Optimize/new route regexp allocations

[titpetric]

What type of PR is this? (check all applicable)

• Refactor
• Feature
• Bug Fix
• Optimization
• Documentation Update

Description

This optimizes NewRouter creation. The change introduces strings.Builder for more efficient strings concatenation, and replaces SplitN with Index, avoiding the allocations for the slice.

Related Tickets & Documents

Test Group	Condition	Average Time (ns/op)	Average Memory (B/op)	Average Allocations
BenchmarkNewRouter	Before	37041	26553	376
	After	32046	25800	347
BenchmarkNewRouterRegexpFunc	Before	4713	2385	75
	After	2792	1640	46

BenchmarkNewRouterRegexpFunc:

Time Improvement: Significant improvement in execution time from 4,713 ns/op to 2,792 ns/op.
Memory Usage: Memory usage per operation dropped from 2,385 bytes to 1,640 bytes.
Allocations: Allocations per operation decreased substantially from 75 to 46.

Added/updated tests?

• Yes

Run verifications and test

• make verify is passing
• make test is passing

[codecov]

Codecov Report

Attention: Patch coverage is 90.90909% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 78.18%. Comparing base (7d9a6f7) to head (f80a252).
Report is 1 commits behind head on main.

❗ Current head f80a252 differs from pull request most recent head b684b38. Consider uploading reports for the commit b684b38 to get more accurate results

Files	Patch %	Lines
regexp.go	90.62%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #732      +/-   ##
==========================================
- Coverage   79.58%   78.18%   -1.40%     
==========================================
  Files           5        5              
  Lines         911      903       -8     
==========================================
- Hits          725      706      -19     
- Misses        131      141      +10     
- Partials       55       56       +1     

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[titpetric]

Rebased off #731

[titpetric]

@AlexVulaj thanks for #731 merge; rebased this one for review. Benchmark still the same as in description.

[titpetric]

@coreydaley is there anything i can/should do to get this reviewed?

[apoorvajagtap]

Hi @titpetric, thanks for working on this!
Also, thanks for being patient while we were adapting to the changes :). I have looked through & added some inputs, please feel free to share your thoughts.

[titpetric]

@apoorvajagtap took your suggestion, added test to cover the expectation of the error return contents, PTAL

[apoorvajagtap]

The lint & security scan errors are not related to the current changes, so I'll go ahead with squash & merge.