Decrement was decrement-first with a single non-retried repair CAS. From zero,
two unmatched decrements (SignalR calls OnDisconnectedAsync for a connection
whose OnConnectedAsync faulted) capture -1 and -2; a real Increment then makes
the count -1, and the first decrementer's stale CompareExchange(0, -1) matches
and resets to zero — erasing a live connection, so the idle gate freezes an open
dashboard. The same lost race also made Decrement report 0 when it had not
written 0.
Clamping now happens inside the compare-and-swap: read, clamp, publish, retry on
loss. A lost race re-reads the fresh value instead of repairing a stale one.
The counter moves to its own file per the one-public-type-per-file convention and
gains direct tests: the zero floor under concurrent unmatched decrements, matched
pairs settling at zero, and an interleaved connect/disconnect stress round. The
stress test asserts the observable invariants only — the specific interleaving
cannot be forced through the public API (verified: the previous implementation
passes it), which its remarks now state rather than implying a reproducer. A hub
wiring test is skipped for the EventsHub reason: driving Hub.OnConnectedAsync
needs caller-clients and connection-context fakes, and the overrides are two
lines of delegation to the tested type.
Also documents that the API-key refresh's pre-gate time check races benignly.
The snapshot publisher broadcast to Clients.All on every ~1s tick forever, with
zero viewers. Each tick cost a session-registry snapshot and sort, a metrics
snapshot that copies dictionaries under the global metrics lock, a full rebuild
of EffectiveGatewayConfiguration, and a SQLite read of the API key table.
DashboardSnapshotHub now counts live connections into the singleton
DashboardSnapshotHubConnectionCounter (clamped at zero, since SignalR can call
OnDisconnectedAsync for a connection whose OnConnectedAsync faulted). The
publisher drives the snapshot enumerator by hand instead of await foreach: with
no connections it does not call MoveNextAsync at all, so the producing iterator
stays suspended at its yield and no snapshot is built — the gate removes the
build, not just the broadcast. It re-checks once a second, so the first viewer
resumes the tick within about one interval; that viewer is seeded immediately by
DashboardPageBase's synchronous GetSnapshot() and by the hub's OnConnectedAsync.
Two per-tick costs are bounded independently of the gate: the effective
configuration is startup-static (options are bound once at boot and never
reloaded), so it is built once and cached; and the API key summaries refresh at
most every 15s, since the list only changes when an operator creates, rotates,
or revokes a key. Only a successful refresh restarts the interval, so a failed
or timed-out read is still retried on the next tick with the previous summaries
left on screen.
Adds missing <summary>/<param> XML docs across 99 server, worker, and test
files so CommentChecker reports zero issues (TreatWarningsAsErrors needs the
analyzer clean). Bundles in WIP dashboard work: NavSection extraction,
MainLayout/site.css/js styling alignment, and DashboardOptions/Auth tweaks.
Layout
------
DashboardLayout.razor replaces the inline header nav with a left side rail
modelled on the OtOpcUa admin (Dashboard B). The top bar keeps only the
brand, breadcrumb, and signed-in status pill; navigation moves into a
fixed-width 218px rail with grouped section eyebrows (Overview,
Runtime, Galaxy, Admin) and a Session footer carrying the user name,
role claims, and a Sign-out button. dashboard.css gains the
`.app-shell` flex container, `.side-rail` column, `.rail-eyebrow`,
`.rail-link[.active]`, `.rail-foot`, `.rail-user`, `.rail-roles`, and
`.rail-btn` rules (all driven by the existing theme.css tokens, no new
hard-coded colours).
SignalR (push)
--------------
Adds three hubs under `Dashboard/Hubs/`, all gated by the
`HubClientsPolicy` registered in the previous commit:
* DashboardSnapshotHub (/hubs/snapshot)
Broadcasts the full DashboardSnapshot on every change. Sends the
current snapshot to a new caller in OnConnectedAsync so the first
paint is immediate.
* AlarmsHub (/hubs/alarms)
Connected clients auto-join the `__alarms__` group. Receives
AlarmFeedMessage values (active_alarm / snapshot_complete /
transition) re-broadcast from the gateway's central alarm monitor.
* EventsHub (/hubs/events)
Per-session push surface. Clients call SubscribeSession(sessionId)
to join `session:{id}`. The publisher side is intentionally a
follow-up — the snapshot hub already carries recent-events
rollups; a dedicated MxEvent broadcaster on EventStreamService
will plug into this hub's group convention.
Two BackgroundService publishers wire server-side data sources to the
hubs:
* DashboardSnapshotPublisher subscribes to
`IDashboardSnapshotService.WatchSnapshotsAsync` and forwards every
snapshot to all connected hub clients.
* AlarmsHubPublisher subscribes to `IGatewayAlarmService.StreamAsync`
(no filter) and forwards every AlarmFeedMessage to the
`__alarms__` group, reconnecting with a 5-second backoff if the
stream faults.
Connection + auth plumbing
--------------------------
* `GET /hubs/token` issues a fresh data-protected bearer token
bound to the calling user's identity and roles. Gated by the
cookie-only ViewerPolicy so a Blazor circuit (cookie-authenticated)
can mint a token, but a hub bearer cannot self-bootstrap a new
one.
* DashboardHubConnectionFactory (scoped) is the client-side helper
Razor pages inject. It builds a HubConnection with an
AccessTokenProvider that calls HubTokenService.Issue on every
(re)connect — keeps the connection alive across cookie refresh
boundaries.
Pull → push refactor
--------------------
DashboardPageBase no longer drives its own `WatchSnapshotsAsync`
async-foreach loop. It now:
1. seeds Snapshot synchronously from `IDashboardSnapshotService.GetSnapshot()`
so the first render is non-empty;
2. opens a `DashboardSnapshotHub` connection via the connection
factory;
3. updates Snapshot + triggers StateHasChanged on each
`SnapshotUpdated` push.
The hub connection is best-effort: if SignalR can't start, the
synchronous snapshot seed keeps the UI populated. SignalR's
WithAutomaticReconnect handles the recovery path.
Package
-------
Adds `Microsoft.AspNetCore.SignalR.Client` 10.0.0 to the server csproj
so the in-process Blazor pages can open hub connections back to their
own hosting process.
Verification: 475 server tests (+ 2 new
`DashboardHubsRegistrationTests` that pin the hub negotiate endpoints
and the singleton/scoped DI shape), 275 worker tests (+ 9 dev-rig
skips), 18 integration tests (live MxAccess + LDAP + Galaxy) all pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Joseph Doherty