fix: gateway reflects configured forced provider mode into gauge/feed (#2)

src/ZB.MOM.WW.MxGateway.Server/Alarms/GatewayAlarmMonitor.cs

@@ -157,19 +157,48 @@ public sealed class GatewayAlarmMonitor : BackgroundService, IGatewayAlarmServic
     private async Task RunMonitorAsync(string subscription, CancellationToken stoppingToken)
     {
         _state = GatewayAlarmMonitorState.Starting;
+
+        // Derive the lifecycle baseline from the configured forced mode so a
+        // ForceSubtag / ForceAlarmManager start advertises the correct mode even
+        // though no OnAlarmProviderModeChanged event is raised in those modes
+        // (only Auto/failover produces that event). ForceSubtag starts degraded.
+        AlarmProviderMode initialMode;
+        bool initialDegraded;
+        string initialReason;
+        switch (MapForcedMode(_options.Fallback.Mode))
+        {
+            case AlarmProviderMode.Subtag:
+                initialMode = AlarmProviderMode.Subtag;
+                initialDegraded = true;
+                initialReason = "Forced subtag mode (configuration)";
+                break;
+            case AlarmProviderMode.Alarmmgr:
+                initialMode = AlarmProviderMode.Alarmmgr;
+                initialDegraded = false;
+                initialReason = string.Empty;
+                break;
+            default:
+                // Unspecified (Auto): the failover consumer starts on the
+                // alarm-manager primary and only degrades to subtag on failure.
+                initialMode = AlarmProviderMode.Alarmmgr;
+                initialDegraded = false;
+                initialReason = string.Empty;
+                break;
+        }
+
         lock (_sync)
         {
             // Re-baseline the provider status for this lifecycle so a restarted
-            // monitor advertises alarm-manager/not-degraded until told otherwise.
-            _providerMode = AlarmProviderMode.Alarmmgr;
-            _providerDegraded = false;
-            _providerReason = string.Empty;
+            // monitor advertises the configured mode until told otherwise.
+            _providerMode = initialMode;
+            _providerDegraded = initialDegraded;
+            _providerReason = initialReason;
             _providerSince = DateTimeOffset.UtcNow;
         }
 
-        // Align the observable gauge with the Alarmmgr baseline without recording
+        // Align the observable gauge with the lifecycle baseline without recording
         // a switch — the gauge was 0 (unknown) from construction until now.
-        _metrics.SetAlarmProviderMode(ModeToInt(AlarmProviderMode.Alarmmgr));
+        _metrics.SetAlarmProviderMode(ModeToInt(initialMode));
 
         GatewaySession session = await _sessionManager.OpenSessionAsync(
                 new SessionOpenRequest(BackendName, MonitorClientName, Guid.NewGuid().ToString("N"), CommandTimeout: null),
@@ -256,6 +285,10 @@ public sealed class GatewayAlarmMonitor : BackgroundService, IGatewayAlarmServic
 
         AlarmProviderMode forcedMode = MapForcedMode(_options.Fallback.Mode);
 
+        _logger.LogInformation(
+            "Alarm subscribe: forcedMode={ForcedMode} configMode={ConfigMode} watchList={WatchListCount}.",
+            forcedMode, _options.Fallback.Mode, watchList.Count);
+
         // When the forced mode is Unspecified (the "Auto" case) and the resolved
         // watch-list is empty — the common alarmmgr-only deployment — the command
         // is identical-in-effect to the historical SubscribeAlarms (wnwrap only):

src/ZB.MOM.WW.MxGateway.Tests/Alarms/GatewayAlarmMonitorProviderModeTests.cs

@@ -156,6 +156,151 @@ public sealed class GatewayAlarmMonitorProviderModeTests
         await monitor.StopAsync(CancellationToken.None);
     }
 
