_alarms was a plain Dictionary<string, AlarmState> mutated under the
_evalGate semaphore, but four read paths (GetState, GetAllStates, the
LoadedAlarmIds property, and RunShelvingCheck) touched it from arbitrary
threads with no synchronisation. A Dictionary read concurrent with a
writer's entry reassignment can throw InvalidOperationException or return
torn state.
Switched _alarms to ConcurrentDictionary<string, AlarmState>. The only
write shapes are indexer-set and Clear, both atomic on ConcurrentDictionary,
so all mutations stay correct without further change; reads now get safe
snapshot semantics. LoadedAlarmIds materialises the key snapshot to keep
its IReadOnlyCollection<string> return type. This matches _valueCache,
which is already a ConcurrentDictionary.
Added a regression test (Concurrent_reads_during_mutation_do_not_throw)
that hammers the engine with state mutations while four reader threads
continuously call the three unguarded read paths.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Group all 69 projects into category subfolders under src/ and tests/ so the
Rider Solution Explorer mirrors the module structure. Folders: Core, Server,
Drivers (with a nested Driver CLIs subfolder), Client, Tooling.
- Move every project folder on disk with git mv (history preserved as renames).
- Recompute relative paths in 57 .csproj files: cross-category ProjectReferences,
the lib/ HintPath+None refs in Driver.Historian.Wonderware, and the external
mxaccessgw refs in Driver.Galaxy and its test project.
- Rebuild ZB.MOM.WW.OtOpcUa.slnx with nested solution folders.
- Re-prefix project paths in functional scripts (e2e, compliance, smoke SQL,
integration, install).
Build green (0 errors); unit tests pass. Docs left for a separate pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
