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[sdk-metrics] Exemplar spec improvements (#5386)
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CodeBlanch authored Feb 27, 2024
1 parent 24d52c4 commit 42c593d
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44 changes: 29 additions & 15 deletions src/OpenTelemetry.Exporter.Console/ConsoleMetricExporter.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -188,30 +188,44 @@ public override ExportResult Export(in Batch<Metric> batch)
}

var exemplarString = new StringBuilder();
foreach (var exemplar in metricPoint.GetExemplars())
if (metricPoint.TryGetExemplars(out var exemplars))
{
if (exemplar.Timestamp != default)
foreach (ref readonly var exemplar in exemplars)
{
exemplarString.Append("Value: ");
exemplarString.Append(exemplar.DoubleValue);
exemplarString.Append(" Timestamp: ");
exemplarString.Append("Timestamp: ");
exemplarString.Append(exemplar.Timestamp.ToString("yyyy-MM-ddTHH:mm:ss.fffffffZ", CultureInfo.InvariantCulture));
exemplarString.Append(" TraceId: ");
exemplarString.Append(exemplar.TraceId);
exemplarString.Append(" SpanId: ");
exemplarString.Append(exemplar.SpanId);
if (metricType.IsDouble())
{
exemplarString.Append(" Value: ");
exemplarString.Append(exemplar.DoubleValue);
}
else if (metricType.IsLong())
{
exemplarString.Append(" Value: ");
exemplarString.Append(exemplar.LongValue);
}

if (exemplar.FilteredTags != null && exemplar.FilteredTags.Count > 0)
if (exemplar.TraceId != default)
{
exemplarString.Append(" Filtered Tags : ");
exemplarString.Append(" TraceId: ");
exemplarString.Append(exemplar.TraceId.ToHexString());
exemplarString.Append(" SpanId: ");
exemplarString.Append(exemplar.SpanId.ToHexString());
}

foreach (var tag in exemplar.FilteredTags)
bool appendedTagString = false;
foreach (var tag in exemplar.FilteredTags)
{
if (ConsoleTagTransformer.Instance.TryTransformTag(tag, out var result))
{
if (ConsoleTagTransformer.Instance.TryTransformTag(tag, out var result))
if (!appendedTagString)
{
exemplarString.Append(result);
exemplarString.Append(' ');
exemplarString.Append(" Filtered Tags : ");
appendedTagString = true;
}

exemplarString.Append(result);
exemplarString.Append(' ');
}
}

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93 changes: 33 additions & 60 deletions src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/MetricItemExtensions.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@
// SPDX-License-Identifier: Apache-2.0

using System.Collections.Concurrent;
using System.Diagnostics;
using System.Runtime.CompilerServices;
using Google.Protobuf;
using Google.Protobuf.Collections;
Expand Down Expand Up @@ -267,37 +268,12 @@ internal static OtlpMetrics.Metric ToOtlpMetric(this Metric metric)
}
}

var exemplars = metricPoint.GetExemplars();
foreach (var examplar in exemplars)
if (metricPoint.TryGetExemplars(out var exemplars))
{
if (examplar.Timestamp != default)
foreach (ref readonly var exemplar in exemplars)
{
byte[] traceIdBytes = new byte[16];
examplar.TraceId?.CopyTo(traceIdBytes);

byte[] spanIdBytes = new byte[8];
examplar.SpanId?.CopyTo(spanIdBytes);

var otlpExemplar = new OtlpMetrics.Exemplar
{
TimeUnixNano = (ulong)examplar.Timestamp.ToUnixTimeNanoseconds(),
TraceId = UnsafeByteOperations.UnsafeWrap(traceIdBytes),
SpanId = UnsafeByteOperations.UnsafeWrap(spanIdBytes),
AsDouble = examplar.DoubleValue,
};

if (examplar.FilteredTags != null)
{
foreach (var tag in examplar.FilteredTags)
{
if (OtlpKeyValueTransformer.Instance.TryTransformTag(tag, out var result))
{
otlpExemplar.FilteredAttributes.Add(result);
}
}
}

dataPoint.Exemplars.Add(otlpExemplar);
dataPoint.Exemplars.Add(
ToOtlpExemplar(exemplar.DoubleValue, in exemplar));
}
}

