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Adjust DNS metrics (#89813)
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Adjust DNS metrics according to https://github.com/lmolkova/semantic-conventions/blob/dotnet8-metrics/docs/dotnet/dotnet-dns-metrics.md
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@antonfirsov
antonfirsov committed Aug 3, 2023
1 parent a3408d4 commit f447532
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Showing 4 changed files with 63 additions and 62 deletions.
22 changes: 11 additions & 11 deletions src/libraries/System.Net.NameResolution/src/System/Net/Dns.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -24,13 +24,13 @@ public static string GetHostName()
{
name = NameResolutionPal.GetHostName();
}
catch when (LogFailure(startingTimestamp))
catch when (LogFailure(string.Empty, startingTimestamp))
{
Debug.Fail("LogFailure should return false");
throw;
}

NameResolutionTelemetry.Log.AfterResolution(startingTimestamp, successful: true);
NameResolutionTelemetry.Log.AfterResolution(string.Empty, startingTimestamp, successful: true);

if (NetEventSource.Log.IsEnabled()) NetEventSource.Info(null, name);
return name;
Expand Down Expand Up @@ -395,13 +395,13 @@ private static object GetHostEntryOrAddressesCore(string hostName, bool justAddr
Aliases = aliases
};
}
catch when (LogFailure(startingTimestamp))
catch when (LogFailure(hostName, startingTimestamp))
{
Debug.Fail("LogFailure should return false");
throw;
}

NameResolutionTelemetry.Log.AfterResolution(startingTimestamp, successful: true);
NameResolutionTelemetry.Log.AfterResolution(hostName, startingTimestamp, successful: true);

return result;
}
Expand Down Expand Up @@ -435,13 +435,13 @@ private static object GetHostEntryOrAddressesCore(IPAddress address, bool justAd
}
Debug.Assert(name != null);
}
catch when (LogFailure(startingTimestamp))
catch when (LogFailure(address, startingTimestamp))
{
Debug.Fail("LogFailure should return false");
throw;
}

NameResolutionTelemetry.Log.AfterResolution(startingTimestamp, successful: true);
NameResolutionTelemetry.Log.AfterResolution(address, startingTimestamp, successful: true);

// Do the forward lookup to get the IPs for that host name
startingTimestamp = NameResolutionTelemetry.Log.BeforeResolution(name);
Expand All @@ -465,13 +465,13 @@ private static object GetHostEntryOrAddressesCore(IPAddress address, bool justAd
AddressList = addresses
};
}
catch when (LogFailure(startingTimestamp))
catch when (LogFailure(name, startingTimestamp))
{
Debug.Fail("LogFailure should return false");
throw;
}

NameResolutionTelemetry.Log.AfterResolution(startingTimestamp, successful: true);
NameResolutionTelemetry.Log.AfterResolution(name, startingTimestamp, successful: true);

// One of three things happened:
// 1. Success.
Expand Down Expand Up @@ -603,7 +603,7 @@ static async Task<T> CompleteAsync(Task task, string hostName, long startingTime
}
finally
{
NameResolutionTelemetry.Log.AfterResolution(startingTimestamp, successful: result is not null);
NameResolutionTelemetry.Log.AfterResolution(hostName, startingTimestamp, successful: result is not null);
}
}
}
Expand All @@ -628,9 +628,9 @@ private static void ValidateHostName(string hostName)
}
}

private static bool LogFailure(long? startingTimestamp)
private static bool LogFailure(object hostNameOrAddress, long? startingTimestamp)
{
NameResolutionTelemetry.Log.AfterResolution(startingTimestamp, successful: false);
NameResolutionTelemetry.Log.AfterResolution(hostNameOrAddress, startingTimestamp, successful: false);
return false;
}

