Optimize retrieving display name when searching for users in a group

This is recurrent scenario that we are searching for users and then for
each users we fetch the displayName. This is inefficient, so instead try
to do one query to fetch everything (e.g. Database backend) or use the
already existing DisplayNameCache helper.

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

3 files changed, 39 insertions, 2 deletions

diff --git a/lib/public/Group/Backend/ABackend.php b/lib/public/Group/Backend/ABackend.php
index 7f5cf732335..e76285dfda9 100644
--- a/lib/public/Group/Backend/ABackend.php
+++ b/lib/public/Group/Backend/ABackend.php
@@ -26,6 +26,10 @@ declare(strict_types=1);
 namespace OCP\Group\Backend;
 
 use OCP\GroupInterface;
+use OCP\IUserManager;
+use OCP\Server;
+use OC\User\LazyUser;
+use OC\User\DisplayNameCache;
 
 /**
  * @since 14.0.0
@@ -65,4 +69,15 @@ abstract class ABackend implements GroupInterface {
 
 		return (bool)($actions & $implements);
 	}
+
+	public function searchInGroup(string $gid, string $search = '', int $limit = -1, int $offset = 0): array {
+		// Default implementation for compatibility reasons
+		$displayNameCache = Server::get(DisplayNameCache::class);
+		$userManager = Server::get(IUserManager::class);
+		$users = [];
+		foreach ($this->usersInGroup($gid, $search, $limit, $offset) as $userId) {
+			$users[$userId] = new LazyUser($userId, $displayNameCache, $userManager);
+		}
+		return $users;
+	}
 }
diff --git a/lib/public/GroupInterface.php b/lib/public/GroupInterface.php
index b7c07136126..07fd5cb50c4 100644
--- a/lib/public/GroupInterface.php
+++ b/lib/public/GroupInterface.php
@@ -106,13 +106,35 @@ interface GroupInterface {
 	public function groupExists($gid);
 
 	/**
-	 * get a list of all users in a group
+	 * @brief Get a list of user ids in a group matching the given search parameters.
+	 *
 	 * @param string $gid
 	 * @param string $search
 	 * @param int $limit
 	 * @param int $offset
 	 * @return array an array of user ids
 	 * @since 4.5.0
+	 * @deprecated 25.0.0 Use searchInGroup instead, for performance reasons
 	 */
 	public function usersInGroup($gid, $search = '', $limit = -1, $offset = 0);
+
+	/**
+	 * @brief Get a list of users matching the given search parameters.
+	 *
+	 * Implementations of this method should return lazy evaluated user objects and
+	 * preload if possible the display name.
+	 *
+	 * <code>
+	 * $users = $groupBackend->searchInGroup('admin', 'John', 10, 0);
+	 * </code>
+	 *
+	 * @param string $gid    The group id of the user we want to search
+	 * @param string $search The part of the display name or user id of the users we
+	 *                       want to search. This can be empty to get all the users.
+	 * @param int $limit     The limit of results
+	 * @param int $offset    The offset of the results
+	 * @return IUser[]
+	 * @since 25.0.0
+	 */
+	public function searchInGroup(string $gid, string $search = '', int $limit = -1, int $offset = 0): array;
 }
diff --git a/lib/public/IGroup.php b/lib/public/IGroup.php
index ba13359c472..ec26cc55b69 100644
--- a/lib/public/IGroup.php
+++ b/lib/public/IGroup.php
@@ -99,7 +99,7 @@ interface IGroup {
 	 * @return \OCP\IUser[]
 	 * @since 8.0.0
 	 */
-	public function searchUsers($search, $limit = null, $offset = null);
+	public function searchUsers(string $search, ?int $limit = null, ?int $offset = null): array;
 
 	/**
 	 * returns the number of users matching the search string