+    [Fact]
+    public async Task ForceSubtagConfig_BaselinesProviderStatusToSubtagDegraded_WithoutSwitch()
+    {
+        using GatewayMetrics metrics = new();
+        long switchCount = 0;
+        int gaugeValue = -1;
+        using MeterListener listener = new();
+        listener.InstrumentPublished = (instrument, meterListener) =>
+        {
+            if (ReferenceEquals(instrument.Meter, metrics.Meter)
+                && (instrument.Name == "mxgateway.alarms.provider_switches"
+                    || instrument.Name == "mxgateway.alarms.provider_mode"))
+            {
+                meterListener.EnableMeasurementEvents(instrument);
+            }
+        };
+        listener.SetMeasurementEventCallback<long>(
+            (instrument, measurement, _, _) =>
+            {
+                if (ReferenceEquals(instrument.Meter, metrics.Meter)
+                    && instrument.Name == "mxgateway.alarms.provider_switches")
+                {
+                    Interlocked.Add(ref switchCount, measurement);
+                }
+            });
+        listener.SetMeasurementEventCallback<int>(
+            (instrument, measurement, _, _) =>
+            {
+                if (ReferenceEquals(instrument.Meter, metrics.Meter)
+                    && instrument.Name == "mxgateway.alarms.provider_mode")
+                {
+                    Interlocked.Exchange(ref gaugeValue, measurement);
+                }
+            });
+        listener.Start();
+
+        FakeSessionManager sessions = new();
+        using GatewayAlarmMonitor monitor = CreateMonitor(sessions, metrics, "ForceSubtag");
+
+        using CancellationTokenSource cts = new();
+        await monitor.StartAsync(cts.Token);
+        await sessions.WaitForSubscribeAsync(WaitTimeout);
+
+        using CancellationTokenSource streamCts = new();
+        AlarmFeedMessage? first = null;
+        Task reader = Task.Run(async () =>
+        {
+            await foreach (AlarmFeedMessage message in monitor.StreamAsync(null, streamCts.Token))
+            {
+                first = message;
+                break;
+            }
+        });
+
+        await WaitUntilAsync(() => first is not null, WaitTimeout);
+
+        Assert.NotNull(first);
+        Assert.Equal(AlarmFeedMessage.PayloadOneofCase.ProviderStatus, first!.PayloadCase);
+        Assert.Equal(AlarmProviderMode.Subtag, first.ProviderStatus.Mode);
+        Assert.True(first.ProviderStatus.Degraded);
+
+        // The observable gauge must read subtag (2) after start.
+        listener.RecordObservableInstruments();
+        Assert.Equal(2, Volatile.Read(ref gaugeValue));
+
+        // The initial set must not record a provider switch.
+        Assert.Equal(0, Interlocked.Read(ref switchCount));
+
+        await streamCts.CancelAsync();
+        await reader;
+        await cts.CancelAsync();
+        await monitor.StopAsync(CancellationToken.None);
+    }
+
+    [Fact]
+    public async Task ForceAlarmManagerConfig_BaselinesProviderStatusToAlarmmgr_WithoutSwitch()
+    {
+        using GatewayMetrics metrics = new();
+        long switchCount = 0;
+        int gaugeValue = -1;
+        using MeterListener listener = new();
+        listener.InstrumentPublished = (instrument, meterListener) =>
+        {
+            if (ReferenceEquals(instrument.Meter, metrics.Meter)
+                && (instrument.Name == "mxgateway.alarms.provider_switches"
+                    || instrument.Name == "mxgateway.alarms.provider_mode"))
+            {
+                meterListener.EnableMeasurementEvents(instrument);
+            }
+        };
+        listener.SetMeasurementEventCallback<long>(
+            (instrument, measurement, _, _) =>
+            {
+                if (ReferenceEquals(instrument.Meter, metrics.Meter)
+                    && instrument.Name == "mxgateway.alarms.provider_switches")
+                {
+                    Interlocked.Add(ref switchCount, measurement);
+                }
+            });
+        listener.SetMeasurementEventCallback<int>(
+            (instrument, measurement, _, _) =>
+            {
+                if (ReferenceEquals(instrument.Meter, metrics.Meter)
+                    && instrument.Name == "mxgateway.alarms.provider_mode")
+                {
+                    Interlocked.Exchange(ref gaugeValue, measurement);
+                }
+            });
+        listener.Start();
+
+        FakeSessionManager sessions = new();
+        using GatewayAlarmMonitor monitor = CreateMonitor(sessions, metrics, "ForceAlarmManager");
+
+        using CancellationTokenSource cts = new();
+        await monitor.StartAsync(cts.Token);
+        await sessions.WaitForSubscribeAsync(WaitTimeout);
+
+        using CancellationTokenSource streamCts = new();
+        AlarmFeedMessage? first = null;
+        Task reader = Task.Run(async () =>
+        {
+            await foreach (AlarmFeedMessage message in monitor.StreamAsync(null, streamCts.Token))
+            {
+                first = message;
+                break;
+            }
+        });
+
+        await WaitUntilAsync(() => first is not null, WaitTimeout);
+
+        Assert.NotNull(first);
+        Assert.Equal(AlarmFeedMessage.PayloadOneofCase.ProviderStatus, first!.PayloadCase);
+        Assert.Equal(AlarmProviderMode.Alarmmgr, first.ProviderStatus.Mode);
+        Assert.False(first.ProviderStatus.Degraded);
+
+        listener.RecordObservableInstruments();
+        Assert.Equal(1, Volatile.Read(ref gaugeValue));
+        Assert.Equal(0, Interlocked.Read(ref switchCount));
+
+        await streamCts.CancelAsync();
+        await reader;
+        await cts.CancelAsync();
+        await monitor.StopAsync(CancellationToken.None);
+    }
+
     [Fact]
     public async Task SubscribeAlarms_SendsForcedModeAndWatchList_FromConfiguration()
     {
@@ -259,6 +404,22 @@ public sealed class GatewayAlarmMonitorProviderModeTests
             NullLogger<GatewayAlarmMonitor>.Instance);
     }
 
+    private static GatewayAlarmMonitor CreateMonitor(FakeSessionManager sessions, GatewayMetrics metrics, string mode)
+    {
+        AlarmsOptions options = new()
+        {
+            Enabled = true,
+            SubscriptionExpression = @"\\NODE\Galaxy!Area",
+            Fallback = new AlarmFallbackOptions { Mode = mode },
+        };
+        return new GatewayAlarmMonitor(
+            sessions,
+            new StubWatchListResolver([]),
+            metrics,
+            Microsoft.Extensions.Options.Options.Create(new GatewayOptions { Alarms = options }),
+            NullLogger<GatewayAlarmMonitor>.Instance);
+    }
+
     private static async Task<AlarmFeedMessage> WaitForAsync(
         List<AlarmFeedMessage> received,
         Func<AlarmFeedMessage, bool> predicate,