fix(sessions): account SessionClosed for sweep-driven closes

TryBeginCloseIfExpired set _closeStarted when it reserved a session, so the sweep's own CloseAsync reported AlreadyClosed: true and CloseSessionCoreAsync skipped SessionClosed: lease-expired, faulted-reaped and detach-grace-expired closes never left the sessions.open gauge and under-counted sessions.closed. The reservation now writes Closing only; the first CloseAsync to take the close lock does the accounting exactly once.
2026-10-22 06:19:20 -04:00
parent 87f23d9712
commit 09666cc719
3 changed files with 75 additions and 1 deletions
@@ -1095,6 +1095,59 @@ public sealed class SessionManagerTests
        Assert.Equal(0, activeClient.ShutdownCount);
    }

+    /// <summary>
+    ///     Every sweep-driven close — lease expiry, faulted reap and detach-grace expiry — must
+    ///     account <c>SessionClosed</c> exactly once. The sweep begins the close itself
+    ///     (<c>TryBeginCloseIfExpired</c>) before delegating to the shared close path, and that
+    ///     reservation must not make the delegated close look like a second, already-running close
+    ///     whose accounting is skipped: the open-session gauge would then never drop for swept
+    ///     sessions and the closed counter would under-count them.
+    /// </summary>
+    /// <param name="sweepKind">Which sweep condition selects the session.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    [Theory]
+    [InlineData(SessionManager.LeaseExpiredReason)]
+    [InlineData(SessionManager.FaultedReason)]
+    [InlineData(SessionManager.DetachGraceExpiredReason)]
+    public async Task CloseExpiredLeasesAsync_SweptClose_AccountsSessionClosedExactlyOnce(string sweepKind)
+    {
+        FakeWorkerClient workerClient = new();
+        FakeTimeProvider clock = new(DateTimeOffset.UtcNow);
+        using GatewayMetrics metrics = new();
+        SessionManager manager = CreateManager(
+            new FakeSessionWorkerClientFactory(workerClient),
+            metrics: metrics,
+            options: CreateOptions(detachGraceSeconds: 30),
+            timeProvider: clock);
+        GatewaySession session = await manager.OpenSessionAsync(CreateOpenRequest(), "client-1", ownerKeyId: null, CancellationToken.None);
+        Assert.Equal(1, metrics.GetSnapshot().OpenSessions);
+
+        switch (sweepKind)
+        {
+            case SessionManager.LeaseExpiredReason:
+                SetLeaseExpiry(session, clock.GetUtcNow().AddSeconds(-1));
+                break;
+            case SessionManager.FaultedReason:
+                session.MarkFaulted("test-fault");
+                break;
+            case SessionManager.DetachGraceExpiredReason:
+                session.AttachEventSubscriber(maxSubscribers: 1).Dispose();
+                clock.Advance(TimeSpan.FromSeconds(31));
+                break;
+            default:
+                throw new ArgumentOutOfRangeException(nameof(sweepKind), sweepKind, "Unknown sweep kind.");
+        }
+
+        int closedCount = await manager.CloseExpiredLeasesAsync(clock.GetUtcNow(), CancellationToken.None);
+
+        Assert.Equal(1, closedCount);
+        Assert.Equal(SessionState.Closed, session.State);
+        Assert.False(manager.TryGetSession(session.SessionId, out _));
+        GatewayMetricsSnapshot snapshot = metrics.GetSnapshot();
+        Assert.Equal(1, snapshot.SessionsClosed);
+        Assert.Equal(0, snapshot.OpenSessions);
+    }
+
    /// <summary>Verifies that an expired-lease sweep leaves a session with an active event subscriber open.</summary>
    /// <returns>A task that represents the asynchronous operation.</returns>
    [Fact]
@@ -1436,6 +1489,17 @@ public sealed class SessionManagerTests
        };
    }

+    /// <summary>
+    ///     Moves a session's lease expiry by back-dating its last client activity, which is the only
+    ///     production path that moves the lease (<c>_leaseExpiresAt = activityAt + LeaseDuration</c>).
+    /// </summary>
+    /// <param name="session">Session whose lease to move.</param>
+    /// <param name="leaseExpiresAt">Wanted lease expiry.</param>
+    private static void SetLeaseExpiry(GatewaySession session, DateTimeOffset leaseExpiresAt)
+    {
+        session.TouchClientActivity(leaseExpiresAt - session.LeaseDuration);
+    }
+
    private static SessionOpenRequest CreateOpenRequest()
    {
        return new SessionOpenRequest(