Optimize Base#relevant_file?

[fatkodima]

I identified the problem, fixed and then discovered #967. So this is another implementation, with possibly the smallest change possible.

So, I profiled rubocops memory usage while running on itself:

bundle exec bin/rubocop-profile --memory lib/rubocop/cop

And get the following:

Before

Total allocated: 1.14 GB (16969980 objects)
Total retained:  7.35 MB (54861 objects)

allocated memory by gem
-----------------------------------
 408.41 MB  rubocop/lib
 297.48 MB  parser-2.7.2.0
 195.80 MB  rubocop-ast-1.0.1
 112.66 MB  rubocop-rspec-1.43.2
.....
allocated memory by file
-----------------------------------
 125.46 MB  /Users/fatkodima/.rbenv/versions/2.7.0/lib/ruby/gems/2.7.0/gems/parser-2.7.2.0/lib/parser/source/tree_rewriter.rb
 110.64 MB  /Users/fatkodima/.rbenv/versions/2.7.0/lib/ruby/gems/2.7.0/gems/rubocop-rspec-1.43.2/lib/rubocop/cop/rspec/base.rb
....

After

Total allocated: 1.01 GB (15940558 objects)
Total retained:  6.92 MB (49414 objects)

allocated memory by gem
-----------------------------------
 409.73 MB  rubocop/lib
 300.32 MB  parser-2.7.2.0
 197.03 MB  rubocop-ast-1.0.1
  29.16 MB  other
  23.92 MB  rubocop-performance-1.8.1
  20.42 MB  set
   6.15 MB  ast-2.4.1
   5.84 MB  regexp_parser-1.8.2
   5.22 MB  unicode-display_width-1.7.0
   4.11 MB  psych
   2.24 MB  rubocop-rspec/lib
   2.17 MB  erb
....
allocated memory by file
-----------------------------------
 125.46 MB  /Users/fatkodima/.rbenv/versions/2.7.0/lib/ruby/gems/2.7.0/gems/parser-2.7.2.0/lib/parser/source/tree_rewriter.rb
  60.59 MB  /Users/fatkodima/.rbenv/versions/2.7.0/lib/ruby/gems/2.7.0/gems/rubocop-ast-1.0.1/lib/rubocop/ast/node.rb
....
 204.78 kB  /Users/fatkodima/Desktop/oss/rubocop-rspec/lib/rubocop/cop/rspec/base.rb
....

And measured the impact of just rubocop-rspec.

bundle exec bin/rubocop-profile --memory --only RSpec lib/rubocop/cop

Before

Total allocated: 354.84 MB (4610105 objects)
Total retained:  5.84 MB (42878 objects)
....
allocated memory by file
-----------------------------------
 101.90 MB  /Users/fatkodima/Desktop/oss/rubocop-rspec/lib/rubocop/cop/rspec/base.rb
  40.35 MB  /Users/fatkodima/.rbenv/versions/2.7.0/lib/ruby/gems/2.7.0/gems/parser-2.7.2.0/lib/parser/lexer.rb
....

After

Total allocated: 253.12 MB (3946086 objects)
Total retained:  5.86 MB (43001 objects)
....
allocated memory by file
-----------------------------------
  40.35 MB  /Users/fatkodima/.rbenv/versions/2.7.0/lib/ruby/gems/2.7.0/gems/parser-2.7.2.0/lib/parser/lexer.rb
  29.81 MB  /Users/fatkodima/.rbenv/versions/2.7.0/lib/ruby/gems/2.7.0/gems/rubocop-ast-1.0.1/lib/rubocop/ast/node.rb
....
 43.97 kB  /Users/fatkodima/Desktop/oss/rubocop-rspec/lib/rubocop/cop/rspec/base.rb
....

So, ~30% reducing in memory.

[pirj]

Thanks a lot!
We've been looking to improve #967, so probably will just merge your solution instead.

There's a semi-related #1044, but the problem there is that cops from the same department should have different Patterns

[bquorning]

Fixed in #1063.