Expand Down
40 changes: 7 additions & 33 deletions src/libraries/System.Net.NameResolution/src/System/Net/NameResolutionMetrics.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,42 +12,16 @@ internal static class NameResolutionMetrics
{
private static readonly Meter s_meter = new("System.Net.NameResolution");

private static readonly Counter<long> s_lookupsRequestedCounter = s_meter.CreateCounter<long>(
name: "dns-lookups-requested",
description: "Number of DNS lookups requested.");
private static readonly Histogram<double> s_lookupDuration = s_meter.CreateHistogram<double>(
name: "dns.lookups.duration",
unit: "s",
description: "Measures the time taken to perform a DNS lookup.");

public static bool IsEnabled() => s_lookupsRequestedCounter.Enabled;
public static bool IsEnabled() => s_lookupDuration.Enabled;

public static void BeforeResolution(object hostNameOrAddress, out string? host)
public static void AfterResolution(TimeSpan duration, string hostName)
{
if (s_lookupsRequestedCounter.Enabled)
{
host = GetHostnameFromStateObject(hostNameOrAddress);

s_lookupsRequestedCounter.Add(1, KeyValuePair.Create("hostname", (object?)host));
}
else
{
host = null;
}
}

public static string GetHostnameFromStateObject(object hostNameOrAddress)
{
Debug.Assert(hostNameOrAddress is not null);

string host = hostNameOrAddress switch
{
string h => h,
KeyValuePair<string, AddressFamily> t => t.Key,
IPAddress a => a.ToString(),
KeyValuePair<IPAddress, AddressFamily> t => t.Key.ToString(),
_ => null!
};

Debug.Assert(host is not null, $"Unknown hostNameOrAddress type: {hostNameOrAddress.GetType().Name}");

return host;
s_lookupDuration.Record(duration.TotalSeconds, KeyValuePair.Create("dns.question.name", (object?)hostName));
}
}
}
45 changes: 36 additions & 9 deletions src/libraries/System.Net.NameResolution/src/System/Net/NameResolutionTelemetry.cs
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Original file line number Diff line number Diff line change
@@ -1,8 +1,10 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Collections.Generic;
using System.Diagnostics;
using System.Diagnostics.Tracing;
using System.Net.Sockets;
using System.Threading;

namespace System.Net
Expand Down Expand Up @@ -60,38 +62,40 @@ protected override void OnEventCommand(EventCommandEventArgs command)
[NonEvent]
public long BeforeResolution(object hostNameOrAddress)
{
// System.Diagnostics.Metrics part
NameResolutionMetrics.BeforeResolution(hostNameOrAddress, out string? host);

// System.Diagnostics.Tracing part
if (IsEnabled())
{
Interlocked.Increment(ref _lookupsRequested);
Interlocked.Increment(ref _currentLookups);

if (IsEnabled(EventLevel.Informational, EventKeywords.None))
{
host ??= NameResolutionMetrics.GetHostnameFromStateObject(hostNameOrAddress);
string host = GetHostnameFromStateObject(hostNameOrAddress);

ResolutionStart(host);
}

return Stopwatch.GetTimestamp();
}

return 0;
return NameResolutionMetrics.IsEnabled() ? Stopwatch.GetTimestamp() : 0;
}

[NonEvent]
public void AfterResolution(long? startingTimestamp, bool successful)
public void AfterResolution(object hostNameOrAddress, long? startingTimestamp, bool successful)
{
Debug.Assert(startingTimestamp.HasValue);
if (startingTimestamp == 0)
{
return;
}

TimeSpan duration = Stopwatch.GetElapsedTime(startingTimestamp.Value);

if (startingTimestamp != 0)
if (IsEnabled())
{
Interlocked.Decrement(ref _currentLookups);

_lookupsDuration?.WriteMetric(Stopwatch.GetElapsedTime(startingTimestamp.Value).TotalMilliseconds);
_lookupsDuration?.WriteMetric(duration.TotalMilliseconds);

if (IsEnabled(EventLevel.Informational, EventKeywords.None))
{
Expand All @@ -103,6 +107,29 @@ public void AfterResolution(long? startingTimestamp, bool successful)
ResolutionStop();
}
}

if (NameResolutionMetrics.IsEnabled())
{
NameResolutionMetrics.AfterResolution(duration, GetHostnameFromStateObject(hostNameOrAddress));
}
}

private static string GetHostnameFromStateObject(object hostNameOrAddress)
{
Debug.Assert(hostNameOrAddress is not null);

string host = hostNameOrAddress switch
{
string h => h,
KeyValuePair<string, AddressFamily> t => t.Key,
IPAddress a => a.ToString(),
KeyValuePair<IPAddress, AddressFamily> t => t.Key.ToString(),
_ => null!
};