Expand Down Expand Up @@ -379,51 +355,48 @@ private static void AddScopeAttributes(IEnumerable<KeyValuePair<string, object>>
}
}

/*
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static OtlpMetrics.Exemplar ToOtlpExemplar(this IExemplar exemplar)
private static OtlpMetrics.Exemplar ToOtlpExemplar<T>(T value, in Metrics.Exemplar exemplar)
where T : struct
{
var otlpExemplar = new OtlpMetrics.Exemplar();
if (exemplar.Value is double doubleValue)
var otlpExemplar = new OtlpMetrics.Exemplar
{
otlpExemplar.AsDouble = doubleValue;
}
else if (exemplar.Value is long longValue)
TimeUnixNano = (ulong)exemplar.Timestamp.ToUnixTimeNanoseconds(),
};

if (exemplar.TraceId != default)
{
otlpExemplar.AsInt = longValue;
byte[] traceIdBytes = new byte[16];
exemplar.TraceId.CopyTo(traceIdBytes);

byte[] spanIdBytes = new byte[8];
exemplar.SpanId.CopyTo(spanIdBytes);

otlpExemplar.TraceId = UnsafeByteOperations.UnsafeWrap(traceIdBytes);
otlpExemplar.SpanId = UnsafeByteOperations.UnsafeWrap(spanIdBytes);
}
else

if (typeof(T) == typeof(long))
{
// TODO: Determine how we want to handle exceptions here.
// Do we want to just skip this exemplar and move on?
// Should we skip recording the whole metric?
throw new ArgumentException();
otlpExemplar.AsInt = (long)(object)value;
}
otlpExemplar.TimeUnixNano = (ulong)exemplar.Timestamp.ToUnixTimeNanoseconds();
// TODO: Do the TagEnumerationState thing.
foreach (var tag in exemplar.FilteredTags)
else if (typeof(T) == typeof(double))
{
otlpExemplar.FilteredAttributes.Add(tag.ToOtlpAttribute());
otlpExemplar.AsDouble = (double)(object)value;
}
if (exemplar.TraceId != default)
else
{
byte[] traceIdBytes = new byte[16];
exemplar.TraceId.CopyTo(traceIdBytes);
otlpExemplar.TraceId = UnsafeByteOperations.UnsafeWrap(traceIdBytes);
Debug.Fail("Unexpected type");
otlpExemplar.AsDouble = Convert.ToDouble(value);
}

if (exemplar.SpanId != default)
foreach (var tag in exemplar.FilteredTags)
{
byte[] spanIdBytes = new byte[8];
exemplar.SpanId.CopyTo(spanIdBytes);
otlpExemplar.SpanId = UnsafeByteOperations.UnsafeWrap(spanIdBytes);
if (OtlpKeyValueTransformer.Instance.TryTransformTag(tag, out var result))
{
otlpExemplar.FilteredAttributes.Add(result);
}
}

