merge: tag-resolution counts fixed on first subscribe (register row 55) — HandleSubscribeCompleted was the missing fourth UpdateTagResolution push site, so a perfectly healthy connection reported 0/0 forever

2026-08-15 17:56:14 -04:00
parent c26b52ad68 5da27e05c7
commit 230c841d35
3 changed files with 74 additions and 1 deletions
@@ -414,7 +414,9 @@ Note: Pre-deployment validation at central does **not** verify that tag paths re
 The DCL reports the following metrics to the Health Monitoring component via the existing periodic heartbeat:

 - **Connection status**: `connected`, `disconnected`, or `reconnecting` per data connection.
- **Tag resolution counts**: Per connection, the number of total subscribed tags vs. successfully resolved tags. This gives operators visibility into misconfigured templates without needing to open the debug view for individual instances. Both numbers are **derived at report time from the connection actor's authoritative per-tag state**, never accumulated in counters: the total is the number of distinct tag paths at least one instance currently subscribes to (the per-tag counted set that also drives value fan-out and the last-subscriber release decision), and the resolved count is the number of tags for which the adapter currently holds a subscription handle. A tag counts toward the total from the moment an instance registers it, whatever its resolution outcome — resolved, awaiting a resolution retry, or failed at connection level — so resolved can never exceed total. Deriving rather than accumulating is deliberate: increment/decrement counters drifted whenever an unsubscribe landed inside a reconnect window (the reconnect clears the per-tag maps the decrements keyed off), leaking a phantom tag into the reported total on every churn cycle.
+- **Tag resolution counts**: Per connection, the number of total subscribed tags vs. successfully resolved tags. This gives operators visibility into misconfigured templates without needing to open the debug view for individual instances. Both numbers are **derived from the connection actor's authoritative per-tag state**, never accumulated in counters: the total is the number of distinct tag paths at least one instance currently subscribes to (the per-tag counted set that also drives value fan-out and the last-subscriber release decision), and the resolved count is the number of tags for which the adapter currently holds a subscription handle. A tag counts toward the total from the moment an instance registers it, whatever its resolution outcome — resolved, awaiting a resolution retry, or failed at connection level — so resolved can never exceed total. Deriving rather than accumulating is deliberate: increment/decrement counters drifted whenever an unsubscribe landed inside a reconnect window (the reconnect clears the per-tag maps the decrements keyed off), leaking a phantom tag into the reported total on every churn cycle.
+
+  The pair is **pushed to the health collector, not pulled from it**, so it is a cached value that is only as fresh as its last push — and the collector holds it until the next one. Every site that mutates either underlying set must therefore push: entering the Connected state (a legitimate 0/0 — no instance has subscribed yet), the first-subscribe apply, the batch apply (reconnect re-subscribe and resolution probe), and unsubscribe. Missing the first-subscribe push is what made a *perfectly healthy* connection report 0/0 indefinitely — the connect-time 0/0 was never superseded, because a connection whose tags all resolve on the first attempt never reaches the batch path and has its resolution-retry timer cancelled outright for having nothing unresolved. That is the reverse of the usual staleness risk, and it blinded the diagnostic exactly when it should have read clean (deferred-work register row 55; the actor's own `GetHealthReport` reply, which really is derived on demand, was correct throughout).
 - **Tag quality counters** are pushed on a genuine quality **transition** only, coalesced onto a `QualityFlushInterval` (1s) single-shot timer. Counter arithmetic still runs per message; only the collector push is deferred, and a value whose quality is unchanged moves no counter at all. Health reports poll at 30s, so the coalescing loses nothing. Three paths flush **synchronously** because their correctness depends on it: the bad-quality push on disconnect, unsubscribe, and the reconnect counter reset.

 ## Dependencies