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Avoid allocations propagating Activity baggage #132368

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Avoid allocations propagating Activity baggage #132368

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56 changes: 55 additions & 1 deletion src/libraries/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Activity.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -427,13 +427,19 @@ public IEnumerable<ActivityLink> Links
/// <returns><see cref="Enumerator{T}"/>.</returns>
public Enumerator<ActivityLink> EnumerateLinks() => new Enumerator<ActivityLink>(_links?.First);

/// <summary>
/// Enumerate the baggage attached to this Activity object and its ancestors without allocating.
/// </summary>
/// <returns><see cref="BaggageEnumerator"/>.</returns>
internal BaggageEnumerator EnumerateBaggage() => new BaggageEnumerator(this);

/// <summary>
/// Returns the value of the key-value pair added to the activity with <see cref="AddBaggage(string, string)"/>.
/// Returns null if that key does not exist.
/// </summary>
public string? GetBaggageItem(string key)
{
foreach (KeyValuePair<string, string?> keyValue in Baggage)
foreach (KeyValuePair<string, string?> keyValue in EnumerateBaggage())
if (key == keyValue.Key)
return keyValue.Value;
return null;
Expand Down Expand Up @@ -1600,6 +1606,54 @@ public bool MoveNext()
}
}

/// <summary>
/// Enumerates the baggage stored on this Activity and its ancestors without allocating.
/// Mirrors the semantics of the <see cref="Baggage"/> property, which uses an iterator
/// (allocating a state machine on every call) to walk the same data.
/// </summary>
internal struct BaggageEnumerator
{
// The next Activity (if any) to search for a non-empty baggage list. Always points at an
// Activity whose own baggage list has not yet been consumed by this enumerator.
private Activity? _activity;

// The remaining nodes of the baggage list currently being drained.
private DiagNode<KeyValuePair<string, string?>>? _next;

internal BaggageEnumerator(Activity? activity)
{
_activity = activity;
_next = null;
Current = default;
}

public KeyValuePair<string, string?> Current { get; private set; }

public readonly BaggageEnumerator GetEnumerator() => this;
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public bool MoveNext()
{
while (_next is null)
{
if (_activity is null)
{
return false;
}

BaggageLinkedList? baggage = _activity._baggage;
_activity = _activity.Parent;
if (baggage != null)
{
_next = baggage.First;
}
}

Current = _next.Value;
_next = _next.Next;
return true;
}
}

private sealed class BaggageLinkedList : IEnumerable<KeyValuePair<string, string?>>
{
private DiagNode<KeyValuePair<string, string?>>? _first;
Expand Down
27 changes: 15 additions & 12 deletions ...ystem.Diagnostics.DiagnosticSource/src/System/Diagnostics/DistributedContextPropagator.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -122,22 +122,25 @@ public static DistributedContextPropagator Current

// internal stuff

internal static void InjectBaggage(object? carrier, IEnumerable<KeyValuePair<string, string?>> baggage, PropagatorSetterCallback setter)
internal static void InjectBaggage(object? carrier, Activity? activity, PropagatorSetterCallback setter)
{
using (IEnumerator<KeyValuePair<string, string?>> e = baggage.GetEnumerator())
if (activity is null)
{
if (e.MoveNext())
{
StringBuilder baggageList = new StringBuilder();
return;
}

do
{
KeyValuePair<string, string?> item = e.Current;
baggageList.Append(WebUtility.UrlEncode(item.Key)).Append('=').Append(WebUtility.UrlEncode(item.Value)).Append(CommaWithSpace);
} while (e.MoveNext());
Activity.BaggageEnumerator e = activity.EnumerateBaggage();
if (e.MoveNext())
{
StringBuilder baggageList = new StringBuilder();

do
{
KeyValuePair<string, string?> item = e.Current;
baggageList.Append(WebUtility.UrlEncode(item.Key)).Append('=').Append(WebUtility.UrlEncode(item.Value)).Append(CommaWithSpace);
} while (e.MoveNext());

setter(carrier, CorrelationContext, baggageList.ToString(0, baggageList.Length - 2));
}
setter(carrier, CorrelationContext, baggageList.ToString(0, baggageList.Length - 2));
}
}

Expand Down
2 changes: 1 addition & 1 deletion src/libraries/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/LegacyPropagator.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -39,7 +39,7 @@ public override void Inject(Activity? activity, object? carrier, PropagatorSette
setter(carrier, RequestId, id);
}

InjectBaggage(carrier, activity.Baggage, setter);
InjectBaggage(carrier, activity, setter);
}

public override void ExtractTraceIdAndState(object? carrier, PropagatorGetterCallback? getter, out string? traceId, out string? traceState)
Expand Down
11 changes: 4 additions & 7 deletions ...aries/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/PassThroughPropagator.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@ public override void Inject(Activity? activity, object? carrier, PropagatorSette
return;
}

