add lint and fix some issue

[kazeburo]

User description

• add golangci.yml and make lint
• fix for some lint errors

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PR Type

Enhancement, Bug fix

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Description

• Add .golangci.yml configuration for static analysis

• Introduce lint target to the Makefile

• Suppress unused error returns in statsfile.go

• Refactor TCP metric extraction in usageplugin.go

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Diagram Walkthrough

flowchart LR
  Makefile["Makefile"] -- "adds target" --> golangci["golangci-lint"]
  golangci -- "loads config" --> golangci_yml[".golangci.yml"]
  statsfile["statsfile.go"] -- "suppresses errors" --> errcheck["errcheck"]
  usageplugin["usageplugin.go"] -- "refactors code" --> ineffassign["ineffassign"]

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File Walkthrough

	Relevant files
Bug fix	statsfile.go Suppress unused error returns in temporary file handling  statsfile.go Replaces direct error returns with blank identifier assignment +2/-2
Enhancement	usageplugin.go Refactor TCP metric extraction to use local variable          usageplugin.go Introduces local variable for TCP struct to reduce field access +5/-4
Configuration changes	.golangci.yml Add comprehensive golangci-lint configuration for static analysis .golangci.yml Adds static analysis configuration with multiple enabled linters +35/-0    Makefile Add lint makefile target for running static analysis          Makefile Adds lint target to run golangci-lint with timeout +2/-0

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ No major issues detected

[github-actions]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
General	Centralize errcheck exclusions in config Instead of using _ = os.Remove(...) to silence the errcheck linter, add os.Remove to the exclude-functions list in .golangci.yml. This keeps the code cleaner and centralizes lint exceptions. statsfile.go [30-40] if err != nil { newFile.Close() - _ = os.Remove(newFile.Name()) + os.Remove(newFile.Name()) return err } err = newFile.Close() if err != nil { - _ = os.Remove(newFile.Name()) + os.Remove(newFile.Name()) return err } Suggestion importance[1-10]: 5 __ Why: Centralizing linter exclusions in the config file improves code cleanliness and maintainability, though it is a minor stylistic improvement rather than a critical fix.	Low
	Add trailing newline to Makefile Add a trailing newline to the end of the Makefile. Missing newlines can cause issues with some POSIX-compliant tools and linters, and is a standard requirement for text files. Makefile [18-19] +lint: + golangci-lint run --timeout 5m ./... - Suggestion importance[1-10]: 3 __ Why: Adding a trailing newline is a minor formatting fix that improves POSIX compliance but has negligible impact on functionality or correctness.	Low