parser caching update

This patch primarily updates p_cached_xhtml() and p_cached_instructions() to
allow their caching logic to be surrounded by an event trigger.

p_cached_xhtml() has been rewritten as the more general p_cached_output() to
support other render output formats besides 'xhtml'. All calls to
p_cached_xhtml() have been changed to refer to the new function.

New event:

name:        PARSER_CACHE_USE
data:        cache object (see below)
action:      determine if cache file can be used
preventable: yes
result:      bool, true to use cache file, false otherwise

Cache operations have been generalised in a new class, cache, extended to
cache_parser, cache_renderer & cache_instructions. Details can be found in
inc/cache.php

For handling of above event, key properties are:
- page, if present the wiki page id,
        may not always be present, e.g. when called for locale xhtml files
- file, source file
- mode, renderer mode (e.g. 'xhtml') or 'i' for instructions

Other changes:
- cache class counts cache hits against attempts, results are stored in
  {cache_dir}/cache_stats.txt
- adds metadata dependency to renderer page cache
- replaces purgefile dependency for renderer cache with metadata
  'relation references' (internal link) dependency for wiki pages only

darcs-hash:20060911021418-9b6ab-19601ed194b8c8e45236ab72c3e23d78bf777e6c.gz

1 files changed, 2 insertions, 2 deletions

diff --git a/inc/fulltext.php b/inc/fulltext.php
index 94cc947e7..4aeb622e2 100644
--- a/inc/fulltext.php
+++ b/inc/fulltext.php
@@ -119,7 +119,7 @@ function ft_backlinks($id){
     // check instructions for matching links
     foreach($docs as $match){
 /*
-        // orig code, examine each page's instruction list
+// orig code, examine each page's instruction list
         $instructions = p_cached_instructions(wikiFN($match),true);
         if(is_null($instructions)) continue;
 
@@ -137,7 +137,7 @@ function ft_backlinks($id){
             }
         }
 */
-// now with metadata
+// now with metadata (metadata relation reference links are already resolved)
         $links = p_get_metadata($match,"relation references");
         if (isset($links[$id])) $result[] = $match;
     }