cache the displayname of the share owner

Signed-off-by: Robin Appelman <robin@icewind.nl>

apps/files_sharing/lib/Cache.php

@@ -59,6 +59,8 @@ class Cache extends CacheJail {
 
 	private $rootUnchanged = true;
 
+	private $ownerDisplayName;
+
 	/**
 	 * @param \OCA\Files_Sharing\SharedStorage $storage
 	 * @param IStorage $sourceStorage
@@ -120,13 +122,20 @@ class Cache extends CacheJail {
 			$entry['permissions'] = $sharePermissions;
 		}
 		$entry['uid_owner'] = $this->storage->getOwner($path);
-		$entry['displayname_owner'] = \OC_User::getDisplayName($entry['uid_owner']);
+		$entry['displayname_owner'] = $this->getOwnerDisplayName();
 		if ($path === '') {
 			$entry['is_share_mount_point'] = true;
 		}
 		return $entry;
 	}
 
+	private function getOwnerDisplayName() {
+		if (!$this->ownerDisplayName) {
+			$this->ownerDisplayName = \OC_User::getDisplayName($this->storage->getOwner(''));
+		}
+		return $this->ownerDisplayName;
+	}
+
 	/**
 	 * remove all entries for files that are stored on the storage from the cache
 	 */