return otlpExemplar;
}
*/
}
27 changes: 23 additions & 4 deletions src/OpenTelemetry/.publicApi/Experimental/PublicAPI.Unshipped.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -12,16 +12,36 @@ OpenTelemetry.Metrics.AlwaysOnExemplarFilter.AlwaysOnExemplarFilter() -> void
OpenTelemetry.Metrics.Exemplar
OpenTelemetry.Metrics.Exemplar.DoubleValue.get -> double
OpenTelemetry.Metrics.Exemplar.Exemplar() -> void
OpenTelemetry.Metrics.Exemplar.SpanId.get -> System.Diagnostics.ActivitySpanId?
OpenTelemetry.Metrics.Exemplar.FilteredTags.get -> OpenTelemetry.ReadOnlyFilteredTagCollection
OpenTelemetry.Metrics.Exemplar.LongValue.get -> long
OpenTelemetry.Metrics.Exemplar.SpanId.get -> System.Diagnostics.ActivitySpanId
OpenTelemetry.Metrics.Exemplar.Timestamp.get -> System.DateTimeOffset
OpenTelemetry.Metrics.Exemplar.TraceId.get -> System.Diagnostics.ActivityTraceId?
OpenTelemetry.Metrics.Exemplar.TraceId.get -> System.Diagnostics.ActivityTraceId
OpenTelemetry.Metrics.ExemplarFilter
OpenTelemetry.Metrics.ExemplarFilter.ExemplarFilter() -> void
OpenTelemetry.Metrics.MetricPoint.GetExemplars() -> OpenTelemetry.Metrics.Exemplar[]!
OpenTelemetry.Metrics.ExemplarMeasurement<T>
OpenTelemetry.Metrics.ExemplarMeasurement<T>.ExemplarMeasurement() -> void
OpenTelemetry.Metrics.ExemplarMeasurement<T>.Tags.get -> System.ReadOnlySpan<System.Collections.Generic.KeyValuePair<string!, object?>>
OpenTelemetry.Metrics.ExemplarMeasurement<T>.Value.get -> T
OpenTelemetry.Metrics.MetricPoint.TryGetExemplars(out OpenTelemetry.Metrics.ReadOnlyExemplarCollection? exemplars) -> bool
OpenTelemetry.Metrics.MetricStreamConfiguration.CardinalityLimit.get -> int?
OpenTelemetry.Metrics.MetricStreamConfiguration.CardinalityLimit.set -> void
OpenTelemetry.Metrics.ReadOnlyExemplarCollection
OpenTelemetry.Metrics.ReadOnlyExemplarCollection.Enumerator
OpenTelemetry.Metrics.ReadOnlyExemplarCollection.Enumerator.Current.get -> OpenTelemetry.Metrics.Exemplar
OpenTelemetry.Metrics.ReadOnlyExemplarCollection.Enumerator.Enumerator() -> void
OpenTelemetry.Metrics.ReadOnlyExemplarCollection.Enumerator.MoveNext() -> bool
OpenTelemetry.Metrics.ReadOnlyExemplarCollection.GetEnumerator() -> OpenTelemetry.Metrics.ReadOnlyExemplarCollection.Enumerator
OpenTelemetry.Metrics.ReadOnlyExemplarCollection.ReadOnlyExemplarCollection() -> void
OpenTelemetry.Metrics.TraceBasedExemplarFilter
OpenTelemetry.Metrics.TraceBasedExemplarFilter.TraceBasedExemplarFilter() -> void
OpenTelemetry.ReadOnlyFilteredTagCollection
OpenTelemetry.ReadOnlyFilteredTagCollection.Enumerator
OpenTelemetry.ReadOnlyFilteredTagCollection.Enumerator.Current.get -> System.Collections.Generic.KeyValuePair<string!, object?>
OpenTelemetry.ReadOnlyFilteredTagCollection.Enumerator.Enumerator() -> void
OpenTelemetry.ReadOnlyFilteredTagCollection.Enumerator.MoveNext() -> bool
OpenTelemetry.ReadOnlyFilteredTagCollection.GetEnumerator() -> OpenTelemetry.ReadOnlyFilteredTagCollection.Enumerator
OpenTelemetry.ReadOnlyFilteredTagCollection.ReadOnlyFilteredTagCollection() -> void
static OpenTelemetry.Logs.LoggerProviderBuilderExtensions.AddProcessor(this OpenTelemetry.Logs.LoggerProviderBuilder! loggerProviderBuilder, OpenTelemetry.BaseProcessor<OpenTelemetry.Logs.LogRecord!>! processor) -> OpenTelemetry.Logs.LoggerProviderBuilder!
static OpenTelemetry.Logs.LoggerProviderBuilderExtensions.AddProcessor(this OpenTelemetry.Logs.LoggerProviderBuilder! loggerProviderBuilder, System.Func<System.IServiceProvider!, OpenTelemetry.BaseProcessor<OpenTelemetry.Logs.LogRecord!>!>! implementationFactory) -> OpenTelemetry.Logs.LoggerProviderBuilder!
static OpenTelemetry.Logs.LoggerProviderBuilderExtensions.AddProcessor<T>(this OpenTelemetry.Logs.LoggerProviderBuilder! loggerProviderBuilder) -> OpenTelemetry.Logs.LoggerProviderBuilder!
Expand All @@ -38,7 +58,6 @@ static OpenTelemetry.OpenTelemetryBuilderSdkExtensions.WithLogging(this OpenTele
static OpenTelemetry.Sdk.CreateLoggerProviderBuilder() -> OpenTelemetry.Logs.LoggerProviderBuilder!
abstract OpenTelemetry.Metrics.ExemplarFilter.ShouldSample(double value, System.ReadOnlySpan<System.Collections.Generic.KeyValuePair<string!, object?>> tags) -> bool
abstract OpenTelemetry.Metrics.ExemplarFilter.ShouldSample(long value, System.ReadOnlySpan<System.Collections.Generic.KeyValuePair<string!, object?>> tags) -> bool
OpenTelemetry.Metrics.Exemplar.FilteredTags.get -> System.Collections.Generic.List<System.Collections.Generic.KeyValuePair<string!, object?>>?
override OpenTelemetry.Metrics.AlwaysOffExemplarFilter.ShouldSample(double value, System.ReadOnlySpan<System.Collections.Generic.KeyValuePair<string!, object?>> tags) -> bool
override OpenTelemetry.Metrics.AlwaysOffExemplarFilter.ShouldSample(long value, System.ReadOnlySpan<System.Collections.Generic.KeyValuePair<string!, object?>> tags) -> bool
override OpenTelemetry.Metrics.AlwaysOnExemplarFilter.ShouldSample(double value, System.ReadOnlySpan<System.Collections.Generic.KeyValuePair<string!, object?>> tags) -> bool
Expand Down
8 changes: 8 additions & 0 deletions src/OpenTelemetry/CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,14 @@
[IMetricsListener](https://learn.microsoft.com/dotNet/api/microsoft.extensions.diagnostics.metrics.imetricslistener).
([#5265](https://github.com/open-telemetry/opentelemetry-dotnet/pull/5265))

