expose display name cache trough a public interface

lib/private/Files/View.php

@@ -49,9 +49,7 @@
 use Icewind\Streams\CallbackWrapper;
 use OC\Files\Mount\MoveableMount;
 use OC\Files\Storage\Storage;
-use OC\User\DisplayNameCache;
 use OC\User\LazyUser;
-use OC\User\User;
 use OCA\Files_Sharing\SharedMount;
 use OCP\Constants;
 use OCP\Files\Cache\ICacheEntry;
@@ -103,8 +101,6 @@ class View {
 
 	private LoggerInterface $logger;
 
-	private DisplayNameCache $displayNameCache;
-
 	/**
 	 * @param string $root
 	 * @throws \Exception If $root contains an invalid path
@@ -121,7 +117,6 @@ public function __construct($root = '') {
 		$this->lockingProvider = \OC::$server->getLockingProvider();
 		$this->lockingEnabled = !($this->lockingProvider instanceof \OC\Lock\NoopLockingProvider);
 		$this->userManager = \OC::$server->getUserManager();
-		$this->displayNameCache = \OC::$server->get(DisplayNameCache::class);
 		$this->logger = \OC::$server->get(LoggerInterface::class);
 	}
 
@@ -1319,7 +1314,7 @@ public function hasUpdated($path, $time) {
 	 * @return IUser
 	 */
 	private function getUserObjectForOwner(string $ownerId) {
-		return new LazyUser($ownerId, $this->displayNameCache, $this->userManager);
+		return new LazyUser($ownerId, $this->userManager);
 	}
 
 	/**

lib/private/Server.php

@@ -151,6 +151,7 @@
 use OC\Tagging\TagMapper;
 use OC\Talk\Broker;
 use OC\Template\JSCombiner;
+use OC\User\DisplayNameCache;
 use OC\User\Listeners\UserChangedListener;
 use OC\User\Listeners\UserDeletedListener;
 use OCA\Theming\ImageManager;
@@ -474,6 +475,10 @@ public function __construct($webRoot, \OC\Config $config) {
 		$this->registerDeprecatedAlias('UserManager', \OC\User\Manager::class);
 		$this->registerAlias(\OCP\IUserManager::class, \OC\User\Manager::class);
 
+		$this->registerService(DisplayNameCache::class, function (ContainerInterface $c) {
+			return $c->get(\OC\User\Manager::class)->getDisplayNameCache();
+		});
+
 		$this->registerService(\OCP\IGroupManager::class, function (ContainerInterface $c) {
 			$groupManager = new \OC\Group\Manager(
 				$this->get(IUserManager::class),

lib/private/User/LazyUser.php

@@ -29,12 +29,10 @@
 
 class LazyUser implements IUser {
 	private ?IUser $user = null;
-	private DisplayNameCache $displayNameCache;
 	private string $uid;
 	private IUserManager $userManager;
 
-	public function __construct(string $uid, DisplayNameCache $displayNameCache, IUserManager $userManager) {
-		$this->displayNameCache = $displayNameCache;
+	public function __construct(string $uid, IUserManager $userManager) {
 		$this->uid = $uid;
 		$this->userManager = $userManager;
 	}
@@ -53,7 +51,7 @@ public function getUID() {
 	}
 
 	public function getDisplayName() {
-		return $this->displayNameCache->getDisplayName($this->uid);
+		return $this->userManager->getDisplayName($this->uid);
 	}
 
 	public function setDisplayName($displayName) {

lib/private/User/Manager.php

@@ -95,6 +95,8 @@ class Manager extends PublicEmitter implements IUserManager {
 	/** @var IEventDispatcher */
 	private $eventDispatcher;
 
+	private DisplayNameCache $displayNameCache;
+
 	public function __construct(IConfig $config,
 								EventDispatcherInterface $oldDispatcher,
 								ICacheFactory $cacheFactory,
@@ -108,6 +110,7 @@ public function __construct(IConfig $config,
 			unset($cachedUsers[$user->getUID()]);
 		});
 		$this->eventDispatcher = $eventDispatcher;
+		$this->displayNameCache = new DisplayNameCache($cacheFactory, $this);
 	}
 
 	/**
@@ -185,6 +188,10 @@ public function get($uid) {
 		return null;
 	}
 
+	public function getDisplayName(string $uid): string {
+		return $this->displayNameCache->getDisplayName($uid);
+	}
+
 	/**
 	 * get or construct the user object
 	 *
@@ -742,4 +749,8 @@ private function verifyUid(string $uid): bool {
 
 		return !file_exists(rtrim($dataDirectory, '/') . '/' . $uid);
 	}
+
+	public function getDisplayNameCache(): DisplayNameCache {
+		return $this->displayNameCache;
+	}
 }

lib/public/IUserManager.php

@@ -84,6 +84,17 @@ public function clearBackends() ;
 	 */
 	public function get($uid);
 
+	/**
+	 * Get the display name of a user
+	 *
+	 * Note that this will return the uid if the user is not found instead of throwing an exception
+	 *
+	 * @param string $uid
+	 * @return string
+	 * @since 25.0.0
+	 */
+	public function getDisplayName(string $uid): string;
+
 	/**
 	 * check if a user exists
 	 *

tests/lib/User/ManagerTest.php

@@ -50,7 +50,6 @@ protected function setUp(): void {
 		$this->cache = $this->createMock(ICache::class);
 
 		$this->cacheFactory->method('createDistributed')
-			->with('user_backend_map')
 			->willReturn($this->cache);
 	}