Improve group queries

Before we'd also get the diplayname for each group in the backend. In a
separate query. This is of course not ideal as this information is
obtained on each and every query. Now this is queried once and properly
cached.

Also added more caching to the manager.

Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>

lib/private/Group/Database.php

@@ -118,7 +118,10 @@ public function createGroup(string $gid): bool {
 		}
 
 		// Add to cache
-		$this->groupCache[$gid] = $gid;
+		$this->groupCache[$gid] = [
+			'gid' => $gid,
+			'displayname' => $gid
+		];
 
 		return $result === 1;
 	}
@@ -244,15 +247,19 @@ public function getUserGroups($uid) {
 
 		// No magic!
 		$qb = $this->dbConn->getQueryBuilder();
-		$cursor = $qb->select('gid')
-			->from('group_user')
+		$cursor = $qb->select('gu.gid', 'g.displayname')
+			->from('group_user', 'gu')
+			->leftJoin('gu', 'groups', 'g', $qb->expr()->eq('gu.gid', 'g.gid'))
 			->where($qb->expr()->eq('uid', $qb->createNamedParameter($uid)))
 			->execute();
 
 		$groups = [];
 		while ($row = $cursor->fetch()) {
 			$groups[] = $row['gid'];
-			$this->groupCache[$row['gid']] = $row['gid'];
+			$this->groupCache[$row['gid']] = [
+				'gid' => $row['gid'],
+				'displayname' => $row['displayname'],
+			];
 		}
 		$cursor->closeCursor();
 
@@ -309,15 +316,18 @@ public function groupExists($gid) {
 		}
 
 		$qb = $this->dbConn->getQueryBuilder();
-		$cursor = $qb->select('gid')
+		$cursor = $qb->select('gid', 'displayname')
 			->from('groups')
 			->where($qb->expr()->eq('gid', $qb->createNamedParameter($gid)))
 			->execute();
 		$result = $cursor->fetch();
 		$cursor->closeCursor();
 
 		if ($result !== false) {
-			$this->groupCache[$gid] = $gid;
+			$this->groupCache[$gid] = [
+				'gid' => $gid,
+				'displayname' => $result['displayname'],
+			];
 			return true;
 		}
 		return false;
@@ -430,6 +440,10 @@ public function countDisabledInGroup(string $gid): int {
 	}
 
 	public function getDisplayName(string $gid): string {
+		if (isset($this->groupCache[$gid])) {
+			return $this->groupCache[$gid]['displayname'];
+		}
+
 		$this->fixDI();
 
 		$query = $this->dbConn->getQueryBuilder();