* **Experimental (pre-release builds only):** The `Exemplar.FilteredTags`
property now returns a `ReadOnlyFilteredTagCollection` instance and the
`Exemplar.LongValue` property has been added. The `MetricPoint.GetExemplars`
method has been replaced by `MetricPoint.TryGetExemplars` which outputs a
`ReadOnlyExemplarCollection` instance. These are **breaking changes** for
metrics exporters which support exemplars.
([#5386](https://github.com/open-telemetry/opentelemetry-dotnet/pull/5386))

## 1.7.0

Released 2023-Dec-08
Expand Down
8 changes: 4 additions & 4 deletions src/OpenTelemetry/Metrics/AggregatorStore.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ namespace OpenTelemetry.Metrics;

internal sealed class AggregatorStore
{
internal readonly HashSet<string>? TagKeysInteresting;
internal readonly bool OutputDelta;
internal readonly bool OutputDeltaWithUnusedMetricPointReclaimEnabled;
internal readonly int CardinalityLimit;
Expand All @@ -24,7 +25,6 @@ internal sealed class AggregatorStore

private readonly object lockZeroTags = new();
private readonly object lockOverflowTag = new();
private readonly HashSet<string>? tagKeysInteresting;
private readonly int tagsKeysInterestingCount;

// This holds the reclaimed MetricPoints that are available for reuse.
Expand Down Expand Up @@ -84,7 +84,7 @@ internal AggregatorStore(
this.updateLongCallback = this.UpdateLongCustomTags;
this.updateDoubleCallback = this.UpdateDoubleCustomTags;
var hs = new HashSet<string>(metricStreamIdentity.TagKeys, StringComparer.Ordinal);
this.tagKeysInteresting = hs;
this.TagKeysInteresting = hs;
this.tagsKeysInterestingCount = hs.Count;
}

Expand Down Expand Up @@ -1122,9 +1122,9 @@ private int FindMetricAggregatorsCustomTag(ReadOnlySpan<KeyValuePair<string, obj

var storage = ThreadStaticStorage.GetStorage();

Debug.Assert(this.tagKeysInteresting != null, "this.tagKeysInteresting was null");
Debug.Assert(this.TagKeysInteresting != null, "this.tagKeysInteresting was null");

storage.SplitToKeysAndValues(tags, tagLength, this.tagKeysInteresting!, out var tagKeysAndValues, out var actualLength);
storage.SplitToKeysAndValues(tags, tagLength, this.TagKeysInteresting!, out var tagKeysAndValues, out var actualLength);

