With the dispatch flags flipped ON in-test, prove the three receiver-side
liveness properties (production defaults stay OFF):
- P1: while a snapshot (and config-push) transfer is parked in flight on the
slow lane, another endpoint's peer-control message is still processed
promptly on the vtask pool (different thread), with the transfer still
parked — the offloaded transfer does not block the drive path.
- P2: a peer-control ack (classified VTASK_LIVENESS) runs promptly even while
the pool is saturated to the LivenessAdmission reservation boundary with
REQ_BLOCK tasks (one more REQ_BLOCK fast-rejects with -E_XCE_NOT_READY,
proving real saturation). Narrowed to the liveness-dispatch-under-saturation
assertion; commit-advance itself is covered by the commit-engine tests.
- P3: while one endpoint's peer-control body is parked (holding a worker + that
ep busy), another endpoint's body runs concurrently on a different worker —
per-endpoint FIFO does not serialize across endpoints.
All deterministic (cond-var gates, bounded polls). Fixed a flaky teardown-race
hang (bug-1224): the tests released a parked vtask body then immediately called
the cancel-based vtaskmgr_fini while the just-released body was still unwinding
(P2's REQ_BLOCK bodies racing blk_lock teardown the worst). Fix adds end-of-body
completion counters polled to the full expected count before fini, so every
pool body has fully returned (worker idle) before the cancel. slowlane_fini is
graceful (join) so the lane side was already safe.
Verified: 5/5 deterministic isolated runs; full controller suite EXIT=0;
ASan-clean. Completes task 3.4 (3.4a UAF fix + 3.4b tests); the production
flag-flip remains deferred to after the 4.1 partition soak + 4.2 regression
sweep.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S6fDCtXkkEgupu7rUah1y2
When the (still-default-OFF) peer-control dispatch flag is ON,
raft_cb_become_follower runs as a vtask pool worker and frees every peer
vote-ep while other pool workers may still hold those eps' data — a UAF
(bug-1197). This makes that path quiescence-safe so the flag can later be
flipped ON (deferred to the 4.x prod-flip gate; production stays OFF here).
Mechanism (no libxce-wide endpoint refcount; reuses the existing per-ep FIFO +
busy serialization):
- Deferred teardown-as-vtask: the loser loop, when dispatch is ON and the pool
is wired, does per vote-ep endpoint_mark_tearing_down -> iomgr_unmonitor ->
enqueue a VTASK_IO/VTASK_LIVENESS teardown vtask bound to that ep. Per-ep busy
FIFO makes it run strictly after any in-flight/queued same-ep peer-control
vtask; the body NULLs iod->ep before endpoint_fini+free(ep) to disarm
run_task's post-body endpoint_unblock_tasks (which would touch the freed
ep->lock). OFF / pool-unwired path is byte-for-byte the legacy endpoint_fini.
- RCU-like drain closes the dispatch/teardown TOCTOU window: new _Atomic int
endpoint_t.dispatch_inflight (+ tearing_down:1 bit). The ON dispatch brackets
its flag-check+enqueue with fetch_add/fetch_sub (seq_cst);
endpoint_mark_tearing_down sets the flag under ep->lock, releases, then spins
until dispatch_inflight drains to 0. So every dispatch that read the flag
false finishes its enqueue before mark returns (FIFO-before the teardown
vtask); any later dispatch reads the flag set and drops the packet. ep->lock
is deliberately NOT held across the enqueue (it inverts with the taskq lock in
vtask_eligible); the counter is the lock-free handshake. Drain is bounded: the
held window is just a calloc + non-blocking enqueue on the single io_worker.
Still open before the production flag flip (4.x): the borrowed-ep race in
snapshot_lane_fn/configpush_lane_fn is distinct (slowlane thread vs io_worker
RDHUP teardown, not the vtask-pool FIFO) and needs its own per-standby-ep
discipline.
Tests: test_ha_vep_teardown.c — 5 ASan tests (ordering, late-event drop, run_task
unblock disarm, OFF-path unchanged, deterministic mark-drains-inflight-dispatch).
xcelib_test 282/0; controller_unit_test EXIT=0; ASan-clean. Adversarial
cpp-review: no CRITICAL/HIGH; handshake formally sound, flag-ON path race-free.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S6fDCtXkkEgupu7rUah1y2
push_config_transport_only spawns one thread per standby then joins them with a
CONF_PUSH_TIMEOUT_MS bounded wait — blocking the caller. On the requester-less
drive-thread paths (promotion + heartbeat convergence) that wait stalls the
io_worker. Route those through ha_config_push_offloadable, gated by
g_drive_async_configpush_offload (default OFF → inline, byte-for-byte legacy;
ON → slow lane, non-blocking).
