path-scanner.rb

require 'bootsnap'
require 'benchmark/ips'

module Bootsnap
  module LoadPathCache
    module NewPathScanner
      REQUIRABLE_EXTENSIONS = [DOT_RB] + DL_EXTENSIONS
      NORMALIZE_NATIVE_EXTENSIONS = !DL_EXTENSIONS.include?(LoadPathCache::DOT_SO)
      ALTERNATIVE_NATIVE_EXTENSIONS_PATTERN = /\.(o|bundle|dylib)\z/

      BUNDLE_PATH = if Bootsnap.bundler?
        (Bundler.bundle_path.cleanpath.to_s << LoadPathCache::SLASH).freeze
      else
        ''
      end

      class << self
        def call(path)
          path = File.expand_path(path.to_s).freeze

          # If the bundle path is a descendent of this path, we do additional
          # checks to prevent recursing into the bundle path as we recurse
          # through this path. We don't want to scan the bundle path because
          # anything useful in it will be present on other load path items.
          #
          # This can happen if, for example, the user adds '.' to the load path,
          # and the bundle path is '.bundle'.
          contains_bundle_path = BUNDLE_PATH.start_with?(path)

          dirs = []
          requirables = []
          walk(path, nil) do |relative_path, absolute_path, is_directory|
            if is_directory
              dirs << relative_path
              !contains_bundle_path || !absolute_path.start_with?(BUNDLE_PATH)
            elsif relative_path.end_with?(*REQUIRABLE_EXTENSIONS)
              requirables << relative_path
            end
          end
          [requirables, dirs]
        end

        def walk(absolute_dir_path, relative_dir_path, &block)
          Dir.foreach(absolute_dir_path) do |name|
            next if name.start_with?('.')
            relative_path = relative_dir_path ? "#{relative_dir_path}/#{name}" : name.freeze

            absolute_path = "#{absolute_dir_path}/#{name}"
            if File.directory?(absolute_path)
              if yield relative_path, absolute_path, true
                walk(absolute_path, relative_path, &block)
              end
            else
              yield relative_path, absolute_path, false
            end
          end
        end
      end
    end
  end
end


PATH = File.expand_path(ARGV.first || '.')
Benchmark.ips do |x|
  x.config(time: 20, warmup: 2)
  x.report('original') { Bootsnap::LoadPathCache::PathScanner.call(PATH) }
  x.report('new') { Bootsnap::LoadPathCache::NewPathScanner.call(PATH) }
  x.compare!
end

result.txt

Warming up --------------------------------------
            original     1.000  i/100ms
                 new     2.000  i/100ms
Calculating -------------------------------------
            original     18.595  (± 5.4%) i/s -    372.000  in  20.025736s
                 new     25.369  (± 3.9%) i/s -    508.000  in  20.037516s

Comparison:
                 new:       25.4 i/s
            original:       18.6 i/s - 1.36x  (± 0.00) slower