// Actual number of tags depend on how many
// of the incoming tags has user opted to
Expand Down
88 changes: 10 additions & 78 deletions src/OpenTelemetry/Metrics/Exemplar/AlignedHistogramBucketExemplarReservoir.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,92 +8,24 @@ namespace OpenTelemetry.Metrics;
/// <summary>
/// The AlignedHistogramBucketExemplarReservoir implementation.
/// </summary>
internal sealed class AlignedHistogramBucketExemplarReservoir : ExemplarReservoir
internal sealed class AlignedHistogramBucketExemplarReservoir : FixedSizeExemplarReservoir
{
private readonly Exemplar[] runningExemplars;
private readonly Exemplar[] tempExemplars;

public AlignedHistogramBucketExemplarReservoir(int length)
{
this.runningExemplars = new Exemplar[length + 1];
this.tempExemplars = new Exemplar[length + 1];
}

public override void Offer(long value, ReadOnlySpan<KeyValuePair<string, object?>> tags, int index = default)
public AlignedHistogramBucketExemplarReservoir(int numberOfBuckets)
: base(numberOfBuckets + 1)
{
this.OfferAtBoundary(value, tags, index);
}

public override void Offer(double value, ReadOnlySpan<KeyValuePair<string, object?>> tags, int index = default)
public override void Offer(in ExemplarMeasurement<long> measurement)
{
this.OfferAtBoundary(value, tags, index);
Debug.Fail("AlignedHistogramBucketExemplarReservoir shouldn't be used with long values");
}

public override Exemplar[] Collect(ReadOnlyTagCollection actualTags, bool reset)
public override void Offer(in ExemplarMeasurement<double> measurement)
{
for (int i = 0; i < this.runningExemplars.Length; i++)
{
this.tempExemplars[i] = this.runningExemplars[i];
if (this.runningExemplars[i].FilteredTags != null)
{
// TODO: Better data structure to avoid this Linq.
// This is doing filtered = alltags - storedtags.
// TODO: At this stage, this logic is done inside Reservoir.
// Kinda hard for end users who write own reservoirs.
// Evaluate if this logic can be moved elsewhere.
// TODO: The cost is paid irrespective of whether the
// Exporter supports Exemplar or not. One idea is to
// defer this until first exporter attempts read.
this.tempExemplars[i].FilteredTags = this.runningExemplars[i].FilteredTags!.Except(actualTags.KeyAndValues.ToList()).ToList();
}

if (reset)
{
this.runningExemplars[i].Timestamp = default;
}
}

return this.tempExemplars;
}

private void OfferAtBoundary(double value, ReadOnlySpan<KeyValuePair<string, object?>> tags, int index)
{
ref var exemplar = ref this.runningExemplars[index];
exemplar.Timestamp = DateTimeOffset.UtcNow;
exemplar.DoubleValue = value;
exemplar.TraceId = Activity.Current?.TraceId;
exemplar.SpanId = Activity.Current?.SpanId;

if (tags == default)
{
// default tag is used to indicate
// the special case where all tags provided at measurement
// recording time are stored.
// In this case, Exemplars does not have to store any tags.
// In other words, FilteredTags will be empty.
return;
}

if (exemplar.FilteredTags == null)
{
exemplar.FilteredTags = new List<KeyValuePair<string, object?>>(tags.Length);
}
else
{
// Keep the list, but clear contents.
exemplar.FilteredTags.Clear();
}
Debug.Assert(
measurement.ExplicitBucketHistogramBucketIndex != -1,
"ExplicitBucketHistogramBucketIndex was -1");

// Though only those tags that are filtered need to be
// stored, finding filtered list from the full tag list
// is expensive. So all the tags are stored in hot path (this).
// During snapshot, the filtered list is calculated.
// TODO: Evaluate alternative approaches based on perf.
// TODO: This is not user friendly to Reservoir authors
// and must be handled as transparently as feasible.
foreach (var tag in tags)
{
exemplar.FilteredTags.Add(tag);
}
this.UpdateExemplar(measurement.ExplicitBucketHistogramBucketIndex, in measurement);
}
}
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