public class MetricsService(IOptions<MetricsOptions> options, IProvisioning provisioning, ILogger<MetricsService> logger) : BackgroundService
{
 private readonly MetricsOptions _options = options.Value;
 private readonly IProvisioning _provisioning = provisioning ?? throw new ArgumentNullException(nameof(provisioning));
 private readonly ILogger<MetricsService> _logger = logger ?? throw new ArgumentNullException(nameof(logger));
 private SqlClientEventListener? _listener;
 protected override Task ExecuteAsync(CancellationToken stoppingToken)
 {
 if (_options.Enabled)
 {
 _logger.LogInformation("🚀 Metrics service started (frequency: {frequency}s).", _options.Frequency);
 try
 {
 _listener = new SqlClientEventListener(_provisioning.CurrentInstance.Name, _options.Frequency, _logger);
 stoppingToken.Register(() =>
 {
 _logger.LogInformation("🛑 Metrics service stopped.");
 _listener?.Dispose();
 });
 }
 catch (Exception ex )
 {
 _logger.LogError(ex, "An exception occured.");
 }
 }
 else
 {
 _logger.LogInformation("⚠️ Metrics service is disabled.");
 }
 return Task.CompletedTask;
 }
 private sealed class SqlClientEventListener(string instanceName, int frequency, ILogger logger) : EventListener
 {
 private readonly string _instanceName = instanceName;
 private readonly int _frequency = frequency;
 private readonly ILogger _logger = logger;
 protected override void OnEventSourceCreated(EventSource eventSource)
 {
 if (eventSource.Name.Equals("Microsoft.Data.SqlClient.EventSource"))
 {
 _logger.LogInformation("✅ Subscribed to {Source}", eventSource.Name);
 try
 {
 EnableEvents(eventSource, EventLevel.Verbose, EventKeywords.All, new Dictionary<string, string?>
 {
 ["EventCounterIntervalSec"] = _frequency.ToString()
 });
 }
 catch (Exception ex)
 {
 _logger.LogError(ex, "An exception occured.");
 }
 }
 }
 protected override void OnEventWritten(EventWrittenEventArgs eventData)
 {
 if (eventData.EventName != "EventCounters" || eventData.EventSource.Name != "Microsoft.Data.SqlClient.EventSource" || eventData.Payload is null)
 return;
 var payload = (eventData.Payload![0] as IDictionary<string, object>)!;
 string name = payload["Name"].ToString()!;
 object? value = payload.ContainsKey("Mean") ? payload["Mean"] : payload["Increment"];
			_logger.LogInformation("Metric '{name}': {value}", name, value);
 }
 }
}