NameResolutionTelemetry.cs

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using System.Collections.Generic;
using System.Diagnostics.Tracing;
using System.Net.Sockets;
using System.Threading;
using Microsoft.Extensions.Internal;
 
namespace System.Net;
 
[EventSource(Name = "System.Net.NameResolution")]
internal sealed class NameResolutionTelemetry : EventSource
{
    public static readonly NameResolutionTelemetry Log = new NameResolutionTelemetry();
 
    private PollingCounter _lookupsRequestedCounter;
 
    private PollingCounter _currentLookupsCounter;
 
    private EventCounter _lookupsDuration;
 
    private long _lookupsRequested;
 
    private long _currentLookups;
 
    protected override void OnEventCommand(EventCommandEventArgs command)
    {
        if (command.Command != EventCommand.Enable)
        {
            return;
        }
        if (_lookupsRequestedCounter == null)
        {
            _lookupsRequestedCounter = new PollingCounter("dns-lookups-requested", this, () => Interlocked.Read(ref _lookupsRequested))
            {
                DisplayName = "DNS Lookups Requested"
            };
        }
        if (_currentLookupsCounter == null)
        {
            _currentLookupsCounter = new PollingCounter("current-dns-lookups", this, () => Interlocked.Read(ref _currentLookups))
            {
                DisplayName = "Current DNS Lookups"
            };
        }
        if (_lookupsDuration == null)
        {
            _lookupsDuration = new EventCounter("dns-lookups-duration", this)
            {
                DisplayName = "Average DNS Lookup Duration",
                DisplayUnits = "ms"
            };
        }
    }
 
    [Event(1, Level = EventLevel.Informational)]
    private void ResolutionStart(string hostNameOrAddress)
    {
        WriteEvent(1, hostNameOrAddress);
    }
 
    [Event(2, Level = EventLevel.Informational)]
    private void ResolutionStop()
    {
        WriteEvent(2);
    }
 
    [Event(3, Level = EventLevel.Informational)]
    private void ResolutionFailed()
    {
        WriteEvent(3);
    }
 
    [NonEvent]
    public ValueStopwatch BeforeResolution(object hostNameOrAddress)
    {
        if (IsEnabled())
        {
            Interlocked.Increment(ref _lookupsRequested);
            Interlocked.Increment(ref _currentLookups);
            if (IsEnabled(EventLevel.Informational, EventKeywords.None))
            {
                string text2 = ((hostNameOrAddress is string text) ? text : ((hostNameOrAddress is KeyValuePair<string, AddressFamily> keyValuePair) ? keyValuePair.Key : ((hostNameOrAddress is IPAddress iPAddress) ? iPAddress.ToString() : ((!(hostNameOrAddress is KeyValuePair<IPAddress, AddressFamily> keyValuePair2)) ? null : keyValuePair2.Key.ToString()))));
                string hostNameOrAddress2 = text2;
                ResolutionStart(hostNameOrAddress2);
            }
            return ValueStopwatch.StartNew();
        }
        return default(ValueStopwatch);
    }
 
    [NonEvent]
    public void AfterResolution(ValueStopwatch stopwatch, bool successful)
    {
        if (!stopwatch.IsActive)
        {
            return;
        }
        Interlocked.Decrement(ref _currentLookups);
        _lookupsDuration.WriteMetric(stopwatch.GetElapsedTime().TotalMilliseconds);
        if (IsEnabled(EventLevel.Informational, EventKeywords.None))
        {
            if (!successful)
            {
                ResolutionFailed();
            }
            ResolutionStop();
        }
    }
}