Fix installer issues introduces by MediaWikiServices

This fixes three issues with the installer:

1) Make sure LocalizationCache can find the installer's i18n files.
2) Make sure we don't try to use an SqlBagOStuff for caching before we have
   a functioning database.
3) Don't try to output HTML when redirecting (this is unrelated to
   MediaWikiServices, but came up during testing)

Bug: T135169
Change-Id: I7caa932024cd771d6fa226a3ac6001c3148ecc9c

autoload.php

@@ -772,6 +772,7 @@ $wgAutoloadLocalClasses = [
 	'MagicWord' => __DIR__ . '/includes/MagicWord.php',
 	'MagicWordArray' => __DIR__ . '/includes/MagicWordArray.php',
 	'MailAddress' => __DIR__ . '/includes/mail/MailAddress.php',
+	'MainConfigDependency' => __DIR__ . '/includes/cache/CacheDependency.php',
 	'Maintenance' => __DIR__ . '/maintenance/Maintenance.php',
 	'MaintenanceFormatInstallDoc' => __DIR__ . '/maintenance/formatInstallDoc.php',
 	'MakeTestEdits' => __DIR__ . '/maintenance/makeTestEdits.php',

includes/MediaWikiServices.php

@@ -13,6 +13,7 @@ use Liuggio\StatsdClient\Factory\StatsdDataFactory;
 use LoadBalancer;
 use MediaWiki\Services\ServiceContainer;
 use MWException;
+use ObjectCache;
 use ResourceLoader;
 use SearchEngine;
 use SearchEngineConfig;
@@ -222,6 +223,8 @@ class MediaWikiServices extends ServiceContainer {
 		foreach ( $destroy as $name ) {
 			$services->disableService( $name );
 		}
+
+		ObjectCache::clear();
 	}
 
 	/**

includes/cache/CacheDependency.php

@@ -20,6 +20,7 @@
  * @file
  * @ingroup Cache
  */
+use MediaWiki\MediaWikiServices;
 
 /**
  * This class stores an arbitrary value along with its dependencies.
@@ -244,6 +245,34 @@ class GlobalDependency extends CacheDependency {
 	}
 }
 
+/**
+ * @ingroup Cache
+ */
+class MainConfigDependency extends CacheDependency {
+	private $name;
+	private $value;
+
+	function __construct( $name ) {
+		$this->name = $name;
+		$this->value = $this->getConfig()->get( $this->name );
+	}
+
+	private function getConfig() {
+		return MediaWikiServices::getInstance()->getMainConfig();
+	}
+
+	/**
+	 * @return bool
+	 */
+	function isExpired() {
+		if ( !$this->getConfig()->has( $this->name ) ) {
+			return true;
+		}
+
+		return $this->getConfig()->get( $this->name ) != $this->value;
+	}
+}
+
 /**
  * @ingroup Cache
  */

includes/cache/localisation/LocalisationCache.php

@@ -23,6 +23,7 @@
 use Cdb\Reader as CdbReader;
 use Cdb\Writer as CdbWriter;
 use CLDRPluralRuleParser\Evaluator;
+use MediaWiki\MediaWikiServices;
 
 /**
  * Class for caching the contents of localisation files, Messages*.php
@@ -802,12 +803,15 @@ class LocalisationCache {
 	 * @return array
 	 */
 	public function getMessagesDirs() {
-		global $wgMessagesDirs, $IP;
+		global $IP;
+
+		$config = MediaWikiServices::getInstance()->getMainConfig();
+		$messagesDirs = $config->get( 'MessagesDirs' );
 		return [
 			'core' => "$IP/languages/i18n",
 			'api' => "$IP/includes/api/i18n",
 			'oojs-ui' => "$IP/resources/lib/oojs-ui/i18n",
-		] + $wgMessagesDirs;
+		] + $messagesDirs;
 	}
 
