perf: fast-path in validateTraceID for clean trace IDs

[ankurs]

Summary

• Adds a pre-scan loop in validateTraceID that checks if all bytes are already printable ASCII
• If clean (the common case for UUIDs/hex trace IDs), returns the string directly without allocating a strings.Builder

Test plan

• go test -race ./... passes
• make lint — 0 issues

Summary by CodeRabbit

• Chores
  • Optimized trace ID validation performance by adding a fast path for clean input, reducing unnecessary memory allocations in common cases.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 9fa50920-a4e6-4cef-9a8c-dda9c68d8108

📥 Commits

Reviewing files that changed from the base of the PR and between 8099f41 and 09ce4ac.

📒 Files selected for processing (1)

• notifier/notifier.go

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📝 Walkthrough

Walkthrough

The validateTraceID function in notifier/notifier.go is optimized with a fast-path check that detects whether input bytes fall within printable ASCII range (0x20–0x7E). If all bytes are already clean, the truncated string returns immediately without string builder allocation; otherwise, the existing sanitization logic executes.

Changes

Cohort / File(s)	Summary
TraceID Validation Optimization notifier/notifier.go	Added fast-path check to validateTraceID that verifies all bytes are within printable ASCII range before proceeding to slower string building; returns early if input is already clean, avoiding unnecessary allocations.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• security: validate client-supplied trace IDs #26: Directly refines the implementation of validateTraceID with the same printable-ASCII fast path optimization.

Poem

🐰 A rabbit hops through ASCII land,
Fast paths now in every hand,
No builders built when clean is shown,
Just skip ahead and call it home! ✨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: adding a fast-path optimization to validateTraceID for trace IDs that are already clean ASCII.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch perf/validate-trace-fast-path

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[Copilot]

Pull request overview

This PR optimizes validateTraceID by adding a fast path that avoids allocating a strings.Builder when the trace ID is already composed of printable ASCII (the common case for UUID/hex trace IDs).

Changes:

• Add a pre-scan to detect already-clean trace IDs and return early.
• Keep existing sanitization logic as the slow path for “dirty” inputs.

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