feat(datastreams): add span tagging and custom timestamp to TrackDataStreamsTransaction by ericfirth · Pull Request #4499 · DataDog/dd-trace-go

ericfirth · 2026-03-04T19:11:08Z

Why

The first implementation of TrackDataStreamsTransaction recorded transaction checkpoints in the DSM processor but did nothing to tie them back to the active trace. Both dd-trace-js and dd-trace-java tag the active span with dsm.transaction.id and dsm.transaction.checkpoint whenever a transaction is tracked — this correlation is what allows the Datadog UI to link a specific transaction to the trace that processed it.

Additionally, callers sometimes know the relevant timestamp in advance (e.g. they are gathering data from an external source and want to checkpoint their pipeline with when the data came from). The processor already supports arbitrary timestamps internally, but there was no way to supply one from the public API, so every observation was silently stamped with time.Now().

What

Span tagging — TrackDataStreamsTransaction now accepts ctx context.Context as its first argument. If the context carries an active span, it is tagged with dsm.transaction.id and dsm.transaction.checkpoint, matching the tag names used by dd-trace-java exactly. Passing context.Background() skips tagging with no overhead.
Custom timestamp — New TrackDataStreamsTransactionAt(ctx, transactionID, checkpointName, t) lets callers supply the observation time. The processor buckets it into the correct 10-second window just like any other point. Useful when replaying or processing messages that carry their own timestamps.
ext constants — ext.DSMTransactionID and ext.DSMTransactionCheckpoint are exported so integrations can reference the tag names without hardcoding strings.

Breaking change

TrackDataStreamsTransaction gains a leading context.Context parameter. The only known caller is on a branch; the update is straightforward — pass the context that was already in scope, or context.Background().

Test plan

TestTrackDataStreamsTransactionTagsSpan — span in context receives both DSM tags
TestTrackDataStreamsTransactionNoSpanInContextNoops — context with no span does not panic
TestTrackDataStreamsTransactionAtDelegatesToProcessor — ...At variant reaches the processor
TestTrackDataStreamsTransactionAtTagsSpan — ...At variant also tags the span
TestTrackTransactionAtUsesProvidedTime — processor stores caller-supplied timestamp, not time.Now()
go build ./... — clean build

🤖 Generated with Claude Code

…on tracking - Add DSMTransactionID and DSMTransactionCheckpoint tag constants to ext/tags.go - Add ctx parameter to TrackDataStreamsTransaction (breaking change) to tag the active span with dsm.transaction.id and dsm.transaction.checkpoint - Add TrackDataStreamsTransactionAt for caller-supplied timestamps - Add Processor.TrackTransactionAt backed by a shared trackTransactionAt helper - Update api.txt and expand test coverage for all new behaviors Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

codecov · 2026-03-04T19:49:00Z

Codecov Report

❌ Patch coverage is 89.47368% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 60.02%. Comparing base (aa5518d) to head (58d93b0).

Files with missing lines	Patch %	Lines
ddtrace/tracer/data_streams.go	84.61%	1 Missing and 1 partial ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
internal/datastreams/processor.go	`60.28% <100.00%> (ø)`
ddtrace/tracer/data_streams.go	`37.14% <84.61%> (ø)`

... and 432 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

pr-commenter · 2026-03-04T20:07:12Z

Benchmarks

Benchmark execution time: 2026-03-12 14:55:54

Comparing candidate commit 58d93b0 in PR branch eric.firth/transaction-tracking-second-part with baseline commit aa5518d in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 155 metrics, 9 unstable metrics.

Explanation

This is an A/B test comparing a candidate commit's performance against that of a baseline commit. Performance changes are noted in the tables below as:

🟩 = significantly better candidate vs. baseline
🟥 = significantly worse candidate vs. baseline

We compute a confidence interval (CI) over the relative difference of means between metrics from the candidate and baseline commits, considering the baseline as the reference.

If the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD), the change is considered significant.

Feel free to reach out to #apm-benchmarking-platform on Slack if you have any questions.

More details about the CI and significant changes

You can imagine this CI as a range of values that is likely to contain the true difference of means between the candidate and baseline commits.

