feat: enhance AppendInt to utilize cache for small negative integers by ReneWerner87 · Pull Request #168 · gofiber/utils

ReneWerner87 · 2025-12-06T08:10:21Z

Summary by CodeRabbit

Performance
- Improved integer formatting for small negative values (-1 to -99) using a cached fast path, reducing work for common cases.
Tests
- Added a unit test covering small-negative caching and the -100 boundary.
- Expanded benchmarks to run multiple input cases for more representative performance comparisons.

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…and improve benchmark tests

gemini-code-assist · 2025-12-06T08:10:35Z

Summary of Changes

Hello @ReneWerner87, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a targeted performance enhancement to the AppendInt utility function by implementing a caching mechanism for small negative integers. The primary goal is to optimize the conversion of negative numbers between -1 and -99 to byte slices, which are frequently encountered. This change is supported by expanded test coverage to validate the new logic and refined benchmarks to accurately measure the performance improvements.

Highlights

Performance Optimization for Negative Integers: The AppendInt function now utilizes a pre-computed cache (smallNegInts) for negative integers ranging from -1 to -99, significantly improving performance for these commonly used values.
Enhanced Test Coverage: New dedicated test cases have been added to specifically verify the correctness and boundary conditions of the small negative integer caching mechanism, ensuring its reliability.
Improved Benchmarking: The AppendInt benchmarks have been refactored to include specific test scenarios for both cached small negative integers and larger negative integers, allowing for more granular and precise performance analysis.

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codecov · 2025-12-06T08:11:22Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.62%. Comparing base (6c6cf04) to head (924d669).
⚠️ Report is 9 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #168      +/-   ##
==========================================
+ Coverage   84.59%   84.62%   +0.03%     
==========================================
  Files          12       12              
  Lines         954      956       +2     
==========================================
+ Hits          807      809       +2     
  Misses        126      126              
  Partials       21       21

Flag	Coverage Δ
unittests	`84.62% <100.00%> (+0.03%)`	⬆️

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gemini-code-assist

Code Review

This pull request enhances the AppendInt function to use a cache for small negative integers (-1 to -99), which is a nice performance optimization. The implementation is correct, and the change is well-supported by new unit tests and benchmarks. My review includes one suggestion to refactor the new test function using subtests (t.Run) to improve its structure, readability, and failure reporting.

format_test.go

Copilot

Pull request overview

This PR enhances the AppendInt function to utilize a pre-computed cache for small negative integers (-1 to -99), improving performance for this common range. The implementation mirrors the existing optimization pattern used in other formatting functions.

Key Changes:

Added cache lookup for negative integers in range -1 to -99 in AppendInt
Extended test coverage with dedicated boundary and cache validation tests
Enhanced benchmarks to measure performance impact of the cache optimization

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
format.go	Added cache lookup path for small negative integers (n > -100) using the existing `smallNegInts` array, and clarified nolint comment for bounds safety
format_test.go	Added comprehensive test for cache boundary validation (-1 to -99, plus -100), updated existing tests with boundary values, and enhanced benchmarks to compare cached vs non-cached negative integer performance

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coderabbitai · 2025-12-06T08:13:11Z

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Walkthrough

Adds a fast-path in AppendInt to return precomputed bytes for small negative integers (-1..-99) and extends tests and benchmarks to validate and measure this behavior, including a boundary check for -100.

Changes

Cohort / File(s)	Change Summary
Small negative integer caching optimization `format.go`	Added early return in `AppendInt` for negative values with `n > -100`, using a precomputed `smallNegInts` cache for -1..-99. Kept existing handling for other values. Added `// nolint:gosec` comment on the `'-'` use in the buffered path.
Test coverage and benchmarking `format_test.go`	Added `Test_AppendInt_SmallNegativeCache` to verify cache hits for -1..-99 and that -100 does not use the cache. Expanded `Test_AppendInt` data to include `100` and `-100`. Converted `Benchmark_AppendInt` to table-driven sub-benchmarks covering multiple input cases and comparing fiber vs `strconv` implementations.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~15 minutes

Review attention: format.go early-return correctness and nolint:gosec justification.
Tests: verify boundary case (-100) and benchmark correctness for sub-benchmarks.

Possibly related PRs

chore: optimize string manipulation functions and improve error handling #167 — touches the same integer formatting code and small negative cache in format.go; likely addressing similar behavior.

Suggested reviewers

gaby
sixcolors
efectn

Poem

🐰 I hopped through bytes both small and neat,

Cached the negatives, now performance is sweet.
From minus one down to minus ninety-nine,
I sped up AppendInt — a tiny design.
🥕✨

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%.	You can run `@coderabbitai generate docstrings` to improve docstring coverage.

✅ Passed checks (2 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 cache utilization for small negative integers in the AppendInt function.

✨ Finishing touches

📝 Generate docstrings

🧪 Generate unit tests (beta)

Create PR with unit tests
Post copyable unit tests in a comment
Commit unit tests in branch improve_appendInt

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Review profile: CHILL

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📥 Commits

Reviewing files that changed from the base of the PR and between 7ec6cf8 and 924d669.

📒 Files selected for processing (1)

format_test.go (2 hunks)

🚧 Files skipped from review as they are similar to previous changes (1)

format_test.go

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…ation and parallel execution

feat: enhance AppendInt to utilize cache for small negative integers …

7ec6cf8

…and improve benchmark tests

Copilot AI review requested due to automatic review settings December 6, 2025 08:10

ReneWerner87 requested a review from a team as a code owner December 6, 2025 08:10

ReneWerner87 added the 🧹 Updates label Dec 6, 2025

ReneWerner87 requested review from efectn, gaby and sixcolors and removed request for a team December 6, 2025 08:10

ReneWerner87 added the ✏️ Feature label Dec 6, 2025

ReneWerner87 removed the ✏️ Feature label Dec 6, 2025

Copilot started reviewing on behalf of ReneWerner87 December 6, 2025 08:10 View session

gemini-code-assist bot reviewed Dec 6, 2025

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Copilot AI reviewed Dec 6, 2025

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ReneWerner87 added the ✏️ Feature label Dec 6, 2025

test: refactor tests for AppendInt to use subtests for better organiz…

924d669

…ation and parallel execution

ReneWerner87 removed the ✏️ Feature label Dec 6, 2025

ReneWerner87 merged commit f1fb607 into master Dec 6, 2025
21 checks passed

ReneWerner87 deleted the improve_appendInt branch December 6, 2025 12:14

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feat: enhance AppendInt to utilize cache for small negative integers#168

feat: enhance AppendInt to utilize cache for small negative integers#168
ReneWerner87 merged 2 commits intomasterfrom
improve_appendInt

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