Apply SpanPrototype in decorator afterStart (phase 1b) by dougqh · Pull Request #12037 · DataDog/dd-trace-java

dougqh · 2026-07-22T15:43:20Z

What Does This Do

Wires the SpanPrototype from #11894 into the decorator base classes, and modernizes the affected tests.

Production — BaseDecorator / ServerDecorator / ClientDecorator now build a lazily-cached SpanPrototype whose extension chain mirrors the decorator hierarchy (super.buildSpanPrototype() → .extends_(...) → add this level's constants). afterStart applies it via span.setSpanType / span.setAllTags(prototype.tags()) / spanContext().setIntegrationName(...), replacing the previous N separate span.setTag(TagMap.Entry) calls.

This is behavior-identical: setAllTags runs the same constant tags through the same tag-interceptor path the per-tag calls used today; it's a consolidation, not a new code path. Bulk-share (skipping per-tag interception) is deliberately deferred to the dense-store / tag-registry work.

Tests — the four afterStart specs move off Spock mock-interaction assertions to a state-based harness:

RecordingSpan / RecordingSpanContext accumulate the applied state (extends the no-op ImmutableSpan, so only the ~7 mutators afterStart touches are overridden).
ExpectedSpanState builds the expected state per level and asserts it in one shot, with three leniency modes (identity / exact / allow-extra-tags) matching Spock's polymorphic feature-method inheritance down the decorator hierarchy.

Other specs (onPeerConnection / onConnection / onStatement / beforeFinish) are unchanged and still use mocks.

Motivation

Replace BaseDecorator.afterStart's per-tag setTag stamping with a single baked-once SpanPrototype applied via a fast bulk copy, and move the afterStart specs off brittle mock-interaction assertions onto a state-based harness that survives the consolidation.

Additional Notes

Stacked on #11894 (dougqh/span-prototype-api). Review/merge that first; this PR's base retargets to master once #11894 lands.

Drops the born-dead SpanPrototype.Builder.initInstrumentationNames(String[]) overload (no caller; initInstrumentationName covers the single-name case) — shows as a 1-line deletion against the #11894 base.

Test plan:

:dd-java-agent:agent-bootstrap:test — green (afterStart specs exercise the new setAllTags path)
:dd-java-agent:agent-bootstrap:spotbugsMain, spotlessJavaCheck — green
techdebt + perf-review over the branch diff — clean (no hot-path regression; afterStart is a consolidation of existing per-tag work)

🤖 Generated with Claude Code

The builder API (extends_/init*) plus its per-mechanism microbenchmark and a pure-API test, split out from the combined span-prototype work so the abstraction lands independently of the decorator demo. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

A prototype constant that is null or an empty CharSequence should be "no tag" -- matching AgentSpan.setTag and the decorators' cached-Entry path -- not a baked empty tag. Add TagMap.Entry.isEmptyValue as the single definition of an empty value (both Entry.create overloads now delegate to it), and gate SpanPrototype.Builder.initTag on it via the plain set(key, value) path so no Entry is allocated (the wrong path once tags are stored densely). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

@nonnull

Thread a SpanPrototype through span construction: AgentTracer gains buildSpan/startSpan(SpanPrototype, operationName) (defaults seed identity only, correct for the noop tracer, with an explicit NoopTracerAPI.startSpan override). CoreTracer overrides buildSpan to seed the prototype's frozen constant tags in buildSpanContext at the precedence slot just before the builder's own tags (prototype and builder form one precedence atom; explicit builder tags win), and overrides startSpan to seed builder-free via the static CoreSpanBuilder.startSpan path (no MultiSpanBuilder allocation, mirroring startSpan(String,...)). Explicit operationName wins; null falls back to the prototype's. Intercepted constants (e.g. span.kind) seed through the interceptor so their context side-effects still fire. Prototype params @nonnull. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

…formly init* BaseDecorator.afterStart sets the integration name as a side effect alongside the component tag (setIntegrationName(component)), which IntegrationAdder later serializes as _dd.integration. A prototype baking only the component tag would drop that. Add initComponentAndIntegration(component): sets the component tag AND records it as the integration name (inherited via extends_), applied via setIntegrationName at construction. Rename the builder setters to a uniform init* surface now that a component sibling exists and to convey "everything here bakes the prototype's initial state": initComponent -> initComponentOnly, instrumentationName -> initInstrumentationName(s), operationName -> initOperationName, spanType -> initSpanType. Accessors are unchanged. Renames are confined to SpanPrototype.Builder and its callers. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

A dd-trace-core JMH benchmark covering the full create -> (tag) -> finish lifecycle, finished against a no-op DropWriter so -prof gc isolates create/tag/finish allocation from serialization. Pairs baseline shapes (web-server 7 tags, JDBC 9 tags; setTag and builder-withTag) with prototype arms: buildSpan(SpanPrototype).start() and the builder-free startSpan(SpanPrototype). Measured (Threads(8), -f3 -wi5 -i5 -prof gc): prototype construction cuts gc.alloc.rate.norm ~-5% web (-80 B/op) / ~-10% jdbc (-120 B/op) vs baseline -- tracking the number of baked constants (fewer per-span TagMap.Entry allocations). The builder-free startSpan is deterministic (no MultiSpanBuilder); buildSpan's builder is escape-analyzed away in this shallow micro, so startSpan is the EA-independent path for production's deeper/megamorphic call sites. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

dougqh · 2026-07-22T15:43:30Z

@codex review

chatgpt-codex-connector · 2026-07-22T15:51:25Z

Codex Review: Didn't find any major issues. More of your lovely PRs please.

