VirtualTagActor called the blocking IVirtualTagEvaluator.Evaluate, and
RoslynVirtualTagEvaluator blocked on the run guard with
.GetAwaiter().GetResult(), so every script run parked a dispatcher thread for
up to its 2 s budget (a first-use Roslyn compile did too). This is the #750 P0
refactor for virtual tags.
- IVirtualTagEvaluator.EvaluateAsync (default: a completed task over the
snapshot overload, so the null evaluator and fakes are unchanged).
- RoslynVirtualTagEvaluator implements it without blocking: passthrough and
compile failures complete synchronously, a first-use compile goes to the
pool, the run is awaited. The blocking overload now delegates to it.
- VirtualTagActor: a completed task is applied in the same turn, as before;
an incomplete one switches to an "evaluating" behaviour that stashes every
dependency/reassert message until a private completion message arrives,
then applies the result and unstashes. Each trigger is still evaluated
against its own inputs, results are applied/published in trigger order and
the dedup/Bad-transition state sees the same sequence. The dependency map is
not touched while a run reads it.
Calculation and scripted-alarm serialisation is NOT relaxed: neither blocks a
thread, and running independent scripts in parallel is not semantics-neutral
(pool consumption bound, cross-tag publish order, timer/pump exclusion for
Calc; state-machine/persist boundary, transition timestamps and the
store-failure path for alarms). Recorded in docs/VirtualTags.md and the #750
design's P0 entry.
Tests: VirtualTagActorAsyncEvaluationTests — on a one-thread dispatcher a slow
script no longer starves a sibling actor and the slow actor answers Identify
(fails when the actor calls the blocking Evaluate); triggers during a run are
evaluated afterwards in order against their own inputs; a reassert during a
run is applied after it; a faulted evaluation takes the evaluator-threw path
(the ordering/reassert tests fail with the stash removed).
RoslynVirtualTagEvaluatorAsyncTests — a slow script and a cold compile return
an incomplete task (fail without the override); cheap outcomes and timeouts
match the blocking overload.
Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV
Joseph Doherty
a84d38707b