Release the locks of a killed restore when it runs again; legacy test without empty folders

A killed restore left its leases for up to two hours, so the first backup of the recovered
server was refused. A backup from before 1.0.3 records no empty folders: the test now expects that.

lib/Service/BackupService.php

@@ -79,7 +79,7 @@ final class BackupService {
 		try {
 			return $this->leases->with(PruneService::lockKey($target), LeaseService::EXCLUSIVE, 60, fn () => $this->createRun($target, $label));
 		} catch (LockedException) {
-			throw new \RuntimeException('A cleanup or another start for ' . $target->getName() . ' is running; try again later');
+			throw new \RuntimeException('A cleanup, a restore or another start for ' . $target->getName() . ' is running, or one was stopped by force (that clears by itself within two hours); try again later');
 		}
 	}
 

lib/Service/LeaseService.php

@@ -76,6 +76,15 @@ final class LeaseService {
 		$qb->executeStatement();
 	}
 
+	/** Remove the shared leases on $name, for a caller that knows their holders were stopped. */
+	public function dropShared(string $name): void {
+		$qb = $this->db->getQueryBuilder();
+		$qb->delete('ngb_leases')
+			->where($qb->expr()->eq('name', $qb->createNamedParameter($name)))
+			->andWhere($qb->expr()->eq('mode', $qb->createNamedParameter(self::SHARED)));
+		$qb->executeStatement();
+	}
+
 	/** Wraps $refresh so calling it often (per file, per row batch) only touches the database every $seconds. */
 	public static function throttled(callable $refresh, int $seconds = 60): \Closure {
 		$last = time();

lib/Service/RestoreFullService.php

@@ -151,6 +151,12 @@ final class RestoreFullService {
 			// The database cannot go into this installation; the files can.
 			$check['dbUnreadable'] = 'the database cannot be restored here: ' . $this->describeBlockers($check);
 		}
+		if ($interrupted) {
+			// A restore that was killed leaves its leases, for up to two hours: they would keep
+			// the first backup of the recovered server waiting after this restore completes.
+			// In maintenance mode, on a partly restored instance, nothing else reads the location.
+			$this->leases->dropShared(PruneService::lockKey($target));
+		}
 		$appConfig->setValueInt(\OCA\NgBackup\AppInfo\Application::APP_ID, self::INTERRUPTED_KEY, time());
 		$result = $this->restoreInMaintenance($target, $snapshotId, $skipMissingTables, $check, $salvage);
 		$appConfig->deleteKey(\OCA\NgBackup\AppInfo\Application::APP_ID, self::INTERRUPTED_KEY);