Code-review follow-ups on the poll-loop collapse: (1) RetireAsync is fire-and-
forget and does NOT guarantee zero overlap — the retired loop runs until its
in-flight read+tick finish and it observes cancellation, so a device transition
landing in that one-tick window can fire once on both loops (at most ONE
duplicate raise/clear per reconnect, transient + self-correcting; upstream Part
9 conditions dedupe on ConditionId). Documented in both RetireAsync XML docs so
it isn't mistaken for a zero-overlap guarantee. (2) wrap Cts.Dispose() so the
fire-and-forget task has no theoretical unobserved-exception path.
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collapse must also CANCEL the superseded loops, not just drop references.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).
The plan + task list for the write-outcome self-correction work (B1, already
shipped via master 1d797c1c). Its design-doc counterpart is already committed;
this adds the matching plan artifacts, consistent with the other docs/plans/.
User-published 0.1.1 of the MxGateway client + contracts packages into the
local-mxgw vendored source (nuget-packages/). Bumps Directory.Packages.props to
match and adds the 0.1.1 .nupkg artifacts alongside the existing 0.1.0 ones.
Full solution builds clean against 0.1.1.
GalaxyDriver's StreamAlarms feed is session-less and survives an in-place
reconnect, so DriverInstanceActor re-subscribed on every Connected re-entry
(after dropping its own cached handle without an Unsubscribe — sync teardown).
The re-subscribe was additive: _alarmSubscriptions.Add grew the list by one
untracked handle per reconnect cycle — a slow unbounded leak. Functionally
harmless (the gate is Count>0 and OnAlarmFeedTransition only reads [0], firing
once regardless), but it accumulated forever.
Fix: SubscribeAlarmsAsync clears the set before adding, collapsing to a single
live handle (under the existing _alarmHandlersLock, atomic w.r.t. the fan-out
reader). There is exactly one consumer per driver instance (factory-per-actor
lifecycle), so replacing the set with the latest handle is faithful. Chosen
over making the actor's sync DetachAlarmSource call UnsubscribeAlarmsAsync
async/fire-and-forget — disproportionate for a minor leak.
Regression test Re_subscribe_collapses_to_a_single_handle_no_accumulation
(TDD-verified: FAILS without the Clear — releasing the latest handle leaves
the feed open because stale handles remain; PASSES with the fix). Galaxy tests
263 pass / 3 skip; Runtime native-alarm 24 pass. Code-reviewed (approved).
HandleRestartDriver stopped + respawned the child within one synchronous
message handler, reusing the base actor name drv-<id>. Context.Stop is async
(the child processes its own stop on its own mailbox), so the old child was
ALWAYS still registered when the respawn ran — Context.ActorOf threw
InvalidActorNameException deterministically on every AdminUI Restart press,
crashing + restarting the host.
Fix: a monotonic _childSpawnGeneration counter (single-threaded actor) feeds a
-g<gen> suffix on every spawned child name, so a respawn can never collide with
the still-terminating predecessor. Children are tracked by the _children dict
(by IActorRef), never by actor path, so the suffix is invisible to callers.
This also closes the same-shaped latent race in the reconcile path (a removed-
then-readded instance, and a driver-type-change ToStop+ToSpawn in one plan).
Regression test RestartDriver_respawns_the_child_without_an_actor_name_collision
(verified: FAILS on the old code with the exact InvalidActorNameException,
PASSES with the fix). Runtime.Tests 238/238 green. Code-reviewed (approved).
C1 (critical): a boundary tie cluster larger than NumValuesPerNode could
silently truncate a resumed read to GoodNoData, permanently dropping the
un-emitted ties — the (timestamp, skip) cursor cannot advance past a single
timestamp the fixed-(start,end,cap) backend keeps re-returning. Now detected
and failed LOUDLY per node with BadHistoryOperationUnsupported + a log naming
the tag/timestamp/cap; documented in Historian.md with the larger-cap remedy.
Regression test Raw_tie_cluster_larger_than_page_fails_loudly_not_silently.
I3: build HistoryData before Save() so a projection failure can never orphan a
stored continuation cursor.
N1 (YAGNI): drop the never-produced HistoryReadKind enum + Processed-only
Aggregate/IntervalTicks fields from HistoryContinuationState — only Raw pages.
N3: ComputeResumeCursor guards its documented non-empty precondition.
I1: document InMemoryHistoryContinuationStore's eventual-consistency (test double).
Build clean, 182/182 OpcUaServer tests pass.
The Wonderware historian backend is single-shot — it returns up to
NumValuesPerNode samples with a null continuation point — so paging is
synthesised server-side, time-based, for the only count-capped arm (Raw):
- A full page (count == NumValuesPerNode, NumValuesPerNode > 0) emits an
opaque 16-byte continuation point and stores a resume cursor; a short page
(or NumValuesPerNode == 0 "all values") emits none.
