protected override void OnEventWritten(EventWrittenEventArgs eventData)
{
if (eventData.EventName != "EventCounters" || eventData.Payload == null || eventData.Payload.Count == 0)
{
return; // not a counter with readable data
}
if (eventData.Payload[0] == null || eventData.Payload[0] is not IDictionary <string, object> )
{
return; // expecting a dictionary
}
var payload = (IDictionary <string, object>)eventData.Payload[0] !;
if (!payload.TryGetValue("CounterType", out var counterType) ||
!payload.TryGetValue("Name", out var name))
{
return; // payload is missing counter type and name
}
if (!(counterType is string counterTypeString) || string.IsNullOrWhiteSpace(counterTypeString))
{
return; // invalid counter type
}
if (!(name is string nameString) || string.IsNullOrWhiteSpace(nameString))
{
return; // invalid name
}
var metricName = $"{eventData.EventSource.Name}.{nameString}";
if (!_registry.TryGetMetric(new MetricName(typeof(MetricsHost), metricName), out var metric))
{
throw new InvalidOperationException(
$"EventSource '{eventData.EventSource.Name}' was registered for metrics, but no metric found for '{metricName}'");
}
if (!(metric is CounterMetric counter))
{
throw new InvalidOperationException(
$"EventSource '{eventData.EventSource.Name}' was registered for metrics, but metric '{metricName}' is not a counter.");
}
if (counterTypeString.Equals("Sum") && payload.TryGetValue("Increment", out var increment))
{
if (increment is double value)
{
if (value == 0d)
{
return;
}
if (value < 0d)
{
counter.Decrement(Convert.ToInt64(value));
}
else
{
counter.Increment(Convert.ToInt64(value));
}
}
else
{
throw new InvalidOperationException("unexpected increment type " + increment.GetType());
}
}
}