♻️ Refactor: Migrate randString to rand v2

[ksw2000]

Description

This PR migrates randString from math/rand to math/rand/v2 to improve randomness quality and concurrency safety. In addition, it reduces execution time by approximately 97%, as shown in the benchmark test below.

func Benchmark_RandomString(b *testing.B) {
	for i := 0; i < b.N; i++ {
		_ = randString(100)
	}
}

goos: linux
goarch: amd64
pkg: github.com/gofiber/fiber/v3/client
cpu: AMD EPYC 7763 64-Core Processor                
                │   old.txt    │               new.txt               │
                │    sec/op    │   sec/op     vs base                │
_RandomString-4   9862.0n ± 0%   252.1n ± 3%  -97.44% (p=0.000 n=10)

Changes introduced

List the new features or adjustments introduced in this pull request. Provide details on benchmarks, documentation updates, changelog entries, and if applicable, the migration guide.

• Benchmarks: Describe any performance benchmarks and improvements related to the changes.
• Documentation Update: Detail the updates made to the documentation and links to the changed files.
• Changelog/What's New: Include a summary of the additions for the upcoming release notes.
• Migration Guide: If necessary, provide a guide or steps for users to migrate their existing code to accommodate these changes.
• API Alignment with Express: Explain how the changes align with the Express API.
• API Longevity: Discuss the steps taken to ensure that the new or updated APIs are consistent and not prone to breaking changes.
• Examples: Provide examples demonstrating the new features or changes in action.

Type of change

• Performance improvement (non-breaking change which improves efficiency)
• Code consistency (non-breaking change which improves code reliability and robustness)

Checklist

Before you submit your pull request, please make sure you meet these requirements:

• Followed the inspiration of the Express.js framework for new functionalities, making them similar in usage.
• Conducted a self-review of the code and provided comments for complex or critical parts.
• Updated the documentation in the /docs/ directory for Fiber's documentation.
• Added or updated unit tests to validate the effectiveness of the changes or new features.
• Ensured that new and existing unit tests pass locally with the changes.
• Verified that any new dependencies are essential and have been agreed upon by the maintainers/community.
• Aimed for optimal performance with minimal allocations in the new code.
• Provided benchmarks for the new code to analyze and improve upon.

[coderabbitai]

Walkthrough

The changes modify the random string generation logic in the client/hooks.go file. The code now imports math/rand/v2, changes the header declaration from a variable to a constant, and adjusts the letter index calculation. The function previously named randString has been renamed to unsafeRandString and updated to use rand.Uint64() for random value generation. Correspondingly, tests in client/hooks_test.go now call unsafeRandString instead of the old function.

Changes

File	Change Summary
client/hooks.go	- Updated import from math/rand to math/rand/v2 - Changed headerAccept from a variable to a constant - Modified letterIdxMax calculation from 63 to 64 - Renamed randString to unsafeRandString and updated its implementation to use rand.Uint64() - Updated boundary generation
client/hooks_test.go	Replaced call from randString to unsafeRandString in the Test_Rand_String function

Sequence Diagram(s)

sequenceDiagram
    participant P as ParserRequestHeader
    participant U as unsafeRandString
    participant R as math/rand/v2

    P ->> U: Request random string (length 16)
    U ->> R: Generate random value via rand.Uint64()
    R -->> U: Return random value
    U -->> P: Return generated random string

Loading

Poem

I’m the rabbit hopping through code so fine,
Tweaking constants and functions line by line.
From var to const, a switch so neat,
And random numbers now rhythmically beat.
With math/rand/v2 lighting the way,
My code hops light, come what may! 🐇🥕

---

📜 Recent review details

Configuration used: CodeRabbit UI
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 3f93555 and 4930b6c.

📒 Files selected for processing (2)

• client/hooks.go (3 hunks)
• client/hooks_test.go (1 hunks)

🔇 Additional comments (9)

client/hooks_test.go (1)

41-41: Function name updated to match implementation change.

The test now correctly calls the renamed unsafeRandString function instead of the old randString function, maintaining test coverage after the refactoring.

client/hooks.go (8)

6-6: Upgraded to math/rand/v2 package.

This change is aligned with the PR objective to migrate to the newer version of the rand package, which provides better randomness quality and concurrency safety.

---

20-21: Changed headerAccept from var to const.

Good practice to declare string constants as const rather than var since they're immutable.

---

31-31: Adjusted letterIdxMax calculation from 63 to 64 bits.

This adjustment matches the v2 package, which uses a full 64-bit random number generation via Uint64(). The previous calculation was based on 63 bits due to limitations in the v1 package.

---

34-40: Refactored randString to unsafeRandString with v2 implementation.

This implementation change:

1. Renames the function to indicate it uses unsafe string conversion
2. Uses rand.Uint64() directly instead of creating a new source with timestamp
3. Improves concurrency safety by avoiding global state
4. Achieves significant performance improvement as mentioned in the PR objectives

The benchmark results (97.44% performance improvement) support this change.

---

42-44: Updated random number generation for new cache.

The code correctly refreshes the random number cache when exhausted, now using rand.Uint64() from v2 package.

---

46-51: Improved bit manipulation for letter selection.

The implementation efficiently extracts random indices from the generated random number, utilizing the full 64 bits available in v2.

---

136-137: Updated randString call to unsafeRandString.

The function call has been updated to use the new implementation for boundary generation, maintaining consistent usage throughout the codebase.

---

1-321:

❓ Verification inconclusive

Verify the migration completeness with benchmark tests.

The code changes look solid and align with the PR objectives. The migration to rand/v2 should provide better randomness quality and concurrency safety. The benchmark results claimed in the PR (97.44% performance improvement) are significant.

Consider documenting this significant performance improvement in any relevant API documentation to inform users of the benefits.

---

🏁 Script executed:

#!/bin/bash
# Search for any remaining uses of old randString function or math/rand package
grep -r "randString" --include="*.go" . | grep -v "unsafeRandString"
grep -r "math/rand\"" --include="*.go" . | grep -v "math/rand/v2"

Length of output: 131

---

🏁 Script executed:

#!/bin/bash
echo "Searching for old math/rand references (excluding math/rand/v2)..."
rg '"math/rand"' --include="*.go" | grep -v "rand/v2"
echo "Searching for any usage of randString that is not unsafeRandString..."
rg "randString" --include="*.go" | grep -v "unsafeRandString"

Length of output: 1289

---

Migration Verified – Benchmark Documentation Recommended

• Verified that there are no legacy references to the old math/rand or the previous randString implementation in the codebase.
• The significant benchmark improvement (97.44%) seems promising. Please ensure that these benchmarks are manually verified and that the performance gains are documented in the API docs.

✨ Finishing Touches

• 📝 Generate Docstrings (Beta)

---

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.25%. Comparing base (3f93555) to head (4930b6c).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3329   +/-   ##
=======================================
  Coverage   84.25%   84.25%           
=======================================
  Files         116      116           
  Lines       11555    11556    +1     
=======================================
+ Hits         9736     9737    +1     
  Misses       1391     1391           
  Partials      428      428           

Flag	Coverage Δ
unittests	84.25% <100.00%> (+<0.01%)	⬆️

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[gaby]

More information here: https://go.dev/blog/randv2

[gaby]

👍 LGTM