1 files changed, 76 insertions, 0 deletions
diff --git a/lib/private/Group/DisplayNameCache.php b/lib/private/Group/DisplayNameCache.php
new file mode 100644
index 00000000000..fef8d40a05f
--- /dev/null
+++ b/lib/private/Group/DisplayNameCache.php
@@ -0,0 +1,76 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * SPDX-FileCopyrightText: 2022 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OC\Group;
+
+use OCP\Cache\CappedMemoryCache;
+use OCP\EventDispatcher\Event;
+use OCP\EventDispatcher\IEventListener;
+use OCP\Group\Events\GroupChangedEvent;
+use OCP\Group\Events\GroupDeletedEvent;
+use OCP\ICache;
+use OCP\ICacheFactory;
+use OCP\IGroupManager;
+
+/**
+ * Class that cache the relation Group ID -> Display name
+ *
+ * This saves fetching the group from the backend for "just" the display name
+ * @template-implements IEventListener<GroupChangedEvent|GroupDeletedEvent>
+ */
+class DisplayNameCache implements IEventListener {
+	private CappedMemoryCache $cache;
+	private ICache $memCache;
+	private IGroupManager $groupManager;
+
+	public function __construct(ICacheFactory $cacheFactory, IGroupManager $groupManager) {
+		$this->cache = new CappedMemoryCache();
+		$this->memCache = $cacheFactory->createDistributed('groupDisplayNameMappingCache');
+		$this->groupManager = $groupManager;
+	}
+
+	public function getDisplayName(string $groupId): ?string {
+		if (isset($this->cache[$groupId])) {
+			return $this->cache[$groupId];
+		}
+		$displayName = $this->memCache->get($groupId);
+		if ($displayName) {
+			$this->cache[$groupId] = $displayName;
+			return $displayName;
+		}
+
+		$group = $this->groupManager->get($groupId);
+		if ($group) {
+			$displayName = $group->getDisplayName();
+		} else {
+			$displayName = null;
+		}
+		$this->cache[$groupId] = $displayName;
+		$this->memCache->set($groupId, $displayName, 60 * 10); // 10 minutes
+
+		return $displayName;
+	}
+
+	public function clear(): void {
+		$this->cache = new CappedMemoryCache();
+		$this->memCache->clear();
+	}
+
+	public function handle(Event $event): void {
+		if ($event instanceof GroupChangedEvent && $event->getFeature() === 'displayName') {
+			$groupId = $event->getGroup()->getGID();
+			$newDisplayName = $event->getValue();
+			$this->cache[$groupId] = $newDisplayName;
+			$this->memCache->set($groupId, $newDisplayName, 60 * 10); // 10 minutes
+		}
+		if ($event instanceof GroupDeletedEvent) {
+			$groupId = $event->getGroup()->getGID();
+			unset($this->cache[$groupId]);
+			$this->memCache->remove($groupId);
+		}
+	}
+}