forces adisconnect()/connect(). That drives the existingOnline -> resubscribepath, which rebuilds the order and chat subscriptions.should_force_reconnectthe decision is a pure function, unit-tested in isolation (online vs offline, threshold boundary, and the never-seen-traffic startup case).SILENCE_TIMEOUT_SECSis 210s: above the ~60s Android relay-drop cycle (so normal churn doesn't trip it), well under the ~22-min failure window.Testing
should_force_reconnect(all pass).cargo clippy/cargo fmtclean on the changed file.Online. The watchdog fired each time, reconnected, resubscribed, and a subsequent order completed end-to-end through the recovered connection.Follow-up (separate PR)
A Dart lifecycle resume-hook to reconnect eagerly on app-foreground, rather than waiting for the next watchdog tick.
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