- A resume read takes the stored cursor, reads the next page from the boundary
forward, and emits a fresh CP only if that page is also full.
- The resume cursor is tie-safe (HistoryPaging.ComputeResumeCursor /
TrimBoundaryDuplicates): the next page resumes from the boundary timestamp
INCLUSIVE and drops the head ties already returned, so samples sharing the
boundary SourceTimestamp are neither duplicated nor skipped.
Continuation points are bound to the OPC UA session via the SDK's
ISession.SaveHistoryContinuationPoint / RestoreHistoryContinuationPoint store
(SessionHistoryContinuationStore) — capped by ServerConfiguration.
MaxHistoryContinuationPoints (default 100, oldest-evicted) and disposed on
session close. releaseContinuationPoints is honoured via an override of
HistoryReleaseContinuationPoints (the base dispatcher routes release-only reads
there, never to the per-details arms). An unknown / evicted / released point
resumes to BadContinuationPointInvalid.
Processed and AtTime stay single-shot: neither details type carries a client
count cap, so the single-shot backend returns the complete result in one read
and there is no "full page" signal to page on (spec-conformant). Modified-value
history remains out of scope.
The pure paging decisions + CP store contract are unit-tested via HistoryPaging
+ InMemoryHistoryContinuationStore; the full multi-page round trip is driven
end-to-end through the node manager with an in-memory store + a series-backed
fake historian (the in-process harness is session-less).
- A.1 (false-rejection safety): restrict the structural fail-fast's confident-mismatch check to
the CLOSED set of built-in types ResolveBuiltInDataType emits (numeric families + Boolean/
String/DateTime/ByteString). Any other expected type (Enumeration, Guid, …) now defers to the
SDK, so a coercible write (Int32→Enumeration) is never false-rejected. + A7/A8 regression tests.
- C.1: guard BuildWriteFailureAuditEvent (under Lock) in try/catch like ReportAuditEvent, so a
SetChildValue surprise is swallowed+logged, never thrown out of the fire-and-forget continuation.
Three deferred 'surface the failed write' enhancements on the write-outcome
self-correction path in OtOpcUaNodeManager:
- Item A: synchronous structural fail-fast. EvaluateEquipmentWriteStructure
(pure static) rejects a structurally-invalid write INLINE (Bad sync) after
the authz gate but before the optimistic dispatch, so the SDK never applies
it. Null payload -> BadTypeMismatch; plus a confidence-gated cheap built-in
type compatibility check (numeric widening + BaseDataType wildcard tolerated;
uncertain cases defer to the SDK's own coercion).
- Item B: Bad-quality blip on device-write failure. On a revert,
RevertOptimisticWriteIfNeeded first publishes the still-applied optimistic
value with StatusCode BadDeviceFailure, then restores the prior value/status
(both under the existing Lock). Documents the queue-coalescing caveat (a slow
subscriber may see only the restored value -> the audit event is the reliable
signal).
- Item C: Part 8 AuditWriteUpdateEvent on device-write failure. Builds an
AuditWriteUpdateEventState (SourceNode=node, AttributeId=Value, OldValue=prior,
NewValue=attempted, ClientUserId from the threaded identity, Message carries
outcome.Reason) under Lock and reports it via Server.ReportEvent OUTSIDE Lock.
Guarded so auditing-disabled / report failure never breaks the revert.
Threads the writing identity's user-id + node into the continuation. Adds 6
unit tests for EvaluateEquipmentWriteStructure. Build clean (0 warnings);
158/158 OpcUaServer.Tests green.
Native-alarm delivery through OnAlarmFeedTransition was a black box — there was no way
to answer 'is the gateway feed delivering / is a subscription un-gating it', which is
partly why the missing-SubscribeAlarmsAsync wiring shipped undetected. Add a single
per-transition Debug line (kind, ref, live subscription count, fanout flag). Debug so a
flapping galaxy doesn't flood prod, but available on demand.
- Correct the misleading DetachAlarmSource comment: a session-less feed (Galaxy) is NOT
torn down on an in-place reconnect, so re-subscribe is additive (harmless; gate reads [0]).
- Add trace-only SubscribeAlarms drop handlers in Connecting/Reconnecting (symmetry with
NativeAlarmRaised) so a self-tell overtaken by a queued disconnect doesn't dead-letter.
- Document the deliberate no-unsubscribe-on-empty asymmetry vs the value path.
Behavior-neutral for the un-gate path. Minor handle-accumulation leak tracked as follow-up.
Phase B native alarms never fired end-to-end: GalaxyDriver suppresses OnAlarmEvent until
an alarm subscription exists (_alarmSubscriptions.Count > 0), but the runtime only attached
the OnAlarmEvent handler and never called SubscribeAlarmsAsync — so the central feed stayed
gated and no transition reached the Part 9 condition / /alerts. Unit tests passed because
they inject through the IAlarmSource seam directly; the deferred live /run surfaced it.
