Add BacklinkCacheFactory Service

Bug: T279433
Change-Id: I2943935e2d8148fce4457f76eca0234be72a5a5a

RELEASE-NOTES-1.37

@@ -631,6 +631,8 @@ because of Phabricator reports.
   It wasn't used and job given the purpose of JobSpecification class it's
   not needed.
 * The protected method File::getImageSize() is deprecated.
+* BacklinkCache::get() was deprecated, use
+  BacklinkCacheFactory::getBacklinkCache() instead.
 * MediaHandler::getImageSize(), ::getMetadata() and ::isMetadataValid were
   deprecated and should no longer be overridden. Instead, subclasses should
   override getSizeAndMetadata().

includes/MediaWikiServices.php

@@ -38,6 +38,7 @@ use MediaWiki\Block\BlockUserFactory;
 use MediaWiki\Block\BlockUtils;
 use MediaWiki\Block\DatabaseBlockStore;
 use MediaWiki\Block\UnblockUserFactory;
+use MediaWiki\Cache\BacklinkCacheFactory;
 use MediaWiki\Cache\LinkBatchFactory;
 use MediaWiki\Collation\CollationFactory;
 use MediaWiki\Config\ConfigRepository;
@@ -607,6 +608,14 @@ class MediaWikiServices extends ServiceContainer {
 		return $this->getService( 'AuthManager' );
 	}
 
+	/**
+	 * @since 1.37
+	 * @return BacklinkCacheFactory
+	 */
+	public function getBacklinkCacheFactory(): BacklinkCacheFactory {
+		return $this->getService( 'BacklinkCacheFactory' );
+	}
+
 	/**
 	 * @since 1.34
 	 * @return BadFileLookup

includes/ServiceWiring.php

@@ -58,6 +58,7 @@ use MediaWiki\Block\BlockUtils;
 use MediaWiki\Block\DatabaseBlockStore;
 use MediaWiki\Block\UnblockUserFactory;
 use MediaWiki\Block\UserBlockCommandFactory;
+use MediaWiki\Cache\BacklinkCacheFactory;
 use MediaWiki\Cache\LinkBatchFactory;
 use MediaWiki\Collation\CollationFactory;
 use MediaWiki\Config\ConfigRepository;
@@ -211,6 +212,10 @@ return [
 		return $authManager;
 	},
 
+	'BacklinkCacheFactory' => static function ( MediaWikiServices $services ): BacklinkCacheFactory {
+		return new BacklinkCacheFactory( $services->getMainWANObjectCache() );
+	},
+
 	'BadFileLookup' => static function ( MediaWikiServices $services ): BadFileLookup {
 		return new BadFileLookup(
 			static function () {

includes/cache/BacklinkCache.php

@@ -77,9 +77,7 @@ class BacklinkCache {
 	 */
 	protected $fullResultCache = [];
 
-	/**
-	 * @var WANObjectCache
-	 */
+	/** @var WANObjectCache */
 	protected $wanCache;
 
 	/**
@@ -102,11 +100,12 @@ class BacklinkCache {
 	/**
 	 * Create a new BacklinkCache
 	 *
+	 * @param WANObjectCache $wanCache
 	 * @param PageReference $page Page to create a backlink cache for
 	 */
-	public function __construct( PageReference $page ) {
+	public function __construct( WANObjectCache $wanCache, PageReference $page ) {
 		$this->page = $page;
-		$this->wanCache = MediaWikiServices::getInstance()->getMainWANObjectCache();
+		$this->wanCache = $wanCache;
 	}
 
 	/**
@@ -114,14 +113,23 @@ class BacklinkCache {
 	 * Currently, only one cache instance can exist; callers that
 	 * need multiple backlink cache objects should keep them in scope.
 	 *
+	 * @deprecated since 1.37 Use BacklinkCacheFactory::getBacklinkCache() instead
+	 *
 	 * @param PageReference $page Page to get a backlink cache for
 	 * @return BacklinkCache
 	 */
 	public static function get( PageReference $page ): self {
-		if ( !self::$instance || !self::$instance->page->isSamePageAs( $page ) ) {
-			self::$instance = new self( $page );
-		}
-		return self::$instance;
+		$backlinkCacheFactory = MediaWikiServices::getInstance()->getBacklinkCacheFactory();
+
+		return $backlinkCacheFactory->getBacklinkCache( $page );
+	}
+
+	/**
+	 * @since 1.37
+	 * @return PageReference
+	 */
+	public function getPage(): PageReference {
+		return $this->page;
 	}
 
