[dokuwiki] Re: Content-dependent Purge/Cache


On Jan 10, 2007, at 11:35 AM, Todd Augsburger wrote:
I have a dokuwiki that appears differently to "editors" (those logged in) than to the general public. The editors would like to include comments (on 
wiki pages) that will be invisible to the general public.
So I wrote a plugin which handles the comments properly. However, caching needs to be turned off for pages which contain these comments, since they're 
user-dependent. My solution (which works) is:
1) A syntax plugin renders the comment as either visible or invisible,
depending on the user, then uses p_set_metadata() to set a flag which
suggests that the page be purged.
2) An action plugin hooks PARSER_CACHE_USE and uses p_get_metadata() to get the flag. If set, I then set depends['purge'] = true so that the page is 
refreshed.

[...]

So ... I have 3 specific questions:
1) Is there a better way to accomplish this? (Is there no other way that the 
plugin can request that the page not be cached?)
2) Step 3 seems awkward and inefficient, because I re-read the file when it's rarely changed. Is there some other way to tell if the metadata may 
need a refresh?
This may be entirely too clever to work, but what about this.... Use syntax and action plugins that operate independently (without touching the metadata).
1) Syntax plugin: Same. Displays notes for users that are allowed to see them. 

2) Action plugin - PARSER_CACHE_USE:
Do not use depends['purge']. Instead, partition the cache by changing the cache file name if the user is allowed to view notes. Some pseudo-code: 
$cache = $event->data;
if (user can view notes && $cache->ext=='xhtml') {
        $cache->cache = $cache->cache . '_notes';  //change cache file path
}
This would partition your cache of 'xhtml' data into the default 'xhtml' cache that does not have notes and the 'xhtml_notes' cache. The rest happens automatically, so you retain the speed of cached content. The only obvious down side is that this will double the size of your 'xhtml' cache.
Note: You may also need to do other things to protect the notes, such as preventing guests from displaying the raw dokuwiki markup for pages. See disabled actions in the config documentation. 

Regards, Ben Coburn


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