Debug.Assert(host is not null, $"Unknown hostNameOrAddress type: {hostNameOrAddress.GetType().Name}");

return host;
}
}
}
18 changes: 9 additions & 9 deletions src/libraries/System.Net.NameResolution/tests/FunctionalTests/MetricsTest.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,7 @@ namespace System.Net.NameResolution.Tests
{
public class MetricsTest
{
private const string DnsLookupsRequested = "dns-lookups-requested";
private const string DnsLookupDuration = "dns.lookups.duration";

[ConditionalFact(typeof(RemoteExecutor), nameof(RemoteExecutor.IsSupported))]
public static void ResolveValidHostName_MetricsRecorded()
Expand All @@ -23,7 +23,7 @@ public static void ResolveValidHostName_MetricsRecorded()
{
const string ValidHostName = "localhost";
using var recorder = new InstrumentRecorder<long>(DnsLookupsRequested);
using var recorder = new InstrumentRecorder<double>(DnsLookupDuration);
await Dns.GetHostEntryAsync(ValidHostName);
await Dns.GetHostAddressesAsync(ValidHostName);
Expand All @@ -34,10 +34,10 @@ public static void ResolveValidHostName_MetricsRecorded()
Dns.EndGetHostEntry(Dns.BeginGetHostEntry(ValidHostName, null, null));
Dns.EndGetHostAddresses(Dns.BeginGetHostAddresses(ValidHostName, null, null));
long[] measurements = GetMeasurementsForHostname(recorder, ValidHostName);
double[] measurements = GetMeasurementsForHostname(recorder, ValidHostName);
Assert.Equal(6, measurements.Length);
Assert.All(measurements, m => Assert.Equal(1, m));
Assert.All(measurements, m => Assert.True(m > double.Epsilon));
}).Dispose();
}

Expand All @@ -46,7 +46,7 @@ public static async Task ResolveInvalidHostName_MetricsRecorded()
{
const string InvalidHostName = $"invalid...example.com...{nameof(ResolveInvalidHostName_MetricsRecorded)}";

using var recorder = new InstrumentRecorder<long>(DnsLookupsRequested);
using var recorder = new InstrumentRecorder<double>(DnsLookupDuration);

await Assert.ThrowsAnyAsync<SocketException>(async () => await Dns.GetHostEntryAsync(InvalidHostName));
await Assert.ThrowsAnyAsync<SocketException>(async () => await Dns.GetHostAddressesAsync(InvalidHostName));
Expand All @@ -57,17 +57,17 @@ public static async Task ResolveInvalidHostName_MetricsRecorded()
Assert.ThrowsAny<SocketException>(() => Dns.EndGetHostEntry(Dns.BeginGetHostEntry(InvalidHostName, null, null)));
Assert.ThrowsAny<SocketException>(() => Dns.EndGetHostAddresses(Dns.BeginGetHostAddresses(InvalidHostName, null, null)));

long[] measurements = GetMeasurementsForHostname(recorder, InvalidHostName);
double[] measurements = GetMeasurementsForHostname(recorder, InvalidHostName);

Assert.Equal(6, measurements.Length);
Assert.All(measurements, m => Assert.Equal(1, m));
Assert.All(measurements, m => Assert.True(m > double.Epsilon));
}

private static long[] GetMeasurementsForHostname(InstrumentRecorder<long> recorder, string hostname)
private static double[] GetMeasurementsForHostname(InstrumentRecorder<double> recorder, string hostname)
{
return recorder
.GetMeasurements()
.Where(m => m.Tags.ToArray().Any(t => t.Key == "hostname" && t.Value is string hostnameTag && hostnameTag == hostname))
.Where(m => m.Tags.ToArray().Any(t => t.Key == "dns.question.name" && t.Value is string hostnameTag && hostnameTag == hostname))
.Select(m => m.Value)
.ToArray();
}
Expand Down

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