fix(abcip,focas): collapse alarm projection to a single poll loop (no reconnect leak)

The owning DriverInstanceActor re-subscribes alarms on every Connected entry (DetachAlarmSource nulls its cached handle on Connected->Reconnecting without calling UnsubscribeAlarmsAsync), and the driver object + its alarm projection are reused across every in-place reconnect. Each SubscribeAsync started a fresh, never-cancelled Task.Run poll loop and added it to _subs, so N reconnects leaked N concurrent loops all polling the device and all firing the same raise/clear transitions => duplicate alarm events + CPU/mem growth. Mirrors the Galaxy #399 fix (Clear-before-Add) but for live poll loops the collapse must also CANCEL the superseded loops, not just drop references. SubscribeAsync now snapshots existing subs under _subsLock, clears _subs, adds the new sub, starts its loop, then retires each stale sub out-of-band (RetireAsync: Cancel + await loop + Dispose CTS, fire-and-forget so the new subscription's return isn't blocked on a poll interval). Snapshot+clear under the same lock DisposeAsync uses guarantees no double-own / double-dispose. There is exactly one consumer per driver instance (factory-per-actor), so retiring all prior subscriptions before starting the new one is faithful. Regression tests (TDD, fail->pass): subscribe twice then drive one device raise; assert OnAlarmEvent fires exactly once (was twice with two leaked loops).
2026-06-15 06:09:38 -04:00
parent 43b3769a1d
commit 6ba59f9d4d
4 changed files with 190 additions and 2 deletions
@@ -119,6 +119,68 @@ public sealed class AbCipAlarmProjectionTests
        await drv.ShutdownAsync(CancellationToken.None);
    }

+    /// <summary>
+    ///     Regression for the reconnect poll-loop leak (#399 sibling): the owning
+    ///     DriverInstanceActor re-subscribes alarms on every Connected entry without first calling
+    ///     Unsubscribe, and the driver object (and its projection) survives the in-place reconnect.
+    ///     Each SubscribeAsync used to start a fresh, never-cancelled poll loop — so after N
+    ///     reconnects there were N live loops all polling the device and all firing the same
+    ///     raise/clear transition, producing DUPLICATE alarm events.
+    ///
+    ///     This simulates two re-subscribes (one reconnect) against the same source, then drives
+    ///     ONE 0->1 device transition. After the collapse-to-single-loop fix exactly one loop is
+    ///     alive so the raise fires exactly once; before the fix both loops fire it ⇒ two events.
+    /// </summary>
+    [Fact]
+    public async Task Resubscribe_Collapses_To_Single_Loop_No_Duplicate_Raise()
+    {
+        var factory = new FakeAbCipTagFactory();
+        var opts = new AbCipDriverOptions
+        {
+            Devices = [new AbCipDeviceOptions(Device)],
+            Tags = [AlmdTag("HighTemp")],
+            EnableAlarmProjection = true,
+            AlarmPollInterval = TimeSpan.FromMilliseconds(20),
+            EnableDeclarationOnlyUdtGrouping = true,
+        };
+        var drv = new AbCipDriver(opts, "drv-1", factory);
+        await drv.InitializeAsync("{}", CancellationToken.None);
+
+        var raises = new List<AlarmEventArgs>();
+        drv.OnAlarmEvent += (_, e) =>
+        {
+            if (e.Message.Contains("raised")) lock (raises) raises.Add(e);
+        };
+
+        // First subscribe creates + starts polling the HighTemp runtime. Seed InFaulted=false +
+        // a severity so the loop's baseline settles on "not faulted".
+        var sub1 = await drv.SubscribeAlarmsAsync(["HighTemp"], CancellationToken.None);
+        await WaitForTagCreation(factory, "HighTemp");
+        factory.Tags["HighTemp"].ValuesByOffset[0] = 0;   // InFaulted=false at offset 0
+        factory.Tags["HighTemp"].ValuesByOffset[8] = 500; // Severity at offset 8
+        await Task.Delay(80); // let sub1's loop seed its "last-seen false" baseline
+
+        // Second subscribe = the actor re-subscribing across a reconnect. Its loop reads the same
+        // shared HighTemp runtime; give it time to seed its own "last-seen false" baseline too.
+        var sub2 = await drv.SubscribeAlarmsAsync(["HighTemp"], CancellationToken.None);
+        await Task.Delay(80);
+
+        factory.Tags["HighTemp"].ValuesByOffset[0] = 1; // one 0->1 transition
+        // Wait past several 20ms poll intervals so any leaked second loop has ample time to also
+        // fire its duplicate raise before we assert.
+        await Task.Delay(250);
+
+        await drv.UnsubscribeAlarmsAsync(sub1, CancellationToken.None);
+        await drv.UnsubscribeAlarmsAsync(sub2, CancellationToken.None);
+        await drv.ShutdownAsync(CancellationToken.None);
+
+        lock (raises)
+        {
+            raises.Count.ShouldBe(1,
+                "exactly one poll loop must survive a re-subscribe; a leaked loop fires a duplicate raise");
+        }
+    }
+
    /// <summary>Verifies that alarm clear event fires on 1-to-0 transition.</summary>
    [Fact]
    public async Task Clear_Event_Fires_On_1_to_0_Transition()