Deprecate TagMap.create(int) — its size hint is a no-op

[dougqh]

What Does This Do

TagMap.create(int size) ignores its size — the body is just return new OptimizedTagMap();. TagMap's storage can't honor a size hint without compromising its other optimizations, so the size arg is vestigial and misleading (callers think they're pre-sizing; they aren't).

• Mark create(int) @Deprecated, pointing at create(), with a javadoc explaining the size is ignored.
• Migrate the two TagMap-internal callers off it — fromMap and Ledger.build() — since those components already know create does nothing with the size.

Deliberately left

The three external callers keep using it for now: CoreTracer, DDSpanContext, and TagContext. Their deprecation warnings are a useful to-do list — a dedicated sizing mechanism is being developed separately (for the upcoming dense storage), and DDSpanContext in particular is its main target, so those sites will be converted there rather than churned here.

Notes

• Behavior-neutral: create(int) and create() are identical today, so the migrated calls change nothing at runtime.
• Ledger.estimateSize() stays (uncalled internally now, but plausibly a future sizing-hint input).
• Verified: internal-api + dd-trace-core compile (deprecation is a warning, not an error), SpotBugs clean, TagMap suite green, coverage gate green.

tag: ai generated
tag: no release note

🤖 Generated with Claude Code

[datadog-datadog-prod-us1]

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 57.16% (-0.13%)

_{This comment will be updated automatically if new data arrives.
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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	14.00 s	14.02 s	[-1.1%; +0.8%] (no difference)
startup:insecure-bank:tracing:Agent	12.97 s	13.05 s	[-1.2%; +0.0%] (no difference)
startup:petclinic:appsec:Agent	17.43 s	17.22 s	[+0.4%; +2.1%] (maybe worse)
startup:petclinic:iast:Agent	17.25 s	17.44 s	[-1.8%; -0.4%] (maybe better)
startup:petclinic:profiling:Agent	17.42 s	16.56 s	[+0.9%; +9.6%] (maybe worse)
startup:petclinic:sca:Agent	17.48 s	17.39 s	[-0.6%; +1.5%] (no difference)
startup:petclinic:tracing:Agent	16.60 s	16.54 s	[-0.6%; +1.3%] (no difference)

Commit: 9ee448a7 · CI Pipeline · Benchmarking Platform UI

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