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e6c56ee5ee
## Summary
Before the relay opened its listener, it reconciled the NIP-43
membership snapshot for every active community. Each community costs two
writer round trips, one after the other. On a production deployment with
about 80k communities, this one step averaged 174s of a roughly 180s
boot (max 324s). Pods in an availability zone farther from the writer
took 3–4× longer than pods in the writer's zone.
The step doesn't need to block startup. The snapshots live in the shared
database, and the replicas that are already running serve the same
snapshots. A new replica has nothing of its own to repair before it
serves. The sweep before bind did the same work as the background
maintenance sweep; only the metric labels differed.
This PR:
- Removes the NIP-43 sweep that ran before bind.
- Moves the background loop into
`side_effects::spawn_nip43_membership_reconciler`. Its first sweep now
runs as soon as the task starts. Before, the loop skipped its first
tick, so the first maintenance sweep waited a full
`BUZZ_NIP43_RECONCILE_INTERVAL_SECS`.
- Runs that loop on one replica only. The replica holding the
`NIP43_RECONCILE_LOCK_KEY` session advisory lock sweeps; the others
retry the lock every `NIP43_STANDBY_RETRY` (5s, capped at the interval).
This reuses the usage-metrics leader lease (a detached Postgres
session), renamed from `UsageMetricsLeader`/`try_lock_usage_metrics` to
the generic `SessionLeader`/`try_lock_session_leader`.
- Waits a full interval after each sweep (sleep after sweep), so a sweep
longer than the interval never runs straight into the next one.
- `reconcile_nip43_membership_snapshots` is now the only entry point and
keeps its original signature (`-> Result<usize>`). It's no longer
deprecated.
### What got simpler
Deleted:
- `Nip43ReconciliationPurpose` (the `Bootstrap`/`Maintenance` purposes)
and `reconcile_nip43_membership_snapshots_with_purpose`
- `Db::bootstrap_community_hosts` and
`Db::nip43_membership_snapshot_needs_reconciliation_for_bootstrap`
- The startup progress log (`NIP-43 startup reconciliation progress`,
`nip43_progress_due`) and its test
- The `nip43_reconcile` startup phase: `StartupStep::ALL` goes from 19
to 18 steps
The leader lock reuses the existing usage-metrics lease rather than
adding a second leader primitive. `StorageAccountingLeader` is still a
near-duplicate of it; folding that in is left as identified debt.
### Trade-offs
- **Repair before serving.** A newly started replica no longer
guarantees it has repaired stale snapshots before serving. The running
fleet doesn't guarantee that today either: the background sweep is what
repairs drift, and the leader starts it as soon as it takes the lock.
- **Rollout load.** Before, every replica swept before binding, and
every replica also ran the background loop. Now there is one sweeper in
steady state, so writer load from this job drops from one sweep per
replica to one per deployment, and rollouts no longer stack boot sweeps.
Standbys add one lock attempt every 5s each.
- **Leader handoff.** When the leader's process exits (including
SIGKILL), its connection closes, Postgres releases the session lock, and
a standby retries the lock at least every `NIP43_STANDBY_RETRY` (5s) and
sweeps as soon as it gets it. Each attempt also waits for a writer
connection, so under database pressure takeover can take longer than 5s.
Before this, a standby waited a full interval (3600s in production), so
after a rollout replaced the leader nothing swept for up to an hour. If
the leader is lost with its host or network instead, the lock is held
until the database server's TCP keepalive drops the session, and nobody
sweeps meanwhile. The usage-metrics leader already has the same
exposure. The lease is checked only between sweeps, so a leader that
loses its session mid-sweep finishes that sweep while the new leader
starts one; the per-community publication lock keeps that overlap safe.
- **Snapshot window.** A missing or stale kind:13534 snapshot is served
until the leader's sweep reaches that community; before, a booting
replica blocked until it was repaired. Admission reads canonical
`relay_members`, so this window doesn't change who's admitted. It does
affect clients that read the snapshot: desktop onboarding shows the
membership-denied page to a member missing from it, the desktop/mobile
member lists and join alerts lag, and desktop mesh discovery keeps its
existing allowlist when the snapshot is missing. In production the
inline publications that keep it current have not failed since
2026-10-07, and the sweep repaired no snapshots in the last 30 days.
- **Dashboards and alerts.** The
`buzz_startup_phase_seconds{phase="nip43_reconcile"}` series stops
reporting. Anything charting or alerting on it should move to the
sweep's existing counters
(`buzz_nip43_membership_reconciliations_total`,
`buzz_nip43_membership_reconciliation_failures_total`).
### Related issue
None found.
### Merge order
#8468 is stacked on this PR. Both remove a startup phase, and with the
old fixed-length `StartupStep::ALL` array, merging both would have built
a 17-entry `[Self; 18]` that doesn't compile. Merge this PR first; #8468
makes `ALL` a slice.
### Testing
- `background_reconciler_sweeps_immediately` (private scratch database):
spawns the production reconciler with a 24h interval and 24h standby
retry, and requires the first sweep to publish a missing snapshot. Fails
if the skipped first tick is restored.
- `background_reconciler_standby_takes_over_on_short_retry` (private
scratch database): with a 24h interval and 100ms standby retry, nothing
publishes while another session holds the leader lock; once it's
released the standby must publish within 10s. Fails if the standby
sleeps the full interval again (checked by reverting that line).
- `test_usage_metrics_lock_has_single_owner_and_releases_on_drop` covers
the renamed lease.
- `maintenance_sweep_skips_archived_and_deleted_communities` now calls
the single entry point.
- Runtime E2E at `574b28b3`: two real relays sharing one database, 3600s
sweep interval, production 5s standby retry. While the leader was alive,
the standby made only lock attempts (no sweep or snapshot-comparison
reads). SIGKILL of the actual lock holder, 3/3 trials: the survivor took
the lock in 4.81–4.86s and repaired the snapshot within 10ms after that.
Both replicas served authenticated reads while the initial publication
was stalled.
- Blox, at `574b28b3`: `just fmt-check clippy security-review-check
file-size-check` passes. Every `test-unit` step and `just test` (118
suites) passes except the `buzz-acp` `git_bootstrap` native-git tests,
which fail the same way at base `b6aa5539` on Blox (environment, not
this change).
---------
Signed-off-by: Elrond <28d6302a099e5225b02c4155ac4236e4912603df2ab08dbfc2f4fef08ce598c8@buzz.block.builderlab.xyz>
Co-authored-by: Elrond <28d6302a099e5225b02c4155ac4236e4912603df2ab08dbfc2f4fef08ce598c8@buzz.block.builderlab.xyz>