Tag consumer spans with the pathway hash on every data streams checkpoint

[ericfirth]

What

Set the pathway.hash span tag inside DefaultDataStreamsMonitoring.setCheckpoint(span, context) so it is applied on every checkpoint that has a span — consume side included — not only on produce/inject.

Why

Today pathway.hash is written in exactly one place: DataStreamsPropagator.inject(...), which only runs on the produce/inject path. Consumers that checkpoint without injecting downstream context — e.g. RabbitMQ's basicGet/basicConsume, which call getDataStreamsMonitoring().setCheckpoint(span, ...) — compute and emit the pathway hash but never tag their span with it. So consumer spans are missing pathway.hash and can't be correlated back to the pathway.

Some consumers (e.g. SQS) happen to get the tag only because their integration also calls dsmPropagator.inject(...) during receive — an integration-specific side effect, not a guarantee.

The JS (processor.js → recordCheckpoint) and Python (processor.py → set_checkpoint) tracers already set the tag in their central checkpoint method, so it lands on both produce and consume. This change brings Java to parity by doing the same in the core setCheckpoint.

Change

After pathwayContext.setCheckpoint(...), tag the span with pathway.hash when the hash is non-zero. The produce path is unchanged (the propagator still tags on inject; the value is identical, so this is idempotent for producers that also flow through setCheckpoint).

Tests

Added three unit tests in DefaultDataStreamsMonitoringTest:

• tags the span with the unsigned pathway hash when the hash is non-zero,
• does not tag when the hash is zero,
• does not tag when there is no pathway context.

./gradlew :dd-trace-core:test --tests "datadog.trace.core.datastreams.DefaultDataStreamsMonitoringTest" → 36 tests, 0 failures.

Context

Found while working on RabbitMQ DSM (the consumer span had no pathway.hash while the producer did). Independent of, and complementary to, the RabbitMQ default-exchange topic fix (#11805).

[Copilot]

Pull request overview

This PR updates the Java Data Streams Monitoring (DSM) core checkpointing path so spans are tagged with pathway.hash on every DSM checkpoint that has an associated span (including consumer-side checkpoints), aligning behavior with other tracers and improving pathway/span correlation.

Changes:

• Tag spans with pathway.hash inside DefaultDataStreamsMonitoring.setCheckpoint(span, context) when a non-zero pathway hash is available.
• Add unit tests to validate tagging behavior (non-zero hash, zero hash, and missing pathway context).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
dd-trace-core/src/main/java/datadog/trace/core/datastreams/DefaultDataStreamsMonitoring.java	Tags spans with pathway.hash after PathwayContext.setCheckpoint(...) when hash is non-zero.
dd-trace-core/src/test/java/datadog/trace/core/datastreams/DefaultDataStreamsMonitoringTest.java	Adds unit tests covering new span-tagging behavior for setCheckpoint.

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[datadog-datadog-prod-us1-2]

🎯 Code Coverage (details)
• Patch Coverage: 0.00%
• Overall Coverage: 56.65% (-0.40%)

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[dd-octo-sts]

🟢 Java Benchmark SLOs — All performance SLOs passed

Suite	Status
Startup	🟢 pass

SLO thresholds are defined here based on automatically generated metrics. A warning is raised when results are within 5% of the threshold.

PR vs. master results

Scenario	Candidate	master	Δ (95% CI of mean)
startup:insecure-bank:iast:Agent	13.92 s	13.97 s	[-1.1%; +0.4%] (no difference)
startup:insecure-bank:tracing:Agent	13.00 s	13.06 s	[-1.5%; +0.7%] (no difference)
startup:petclinic:appsec:Agent	16.78 s	16.77 s	[-0.9%; +1.0%] (no difference)
startup:petclinic:iast:Agent	16.77 s	16.88 s	[-1.3%; -0.0%] (maybe better)
startup:petclinic:profiling:Agent	16.58 s	16.71 s	[-1.7%; +0.1%] (no difference)
startup:petclinic:sca:Agent	16.17 s	16.75 s	[-7.8%; +0.8%] (no difference)
startup:petclinic:tracing:Agent	16.06 s	16.14 s	[-1.3%; +0.3%] (no difference)

Commit: 945d3d83 · CI Pipeline · Benchmarking Platform UI

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[ericfirth]

/merge

[gh-worker-devflow-routing-ef8351]

View all feedbacks in Devflow UI.

2026-07-14 12:21:34 UTC ℹ️ Start processing command /merge

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2026-07-14 12:21:39 UTC ℹ️ MergeQueue: pull request added to the queue

The expected merge time in master is approximately 2h (p90).

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2026-07-14 13:23:13 UTC ℹ️ MergeQueue: This merge request was merged