🧹 chore: Improve ToLower/ToUpper performance#119
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WalkthroughThe Changes
Sequence Diagram(s)sequenceDiagram
participant Caller
participant strings.go
Caller->>strings.go: ToLower(input)
strings.go->>strings.go: Iterate over input, compare with lower-case
alt All chars already lower
strings.go-->>Caller: Return original input (no allocation)
else
strings.go->>strings.go: Allocate new slice, convert remainder
strings.go-->>Caller: Return new string
end
Caller->>strings.go: ToUpper(input)
strings.go->>strings.go: Iterate over input, compare with upper-case
alt All chars already upper
strings.go-->>Caller: Return original input (no allocation)
else
strings.go->>strings.go: Allocate new slice, convert remainder
strings.go-->>Caller: Return new string
end
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Summary of Changes
Hello @gaby, 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 focuses on optimizing the ToLower and ToUpper string conversion functions. The primary goal is to enhance performance by reducing memory allocations, particularly for strings that are already in their desired case, thereby improving efficiency and reducing garbage collection pressure.
Highlights
- Performance Optimization: The
ToLowerandToUpperfunctions have been refactored to significantly improve performance by avoiding unnecessary memory allocations. Previously, these functions would always allocate a new byte slice. Now, they first check if the input string is already in the target case (all lowercase or all uppercase, respectively). If no characters need changing, the original string is returned directly, eliminating allocation and copying overhead. A new byte slice is only allocated and populated if one or more characters require a case conversion.
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Code Review
This pull request effectively addresses the stated objective of improving the performance of ToLower and ToUpper functions by optimizing them to skip allocation when the input string is already in the desired case. The new implementation correctly identifies whether a conversion is needed and only allocates a new byte slice and performs the conversion if necessary. This is a significant improvement for common use cases where strings might already be lowercase or uppercase, reducing memory allocations and CPU cycles. The changes are well-implemented and align with common Go performance optimization patterns. The existing test suite, including benchmarks, appears to cover these changes adequately.
Codecov ReportAll modified and coverable lines are covered by tests ✅
Additional details and impacted files@@ Coverage Diff @@
## master #119 +/- ##
==========================================
+ Coverage 96.03% 96.13% +0.09%
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Files 9 9
Lines 505 517 +12
==========================================
+ Hits 485 497 +12
Misses 14 14
Partials 6 6
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Can you share the benchmark results for the existing cases |
Summary
ToLowerto skip allocation when the input is already lowercaseToUpperto skip allocation when the input is already uppercaseSummary by CodeRabbit
Performance Improvements
Tests