class Rackup::Server

def check_pid!
  return unless ::File.exist?(options[:pid])
  pid = ::File.read(options[:pid]).to_i
  raise Errno::ESRCH if pid == 0
  Process.kill(0, pid)
  exit_with_pid(pid)
rescue Errno::ESRCH
  ::File.delete(options[:pid])
rescue Errno::EPERM
  exit_with_pid(pid)
end