fix(galaxy,s7): R2 review minors — subscribe-once deadline, probe vs backoff, write-fault ownership, null array elements, write opt-in

- Galaxy: deadline bounds the wait, not the subscribe RPC; BadTimeout for all tags and late handles unsubscribed; doc comment relocated - S7: probe connect runs on the connect deadline so a timeout opens the backoff window - S7: a successful write only retires a Faulted the write side owns - S7: null array elements rejected (BadTypeMismatch); multi-PDU array writes documented non-atomic - S7 integration: array write test gated on S7_SIM_ALLOW_WRITES=1 Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
2026-10-08 07:31:22 -04:00
parent ca0f1e7735
commit e77bca385a
9 changed files with 208 additions and 13 deletions
@@ -442,6 +442,46 @@ public sealed class S7DriverReconnectTests
        drv.GetHostStatuses()[0].State.ShouldBe(HostState.Running);
    }

+    /// <summary>
+    ///     STAB-21 vs the probe. On a black-holed host the probe's connect used to be cut by the (shorter) probe
+    ///     deadline, which is not a caller cancel but was treated as one, so NO failure was recorded and every
+    ///     probe tick paid a fresh connect attempt. The connect must run on the connect deadline and a timeout
+    ///     must open the backoff window: far fewer attempts than ticks.
+    /// </summary>
+    [Fact]
+    public async Task Probe_connect_timeout_on_a_black_holed_host_opens_the_backoff_window()
+    {
+        var opts = new S7DriverOptions
+        {
+            Host = "192.0.2.1",
+            Timeout = TimeSpan.FromMilliseconds(400),
+            Probe = new S7ProbeOptions
+            {
+                Enabled = true,
+                Interval = TimeSpan.FromMilliseconds(20),
+                Timeout = TimeSpan.FromMilliseconds(80),
+            },
+            RawTags = S7RawTags.Entries(new S7TagDefinition("W0", "DB1.DBW0", S7DataType.UInt16, Writable: false)),
+        };
+        var factory = new FakeS7PlcFactory();
+        using var drv = new S7Driver(opts, "s7-probe-blackhole", factory);
+        await drv.InitializeAsync("{}", TestContext.Current.CancellationToken);
+
+        // Kill the live handle (probe fault), then black-hole every reconnect.
+        factory.OpenHangsUntilCancelledCount = int.MaxValue;
+        factory.Created[0].ReadStatusThrows = new System.Net.Sockets.SocketException();
+
+        // First reconnect attempt must have been made and failed (positive control), then observe a window
+        // well inside the 1 s first backoff window.
+        await WaitUntilAsync(() => factory.Created.Count >= 2, TimeSpan.FromSeconds(5));
+        factory.Created.Count.ShouldBeGreaterThanOrEqualTo(2);
+        var atFirstAttempt = factory.Created.Count;
+        await Task.Delay(TimeSpan.FromMilliseconds(900));
+
+        // Without the fix this is ~10+ (one 80 ms-cut attempt per tick); with it the window suppresses them.
+        (factory.Created.Count - atFirstAttempt).ShouldBeLessThanOrEqualTo(1);
+    }
+
    private static S7DriverOptions ProbeEnabledOptions() => new()
    {
        Host = "192.0.2.1",