Cache display name

This should saves some query in the share backend when displaying the
owner and it's not important if the display name is 10 minutes outdated
as it is very rare that this gets changed.

Signed-off-by: Carl Schwan <carl@carlschwan.eu>

1 files changed, 66 insertions, 0 deletions

diff --git a/lib/private/User/DisplayNameCache.php b/lib/private/User/DisplayNameCache.php
new file mode 100644
index 00000000000..f44cdac6e85
--- /dev/null
+++ b/lib/private/User/DisplayNameCache.php
@@ -0,0 +1,66 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright 2022 Carl Schwan <carl@carlschwan.eu>
+ * @license AGPL-3.0-or-later
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program. If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+
+namespace OC\User;
+
+use OCP\ICache;
+use OCP\ICacheFactory;
+use OCP\IUserManager;
+
+/**
+ * Class that cache the relation UserId -> Display name
+ *
+ * This saves fetching the user from a user backend and later on fetching
+ * their preferences. It's generally not an issue if this data is slightly
+ * outdated.
+ */
+class DisplayNameCache {
+	private ICache $internalCache;
+	private IUserManager $userManager;
+
+	public function __construct(ICacheFactory $cacheFactory, IUserManager $userManager) {
+		$this->internalCache = $cacheFactory->createDistributed('displayNameMappingCache');
+		$this->userManager = $userManager;
+	}
+
+	public function getDisplayName(string $userId) {
+		$displayName = $this->internalCache->get($userId);
+		if ($displayName) {
+			return $displayName;
+		}
+
+		$user = $this->userManager->get($userId);
+		if ($user) {
+			$displayName = $user->getDisplayName();
+		} else {
+			$displayName = $userId;
+		}
+		$this->internalCache->set($userId, $displayName, 60 * 10); // 10 minutes
+
+		return $displayName;
+	}
+
+	public function clear(): void {
+		$this->internalCache->clear();
+	}
+}