class ActiveSupport::EventedFileUpdateChecker

def updated?
  @boot_mutex.synchronize do
    if @pid != Process.pid
      boot!
      @pid = Process.pid
      @updated.make_true
    end
  end
  if @missing.any?(&:exist?)
    @boot_mutex.synchronize do
      appeared, @missing = @missing.partition(&:exist?)
      shutdown!
      @dtw += appeared
      boot!
      @updated.make_true
    end
  end
  @updated.true?
end