Add retry logic to cover deadlock situations

Signed-off-by: Louis Chemineau <louis@chmn.me>

Author: artonge

lib/private/Files/Cache/Cache.php

@@ -40,6 +40,7 @@
 
 namespace OC\Files\Cache;
 
+use Doctrine\DBAL\Exception\DeadlockException;
 use Doctrine\DBAL\Exception\UniqueConstraintViolationException;
 use OC\Files\Search\SearchComparison;
 use OC\Files\Search\SearchQuery;
@@ -692,7 +693,6 @@ public function moveFromCache(ICache $sourceCache, $sourcePath, $targetPath) {
 				throw new \Exception('Invalid target storage id: ' . $targetStorageId);
 			}
 
-			$this->connection->beginTransaction();
 			if ($sourceData['mimetype'] === 'httpd/unix-directory') {
 				//update all child entries
 				$sourceLength = mb_strlen($sourcePath);
@@ -715,11 +715,20 @@ public function moveFromCache(ICache $sourceCache, $sourcePath, $targetPath) {
 					$query->set('encrypted', $query->createNamedParameter(0, IQueryBuilder::PARAM_INT));
 				}
 
-				try {
-					$query->execute();
-				} catch (\OC\DatabaseException $e) {
-					$this->connection->rollBack();
-					throw $e;
+				// Retry transaction in case of deadlock.
+				foreach ([1, 2, 3] as $_) {
+					try {
+						$this->connection->beginTransaction();
+						$query->execute();
+						break;
+					} catch (\OC\DatabaseException $e) {
+						$this->connection->rollBack();
+						throw $e;
+					} catch (\Throwable $e) {
+						if (!($e instanceof DeadlockException)) {
+							throw $e;
+						}
+					}
 				}
 			}