Merge "filebackend: clean up some comments and remove unused FileBackendStoreOpHandle...

[lhc/web/wiklou.git] / docs / linkcache.txt

diff --git a/docs/linkcache.txt b/docs/linkcache.txt
index ab36587..cf28762 100644 (file)
--- a/docs/linkcache.txt
+++ b/docs/linkcache.txt
@@ -1,31 +1,24 @@
 linkcache.txt
 
-The LinkCache class maintains a list of article titles and
-the information about whether or not the article exists in
-the database. This is used to mark up links when displaying
-a page. If the same link appears more than once on any page,
-then it only has to be looked up once.
+The LinkCache class maintains a list of article titles and the information about
+whether or not the article exists in the database. This is used to mark up links
+when displaying a page. If the same link appears more than once on any page,
+then it only has to be looked up once. In most cases, link lookups are done in
+batches with the LinkBatch class, or the equivalent in Parser::replaceLinkHolders(),
+so the link cache is mostly useful for short snippets of parsed text (such as
+the site notice), and for links in the navigation areas of the skin.
 
-In practice, what happens is that the global cache object
-$wgLinkCache is consulted and updated every time the function
-getArticleID() from Title is called.
+The link cache was formerly used to track links used in a document for the
+purposes of updating the link tables. This application is now deprecated.
 
-This has a side benefit that we take advantage of. We have
-tables "links" and "brokenlinks" which we use to do things
-like the Orphans page and Whatlinkshere page. It just so
-happens that after we update a page, we display it--and as
-we're displaying it, we look up all the links on that page,
-causing them to be put into the cache. That information is
-exactly what we need to update those two tables. So, we do
-something tricky when we update pages: just after the update
-and before we display, we clear the cache. Then we display
-the updated page. Finally, we put a LinksUpdate object onto
-the deferred updates list, which fetches its information from
-the cache.
+To create a batch, you can use the following code:
 
-There's a minor complication: displaying a page also looks up
-a few things like the talk page link in the quick bar and the
-date links. Since we don't want those in the link tables, we
-must take care to suspend the cache while we look those up.
-Skin.php does exactly that--see dateLink(), for example.
+$pages = [ 'Main Page', 'Project:Help', /* ... */ ];
+$titles = [];
 
+foreach( $pages as $page ){
+       $titles[] = Title::newFromText( $page );
+}
+
+$batch = new LinkBatch( $titles );
+$batch->execute();