Duplicate Code: IdCompressor telemetry session sampler block

[github-actions]

Analysis of commit 694a71fbc34d56871dbf9e0ae00699e045fd30ad

Assignee: @copilot

Summary

A near-identical block constructs an IEventSampler for IdCompressor telemetry sampling (~5% of sessions) in multiple modules. This is real logic duplication (not boilerplate) and risks future divergence (e.g., sampling rate changes, semantics of “session” sampling, logger wiring).

Duplication Details

Pattern: “IdCompressor telemetry session sampler”

• Severity: Medium

• Occurrences: 2

• Locations:

  • packages/runtime/container-runtime/src/containerRuntime.ts (around lines 1192–1203; constant body 1193–1200)
  • experimental/dds/tree/src/SharedTree.ts (around lines 570–581; constant body 571–578)

• Code Sample (duplicated):

  const idCompressorEventSampler: IEventSampler = (() => {
      const isIdCompressorTelemetryEnabled = Math.random() < 0.05;
      return {
          sample: () => {
              return isIdCompressorTelemetryEnabled;
          },
      };
  })();

Impact Analysis

• Maintainability: Any future updates (e.g., tuning 5% rate, sampling strategy, or adding telemetry dimensions) must be applied in multiple places.
• Bug Risk: It’s easy for one site to drift (e.g., different sampling % or sampler lifetime), causing inconsistent telemetry and confusing analysis.
• Code Bloat: Small but repeated logic block.

Refactoring Recommendations

1. Extract a shared helper for “fixed-per-session” sampling

   • Example API: createFixedSessionSampler(probability: number): IEventSampler
   • Suggested location: a shared utilities package already depended on by both call sites (e.g., packages/utils/telemetry-utils/ or a small helper co-located with createSampledLogger if appropriate).
   • Benefits: single source of truth for sampling semantics and rate.

2. (Optional) Consider deterministic sampling

   • If desired, base sampling on a stable session identifier hash rather than Math.random() to improve reproducibility across restarts.

Implementation Checklist

• Confirm dependency direction allows both call sites to use the chosen shared helper
• Introduce helper + unit coverage as appropriate
• Replace both call sites
• Validate telemetry behavior unchanged (still ~5% per session)

Analysis Metadata

• Analyzed Files: Focused semantic scan of high-churn changed .ts/.cjs/.mjs files in the commit
• Detection Method: Serena symbol inspection + normalized duplicate-window scan
• Commit: 694a71fbc34d56871dbf9e0ae00699e045fd30ad
• Analysis Date: 2026-04-09T21:51:31.360Z

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