Root cause (found via ha-convergence-recovery task 8 live 3-node E2E): a
controller with no local config (config_version_tag==0) could become PRIMARY
and push an empty config, breaking replication.
Two upstream election-safety gaps, both outside ha-convergence-recovery:
1. RDHUP re-election bypassed the no-config 'voter only' guard. The startup
path (ha_start_election_async) refuses to start an election when
my_config_tag==0 && n_peers>1, but the RDHUP failover path
(ha_on_primary_ctrl_fd_rdhup) called raft_on_leader_lost unconditionally.
Fix: mirror the guard before elect_ctx alloc / hook / raft_on_leader_lost;
a config-less node stays CTRL_STANDBY (voter only) and grants the
configured peer instead of starting (and winning) its own election.
2. Voter freshness gate compared the candidate only against the voter's LOCAL
config, ignoring the cluster's known committed state. Fix: ha_vote_self_freshness
floors the comparison at max(local, learned-committed config_tag / committed_lsn),
so a voter denies any candidate whose config/cluster state is outdated vs
what the cluster has committed. Strictly additive (never denies the freshest
node — Leader Completeness preserves liveness).
TDD: test_rdhup_noconfig_node_does_not_elect + configured-node contrast;
test_ha_vote_gate learned-floor deny + liveness + backward-compat. Full
controller suite green under ASAN. commit.c and ha-convergence-recovery
files untouched.
Full controller suite green under ASAN (508 PASS / 0 FAIL / 0 sanitizer
aborts, independently re-censused). All 16 tasks complete; barrier
before reply proven across all restructured opcodes; classification
guard active; barrier-before-state-removal precondition for
ha-single-leader-role satisfied. spec phase=implemented; roadmap
updated. Sub-spec 2 of 4 of the ha-consistency-invariants umbrella.
43-site classification (8 category-A barrier-gated, 6 category-B
receipt-ACK, ~29 category-C) recorded in tasks.md. Reviewer-confirmed
exhaustive from the producer side and the opcode dispatch: every
WAIT-class WAL producer reaches its requester reply only through a
commit barrier; no handler bypasses wal_classify. Zero production
changes. Noted: WORKER_UPDATE has a reply-less second producer
(mark_worker_back liveness sweep) — not a violation, future RETAIN
refinement candidate.
Guards at the top of mark_job_start/finish/update under the caller's
job lock, before BEFORE_EVENT: duplicate (FINISH on terminal) → INFO
no-op skipping the AFTER_EVENT hook (no WAL append, lsn frozen);
terminal→non-terminal backward (START/UPDATE) → WARN reject preserving
state. Shared job_state_is_backward predicate provably admits every
production forward merge (PDONE/PERR/suspend bit-OR) while rejecting
overwrites. mark_job_fail intentionally unguarded (its merges are
always terminal-forward; job_ctrl pre-gates terminal). 5/5 guard tests
green; full job-lifecycle suite green; census 0 FAIL.
3 RED carriers (duplicate FINISH on DONE appends a 2nd WAL entry +
overwrites state; START on terminal clobbers it; replay non-equivalent)
+ 2 preservation pins (forward postdone PDONE-merge, fail-after-finish
PERR-merge) that 6.2 must not break. Reviewer-confirmed: the
UPDATE-clears-terminal arm is production-unreachable (pinned, not
driven). 22 tests / 3 RED; census 508 distinct triples, only those 3
fail.
configAck branch: per-push majority (acked_config_lsn >= push_tag,
1+count > n_peers/2 over r->ce->n_peers, n_peers<=1 immediate,
ce==NULL -EINVAL); legacy >0 counting and n_active==0 shortcut dead.
push_config_to_standbys returns the barrier result; upgrade failure ->
send_upgrade_error (rc forwarded), no success ACK, no restart,
committed_config_tag success-only.
Remediation r1 (two CRITICAL review findings):
- F1: wire production config-ACK ingestion — replconfigpushreplymsg
decode branch in repl_ack_decode_and_dispatch -> repl_on_config_ack
on the promoted-vote ep; + defensive cluster.c OPCode_reply case.
Closes the unlanded half of ha-config-bootstrap 8.1; without this the
barrier would brick every multi-member config upgrade. No schema change.
- F2: keep the barrier off the iomgr thread — export
push_config_transport_only (non-blocking) for the 5 ha.c + join.c
streaming sites; barrier path now vtask-only (do_upgrade_config).
Wire-path test drives real capnp ACK bytes through the production decode
branch. 30/30 rollout, 6/6 repl_majority, 46/46 config_repl; census 0
FAIL; pre-existing fixture leak only (less than baseline).
Green integration proof: 4 facts driven during total quorum loss append
RETAIN with rc 0 in <1000ms (vs 5000ms timeout — wrongly-applied WAIT
tripwire), pending with retained-depth=4 logged, present exactly once
on disk (real WAL header scan); reconnect + one covering ACK commits
the suffix with current_lsn unchanged (no redelivery). Completes the
bug-396 fix evidence (umbrella Req 2.8). Census 495/495.
notify/update/setpreason/clrpreason admitted in CTRL_PRIMARY without
write quorum (Req 3.2 / umbrella 2.8 / bug-396): all four terminate in
receipt-style RETAIN fact paths — reviewer-traced no-block proof (no
admitted opcode reaches a barrier/WAIT path; request opcodes stay
rejected). 21/21 group; census 494/494 zero FAIL; RED→GREEN
independently reproduced via stash-rebuild.
