fix(galaxy): authoritative handle resolution + review cleanups

Make SubscriptionRegistry.TryResolveItemHandle confirm a live subscription genuinely binds fullRef->handle (via the reverse index) rather than trusting the forward-map hint + a bare liveness check. Fixes the cross-ref-same-handle hazard (wrong-tag borrow) while preserving the legitimate multiple-subscriptions-per-tag borrow. Adds cross-ref + same-ref-multi-sub tests; drops a duplicate SubscriptionEntry <summary>; documents the writer's supervisory-advise reconnect lifecycle.
2026-06-18 04:29:45 -04:00
parent 3ffe45db53
commit e9da9c29d2
3 changed files with 61 additions and 8 deletions
@@ -114,4 +114,43 @@ public sealed class SubscriptionRegistryHandleResolveTests
        // must return null regardless of whether the forward entry was cleaned up.
        registry.TryResolveItemHandle("Tag.A").ShouldBeNull();
    }
+
+    /// <summary>
+    ///     A tag may legitimately appear in multiple driver subscriptions (separate OPC UA monitored
+    ///     items on the same Galaxy attribute) — they share one gw item handle. Removing ONE of them
+    ///     must keep the tag resolvable while another subscription still binds it, so the writer keeps
+    ///     borrowing instead of falling back to AddItem.
+    /// </summary>
+    [Fact]
+    public void Remove_OneOfTwoSubscribersForSameRef_StillResolves()
+    {
+        var registry = new SubscriptionRegistry();
+        registry.Register(1, [new TagBinding("Tag.A", 5)]);
+        registry.Register(2, [new TagBinding("Tag.A", 5)]);
+
+        registry.Remove(1);
+
+        // sub2 still binds Tag.A -> 5, so the borrow must still be offered.
+        registry.TryResolveItemHandle("Tag.A").ShouldBe(5);
+    }
+
+    /// <summary>
+    ///     Authoritative resolution: if two DIFFERENT refs ever map to the same numeric handle and the
+    ///     subscription for one is removed, that ref must NOT resolve to the handle that now belongs to
+    ///     the other ref — a wrong-tag write would be the worst outcome. Resolution confirms a live
+    ///     subscription genuinely binds fullRef -> handle, not just that the handle is alive.
+    /// </summary>
+    [Fact]
+    public void Remove_CrossRefSameHandle_DoesNotResolveToTheOtherRefsHandle()
+    {
+        var registry = new SubscriptionRegistry();
+        registry.Register(1, [new TagBinding("Tag.A", 5)]);
+        registry.Register(2, [new TagBinding("Tag.B", 5)]);
+
+        registry.Remove(1);
+
+        // Tag.A's subscription is gone; handle 5 is still alive but now only Tag.B binds it.
+        registry.TryResolveItemHandle("Tag.A").ShouldBeNull();
+        registry.TryResolveItemHandle("Tag.B").ShouldBe(5);
+    }
 }