WIP: Baggage Span Tags

[rachelyangdog]

Summary of changes

Reason for change

Implementation details

Test coverage

Other details

[rachelyangdog]

try not to do any heap allocations (don't do Split) --> go around this

[lucaspimentel]

If we change settings.BaggageTagKeys to a string[] and do the split when we read the config (see my other comment in TracerSettings.cs), then we don't need to split here anymore.

You can remove this line and change the foreach below to something like:

foreach (var key in baggageTagKeys)

[datadog-datadog-prod-us1]

Datadog Report

Branch report: rachel.yang/baggage-span-tags
Commit report: 9216bc7
Test service: dd-trace-dotnet

✅ 0 Failed, 53 Passed, 0 Skipped, 32m 26.97s Total Time

[lucaspimentel]

You'll want to do this for other web server spans as well.

[lucaspimentel]

Try making BaggageTagKeys a string[] and splitting here so we only do it once and not when we try to apply this setting in each incoming http request. See disabledIntegrationNames around line 331 above as an example. Probably just need to add Split(), like:

Suggested change

	BaggageTagKeys = config
	.WithKeys(ConfigurationKeys.BaggageTagKeys)
	.AsString(defaultValue: "user.id,session.id,account.id");
	BaggageTagKeys = config
	.WithKeys(ConfigurationKeys.BaggageTagKeys)
	.AsString(defaultValue: "user.id,session.id,account.id")
	.Split([','], StringSplitOptions.RemoveEmptyEntries);

You'll have to change the property in line 1067 below, too:

- internal string BaggageTagKeys { get; }
+ internal string[] BaggageTagKeys { get; }