4 RED carriers (notify/update/setpreason/clrpreason must be admitted
without quorum — currently NOT_READY, the bug-396 hole) + 2 pins (six
request opcodes stay rejected; quorum-present admits all ten). Census
494 = 488 + 6; exactly 4 FAILs.
4 green pins: handle_jobdispatch replies receipt-only with zero WAL
appends through a real 2-alloc dispatch cycle (notify outcomes intact,
reply-precedes-processing); set/clr_preason and do_update_op rusage
stay receipt-style with RETAIN-pending fact appends ACK-committed.
Umbrella Reply-Ordering Contract cited per pin. DISCOVERY bug-451
(reviewer-verified): RUSAGE hook va_list type confusion — 4-byte OOB
read + garbage state in WAL_JOB_RUSAGE payloads; fix deferred to 7.1.
Census 488; zero failures.
7 cases: two covered short-circuits, timeout with committed_lsn
unmoved, covering-ACK release, sync_timeout_ms fallback (bounded both
directions), n_peers=1 standalone, NOT_READY passthrough via cap
saturation. Watermark resolved to current_lsn - 1 (design's literal
phrasing unsatisfiable per persist.h:71 invariant) with off-by-one
killing power both ways. 15 tests / 7 RED; suite baseline zero.
Verified table implemented (STOP/RESUME/UPDATE/FAIL RETAIN per
supersession; WORKER detail switch; CHECKPOINT LOCAL); unknown type =
ERROR + XCE_TESTING abort + production RETAIN fallback. All three
hooks route through wal_hook_append_classified (zero bare async
appends); RETAIN registers with the engine lock-free; facts propagate
local append rc only. 8/8 group tests green; full suite 465/465.
Fixed the 3 bug-411 baseline failures honestly: stale timeout
expectation updated to the reject-on-timeout contract (engine-wired
fixture, killing power retained); two healthy-primary gate fixtures
populated with standby_endpoints (gate logic untouched). Census: 46
groups / 467 tests / 0 failures standalone under default ASAN.
Audit (reviewer-confirmed, recorded in tasks.md): no production walAck
path reaches the deprecated acked_lsn>0 counting or n_active==0
short-circuit except the documented LSN-0 first entry. Leak inventory
for 6 groups documented as follow-up.
cluster_t embeds commit_engine_t; init in cluster_init_phase2 after the
vtaskmgr guard (idempotence-guarded — phase2 can run twice), wiring
repl_set_commit_engine + ha.repl back-pointer before any standby can
register; fini after iomgr/vtask shutdown. persist_wal_sync_append
passes written_lsn; engine-wired path drops -ENODEV and the
committed_lsn store (engine owns advancement); LSN-0 first-entry
routes to legacy per the accepted interim. p2 -ENODEV pin updated to
the Req 6.3 contract. 34/34 + 6/6 green through honest delegation;
census exactly at the 3 validated baselines; production binary links.
replicator_t gains ce pointer (set-once-before-traffic contract).
repl_on_ack feeds commit_on_ack after releasing r->lock (iomgr-safe);
four membership mutators feed commit_on_membership_change post-unlock,
gated on actual mutation. walAck branch delegates to commit_submit(WAIT)
when ce wired AND entry_lsn != 0 (LSN-0 interim guard until 5.3);
legacy counting kept for ce==NULL, marked DEPRECATED. commit.c linked
into production target (inert until 5.3 wiring). Tests 30-31 + all
repl_majority walAck cases green; 33/34 remain RED for 5.3; baseline
unchanged.
repl_active_standby_count: registry truth (ep != NULL && !in_catch_up)
under r->lock. ha_state_t gains repl back-pointer (wired at init by
task 5.3); ha_has_write_quorum uses registry truth when wired, exact
legacy fallback when NULL; formula unchanged. Test 29 (wired gate,
catch-up-only standby → NOT_READY, admits after clear) captured RED
pre-fix. 29/29 group tests; suite at the 3-failure baseline.
Tests 21-28: repl_active_standby_count contract (5 RED vs inert -1
stub) + 3 gate-level pins (n_peers<=1 always-true, zero-connected
reject, stateless re-accept) that 4.2 must preserve. Declaration in
repl.h; ha.c/ha.h untouched (4.2 boundary). 28 tests / 5 RED; suite
at the 3-failure baseline with unchanged signatures.
Tests 17-20: catch-up ACK exclusion vs pending waiter, membership-change
wake of covered waiter, removal-below-majority fails at own deadline
(no forced early-fail), non-blocking bound. Landed GREEN: task 1.2's
commit_on_membership_change already implements the full 3.2 contract,
so RED was unachievable; reviewer confirmed mutation-killing power and
zero production changes. 20/20 group tests; suite at baseline.
commit_submit(WAIT): n_vcpus-relative admission cap with fast retriable
NOT_READY (admission-cap-only per corrected contract), CLOCK_REALTIME
timedwait loop on the per-LSN + gate predicate, post-timeout predicate
re-check, n_peers<=1 self-quorum through the single advancement site.
Inflight counter accurate under engine lock for the full blocking
interval with XCE_TESTING asserts. 16/16 group tests green unmodified;
full suite at the 3-failure baseline.
9 new cases (8-16): block-until-majority, deadline timeout, standalone
fast path, zero-ACK regression, n_vcpus-relative cap with floor, ACK
progress at saturation, gate as blocking predicate (NOT_READY is
admission-cap-only per corrected contract). Main-thread-only assertions
after joins; 16 tests / 9 RED failures; baseline unchanged.
