fix(r2-01): cancellation observed mid-PDU marks the connection dead before propagating (STAB-15a, task 8)

2026-07-13 10:01:20 -04:00
parent dab0029add
commit 33044061c3
3 changed files with 78 additions and 3 deletions
@@ -291,6 +291,66 @@ public sealed class S7DriverReconnectTests
        factory.Created[0].Disposed.ShouldBeTrue();
    }

+    // ---- STAB-15a: cancellation observed mid-I/O must mark the handle dead ----
+
+    /// <summary>
+    ///     T6 (STAB-15a). Cancellation observed WHILE a read is in flight abandons a half-read
+    ///     ISO-on-TCP response on the single gated stream — the handle can't be reused. The OCE
+    ///     must propagate (caller cancelled; nobody consumes the batch) AND mark the handle dead so
+    ///     the next read reopens. Before the fix the read path converted the OCE to a Bad snapshot
+    ///     and kept the desynced handle.
+    /// </summary>
+    [Fact]
+    public async Task Cancelled_read_marks_handle_dead_and_next_read_reopens()
+    {
+        var factory = new FakeS7PlcFactory();
+        using var drv = new S7Driver(Options(), "s7-cancel-read", factory);
+        await drv.InitializeAsync("{}", TestContext.Current.CancellationToken);
+
+        factory.Created[0].ReadHangsUntilCancelled = true;
+        using var cts = new CancellationTokenSource();
+        cts.CancelAfter(50);
+        await Should.ThrowAsync<OperationCanceledException>(
+            async () => await drv.ReadAsync(["W0"], cts.Token));
+
+        // Fresh-token read reopens a fresh connection.
+        var recovered = await drv.ReadAsync(["W0"], TestContext.Current.CancellationToken);
+        recovered[0].StatusCode.ShouldBe(0u);
+        factory.Created.Count.ShouldBe(2);
+        factory.Created[0].Disposed.ShouldBeTrue();
+    }
+
+    /// <summary>
+    ///     T7 (STAB-15a). Cancellation observed while a WRITE is in flight likewise marks the
+    ///     handle dead before propagating (the OCE already propagated pre-fix; the reopen is what
+    ///     was missing).
+    /// </summary>
+    [Fact]
+    public async Task Cancelled_write_marks_handle_dead_and_next_read_reopens()
+    {
+        var opts = new S7DriverOptions
+        {
+            Host = "192.0.2.1",
+            Timeout = TimeSpan.FromMilliseconds(250),
+            Probe = new S7ProbeOptions { Enabled = false },
+            Tags = [new S7TagDefinition("WW0", "DB1.DBW0", S7DataType.UInt16, Writable: true)],
+        };
+        var factory = new FakeS7PlcFactory();
+        using var drv = new S7Driver(opts, "s7-cancel-write", factory);
+        await drv.InitializeAsync("{}", TestContext.Current.CancellationToken);
+
+        factory.Created[0].WriteHangsUntilCancelled = true;
+        using var cts = new CancellationTokenSource();
+        cts.CancelAfter(50);
+        await Should.ThrowAsync<OperationCanceledException>(
+            async () => await drv.WriteAsync([new WriteRequest("WW0", (ushort)1)], cts.Token));
+
+        var recovered = await drv.ReadAsync(["WW0"], TestContext.Current.CancellationToken);
+        recovered[0].StatusCode.ShouldBe(0u);
+        factory.Created.Count.ShouldBe(2);
+        factory.Created[0].Disposed.ShouldBeTrue();
+    }
+
    // ---- fakes ----

    private sealed class FakeS7PlcFactory : IS7PlcFactory