Core.ScriptedAlarms-009 resolution: replace the per-call Dictionary +
AlarmPredicateContext allocation with a per-alarm reusable AlarmScratch
held in _scratchByAlarmId, refilled in place under _evalGate on each
evaluation. The hot path no longer allocates per upstream tag change.
Why this matters:
On a busy line where many tags feeding many alarms change frequently,
the old BuildReadCache allocated a fresh dictionary + context on every
predicate evaluation — a steady stream of short-lived allocations the
GC eventually has to reclaim. With the reuse, the dictionary and
context are allocated once per alarm (on first evaluation) and refilled
in place across every subsequent re-eval.
Implementation:
- New private AlarmScratch class holds the reusable
Dictionary<string, DataValueSnapshot> read cache (pre-sized to the
alarm's Inputs.Count) and the AlarmPredicateContext that wraps it by
reference. The context observes refilled values without being
re-created.
- ConcurrentDictionary<string, AlarmScratch> _scratchByAlarmId on the
engine, cleared in LoadAsync alongside _alarms so a config-publish
drops the prior generation's scratch (Inputs / Logger may change).
- EvaluatePredicateToStateAsync looks up scratch via GetOrAdd, calls
the new RefillReadCache(Dictionary, IReadOnlySet) helper to clear +
repopulate the dictionary in place, then runs the predicate against
the reused context.
- BuildReadCache removed.
Safety:
Reuse is serialised under _evalGate which guarantees no two threads
ever observe the same scratch in a half-refilled state. The
AlarmPredicateContext is bound to the scratch dictionary by reference,
so the predicate's ctx.GetTag(path) sees the freshly-refilled values
rather than a stale snapshot.
Verification:
- All 66 ScriptedAlarms tests pass (was 63 — three new regression tests
locking the reuse contract).
- All 56 VirtualTags tests still pass (unchanged).
- All 104 Core.Scripting tests still pass (unchanged).
New tests in ScriptedAlarmEngineTests:
- Reevaluation_reuses_the_same_read_cache_dictionary — asserts
ReferenceEquals(scratch_before, scratch_after) across two
evaluations of the same alarm.
- Reevaluation_reuses_the_same_predicate_context — same, for the
context.
- LoadAsync_drops_the_prior_generations_scratch — asserts a config
publish wipes the prior scratch (so a stale Logger / Inputs can't
leak into the new generation).
Internal test hooks TryGetScratchReadCacheForTest /
TryGetScratchContextForTest added via the existing
InternalsVisibleTo for the tests project. Kept internal — not part of
the public engine surface.
Docs:
- docs/v2/Galaxy.Performance.md "Scripted-alarm engine" section
rewritten as "hot-path allocation reuse" documenting the new
contract + reuse safety reasoning + the three regression tests.
- code-reviews/Core.ScriptedAlarms/findings.md -009 flipped
Won't Fix → Resolved.
- code-reviews/README.md regenerated.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
- Core.ScriptedAlarms-003: emit OnEvent OUTSIDE _evalGate by collecting
pending emissions during the gate-held section and flushing them after
release; eliminates re-entrancy deadlock the docs already promised.
- Core.ScriptedAlarms-006: track every fire-and-forget Reevaluate /
ShelvingCheck task in _inFlight; Dispose drains the set so the engine
no longer races store writes against teardown.
- Core.ScriptedAlarms-008: store comments as ImmutableList<AlarmComment>
so AppendComment is O(log n) instead of O(n).
- Core.ScriptedAlarms-010: document the deliberate input-quality
asymmetry (Uncertain drives the predicate, renders {?} in the message)
in docs/ScriptedAlarms.md and on MessageTemplate.Resolve remarks.
- Core.ScriptedAlarms-011: propagate the no-op reason through
TransitionResult.NoOp(state, reason) and log it from
ScriptedAlarmEngine.ApplyAsync.
- Core.ScriptedAlarms-009 (Won't Fix per recommendation): documented the
per-evaluation dictionary allocation in docs/v2/Galaxy.Performance.md
with a mitigation path if a future soak surfaces pressure.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Add engine-level tests covering the six gaps identified in the finding:
(1) timed-shelve auto-expiry driven via injectable clock + RunShelvingCheckForTest
hook so timer tests are deterministic;
(2) ConfirmAsync, TimedShelveAsync/UnshelveAsync round-trip, EnableAsync engine
methods exercised end-to-end;
(3) OnEvent subscriber-throws isolation — engine state advances and stays
operational after a subscriber throws;
(4) IAlarmStateStore.SaveAsync failure leaves in-memory state unchanged (locks in
the persist-before-update invariant from finding-007);
(5) second LoadAsync does not leak the old timer (regression for finding-002);
(6) AreInputsReady cold-start guard correctly blocks on Bad/missing inputs and
allows Uncertain-quality inputs through.
Expose RunShelvingCheckForTest() internal method on ScriptedAlarmEngine to
support deterministic timer tests.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
_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>
