Eliminate performance bottleneck for advanced help file parsing (when many modules are enabled)

@c960657: thanks for your answer

Are you a maintainer of this module?
My suggested patch was intended to give an idea how the advanced_help module's performance could be improved. So I tried to make only small modifications to make it clear what is needed to increase performance. Since I don't use the 7.x advanced_help module and due to time limitations, I won't modify my initial patch.

@c960657 or anybody else: Feel free to change the patch above (see #1). I would welcome seeing it in a next release.

@c960657: I reviewed your code and it looks ok --> maybe another user could test your patch (especially for the 7.x version) to make this issue "rtbc"

Your modifications in advanced_help_get_topics() and advanced_help_get_settings() are unnecessary in my opinion, but maybe it is more straightforward to switch to "your" $ini variable name also in this 2 functions.
Many thanks for your effort.
I would like to see the patches in future relases.

I found that there must be language specific cache IDs for proper working in multi-language Drupal sites.

So all you have to do is adding
$GLOBALS['language']->language
at the end of the $cid parameter of each cache_get() or cache_set() call.

For my initial patch the new lines must look so:

function _advanced_help_parse_ini() {
  static $cache = NULL;

  // NEW: Try to find $cache array in cache table.
  if (!isset($cache)) {
    $cache = cache_get('advanced_help_parse_ini_'. $GLOBALS['language']->language);
    if (!empty($cache->data)) {
      $cache = $cache->data;
    }
    else {
      unset($cache);
    }
  }
  // END NEW: Go on with old (expensive) file detection if no cached value could be found.
  if (!isset($cache)) {
    ...
    drupal_alter('advanced_help_topic_info', $cache);
    // NEW: Store $cache array in cache table.
    cache_set('advanced_help_parse_ini_'. $GLOBALS['language']->language, $cache);
  }
  return $cache;
}

Has anybody tested these patches?

I also run the D6 patch successfully since some months, so issue status should be changed to "rtbc", right?

It seems that our performance improvement isn't a big topic of interest in the community... ;-)

I reviewed the Drupal 7 patch and see no problems. It looks fine.
So ready for "rtbc"? I would say "yes".