fix: Avoid race condition that may initialize a document twice on the clients

Signed-off-by: Julius Härtl <[email protected]>

Author: juliusknorr

lib/Service/ApiService.php

@@ -37,6 +37,7 @@
 use OCP\AppFramework\Http;
 use OCP\AppFramework\Http\DataResponse;
 use OCP\Constants;
+use OCP\Files\AlreadyExistsException;
 use OCP\Files\Lock\ILock;
 use OCP\Files\NotFoundException;
 use OCP\Files\NotPermittedException;
@@ -119,7 +120,12 @@ public function create($fileId = null, $filePath = null, ?string $token = null,
 
 			if ($freshSession) {
 				$this->logger->info('Create new document of ' . $file->getId());
-				$document = $this->documentService->createDocument($file);
+				try {
+					$document = $this->documentService->createDocument($file);
+				} catch (AlreadyExistsException) {
+					$freshSession = false;
+					$document = $this->documentService->getDocument($file->getId());
+				}
 			} else {
 				$this->logger->info('Keep previous document of ' . $file->getId());
 			}

lib/Service/DocumentService.php

@@ -40,6 +40,7 @@
 use OCP\Constants;
 use OCP\DB\Exception;
 use OCP\DirectEditing\IManager;
+use OCP\Files\AlreadyExistsException;
 use OCP\Files\Config\IUserMountCache;
 use OCP\Files\File;
 use OCP\Files\Folder;
@@ -158,7 +159,7 @@ public function createDocument(File $file): Document {
 		} catch (Exception $e) {
 			if ($e->getReason() === Exception::REASON_UNIQUE_CONSTRAINT_VIOLATION) {
 				// Document might have been created in the meantime
-				return $this->documentMapper->find($file->getId());
+				throw new AlreadyExistsException();
 			}
 
 			throw $e;