5.2: clean failover STRICT_TERM verified — committed prefix byte-identical
(term,pcrc) across all 3 members; standbys persist non-zero term;
0 committed-job loss.
5.4: chaotic 3-round soak — zero job loss; committed prefix consistent
at every walcompare checkpoint; all 3 nodes led; round-3 election
stall is pre-existing bug-851/795 family (NOT regression).
5.5: build+unit suite green (19 groups 0 failures, ASAN clean).
Ha-term-safety: ALL 21 tasks complete. Spec done.
Co-Authored-By: Claude <noreply@anthropic.com>
Adds two controller-level regression tests driving the production raft_on_vote_reply
via ha->raft (test_ha_election.c): a duplicated vote-grant from one peer must not
double-count toward quorum (bug-1095) and a stale-term reply must be dropped
(bug-1096) — both asserted on role/promotion (no two leaders per term). Formally
absorbs bug-1095/1096 into the ha-term-safety spec (Implementation Note) mapping to
its Requirement 1 / Objective; the raft.c fix (b5b7e01) is owned there with
protocol-suite regression at both the libxce (test_vote_reply_*) and controller
(test_ha_election) levels. No production source changed.
Ran clean_failover_preservation.sh on a real fs ($HOME/tmp/xce-ha-deploy, ext4).
PAYLOAD run CONFIRMED bug-990 fixed live: standbys persist the leader's real
term (2) for the committed prefix; walcompare OK.
Harness fixes: robust failover detection (any post-kill CTRL_PRIMARY promotion,
45s settle) + a wait-for-commit-before-kill gate (jobsub returns on accept not
commit, so the prior harness raced replication vs kill).
That commit-wait gate exposed bug-991: on a STABLE cluster, jobs replicate to
all members (durable LSN 5) but committed_lsn pins at 1. Catch-up-delivered
entries don't advance the library commit_index, so task-2.4's ceiling
min(durable-majority, raft_commit_index) starves commit below the durable
majority. A real regression from the commit-source switch (2.4+3.3), invisible
to the steady-state-only unit tests.
Closes bug-990: the live replicator repl_broadcast wire-encoded term=0
(entry.term was never set), so standbys persisted hdr.term=0 and took the
legacy direct-apply path instead of the library (term,lsn) intake. Now the
live broadcast and catch-up streamer carry the leader's real term + AE prev
tuple; ha_apply_wal_catchup_entry routes every term-carrying entry through
raft_on_append_entries_request -> on_persist_entry (leader term stamped),
retiring the term-0 direct-apply. Standbys now persist the leader's real term
and reconcile by (term,lsn); the live commit chain is end-to-end.
848/849/850 + persist-before-ACK + commit-barrier + bug-960 preserved.
Proven at integration level; the definitive live STRICT_TERM failover run is
env-blocked here (bug-924 overlayfs) and recommended on a real fs.
Task 5.2 harness deploys a real 3-node localhost cluster, kills the primary,
promotes a standby, restarts the old primary, and asserts convergence via
walcompare --committed + per-job expect-job. Runs GREEN in PAYLOAD mode
(guards 848/849/850 + no committed-job loss).
The term-identity half of R5.1 is BLOCKED (bug-990): live replication still
uses term-0 repl_broadcast; the library send loop (on_send_append_entries) has
no live caller, so standbys persist hdr.term=0. The live-send retirement was
deferred across tasks 3.2/3.3 into verification tasks 5.2/5.4 that cannot
contain the production cutover. Needs a dedicated implementation task.
Diffs member WALs by (lsn -> term, pcrc) over the committed prefix, exits non-zero
on any committed-prefix divergence with the diverging LSN + per-member entry
identities. Reuses the canonical waldump decoder via a new per-entry visitor seam
(no second WAL parser). Detects same-LSN/diff-term and same-LSN/diff-content
divergences (the bug-851 class) that an LSN-range check would mask.
Wires config_committed_marker to a production consumer (config_activate_committed):
verifies pushed bytes' sha256 against the committed marker before activation, fences
(loud, non-serving, stay-alive) on mismatch, and activates the latest committed marker
on recovery. Enforced via ha_dispatch_gate + promotion gate.
Fixes bug-981: a 2nd+ config upgrade could permanently fence a standby on a
push-before-commit ordering. Adds an off-iomgr delaymgr retry scheduled from the
commit-advance hook (atomic read + non-blocking enqueue only on the ACK thread) that
re-activates and clears the stale fence once the new marker commits and bytes verify.
