Merge pull request #7737 from nextcloud/backport/7703/stable32

[stable32] fix(DocumentService): Return 200 steps before saved version in SyncStep2

Author: mejo-

lib/Db/StepMapper.php

@@ -56,6 +56,25 @@ public function getLatestVersion(int $documentId): ?int {
 		return $data['id'];
 	}
 
+	public function getBeforeVersion(int $documentId, int $version, int $offset): int {
+		$qb = $this->db->getQueryBuilder();
+		$result = $qb->select('id')
+			->from($this->getTableName())
+			->where($qb->expr()->eq('document_id', $qb->createNamedParameter($documentId)))
+			->andWhere($qb->expr()->lt('id', $qb->createNamedParameter($version)))
+			->setMaxResults($offset)
+			->orderBy('id', 'DESC')
+			->executeQuery();
+
+		$rows = $result->fetchAll();
+		$data = end($rows);
+		if ($data === false) {
+			return $version;
+		}
+
+		return $data['id'];
+	}
+
 	public function deleteAll(int $documentId): void {
 		$qb = $this->db->getQueryBuilder();
 		$qb->delete($this->getTableName())

lib/Service/DocumentService.php

@@ -239,8 +239,9 @@ public function addStep(Document $document, Session $session, array $steps, int
 				$stateFile = $this->getStateFile($documentId);
 				$documentState = $stateFile->getContent();
 				$this->logger->debug('Existing document, state file loaded ' . $documentId);
-				// If there were any queries in the steps, send all steps since last save.
-				$getStepsSinceVersion = $document->getLastSavedVersion();
+				// If there were any queries in the steps, send all steps starting 200 steps before last save.
+				// Adding 200 previous steps to workaround race conditions where state with missing step got persisted in the document state. See #7692
+				$getStepsSinceVersion = $this->stepMapper->getBeforeVersion($documentId, $document->getLastSavedVersion(), 200);
 			} catch (NotFoundException $e) {
 				$this->logger->debug('Existing document, but no state file found for ' . $documentId);
 				// If there is no state file, include all the steps.