[blazor] fix multiple calls to OnConnectionDownAsync (#62518)

Author: pavelsavara

src/Components/Server/src/Circuits/CircuitHost.cs

@@ -30,6 +30,7 @@ internal partial class CircuitHost : IAsyncDisposable
     private CircuitHandler[] _circuitHandlers;
     private bool _initialized;
     private bool _isFirstUpdate = true;
+    private bool _onConnectionDownFired;
     private bool _disposed;
     private long _startTime;
     private PersistedCircuitState _persistedCircuitState;
@@ -279,6 +280,7 @@ private async Task OnCircuitOpenedAsync(CancellationToken cancellationToken)
 
     public async Task OnConnectionUpAsync(CancellationToken cancellationToken)
     {
+        _onConnectionDownFired = false;
         Log.ConnectionUp(_logger, CircuitId, Client.ConnectionId);
         _circuitMetrics?.OnConnectionUp();
 
@@ -309,6 +311,12 @@ public async Task OnConnectionUpAsync(CancellationToken cancellationToken)
 
     public async Task OnConnectionDownAsync(CancellationToken cancellationToken)
     {
+        if(_onConnectionDownFired)
+        {
+            return;
+        }
+
+        _onConnectionDownFired = true;
         Log.ConnectionDown(_logger, CircuitId, Client.ConnectionId);
         _circuitMetrics?.OnConnectionDown();
 

src/Components/Server/src/Circuits/CircuitMetrics.cs

@@ -70,11 +70,6 @@ public void OnCircuitDown(long startTimestamp, long currentTimestamp)
             _circuitActiveCounter.Add(-1);
         }
 
-        if (_circuitConnectedCounter.Enabled)
-        {
-            _circuitConnectedCounter.Add(-1);
-        }
-
         if (_circuitDuration.Enabled)
         {
             var duration = Stopwatch.GetElapsedTime(startTimestamp, currentTimestamp);

src/Components/Server/src/Circuits/CircuitRegistry.cs

@@ -311,6 +311,7 @@ private async Task PauseAndDisposeCircuitHost(CircuitHost circuitHost, bool save
     {
         await _circuitPersistenceManager.PauseCircuitAsync(circuitHost, saveStateToClient);
         circuitHost.UnhandledException -= CircuitHost_UnhandledException;
+        circuitHost.Client.SetDisconnected();
         await circuitHost.DisposeAsync();
     }
 

src/Components/Server/test/Circuits/CircuitMetricsTest.cs

@@ -108,15 +108,11 @@ public async Task OnCircuitDown_UpdatesCountersAndRecordsDuration()
 
         // Assert
         var activeMeasurements = activeCircuitCounter.GetMeasurementSnapshot();
-        var connectedMeasurements = connectedCircuitCounter.GetMeasurementSnapshot();
         var durationMeasurements = circuitDurationCollector.GetMeasurementSnapshot();
 
         Assert.Single(activeMeasurements);
         Assert.Equal(-1, activeMeasurements[0].Value);
 
-        Assert.Single(connectedMeasurements);
-        Assert.Equal(-1, connectedMeasurements[0].Value);
-
         Assert.Single(durationMeasurements);
         Assert.True(durationMeasurements[0].Value > 0);
     }
@@ -162,7 +158,10 @@ public void FullCircuitLifecycle_RecordsAllMetricsCorrectly()
         // 4. Connection re-established
         circuitMetrics.OnConnectionUp();
 
-        // 5. Circuit closes
+        // 5. Connection drops
+        circuitMetrics.OnConnectionDown();
+
+        // 6. Circuit closes
         Thread.Sleep(10); // Add a small delay to ensure a measurable duration
         var endTime = Stopwatch.GetTimestamp();
         circuitMetrics.OnCircuitDown(startTime, endTime);