resourceloader: Remove unused logic for WikiModule::getDB() as null

This was intended at some point for GlobalCssJs but ended up
being implemented differently once we realised that not having
any information about the remote wiki was unacceptable.

The local placeholder that points to metawiki (in case of GlobalCssJs)
must still at the very least be able to query version information
so that it gets a new version hash after changes etc. to ensure
cache rolls over.

This is being removed in preparation for refactoring where
compatibility with this broken model is no longer kept.

Change-Id: I4f1a06ace881daf1a5f202bdba0075460804de57

diff --git a/includes/resourceloader/ResourceLoaderWikiModule.php b/includes/resourceloader/ResourceLoaderWikiModule.php
index 276d9a1..4c11fce 100644 (file)
--- a/includes/resourceloader/ResourceLoaderWikiModule.php
+++ b/includes/resourceloader/ResourceLoaderWikiModule.php
@@ -144,15 +144,18 @@ class ResourceLoaderWikiModule extends ResourceLoaderModule {
        }
 
        /**
-        * Get the Database object used in getTitleInfo().
+        * Get the Database handle used for computing the module version.
         *
-        * Defaults to the local replica DB. Subclasses may want to override this to return a foreign
-        * database object, or null if getTitleInfo() shouldn't access the database.
+        * Subclasses may override this to return a foreign database, which would
+        * allow them to register a module on wiki A that fetches wiki pages from
+        * wiki B.
         *
-        * NOTE: This ONLY works for getTitleInfo() and isKnownEmpty(), NOT FOR ANYTHING ELSE.
-        * In particular, it doesn't work for getContent() or getScript() etc.
+        * The way this works is that the local module is a placeholder that can
+        * only computer a module version hash. The 'source' of the module must
+        * be set to the foreign wiki directly. Methods getScript() and getContent()
+        * will not use this handle and are not valid on the local wiki.
         *
-        * @return IDatabase|null
+        * @return IDatabase
         */
        protected function getDB() {
                return wfGetDB( DB_REPLICA );
@@ -379,10 +382,6 @@ class ResourceLoaderWikiModule extends ResourceLoaderModule {
         */
        protected function getTitleInfo( ResourceLoaderContext $context ) {
                $dbr = $this->getDB();
-               if ( !$dbr ) {
-                       // We're dealing with a subclass that doesn't have a DB
-                       return [];
-               }
 
                $pageNames = array_keys( $this->getPages( $context ) );
                sort( $pageNames );
@@ -462,8 +461,8 @@ class ResourceLoaderWikiModule extends ResourceLoaderModule {
                        $module = $rl->getModule( $name );
                        if ( $module instanceof self ) {
                                $mDB = $module->getDB();
-                               // Subclasses may disable getDB and implement getTitleInfo differently
-                               if ( $mDB && $mDB->getDomainID() === $db->getDomainID() ) {
+                               // Subclasses may implement getDB differently
+                               if ( $mDB->getDomainID() === $db->getDomainID() ) {
                                        $wikiModules[] = $module;
                                        $allPages += $module->getPages( $context );
                                }