feat(site-runtime): tag-subscribe failure reply frees the in-flight slot, backs off (×2 ±20%, capped) and Success resets to floor (Lever 1)

Also from the Task 3 review: FailedSubscribeResponse_IsRetried guards the failure path again (large ceiling); HandleSubscribeTagsResponse reads state instead of get-or-create; SubscribeToDcl prunes stale retry state on re-entry; doc comments refreshed. Claude-Session: https://claude.ai/code/session_019ZxXT5sxZs5XrtdwYzJDPV
2026-08-28 14:36:22 -04:00
parent 029d39fca2
commit b6b401c879
2 changed files with 95 additions and 10 deletions
@@ -1290,7 +1290,7 @@ public class InstanceActorTests : TestKit, IDisposable
    [Fact]
    public void FailedSubscribeResponse_IsRetried()
    {
-        var options = new SiteRuntimeOptions { TagSubscribeRetryIntervalMs = 200, TagSubscribeInFlightCeilingMs = 200 };
+        var options = new SiteRuntimeOptions { TagSubscribeRetryIntervalMs = 200, TagSubscribeInFlightCeilingMs = 60_000 };
        var (instance, dclProbe) = CreateInstanceWithDataSourcedAttribute(options);

        var first = dclProbe.ExpectMsg<SubscribeTagsRequest>();
@@ -1370,7 +1370,8 @@ public class InstanceActorTests : TestKit, IDisposable
        var first = dclProbe.ExpectMsg<SubscribeTagsRequest>();
        var second = dclProbe.ExpectMsg<SubscribeTagsRequest>(TimeSpan.FromSeconds(3));

-        // A late Success for the FIRST id must not cancel the watchdog guarding the SECOND.
+        // A late Success for the FIRST id is dropped at the pending-map check (its id was
+        // removed at the ceiling); the watchdog guarding the SECOND is untouched.
        instance.Tell(new SubscribeTagsResponse(first.CorrelationId, first.InstanceUniqueName,
            true, null, DateTimeOffset.UtcNow), dclProbe.Ref);
        var third = dclProbe.ExpectMsg<SubscribeTagsRequest>(TimeSpan.FromSeconds(3)); // second eventually re-sent
@@ -1381,4 +1382,60 @@ public class InstanceActorTests : TestKit, IDisposable
            true, null, DateTimeOffset.UtcNow), dclProbe.Ref);
        dclProbe.ExpectNoMsg(TimeSpan.FromMilliseconds(800));
    }
+
+    // --- Lever 1 (2026-08-28): backoff on failure, reset on success ---
+
+    [Fact]
+    public void RepeatedFailures_BackOff_AndSuccessResetsToFloor()
+    {
+        // Floor 200 ms, max 800 ms. Jitter is ±20 % so bound the assertions, don't pin them.
+        var options = new SiteRuntimeOptions
+        {
+            TagSubscribeRetryIntervalMs = 200,
+            TagSubscribeRetryMaxIntervalMs = 800,
+            TagSubscribeInFlightCeilingMs = 60_000, // guard never expires; only replies drive retries
+        };
+        var (instance, dclProbe) = CreateInstanceWithDataSourcedAttribute(options);
+
+        var req = dclProbe.ExpectMsg<SubscribeTagsRequest>();
+        var gaps = new List<TimeSpan>();
+        for (var i = 0; i < 3; i++)
+        {
+            instance.Tell(new SubscribeTagsResponse(req.CorrelationId, req.InstanceUniqueName,
+                false, "gateway busy", DateTimeOffset.UtcNow), dclProbe.Ref);
+            var sw = System.Diagnostics.Stopwatch.StartNew();
+            req = dclProbe.ExpectMsg<SubscribeTagsRequest>(TimeSpan.FromSeconds(5));
+            gaps.Add(sw.Elapsed);
+        }
+
+        // Expected nominal gaps: 400, 800(cap), 800(cap) — each ±20 % jitter and scheduler slack.
+        Assert.InRange(gaps[0].TotalMilliseconds, 300, 560);
+        Assert.InRange(gaps[1].TotalMilliseconds, 600, 1100);
+        Assert.InRange(gaps[2].TotalMilliseconds, 600, 1100);
+
+        // Success resets: no further request follows a confirmed subscription.
+        instance.Tell(new SubscribeTagsResponse(req.CorrelationId, req.InstanceUniqueName,
+            true, null, DateTimeOffset.UtcNow), dclProbe.Ref);
+        dclProbe.ExpectNoMsg(TimeSpan.FromMilliseconds(1200));
+    }
+
+    [Fact]
+    public void FailureReply_ReissuesEvenThoughGuardHasNotExpired()
+    {
+        var options = new SiteRuntimeOptions
+        {
+            TagSubscribeRetryIntervalMs = 200,
+            TagSubscribeRetryMaxIntervalMs = 200,
+            TagSubscribeInFlightCeilingMs = 60_000,
+        };
+        var (instance, dclProbe) = CreateInstanceWithDataSourcedAttribute(options);
+
+        var first = dclProbe.ExpectMsg<SubscribeTagsRequest>();
+        instance.Tell(new SubscribeTagsResponse(first.CorrelationId, first.InstanceUniqueName,
+            false, "Unknown connection: conn-1", DateTimeOffset.UtcNow), dclProbe.Ref);
+
+        // A definite failure clears the in-flight slot, so the watchdog re-sends.
+        var retry = dclProbe.ExpectMsg<SubscribeTagsRequest>(TimeSpan.FromSeconds(3));
+        Assert.NotEqual(first.CorrelationId, retry.CorrelationId);
+    }
 }