[Borewit]

Address excessive tiny file reads during full Matroska traversal on network shares. Read the ID and size VINTs in one bounded peek for random-access inputs, preserving stream parsing and the fallback for small allocation limits. Document indexed parsing for large MKV files on network shares.

Reference: RFC 8794 (July 2020), sections 4–6, variable-size integers, Element ID and Element Data Size. https://www.rfc-editor.org/rfc/rfc8794.html#section-4

Summary by CodeRabbit

• Performance
  • Large MKV files on network shares can benefit from enabling the index option when the file’s index is reliable, reducing time spent traversing cluster headers.
• Documentation
  • Clarified when index-based seeking may improve performance and how default traversal affects network access.

[coderabbitai]

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ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: Repository: Borewit/music-metadata/.coderabbit.yaml
• Review profile: CHILL
• Plan: Advanced
• Run ID: aada7e57-c9f2-47de-847a-cd27289db102

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📥 Commits

Reviewing files that changed from the base of the PR and between efea8ed and f790e96.

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📒 Files selected for processing (3)

• README.md
• lib/ebml/EbmlIterator.ts
• test/test-ebml.ts

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📝 Walkthrough

Walkthrough

EbmlIterator can read element ID and size VINTs together with a random-access tokenizer when its header buffer is 12 bytes. Tests cover this path and its fallback conditions. The README adds guidance for enabling mkvUseIndex on large MKV files on network shares.

Changes

EBML element-header reads

Layer / File(s)

Summary

Combined element-header read lib/ebml/EbmlIterator.ts, test/test-ebml.ts, README.md

EbmlIterator uses a capped reusable buffer to peek both VINTs when the tokenizer supports random access and the buffer is 12 bytes. It validates VINT widths and available bytes, then advances past the fields. Other cases use the existing sequential reads. Tests cover read positions, VINT widths, a one-byte allocation limit, and truncated input. The README documents mkvUseIndex guidance for large MKV files on network shares.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Refactor

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Merge Risk: ⚪ Minimal · up to f790e

This change reduces small header reads on random-access inputs, such as large MKV files on network shares, and keeps the existing parsing path elsewhere. No actionable merge-blocking risk was identified.

Pre-merge checks · 4 · 1

Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 2 files. (1 skipped: 1 …	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks (4 passed)

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main performance change: batching random-access element header reads in EBML parsing.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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Full details: Docstring Coverage

Explanation

Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 2 files. (1 skipped: 1 unsupported.)

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.01%. Comparing base (efea8ed) to head (f790e96).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2803      +/-   ##
==========================================
+ Coverage   96.99%   97.01%   +0.01%     
==========================================
  Files         106      106              
  Lines       15562    15591      +29     
  Branches     1662     1669       +7     
==========================================
+ Hits        15095    15126      +31     
+ Misses        461      459       -2     
  Partials        6        6              

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