Wires do_upgrade_config_with_bytes to append WAL_CONFIG_MARKER through
raft_log_append (live term-stamped consensus record), demotes committed_config_tag
to a non-authoritative cache, and derives the committed config from the latest
committed marker. Preserves the derive across checkpoint compaction via an optional,
backward-compatible config-ref tail in the snapshot sentinel.
Includes fix for bug-960: endpoint-type-aware peer-index resolution
(promoted-vote relative vs heartbeat-standby absolute) with fail-loud
bounds check, preventing an out-of-bounds match_index[] write / wrong-peer
false-quorum on the replication ACK path.
Replaces the stub: builds a WalCatchupEntry AppendEntries to standbys[peer_idx].ep
carrying prev_log_index/prev_log_term; for n_entries==1 sources the entry at
prev_log_index+1 from the local WAL (term via persist_entry_term, type+payload via
ha_read_wal_entry_at); n_entries==0 emits a zero-entry heartbeat. Async send
(xce_wal_batch_req_raw), payload freed on all paths. 2 tests via a capture seam.
Review-applied: corrected the misleading repl.c comment — leader_commit is accepted
but NOT yet wire-encoded (deferred to task 3.2: WalCatchupEntry leaderCommit field +
standby intake). Reviewer APPROVED; per-group 0 failures.
on_get_entry_term → persist_entry_term (recorded term, 0=absent, legacy-0→1; caveat
documented per 1.3 review). on_truncate_from → persist_truncate_wal_above(p, index-1)
(delete LSN>=index), returns rc for library/leader retry; non-promotable fence intact;
replaces the committed-boundary heuristic on the library-driven path. New
truncate_term_index_locked keeps the in-memory per-LSN term index consistent on both
truncate paths (under lock, cutoff-aligned) → no stale-term read after truncation.
3 tests, reviewer APPROVED, per-group 0 failures.
Replaces the iter-1 stub: persist_set_term(p, term) stamps the leader/library term
into hdr.term, then role-routes the write — primary via persist_wal_async, standby
via persist_wal_write_replicated(p, index, ...). Persist failure returns non-zero
(no false ACK; durable_lsn unchanged); bug-850 contiguity guard + persist-before-ACK
preserved beneath. In-flight raft_entry_blob_t {type,payload_len} envelope added to
wal_types.h (never enters the 40-byte header). 3 tests, reviewer APPROVED.
Deferred (recorded in tasks.md): task 3.1 must retire the hand-rolled primary append
so current_lsn tracks the library index; task 3.2 must not call on_persist_entry on
heartbeats. Per-group 0 failures (pre-existing test_commit_barrier_reply leak aside).
persist_set_term sets the live election term so appends stamp hdr.term (fixes the
G1 term-0 stamping); replay_wal builds an in-memory per-LSN term index (freed in
persist_fini, no on-disk change); persist_entry_term reads it back (0=absent).
Legacy-0 -> WAL_LEGACY_TERM=1 at read-back only (raw 0 retained so present-legacy-0
is distinguishable from absent). 40-byte wal_entry_hdr_t preserved (value fix, R1.7).
5 new tests (test_term_safety_adapter.c); reviewer APPROVED. Feeds task 2.2.
All controller test groups report 0 failures; the meson full-suite timeout is the
bug-924 overlayfs /tmp fdatasync artifact, not this task.
bug-918 resolved (c-capnproto flake repin); clean controller build passes full
suite (Ok:1 Fail:0). Earlier wal_catchup failures were a stale incremental-build
artifact, not fsync/regression. Validation gate reliable for remaining tasks.
1.1: WalCatchupEntry gains term@4/prevLogIndex@5/prevLogTerm@6 (append-only).
1.2: RequestVote/PreVote gain lastLogTerm@4/lastLogIndex@5; cluster.c vote callers
fixed to the extended library arity (RESTORES xce_controller + controller_unit_test
compile+link, broken by the raft-commit-safety signature extension); ha.c emits the
candidate's last-log tuple on send.
5 minimal stub log/commit callbacks wired into s_real_cbs so raft_init's new
non-NULL requirement is satisfied — tasks 2.x replace them with real bodies; the
logOk freshness gate is inert until the term seam (1.3) + on_get_entry_term (2.2).
Pre-existing test_repl_unit.c wal_catchup -EAGAIN failures + ASAN leaks are an
overlayfs /tmp fsync env artifact (bug-850), not from this task (untouched paths;
append-only schema cannot affect the @3 entries-list decode). Build/baseline
isolation is blocked by a c-capnproto flake-hash drift — see Implementation Notes.
