Read trace propagation behavior from tracer's config, not global singleton#11327
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Read trace propagation behavior from tracer's config, not global singleton#11327
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…leton CoreSpanBuilder.startSpan was reading Config.get().getTracePropagationBehaviorExtract() from the global Config singleton on every remote-parent span build. The tracer's own configuration was already available via tracer.initialConfig, which is the consistent source used elsewhere in this file (line 841, ConfigSnapshot, etc.). Reading from the singleton has two consequences: - Span behavior depends on whatever the global Config is at build time, not on the tracer's configured behavior. Tracers built via withProperties(...) get a different Config from the singleton, and on master the override is silently ignored. - Extra getfield on a hot path. Marginal but unnecessary. Switch to tracer.initialConfig and add a regression test that builds a CoreTracer with a Properties override and verifies the resulting span reflects the override. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
dougqh
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Another failed Claude experiment |
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Summary
CoreSpanBuilder.startSpanreadsConfig.get().getTracePropagationBehaviorExtract()for every remote-parent span build. Tracers configured viawithProperties(...)end up with aninitialConfigdistinct from the globalConfig.get()singleton, and on master the override is silently ignored — span behavior follows the singleton, not the tracer's configuration.This patch switches that one call site to
tracer.initialConfig.getTracePropagationBehaviorExtract(), matching the pattern already used elsewhere in this file (e.g. line 841 in the constructor, theConfigSnapshotclass, and the variousflush*methods that readinitialConfig). Marginal getfield savings on the hot path; the main benefit is correctness.Test plan
CoreSpanBuilderTest.extractBehaviorReadsTracerConfigNotGlobalSingleton:CoreTracerviatracerBuilder().withProperties(props).build()wherepropsselects RESTART.customTracer.initialConfigreflects the override.ExtractedContextparent and asserts RESTART behavior (parent dropped, parent context attached as a link).Config.get()returns CONTINUE, the parent isn't dropped, andassertNotEquals(extractedContext.getTraceId(), span.getTraceId())fails../gradlew :dd-trace-core:test --tests 'datadog.trace.core.CoreSpanBuilderTest'passes../gradlew :dd-trace-core:spotlessCheckpasses.🤖 Generated with Claude Code