XCECLI_FF_CALL (backing xcecli_heartbeat) can silently rotate+reconnect
the transport entirely inside a single call and still return success, so
heartbeat.go's failure-to-success transition detector could never observe
a reconnect that completes within one heartbeat tick -- the common case,
since elections finish in single-digit seconds against a default 30s
interval. apiserver's application-level rejoin never fired on a real
idle-period failover, and job pushes silently stopped reaching it.
Adds a monotonic reconnect_gen counter to endpoint_t (netio.h), bumped by
xce_ctx_reconnect() (xcectx.c) on every successful reconnect regardless of
trigger path. heartbeat.go now compares this generation every tick instead
of tracking success/failure transitions. Re-validated live against task
5.2's exact scenario (apiserver alone, zero write traffic): rejoin fired
22s after a primary kill, 12s after election.
Reopens and closes out component-failover-adoption's own NO-GO -> GO
validation cycle from 2026-08-15.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
xcecli_heartbeat() is XCECLI_FF_CALL-wrapped -- a deliberately
non-retrying fire-and-forget path that does its own best-effort
one-shot reconnect but never calls xcecli_invoke_rejoin() (that only
fires from the write-call retry path). Left as-is, a controller
failover with no in-flight write request would silently repair the
transport connection without ever re-joining, permanently starving
push notifications.
runHeartbeat() gains two callback hooks fired at the right points --
onFailureToSuccess on a genuine transition, onSuccessTick on every
successful tick thereafter -- wired directly to task 4.3's existing
setNeedsRejoin()/checkAndPerformRejoin() from StartHeartbeat(). No
second rejoin mechanism: checkAndPerformRejoin() is a cheap no-op when
nothing is pending, so calling it unconditionally on every successful
tick is safe and matches the requirement that retry isn't gated on the
transition edge alone.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NNB4zGPCsHyDUCDJyMbiQN
- COR-001: drain runHeartbeat goroutine via done channel before test returns,
eliminating race against concurrent SetHeartbeatInterval tests
- COR-002: replace time.After with time.NewTimer + defer t.Stop() + t.Reset()
to prevent timer goroutine leaks on context cancellation
- COR-005: guard HeartbeatInterval store write with > 0 check in OnClusterUpdated,
keeping store consistent with SetHeartbeatInterval's zero-ignore semantics
- add heartbeat.go with heartbeatIntervalSecs var, SetHeartbeatInterval, runHeartbeat (no build tag, CGO-free)
- add heartbeat_test.go with 5 tests covering interval validation and goroutine lifecycle
- add StartHeartbeat to clib.go (CGO impl calling xcecli_heartbeat)
- remove SetHeartbeatInterval stub from stub.go (now real code in heartbeat.go)
- remove TestSetHeartbeatInterval_StubNoOp from stub_funcs_test.go
- call SetHeartbeatInterval in OnClusterUpdated to track backend-pushed interval
- call backend.StartHeartbeat in cmd/main.go after backend registration