GetRootId(out string? parentId, out string? traceState, out bool isW3c, out IEnumerable<KeyValuePair<string, string?>>? baggage);
GetRootId(out string? parentId, out string? traceState, out bool isW3c, out Activity? rootActivity);
if (parentId is null)
{
return;
Expand All @@ -31,17 +31,14 @@ public override void Inject(Activity? activity, object? carrier, PropagatorSette
setter(carrier, TraceState, traceState);
}

if (baggage is not null)
{
InjectBaggage(carrier, baggage, setter);
}
InjectBaggage(carrier, rootActivity, setter);
}

public override void ExtractTraceIdAndState(object? carrier, PropagatorGetterCallback? getter, out string? traceId, out string? traceState) => LegacyPropagator.Instance.ExtractTraceIdAndState(carrier, getter, out traceId, out traceState);

public override IEnumerable<KeyValuePair<string, string?>>? ExtractBaggage(object? carrier, PropagatorGetterCallback? getter) => LegacyPropagator.Instance.ExtractBaggage(carrier, getter);

private static void GetRootId(out string? parentId, out string? traceState, out bool isW3c, out IEnumerable<KeyValuePair<string, string?>>? baggage)
private static void GetRootId(out string? parentId, out string? traceState, out bool isW3c, out Activity? rootActivity)
{
Activity? activity = Activity.Current;

Expand All @@ -53,7 +50,7 @@ private static void GetRootId(out string? parentId, out string? traceState, out
traceState = activity?.TraceStateString;
parentId = activity?.ParentId ?? activity?.Id;
isW3c = parentId is not null ? Activity.TryConvertIdToContext(parentId, traceState, isRemote: false, out _) : false;
baggage = activity?.Baggage;
rootActivity = activity;
}
}
}
62 changes: 30 additions & 32 deletions src/libraries/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/W3CPropagator.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -49,7 +49,7 @@ public override void Inject(Activity? activity, object? carrier, PropagatorSette
InjectTraceState(traceState, carrier, setter);
}

InjectW3CBaggage(carrier, activity.Baggage, setter);
InjectW3CBaggage(carrier, activity, setter);
}

public override void ExtractTraceIdAndState(object? carrier, PropagatorGetterCallback? getter, out string? traceId, out string? traceState)
Expand Down Expand Up @@ -234,48 +234,46 @@ internal static void InjectTraceState(string traceState, object? carrier, Propag
}
}

internal static void InjectW3CBaggage(object? carrier, IEnumerable<KeyValuePair<string, string?>> baggage, PropagatorSetterCallback setter)
internal static void InjectW3CBaggage(object? carrier, Activity activity, PropagatorSetterCallback setter)
{
using (IEnumerator<KeyValuePair<string, string?>> e = baggage.GetEnumerator())
Activity.BaggageEnumerator e = activity.EnumerateBaggage();
if (e.MoveNext())
{
if (e.MoveNext())
{
ValueStringBuilder encodedBaggage = new ValueStringBuilder(stackalloc char[256]);
ValueStringBuilder encodedBaggage = new ValueStringBuilder(stackalloc char[256]);

int entriesCount = 0;
int lastGoodLength = 0;
int entriesCount = 0;
int lastGoodLength = 0;

do
{
KeyValuePair<string, string?> item = e.Current;
do
{
KeyValuePair<string, string?> item = e.Current;

if (EncodeBaggageKey(item.Key, ref encodedBaggage))
if (EncodeBaggageKey(item.Key, ref encodedBaggage))
{
encodedBaggage.Append(Space);
encodedBaggage.Append(Equal);
encodedBaggage.Append(Space);
if (!string.IsNullOrEmpty(item.Value))
{
encodedBaggage.Append(Space);
encodedBaggage.Append(Equal);
encodedBaggage.Append(Space);
if (!string.IsNullOrEmpty(item.Value))
{
EncodeBaggageValue(item.Value, ref encodedBaggage);
}
encodedBaggage.Append(CommaWithSpace);

entriesCount++;

if (encodedBaggage.Length < MaxBaggageEncodedLength)
{
lastGoodLength = encodedBaggage.Length;
}
EncodeBaggageValue(item.Value, ref encodedBaggage);
}
} while (e.MoveNext() && entriesCount < MaxBaggageEntriesToEmit && encodedBaggage.Length < MaxBaggageEncodedLength);
encodedBaggage.Append(CommaWithSpace);

if (lastGoodLength - 2 > 0)
{
setter(carrier, Baggage, encodedBaggage.AsSpan(0, lastGoodLength - 2).ToString());
entriesCount++;

if (encodedBaggage.Length < MaxBaggageEncodedLength)
{
lastGoodLength = encodedBaggage.Length;
}
}
} while (e.MoveNext() && entriesCount < MaxBaggageEntriesToEmit && encodedBaggage.Length < MaxBaggageEncodedLength);

encodedBaggage.Dispose();
if (lastGoodLength - 2 > 0)
{
setter(carrier, Baggage, encodedBaggage.AsSpan(0, lastGoodLength - 2).ToString());
}

encodedBaggage.Dispose();
}
}

Expand Down
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