 	/**

includes/cache/BacklinkCacheFactory.php

@@ -0,0 +1,63 @@
+<?php
+/**
+ * Remember the page that was previously loaded.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup Cache
+ */
+
+namespace MediaWiki\Cache;
+
+use BacklinkCache;
+use MediaWiki\Page\PageReference;
+use WANObjectCache;
+
+/**
+ * @since 1.37
+ */
+class BacklinkCacheFactory {
+	/** @var BacklinkCache */
+	private $latestBacklinkCache;
+
+	/** @var WANObjectCache */
+	private $wanCache;
+
+	/**
+	 * @param WANObjectCache $wanCache
+	 */
+	public function __construct( WANObjectCache $wanCache ) {
+		$this->wanCache = $wanCache;
+	}
+
+	/**
+	 * Returns a BacklinkCache for $page. May re-use previously
+	 * created instances.
+	 *
+	 * Currently, only one cache instance can exist; callers that
+	 * need multiple backlink cache objects should keep them in scope.
+	 *
+	 * @param PageReference $page Page to get a backlink cache for
+	 * @return BacklinkCache
+	 */
+	public function getBacklinkCache( PageReference $page ): BacklinkCache {
+		if ( !$this->latestBacklinkCache || !$this->latestBacklinkCache->getPage()->isSamePageAs( $page ) ) {
+			$this->latestBacklinkCache = new BacklinkCache( $this->wanCache, $page );
+		}
+		return $this->latestBacklinkCache;
+	}
+}

tests/phpunit/includes/cache/BacklinkCacheTest.php

@@ -1,5 +1,7 @@
 <?php
 
+use MediaWiki\Page\PageReferenceValue;
+
 /**
  * @group Database
  * @group Cache
@@ -172,4 +174,13 @@ class BacklinkCacheTest extends MediaWikiIntegrationTestCase {
 		$this->assertTrue( self::$backlinkCacheTest['title']->isSamePageAs( $array[0] ) );
 	}
 
+	/**
+	 * @covers BacklinkCache::get
+	 */
+	public function testGet() {
+		$page = PageReferenceValue::localReference( NS_CATEGORY, "kittens" );
+		$cache = BacklinkCache::get( $page );
+		$this->assertTrue( $cache->getPage()->isSamePageAs( $page ) );
+	}
+
 }

tests/phpunit/unit/includes/cache/BacklinkCacheFactoryTest.php

@@ -0,0 +1,30 @@
+<?php
+
+use MediaWiki\Cache\BacklinkCacheFactory;
+use MediaWiki\Page\PageReferenceValue;
+
+/**
+ * @group Cache
+ */
+class BacklinkCacheFactoryTest extends MediaWikiUnitTestCase {
+
+	/**
+	 * @covers MediaWiki\Cache\BacklinkCacheFactory::getBacklinkCache
+	 */
+	public function testGetBacklinkCache() {
+		$wanCache = new WANObjectCache( [ 'cache' => new EmptyBagOStuff() ] );
+		$page = PageReferenceValue::localReference( NS_CATEGORY, "kittens" );
+		$factory = new BacklinkCacheFactory( $wanCache );
+		$cache = $factory->getBacklinkCache( $page );
+		$this->assertTrue( $cache->getPage()->isSamePageAs( $page ) );
+
+		$cache2 = $factory->getBacklinkCache( $page );
+		$this->assertSame( $cache, $cache2 );
+
+		$page2 = PageReferenceValue::localReference( NS_CATEGORY, "doggos" );
+		$cache2 = $factory->getBacklinkCache( $page2 );
+		$this->assertNotSame( $cache, $cache2 );
+		$this->assertTrue( $cache2->getPage()->isSamePageAs( $page2 ) );
+	}
+
+}