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[blazor] fix multiple calls to OnConnectionDownAsync #62518

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Merged
merged 5 commits into from
Jul 18, 2025
Merged

[blazor] fix multiple calls to OnConnectionDownAsync #62518

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ebf208f
fix multiple calls to OnConnectionDownAsync
pavelsavara Jul 1, 2025
c25fdf7
Merge branch 'main' into blazor_dedup_OnConnectionDownAsync
pavelsavara Jul 14, 2025
89b709a
fix other scenarios where OnConnectionDownAsync needs to me more expl…
pavelsavara Jul 14, 2025
273fcf1
Merge branch 'main' into blazor_dedup_OnConnectionDownAsync
pavelsavara Jul 16, 2025
4f774f6
feedback
pavelsavara Jul 17, 2025
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5 changes: 4 additions & 1 deletion src/Components/Server/src/Circuits/CircuitHost.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -209,7 +209,10 @@ await Renderer.Dispatcher.InvokeAsync(async () =>

try
{
await OnConnectionDownAsync(CancellationToken.None);
if (this.Client.Connected)
{
await OnConnectionDownAsync(CancellationToken.None);
}
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I don't think this is the right change to fix the metric issue. It's changing an existing behavior of the system that users might be relying on.

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this event is called twice. That's a bug not a feature

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What is causing the 2nd call?

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The proper event is Hub.OnDisconnect()

CircuitHost.OnConnectionDownAsync() is called from CircuitHost.DisposeAsync() regardless if it's connected or not, creating dis-balance.

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@javiercn does this make sense or you have another proposal for the fix ?

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I just tested the "close tab" and "navigate to non-interactive page". Both behave as expected, that is, they call the event once.

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Terminate it's not being fired in those cases.

  • Close tab will likely don't cause unload to fire.
  • navigate to non-interactive page
    • It takes a bit of time for the client to start the circuit disposal.
    • If for some reason it's not happening, it's also a bug.

https://github.com/dotnet/aspnetcore/blob/main/src/Components/Server/src/CircuitDisconnectMiddleware.cs#L81-L87

https://github.com/dotnet/aspnetcore/blob/main/src/Components/Server/src/Circuits/CircuitRegistry.cs#L391

If we check for the circuit to be connected it won't fire when we want to eagerly terminate the circuit.

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Maybe we need to call that event from places that call circuitHost.Client.SetDisconnected() rather than relying that circuitHost.DisposeAsync() would always call it.

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Also I'm not sure that the new PauseAndDisposeCircuitHost is calling SetDisconnected()

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I made the calls to OnConnectionDownAsync more explicit now, instead of relying on the DisposeAsync.

@javiercn please review again.

}
catch
{
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5 changes: 0 additions & 5 deletions src/Components/Server/src/Circuits/CircuitMetrics.cs
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Expand Up @@ -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);
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9 changes: 4 additions & 5 deletions src/Components/Server/test/Circuits/CircuitMetricsTest.cs
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Expand Up @@ -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);
}
Expand Down Expand Up @@ -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);
Expand Down
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