perf(objects): copy small Source contents out of the shared inflate buffer

[davidfirst]

zlib.inflate returns results smaller than its 16KB chunk as a slice of a 16KB buffer. Source.parse kept that slice, so every small file loaded from the scope held 16KB. bit status in this repo loads ~3.2k head-version files (~11MB of content) that held ~55MB.

Source.parse now copies the contents when they use less than half of the underlying buffer (small copies come from Node's shared pool). On bit status, external/buffer memory dropped from ~105MB to ~62MB.

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PR Summary by Qodo

Reduce memory retained by small parsed Source objects

✨ Enhancement 🧪 Tests 🕐 10-20 Minutes

AI Description

• Copy small Source contents so they do not retain an oversized inflate buffer.
• Preserve larger buffers to avoid unnecessary copies.
• Test content, hash, and backing-buffer size after parsing a compressed Source.

Diagram

graph TD
  A["Compressed Source"] --> B["Inflate object"] --> C{"Small slice?"} -->|Yes| D["Copy contents"] --> F["Retained Source"]
  C -->|No| E["Reuse contents"] --> F

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High-Level Assessment

The following are alternative approaches to this PR:

1. Always copy parsed Source contents

• ➕ Simpler rule that never retains the inflate backing buffer.
• ➖ Copies large files unnecessarily, increasing allocation and CPU costs.

Recommendation: Keep the conditional copy: it addresses retention for small files without imposing a copy on larger ones.

Files changed (2) +17 / -0

Enhancement (1) +3 / -0

source.tsCopy small contents during Source parsing +3/-0

Copy small contents during Source parsing

• Source.parse copies contents when they occupy less than half their backing buffer, preventing a small file from retaining a much larger inflate buffer. Larger contents continue to use the original Buffer.

scopes/scope/objects/models/source.ts

Tests (1) +14 / -0

source.spec.tsTest small Source backing-buffer retention +14/-0

Test small Source backing-buffer retention

• Adds a compressed-object parse test that verifies the Source content and hash remain unchanged while its backing buffer is smaller than 16 KB.

scopes/scope/objects/models/source.spec.ts

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Code Review by Qodo

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Review updated until commit 96b49c7 🚀 Fast

Results up to commit 197454b

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Code review by qodo was updated up to the latest commit 96b49c7