Quick and dirty RubyProf wrapper

ruby_profiler.rb

# frozen_string_literal: true

# Ref.: https://hiltmon.com/blog/2012/02/27/quick-and-dirty-rails-performance-profiling/
# Usage:
# RubyProfiler.prof('my_profile') do
#   slow code
#   ...
# end
# You can also pass a `enabled: false` to disable profiler
#
# It will generate 'tmp/profiles/my_profile/<timestamp>_call_stack.html'
module RubyProfiler
  DIR = File.join(Rails.root, 'tmp', 'profiles')

  # @param [String] sub_dir_name name of sub-directory for profiles
  # @param [Object] enabled flag to enable/disable profiler
  def self.prof(sub_dir_name, enabled: true)
    return yield unless enabled

    # create dir & sub_dir automatically
    FileUtils.mkdir_p(DIR) unless File.exist?(DIR)
    subdir = File.join(DIR, sub_dir_name)
    FileUtils.mkdir_p(subdir) unless File.exist?(subdir)

    require 'ruby-prof'
    RubyProf.start

    begin
      yield
    ensure
      results = RubyProf.stop
      file_path = File.join(subdir, "#{Time.now.to_i}_call_stack.html")
      File.open(file_path, 'w') do |file|
        RubyProf::CallStackPrinter.new(results).print(file)
      end
    end
  end
end