Npgsql connections counter publish to Prometheus

1 NpgsqlMetricsCollectionService.cs

    internal sealed class NpgsqlMetricsCollectionService : EventListener, IHostedService
    {
        public Task StartAsync(CancellationToken cancellationToken) => Task.CompletedTask;
        public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;

        protected override void OnEventWritten(EventWrittenEventArgs eventData)
        {
            if (eventData.EventName != "EventCounters"
                || eventData.Payload.Count <= 0
                || !(eventData.Payload[0] is IDictionary<string, object> data)
            )
                return;

            WriteCounters(data);
        }

        private void WriteCounters(IDictionary<string, object> eventPayload)
        {
            switch (eventPayload["Name"])
            {
                case "idle-connections":
                    CommonMetrics.NpgsqlConnections.Labels("idle").Set(Convert.ToSingle(eventPayload["Mean"]));
                    break;
                case "busy-connections":
                    CommonMetrics.NpgsqlConnections.Labels("busy").Set(Convert.ToSingle(eventPayload["Mean"]));
                    break;
                case "connection-pools":
                    CommonMetrics.NpgsqlConnectionsPoolCount.Set(Convert.ToSingle(eventPayload["Mean"]));
                    break;
                case "bytes-written-per-second":
                    var written = Convert.ToSingle(eventPayload["Increment"]);
                    if (written > 0) CommonMetrics.NpgsqlDataCounter.Labels("write").Inc(written);
                    break;
                case "bytes-read-per-second":
                    var read = Convert.ToSingle(eventPayload["Increment"]);
                    if(read > 0 ) CommonMetrics.NpgsqlDataCounter.Labels("read").Inc(read);
                    break;
            }
        }

        protected override void OnEventSourceCreated(EventSource eventSource)
        {
            if (eventSource.Name.Equals("Npgsql", StringComparison.OrdinalIgnoreCase))
            {
                EnableEvents(eventSource, EventLevel.Verbose, EventKeywords.None, new Dictionary<string, string>
                {
                    {"EventCounterIntervalSec", "1"}
                });
            }
        }
    }

2 CommonMetrics.cs

    public static class CommonMetrics
    {
        public static Gauge NpgsqlConnections = new Gauge("npgsql_connections_current", "Number of connections managed by Npgsql (idle/busy)", "type");
        public static Gauge NpgsqlConnectionsPoolCount = new Gauge("npgsql_connection_pools_current", "Number of connection pools managed by Npgsql");
        public static Counter NpgsqlDataCounter = new Counter("npgsql_data_bytes_total", "Amount of byte read/write by Npgsql", "direction");
        public static Counter ExceptionsOccur = new Counter("exceptions_total", "Total number of exceptions happen on site during it's life time");
    }