Flag ON deep-copies the config bytes + sha into a lane ctx (caller keeps owning
and freeing its own buffer); a single cluster-wide single-flight guard
(ha_state_t.configpush_inflight scalar CAS + lane key=1) bounds it to one
config-push fan-out in flight; the in-flight flag is cleared on every terminal
path (two alloc failures, -EEXIST, hard submit error, lane completion). Send
body factored into ha_config_push_do_send.
Three requester-less drive-thread call sites converted: raft_cb_become_leader
(promotion), the HA_REPL_PUSH_CONFIG heartbeat case, and the direct-CTRL_PRIMARY
FSM promotion branch. The admin-upgrade barrier (push_config_to_standbys, has a
waiting requester) and join.c are untouched.
Lands DORMANT like tasks 3.1/3.2: the lane reads c->ha.standby_endpoints and
writes those borrowed standby endpoints, racing io_worker RDHUP teardown if run
off-thread (bug-1197 family). Flag OFF keeps push+teardown serialized on the
io_worker. Task 3.4 flips this ON together with the snapshot and peerctrl flags
after establishing endpoint-lifetime discipline.
Tests (controller suite EXIT=0): test_configpush_offload_runs_on_lane,
test_configpush_inline_when_flag_off, test_configpush_offload_dedups.
Adversarial cpp-review: no CRITICAL/HIGH/MEDIUM findings.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S6fDCtXkkEgupu7rUah1y2
Part B (LIVE, default-ON): trim_wal_segments now bounds WAL-segment deletion
by repl_trim_lsn(&p->repl, active_seg_lsn) = min(active segment LSN, every
active standby acked_lsn, every valid disconnected-slot last_disconnected_lsn),
after repl_expire_disconnect_slots ages out stale slot guards. floor <=
active_seg_lsn structurally, so the guard can only preserve more segments,
never delete one a live standby still needs — closes the bug-795/828
trim-vs-cursor race for connected/recently-disconnected standbys (bug-1147
stopgap; empty/cursor=0 join still needs entity-bearing snapshots).
Part A (DORMANT, g_drive_async_snapshot_offload default OFF): ha_snapshot_send_
dispatch routes HA_REPL_SEND_SNAPSHOT inline (flag OFF — byte-for-byte legacy,
on io_worker) or to slowlane_submit+snapshot_lane_fn (flag ON). Send body
factored into ha_snapshot_do_send. Per-peer single-flight via
ha_state_t.snapshot_inflight[] CAS + slowlane key; in-flight flag cleared on
all four terminal paths, mirroring the reconnect offload (task 2.1).
Lands dormant like task 3.1: snapshot_lane_fn borrows a standby endpoint it
does not own, so flag-ON would race io_worker RDHUP teardown (cross-thread UAF,
bug-1197 family). Flag OFF keeps send+teardown serialized on the io_worker.
Task 3.4 is the single gate that flips both this and the peerctrl flag ON after
establishing endpoint-lifetime discipline; bug-1198 stays open by design until
then. The offload flag was initially authored default-ON (would ship the UAF)
and corrected to OFF in ha.c and the ha.h accessor doc (bug-1210).
Tests (controller 196/0, 0 new leaks): test_snapshot_offload_runs_on_lane,
test_snapshot_inline_when_flag_off, test_snapshot_offload_dedups_per_peer,
test_trim_guard_preserves_standby_segments,
test_trim_without_standbys_proceeds_normally. Adversarial cpp-review: GO.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S6fDCtXkkEgupu7rUah1y2
Ran the live 3-node E2E (the last open task). Result:
PASS: 8 rounds, 30 jobs submitted, zero job loss; all 3 nodes led
(ctrl-1,ctrl-2,ctrl-3) (exit 0)
Live-covered: kill-primary -> promoted standby owns all confirmed jobs
(zero loss across 8 failovers, jobs 3->30, expect-job ok each round);
restart ex-primary -> converged rejoin, 3-of-3 each round, no phantom jobs;
deterministic leadership coverage (ctrl-3 forced via RequestVote-freshness
fence). The soak also served as the live regression for bug-1077 (~40
failover client round-trips, no SEGV) after rebuilding the controller (the
deployed binaries predated that fix).
