I enjoy at least trying to redo these things (whether or not the result is more or less maintainable/elegant is another question). My effort (which I know is probably something like what you already tried):

{
  ## main loop

  show_cache_and_exit("current") if cache_is_good();

  unless (cache_is_stale()) {
   ## cache is dead
   update_cache(),show_cache_and_exit("current") if i_am_the_writer();
   ## we cannot do anything about a bad cache, so retry
   close_cache();
   sleep 5;
   redo;
  }

  ## If I'm not the writer then show old cache
  show_cache_and_exit("stale") unless i_am_the_writer();

  ## If I cannot fork it's up to me
  update_cache(),show_cache_and_exit("current") unless i_can_fork();

  show_cache_and_exit("stale") if i_am_the_parent();

  ## child does:
  be_a_child();
  update_cache();
  exit 0;
}
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