Reviewed commit: 284eae7d8a

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datadog-datadog-prod-us1 · 2026-07-22T16:02:12Z

🎯 Code Coverage (details)
• Patch Coverage: 94.74%
• Overall Coverage: 58.38% (+1.70%)

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

🔗 Commit SHA: 8e3d18f | Docs | View more details | Give us feedback!}

datadog-datadog-prod-us1 · 2026-07-22T16:13:26Z

Bits has a CI fix ready

🟢 Investigated · 🟢 Fix prepared · ⚪ Validation skipped · 🟠 Ready

SpanPrototype.Builder did not meet the coverage threshold because several initialization paths were untested. Added focused coverage for identity initialization, null bases and entries, and populated and empty tag inputs in internal-api/src/test/java/datadog/trace/bootstrap/instrumentation/api/SpanPrototypeTest.java.

Commit fix to this PR

View in Datadog | Reviewed commit 911fc57 · Any feedback? Reach out in #deveng-pr-agent

dd-octo-sts · 2026-07-22T17:18:49Z

🟢 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	14.82 s	14.72 s	[-0.1%; +1.6%] (no difference)
startup:insecure-bank:tracing:Agent	13.57 s	13.74 s	[-1.8%; -0.6%] (maybe better)
startup:petclinic:appsec:Agent	17.43 s	17.18 s	[+0.7%; +2.1%] (maybe worse)
startup:petclinic:iast:Agent	17.31 s	17.51 s	[-2.0%; -0.3%] (maybe better)
startup:petclinic:profiling:Agent	17.36 s	17.41 s	[-1.6%; +1.0%] (no difference)
startup:petclinic:sca:Agent	16.56 s	17.33 s	[-8.5%; -0.3%] (maybe better)
startup:petclinic:tracing:Agent	16.44 s	16.63 s	[-2.1%; -0.1%] (maybe better)

Commit: 8e3d18fb · CI Pipeline · Benchmarking Platform UI

Load and DaCapo benchmarks can be triggered manually in the GitLab pipeline. Results will appear in the Benchmarking Platform UI after completion.

…tion through it Introduce apply(SpanPrototype) as the single seam for stamping a prototype's constant initial state. It applies span type, constant tags, and integration name as fallback defaults -- only where the span has not already set them -- so it never clobbers explicit values, is order-independent, and self-neutralizes once construction has already seeded the same prototype. DDSpanContext.apply is the authoritative implementation (the context owns the tag map and will host the eventual bulk-share fast path + identity short-circuit); DDSpan.apply routes straight to it. The AgentSpan default is the best-effort fallback for non-core spans. The construction path (CoreSpanBuilder) now calls context.apply(prototype) instead of inlining the tag + integration-name seeding. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

… off mocks Have BaseDecorator/ServerDecorator/ClientDecorator build a lazily-cached SpanPrototype (extension chain mirroring the decorator hierarchy) and apply it in afterStart via span.setSpanType/setAllTags/setIntegrationName, replacing the per-Entry setTag calls. Behavior-identical: setAllTags runs the same constant tags through the same interceptor path the per-tag calls used. Migrate the four afterStart specs from Spock mock-interaction assertions to a state-based harness (RecordingSpan/RecordingSpanContext accumulate applied state; ExpectedSpanState asserts the whole state at once), with three leniency modes matching Spock's polymorphic feature-method inheritance across the decorator hierarchy. Other specs (onPeerConnection/onConnection/onStatement/ beforeFinish) are unchanged. Also drop the born-dead SpanPrototype.Builder.initInstrumentationNames(String[]) overload (no caller); initInstrumentationName covers the single-name case. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

…HEAD # Conflicts: # dd-java-agent/agent-bootstrap/src/main/java/datadog/trace/bootstrap/instrumentation/decorator/BaseDecorator.java # dd-java-agent/agent-bootstrap/src/main/java/datadog/trace/bootstrap/instrumentation/decorator/ClientDecorator.java # dd-java-agent/agent-bootstrap/src/main/java/datadog/trace/bootstrap/instrumentation/decorator/ServerDecorator.java # dd-java-agent/agent-bootstrap/src/test/groovy/datadog/trace/bootstrap/instrumentation/decorator/BaseDecoratorTest.groovy # dd-trace-core/src/main/java/datadog/trace/core/CoreTracer.java # internal-api/src/main/java/datadog/trace/bootstrap/instrumentation/api/AgentSpan.java # internal-api/src/main/java/datadog/trace/bootstrap/instrumentation/api/SpanPrototype.java # internal-api/src/test/java/datadog/trace/bootstrap/instrumentation/api/SpanPrototypeTest.java

No caller uses this generic setter -- tag population goes through the more specific component()/spanKind()/language() builder methods.

dougqh and others added 5 commits July 22, 2026 08:11

dougqh added comp: core Tracer core tag: ai generated Largely based on code generated by an AI or LLM tag: no release notes Changes to exclude from release notes type: refactoring labels Jul 22, 2026

dougqh and others added 2 commits July 22, 2026 17:53

dougqh force-pushed the dougqh/decorator-base-prototype branch from 284eae7 to 911fc57 Compare July 22, 2026 21:59

dougqh changed the title ~~Apply SpanPrototype in decorator afterStart~~ Apply SpanPrototype in decorator afterStart (phase 1b) Jul 23, 2026

dougqh force-pushed the dougqh/span-prototype-api branch from eadba23 to c2d5fb9 Compare July 29, 2026 12:17

dougqh added 2 commits August 28, 2026 21:53

Remove unused ExpectedSpanState.tag(String, CharSequence) overload

8e3d18f

No caller uses this generic setter -- tag population goes through the more specific component()/spanKind()/language() builder methods.

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Apply SpanPrototype in decorator afterStart (phase 1b) - #12037

Apply SpanPrototype in decorator afterStart (phase 1b)#12037
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