DriverHostActor computes per-driver alarm refs (alarm-bearing tags' FullNames) and hands them
via SetDesiredSubscriptions; DriverInstanceActor calls SubscribeAlarmsAsync for IAlarmSource
drivers on Connected entry and whenever alarm refs are pushed while Connected (the deploy path),
idempotent via a cached handle reset on detach so reconnect re-subscribes.
The gate reads the literal role string OpcUaDataPlaneRoles.AlarmAck = "AlarmAck"
(OtOpcUaNodeManager.cs:643), but the Role-grant-source section told operators to map
their alarm-ack group to "AlarmAcknowledge" (the PermissionFlags ACL bit, a different
vocabulary) — which silently never satisfies the ack gate. Fix the three role-string
occurrences + add a code-true note; generalize the scripted-alarm note to native alarms.
Code-review refinement of the live-gw read-back helper: complete a
TaskCompletionSource<double?> from the pump instead of a captured local (explicit
cross-task visibility), pass bufferedUpdateIntervalMs:0 (Advise snapshot needs no
SetBufferedUpdateInterval), and document the Advise->OnDataChange filter. Live re-verified 2/2.
Skip-gated (MXGW_ENDPOINT + GALAXY_MXGW_API_KEY) like GatewayGalaxyAlarmFeedLiveTests.
Covers the two seams the unit suite can only fake in isolation:
- reopen: RecreateAsync + InvalidateHandleCaches re-establish write handles
- write: no-login supervisory write commits + persists (fresh-session read-back)
Live-verified 2/2 against 10.100.0.48:5120 (2026-06-14); skips cleanly in CI.
Add AllDeadLetters probe to Native_alarm_during_reconnect_is_dropped_not_forwarded so the
test genuinely guards the Reconnecting state's Receive<NativeAlarmRaised> drop handler —
removing that handler would now cause a dead-letter and fail the assertion (false-negative
gap closed). Reword the ScriptedAlarms.md severity-mapping note: "snaps on the first
transition" → "every transition maps … overriding the authored seed from the first
transition onward", clarifying that MapSeverity runs on every event, not just the first.
- HistoryReadEvents miss path + catch path now both set results[handle.Index] explicitly
(new SdkHistoryReadResult { StatusCode = BadHistoryOperationUnsupported }) — don't rely on
base pre-seeding results[i] so every path sets BOTH errors and results coherently (#1)
- ProjectEventField: SourceName null now emits Variant.Null instead of a String-typed null
variant (evt.SourceName is null ? Variant.Null : new Variant(evt.SourceName)) (#3)
- Comment near the HistoryRead dispatcher block updated: all four arms (Raw/Processed/AtTime
+ Events/Task 4) are now overridden — "left to the base" wording was stale (#5)
- Happy-path test adds ReceiveTime to select clauses and asserts it projects ReceivedTimeUtc
as a DateTime Variant at the correct select-order position (#4)
- Backend-throw test hardened: asserts errors[0] via ServiceResult.IsBad + explicit code,
asserts results[0] is non-null with the Bad code (no longer relies on base seeding),
and asserts EventsEntered to prove the override reached the bridge before the throw (#1)
- RecordingHistorianDataSource gains EventsEntered flag (set before ThrowOnRead check) (#1)
- Events_non_source_node test gains clarifying doc comment explaining the SDK base rejects
variable nodes (EventNotifier=None) for event reads before our override runs; the
override's source-guard is exercised by the promoted-without-source test instead (#2)
Fix A: add Raw_multi_node_per_node_error_isolation test — two historized variables
(eqA/good→A.PV, eqB/bad→B.PV) in one Raw batch; per-tagname fake throws for B.PV,
returns a sample for A.PV; asserts errors[0]=Good+sample, errors[1]=Bad,
HistoryData[1]=null (no cross-slot leak), no exception escapes.
Fix B: collapse double ConcurrentDictionary lookup in ServeNode — TryGetHistorizedTagname
now captures `out var tagname` on the guard; the resolved tagname is threaded into the
read callback as a second parameter (Func<IHistorianDataSource, string, Task<HistorianRead>>),
removing the redundant ResolveTagname helper (deleted) and the tiny race window between
the check and the second lookup. All three call-sites (Raw/Processed/AtTime) updated.
Fix C: rewrite the IsReadModified comment at NodeManagerHistoryReadTests.cs:102 — the
SDK's ReadRawModifiedDetails.Initialize() sets m_isReadModified=true (generated ctor body
in Opc.Ua.DataTypes.cs), so the default IS true; the test must explicitly clear it to
false for a plain raw read. Previous comment said the same thing but imprecisely; now
cites the SDK mechanism (Initialize() call in the public ctor).
Joseph Doherty