 	/**
@@ -958,8 +962,9 @@ class LocalisationCache {
 
 		# Add cache dependencies for any referenced globals
 		$deps['wgExtensionMessagesFiles'] = new GlobalDependency( 'wgExtensionMessagesFiles' );
-		// $wgMessagesDirs is used in LocalisationCache::getMessagesDirs()
-		$deps['wgMessagesDirs'] = new GlobalDependency( 'wgMessagesDirs' );
+		// The 'MessagesDirs' config setting is used in LocalisationCache::getMessagesDirs().
+		// We use the key 'wgMessagesDirs' for historical reasons.
+		$deps['wgMessagesDirs'] = new MainConfigDependency( 'MessagesDirs' );
 		$deps['version'] = new ConstantDependency( 'LocalisationCache::VERSION' );
 
 		# Add dependencies to the cache entry

includes/installer/Installer.php

@@ -20,6 +20,7 @@
  * @file
  * @ingroup Deployment
  */
+use MediaWiki\MediaWikiServices;
 
 /**
  * This documentation group collects source code files with deployment functionality.
@@ -383,14 +384,24 @@ abstract class Installer {
 
 		$configOverrides->set( 'MessagesDirs', $messageDirs );
 
-		return new MultiConfig( [ $configOverrides, $baseConfig ] );
+		$installerConfig = new MultiConfig( [ $configOverrides, $baseConfig ] );
+
+		// make sure we use the installer config as the main config
+		$configRegistry = $baseConfig->get( 'ConfigRegistry' );
+		$configRegistry['main'] = function() use ( $installerConfig ) {
+			return $installerConfig;
+		};
+
+		$configOverrides->set( 'ConfigRegistry', $configRegistry );
+
+		return $installerConfig;
 	}
 
 	/**
 	 * Constructor, always call this from child classes.
 	 */
 	public function __construct() {
-		global $wgMemc, $wgUser;
+		global $wgMemc, $wgUser, $wgObjectCaches;
 
 		$defaultConfig = new GlobalVarConfig(); // all the stuff from DefaultSettings.php
 		$installerConfig = self::getInstallerConfig( $defaultConfig );
@@ -411,6 +422,7 @@ abstract class Installer {
 
 		// Disable object cache (otherwise CACHE_ANYTHING will try CACHE_DB and
 		// SqlBagOStuff will then throw since we just disabled wfGetDB)
+		$wgObjectCaches = MediaWikiServices::getInstance()->getMainConfig()->get( 'ObjectCaches' );
 		$wgMemc = ObjectCache::getInstance( CACHE_NONE );
 
 		// Having a user with id = 0 safeguards us from DB access via User::loadOptions().

includes/installer/WebInstallerOutput.php

@@ -115,7 +115,10 @@ class WebInstallerOutput {
 
 	public function output() {
 		$this->flush();
-		$this->outputFooter();
+
+		if ( !$this->redirectTarget ) {
+			$this->outputFooter();
+		}
 	}
 
 	/**

includes/objectcache/ObjectCache.php

@@ -23,6 +23,7 @@
 
 use MediaWiki\Logger\LoggerFactory;
 use MediaWiki\MediaWikiServices;
+use MediaWiki\Services\ServiceDisabledException;
 
 /**
  * Functions to get cache objects
@@ -226,7 +227,18 @@ class ObjectCache {
 				return self::getInstance( $candidate );
 			}
 		}
-		return self::getInstance( CACHE_DB );
+
+		try {
+			// Make sure we actually have a DB backend before falling back to CACHE_DB
+			MediaWikiServices::getInstance()->getDBLoadBalancer();
+			$candidate = CACHE_DB;
+		} catch ( ServiceDisabledException $e ) {
+			// The LoadBalancer is disabled, probably because
+			// MediaWikiServices::disableStorageBackend was called.
+			$candidate = CACHE_NONE;
+		}
+
+		return self::getInstance( $candidate );
 	}
 
 	/**