gem_analytics.rb

# written for https://github.com/rails/rails/pull/30919
# 1. find all gems that depend on a particular gem
# 2. download them all
# 3. search through their source!

auth = 'Authorization:YOUR_API_KEY'

gems = JSON.parse(`curl -H '#{auth}' https://rubygems.org/api/v1/gems/activerecord/reverse_dependencies.json`); nil

gems.size
# => 4479

dir = Dir.mktmpdir

gems.each_with_index do |name, index|
  next if Dir["#{dir}/#{name}/source/*"].any?

  print "\r"
  print "#{index + 1} / #{gems.size}"

  sleep 1

  download_link = JSON.parse(`curl -s -H '#{auth}' https://rubygems.org/api/v1/gems/#{name}.json`)['gem_uri']

  `curl -s -o #{dir}/#{name}.gem #{download_link}`
  `mkdir -p #{dir}/#{name}/source`
  `tar zxf #{dir}/#{name}.gem -C #{dir}/#{name}`
  `tar zxf #{dir}/#{name}/data.tar.gz -C #{dir}/#{name}/source`
end; nil

gems.map do |name|
  # ** is recursive in Ruby, but not in Bash
  files = Dir["#{dir}/#{name}/source/**/*.rb"].select do |file|
    begin
      File.read(file) =~ /(before|after|around)_save .*(on:|:on) /
    rescue => e
      puts "failed to read #{file}"
    end
  end
  files.map!{ |file| file.sub "#{dir}/#{name}/source/", '' }
  [name, files] if files.any?
end.compact.to_h