Not exercised live (remain unit-covered, tasks 2/4/5): withhold-ACK barrier
single-outcome (test_demotion_convergence) and isolate/heal quorum-WARN
(test_convergence_verification). All 8 tasks now [x]; spec closed.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MSxwb2Xt5F84ATgiAZnH8V
ctx->reply.u is a single untagged union shared across opcodes (debugmsg /
get(dataset_t*) / jobid / clusterconf / ctrlstatus alias the same 8 bytes).
Commit 61e1391 added speculative free-guards
`if (ctx->reply.u.ctrlstatus) free_CtrlStatus_ptr(...)` (and the clusterconf
twin). A non-NULL slot does NOT imply a CtrlStatus*: a failover-aborted
reslist/joblist leaves ctx->reply.u.get == &getreply (a dead STACK pointer)
because xce_get_with_condition/xce_resval only cleared the slot on the success
path, not the xce_get_req<0 / cbuf_get<0 early returns. The next ctrlstatus
reply (worker thread) freed that foreign pointer as a CtrlStatus -> ASan
SEGV / stack-use-after-return in free_CtrlStatus (controller.capnp.c:11638).
Fix (root cause, both layers):
- Revert the unsafe free-guards in xce_handle_reply: MOVE_PTR overwrite only,
never free/deref an untagged union slot by type.
- Clear ctx->reply.u.get = NULL on ALL exit paths of xce_get_with_condition
and xce_resval via a single `goto done` cleanup (forget-proof; the bug was
one forgotten failover path). Also drops the now-unused controller.capnp.h.
- Defense-in-depth: handle_get_reply drops a reply when the slot is NULL.
Regression: expose xce_handle_reply and add
test_handle_reply_ctrlstatus_does_not_free_foreign_slot, which poisons the
shared slot with a foreign heap value and proves the ctrlstatus reply handler
does not free it (RED reproduced the exact free_CtrlStatus_ptr double-free;
GREEN after fix). xcelib_test 244/0, controller_unit_test 166/0, all binaries
build clean.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MSxwb2Xt5F84ATgiAZnH8V
fsync_worker slept the full wal_sync_ms in one uninterruptible nanosleep()
before re-checking fsync_stop. persist_stop sets the flag and immediately
pthread_join()s, so the join blocked until the in-flight sleep returned —
up to a full wal_sync_ms per teardown. Tests set wal_sync_ms=5000 ("slow
fsync — no races"), so each persist_stop cost ~5s; across the ~7 suites
that use it the cumulative teardown time blew past the 300s controller-test
meson cap, killing the suite with SIGTERM.
Replace the nanosleep with pthread_cond_timedwait on a new fsync_mutex/
fsync_cond (added to persist_t, init in persist_init, destroyed in
persist_fini). persist_stop now sets fsync_stop and signals fsync_cond
under fsync_mutex before joining, so the worker wakes immediately. fdatasync
still runs under p->lock, released before re-acquiring fsync_mutex — no lock
nesting. The "commit: WAIT deadline expired" log lines were unrelated
intentional negative tests (50-300ms), not the cause.
Full controller suite now completes in ~10s (was >300s TIMEOUT); 0 failures.
Logged as bug-604.
- Mark the PreVote denial log-reason nit RESOLVED in ha-prevote tasks notes (47f7338).
- File ha-elect-ctx-lifecycle spec scaffold (spec.json + brief.md) capturing the
pre-existing, bounded, UAF-sensitive election-carrier leak and the refcount/
teardown-ordered-free approach across both election and PreVote paths. Deferred
by decision — not folded into ha-prevote to avoid a risky lifetime refactor.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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.
Replace no-send stub with real WAL entry transmission via
xce_wal_batch_req_raw. For each non-catch-up registered standby,
serialize the entry header+payload into a wal_catchup_entry_t
and enqueue. Keep the MAX_PENDING_ACKS eviction guard.
5 new tests: no-standbys, one-standby-send, skip-catch-up,
evict-overloaded, send-failure-continues. Controller suite green.
Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>
Appended "Gap Analysis — Validation Pass (2026-06-09)" to each spec's
research.md with requirement-to-asset maps, status tags, and effort/risk.
Key outcomes:
- ha-repl-hardening: REOPENED with task series 7.1-7.7 — replication
payload data plane is missing (snapshot chunks and WAL catch-up ship
header-only; standbys converge on LSN without holding entity state)
- worker-join-refactor, resval-id-decoupling: marked implemented
(all criteria re-verified, full test suite green)
- buglog: 335/336 (scheduler dequeue, open), 337/338/339 (fixed in
previous commit); cerebrum Decision Log corrected (term-only vote
deny was recorded as intentional but was a regression)