CIs of the difference of means are often centered around 0%, because often changes are not that big:

---------------------------------(------|---^--------)-------------------------------->
                              -0.6%    0%  0.3%     +1.2%
                                 |          |        |
         lower bound of the CI --'          |        |
sample mean (center of the CI) -------------'        |
         upper bound of the CI ----------------------'

As described above, a change is considered significant if the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD).

For instance, for an execution time metric, this confidence interval indicates a significantly worse performance:

----------------------------------------|---------|---(---------^---------)---------->
                                       0%        1%  1.3%      2.2%      3.1%
                                                  |   |         |         |
       significant impact threshold --------------'   |         |         |
                      lower bound of CI --------------'         |         |
       sample mean (center of the CI) --------------------------'         |
                      upper bound of CI ----------------------------------'

datadog-datadog-prod-us1 · 2026-03-05T15:38:31Z

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 84.62%
• Overall Coverage: 59.24%

_{This comment will be updated automatically if new data arrives.

🔗 Commit SHA: 58d93b0 | Docs | Datadog PR Page | Was this helpful? React with 👍/👎 or give us feedback!}

darccio · 2026-03-06T15:13:40Z

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mtoffl01

Marking this as "request changes" until a clear decision has been made on whether to always add this metadata on spans or to do so only when DSM is enabled.

…egate to At variant Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

ericfirth requested review from a team as code owners March 4, 2026 19:11

fix(ddtrace/tracer): regenerate api.txt with official extractor

b6a3808

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

kakkoyun reviewed Mar 5, 2026

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Comment thread ddtrace/tracer/api.txt

Merge branch 'main' into eric.firth/transaction-tracking-second-part

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Merge branch 'main' into eric.firth/transaction-tracking-second-part

5cb113c

chatgpt-codex-connector Bot reviewed Mar 6, 2026

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Comment thread ddtrace/tracer/data_streams.go Outdated

Comment thread ddtrace/tracer/data_streams.go

mtoffl01 requested changes Mar 6, 2026

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Comment thread ddtrace/tracer/data_streams.go

Comment thread ddtrace/tracer/data_streams.go Outdated

refactor(ddtrace/tracer): simplify TrackDataStreamsTransaction to del…

1462c6a

…egate to At variant Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

ericfirth requested a review from mtoffl01 March 9, 2026 14:21

Merge branch 'main' into eric.firth/transaction-tracking-second-part

4b37c67

ericfirth requested a review from kakkoyun March 11, 2026 18:45

mtoffl01 approved these changes Mar 11, 2026

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kakkoyun approved these changes Mar 12, 2026

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kr-igor approved these changes Mar 12, 2026

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gh-worker-dd-devflow-36fce6 Bot added mergequeue-status: queued mergequeue-status: in_progress mergequeue-status: rejected and removed mergequeue-status: queued mergequeue-status: in_progress labels Mar 12, 2026

Merge branch 'main' into eric.firth/transaction-tracking-second-part

58d93b0

gh-worker-dd-devflow-36fce6 Bot added mergequeue-status: waiting mergequeue-status: queued and removed mergequeue-status: rejected mergequeue-status: waiting labels Mar 12, 2026

gh-worker-dd-devflow-36fce6 Bot added mergequeue-status: in_progress and removed mergequeue-status: queued labels Mar 12, 2026

gh-worker-dd-mergequeue-cf854d Bot merged commit cb2ef86 into main Mar 12, 2026
207 checks passed

gh-worker-dd-mergequeue-cf854d Bot deleted the eric.firth/transaction-tracking-second-part branch March 12, 2026 15:11

gh-worker-dd-devflow-36fce6 Bot added mergequeue-status: done and removed mergequeue-status: in_progress labels Mar 12, 2026

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feat(datastreams): add span tagging and custom timestamp to TrackDataStreamsTransaction#4499

feat(datastreams): add span tagging and custom timestamp to TrackDataStreamsTransaction#4499
gh-worker-dd-mergequeue-cf854d[bot] merged 7 commits into
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