The owning DriverInstanceActor re-subscribes alarms on every Connected
entry (DetachAlarmSource nulls its cached handle on Connected->Reconnecting
without calling UnsubscribeAlarmsAsync), and the driver object + its alarm
projection are reused across every in-place reconnect. Each SubscribeAsync
started a fresh, never-cancelled Task.Run poll loop and added it to _subs,
so N reconnects leaked N concurrent loops all polling the device and all
firing the same raise/clear transitions => duplicate alarm events + CPU/mem
growth.
Mirrors the Galaxy #399 fix (Clear-before-Add) but for live poll loops the
collapse must also CANCEL the superseded loops, not just drop references.
SubscribeAsync now snapshots existing subs under _subsLock, clears _subs,
adds the new sub, starts its loop, then retires each stale sub out-of-band
(RetireAsync: Cancel + await loop + Dispose CTS, fire-and-forget so the new
subscription's return isn't blocked on a poll interval). Snapshot+clear under
the same lock DisposeAsync uses guarantees no double-own / double-dispose.
There is exactly one consumer per driver instance (factory-per-actor), so
retiring all prior subscriptions before starting the new one is faithful.
Regression tests (TDD, fail->pass): subscribe twice then drive one device
raise; assert OnAlarmEvent fires exactly once (was twice with two leaked
loops).
Joseph Doherty
6ba59f9d4d