f88e4ef4 moved ha_demotion_convergence_fn's WAL truncate + self-restart
and ha_catchup_continuation_fn's WAL streaming off the delaymgr thread
(which drives heartbeats and election timeouts cluster-wide) onto the
slow lane, but left both flags OFF: flipping them ON hung pre-existing
unit fixtures that demote a primary or trigger catch-up without ever
starting c->slowlane -- the work was queued in a lane with no workers and
never ran.
- slowlane_is_started(): true while the lane has live workers.
- Both dispatchers run inline when the flag is OFF *or* the lane was never
started. Production always starts the lane, so it always offloads; the
lightweight fixtures keep their old inline behaviour, and neither
one-shot action can be silently dropped.
- g_drive_async_demotion_offload / g_drive_async_catchup_offload now
default to 1. The offload tests save and restore the previous value
instead of forcing 0.
New test_catchup_offload_without_started_lane_runs_inline (RED before: the
catch-up body never ran, the stream gate was never reached). Controller
suite 1239/0 with both offloads ON by default.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Dedicated-pthread pool isolated from the vtask pool; non-blocking slowlane_submit
(0 enqueued / -EEXIST deduped / -EAGAIN cap-full-deferred), admission cap on
running tasks, per-key in-flight dedup, run-exactly-once, drain+join fini. Wired
into controller lifecycle (dormant; consumers land in 2.x/3.x). 7 unit tests,
mutation-verified cap+dedup; full suite 194/0 green, 15x ASAN.
