Add AsyncDbWorker: a persistent background thread with dedup queue that
executes DB2 writes asynchronously, keeping the mon 20ms cycle free of
blocking I/O.
Changes:
- async_db_worker.h/.cc: singleton worker, submit() with rule_id dedup,
drain_and_stop() for clean shutdown
- eqp_stat.h/.cc: new update_static(ruleid, shear_times, running_time)
overload that skips redundant DB reads for known values (reduces
5 SELECTs to 3 per persist cycle)
- exp_times.cc: extract persist_exp_times() as a standalone function,
update_history_times() snapshots values and submits to worker
(returns immediately), reset_dev_data() uses direct SHM update
- eqpalg_icei.cpp: alg_mgr_.reset() → drain_and_stop() in destructor
ensures all algorithm threads are stopped before draining the worker
Risk: re-run cmake .. to pick up the new async_db_worker.cc file.
Three fixes in update_history_times():
1. Wrap DB operations in try-catch — exception no longer skips the
snapshot restore, preventing permanent loss of accumulated counts
2. Treat get_history_times() -1 return (DB failure) as skip, not as
"record exists" → no more silent UPDATE on non-existent rows
3. Only call update_static and advance last_load_time_ on success,
so a failed persist retries on the next cycle instead of waiting
another rw_time_ minutes
