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The Journey of
rubocop-daemon into RuboCop
RubyKaigi 2024 LT
2024-05-16 - Hayato Kawai (@fohte)
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Who
Fohte (Hayato Kawai)
Infra Engineer at Wantedly, Inc.
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The Birth of rubocop-daemon
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Motivation for Creating rubocop-daemon
● Running RuboCop in an editor is slow, typically
taking about 1-2 seconds
○ Immediate feedback during coding is essential; the code written 1
second ago is too old!
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Why RuboCop is Slow
● Each command execution reloads RuboCop:
$ rubocop …
require 'rubocop'
RuboCop::CLI.new.run
Terminal RuboCop
$ rubocop …
require 'rubocop'
RuboCop::CLI.new.run
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require 'rubocop' is Slow
● Just require 'rubocop' takes about 0.8 seconds
without even the core 'lint' functionality
$ rubocop …
require 'rubocop'
RuboCop::CLI.new.run
Terminal RuboCop
$ rubocop …
require 'rubocop'
RuboCop::CLI.new.run
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💡
Could I try daemonization?
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I created the
rubocop-daemon
gem in 2018.
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Architecture of rubocop-daemon
● Save require 'rubocop' time by having a
rubocop-daemon server preload it
○ similar to how an HTTP server operates:
rubocop-daemon
(server)
$ rubocop-daemon
exec …
Terminal
$ rubocop-daemon
exec …
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Lessons from rubocop-daemon
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Gained organic recognition
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Exciting OSS Buzz
● Being recognized as a third-party gem within the
RuboCop community is rewarding
● Active issues and patches are also rewarding
○ It signs that the tool is beneficial and widely used
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Challenges of OSS: Increasing Support Needs
● The more widely it is used, the more support for
diverse environments is needed
○ In rubocop-daemon, some editors/plugins require setup guides
■ e.g. Vim, VSCode, …
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Challenges of OSS: Not All Patches Can be Integrated
● Integrating a patch means taking ownership of
that code
○ taking the responsibility for future issues and reviews.
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Challenges of OSS: Not All Patches Can be Integrated
● In recognition of the time spent writing the
patches, I want to integrate them.
○ It would be difficult to maintain everything
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a few years later…
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Finally integrated
into RuboCop core
in 2022 🎉
https://github.com/ruboco
p/rubocop/pull/10706
Big Thanks to @koic
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Finally integrated into RuboCop core in 2022 🎉
● I'm happy that my feature is widely used by the
RuboCop community
○ (I'm honored to have my name credited in the RuboCop files)
● Effectively handed over maintenance to RuboCop
core team, who deserves trusting
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Conclusion: OSS is a Great Culture
● OSS is a great culture but also brings
challenges to OSS owners
● Contributing upstream isn't the only option
○ You can instead start with a third-party gem!