Fix: Prevent deadlocks during mtime/size/etag propagation

Signed-off-by: raul <raul@nextcloud.com>

Author: Raudius

lib/private/Files/Cache/Propagator.php

@@ -24,6 +24,7 @@
 
 namespace OC\Files\Cache;
 
+use Doctrine\DBAL\Exception\RetryableException;
 use OC\Files\Storage\Wrapper\Encryption;
 use OCP\DB\QueryBuilder\IQueryBuilder;
 use OCP\Files\Cache\IPropagator;
@@ -34,6 +35,7 @@
  * Propagate etags and mtimes within the storage
  */
 class Propagator implements IPropagator {
+	public const MAX_RETRIES = 3;
 	private $inBatch = false;
 
 	private $batch = [];
@@ -100,35 +102,42 @@ public function propagateChange($internalPath, $time, $sizeDifference = 0) {
 			$builder->set('etag', $builder->createNamedParameter($etag, IQueryBuilder::PARAM_STR));
 		}
 
-		$builder->execute();
-
 		if ($sizeDifference !== 0) {
-			// we need to do size separably so we can ignore entries with uncalculated size
-			$builder = $this->connection->getQueryBuilder();
-			$builder->update('filecache')
-				->set('size', $builder->func()->greatest(
-					$builder->func()->add('size', $builder->createNamedParameter($sizeDifference)),
-					$builder->createNamedParameter(-1, IQueryBuilder::PARAM_INT)
-				))
-				->where($builder->expr()->eq('storage', $builder->createNamedParameter($storageId, IQueryBuilder::PARAM_INT)))
-				->andWhere($builder->expr()->in('path_hash', $hashParams))
-				->andWhere($builder->expr()->gt('size', $builder->expr()->literal(-1, IQueryBuilder::PARAM_INT)));
+			$hasCalculatedSize = $builder->expr()->gt('size', $builder->expr()->literal(-1, IQUeryBuilder::PARAM_INT));
+			$sizeColumn = $builder->getColumnName('size');
+			$newSize = $builder->func()->greatest(
+				$builder->func()->add('size', $builder->createNamedParameter($sizeDifference)),
+				$builder->createNamedParameter(-1, IQueryBuilder::PARAM_INT)
+			);
+
+			// Only update if row had a previously calculated size
+			$builder->set('size', $builder->createFunction("CASE WHEN $hasCalculatedSize THEN $newSize ELSE $sizeColumn END"));
 
 			if ($this->storage->instanceOfStorage(Encryption::class)) {
 				// in case of encryption being enabled after some files are already uploaded, some entries will have an unencrypted_size of 0 and a non-zero size
-				$eq = $builder->expr()->eq('unencrypted_size', $builder->expr()->literal(0, IQueryBuilder::PARAM_INT));
+				$hasUnencryptedSize = $builder->expr()->neq('unencrypted_size', $builder->expr()->literal(0, IQueryBuilder::PARAM_INT));
 				$sizeColumn = $builder->getColumnName('size');
 				$unencryptedSizeColumn = $builder->getColumnName('unencrypted_size');
-				$builder->set('unencrypted_size', $builder->func()->greatest(
+				$newUnencryptedSize = $builder->func()->greatest(
 					$builder->func()->add(
-						$builder->createFunction("CASE WHEN $eq THEN $unencryptedSizeColumn ELSE $sizeColumn END"),
+						$builder->createFunction("CASE WHEN $hasUnencryptedSize THEN $sizeColumn ELSE $unencryptedSizeColumn END"),
 						$builder->createNamedParameter($sizeDifference)
 					),
 					$builder->createNamedParameter(-1, IQueryBuilder::PARAM_INT)
-				));
+				);
+
+				// Only update if row had a previously calculated size
+				$builder->set('unencrypted_size', $builder->createFunction("CASE WHEN $hasCalculatedSize THEN $newUnencryptedSize ELSE $unencryptedSizeColumn END"));
 			}
+		}
 
-			$builder->execute();
+		for ($i = 0; $i < self::MAX_RETRIES; $i++) {
+			try {
+				$builder->executeStatement();
+			} catch (RetryableException $e) {
+				continue;
+			}
+			break;
 		}
 	}