From fa8934b175467d589dd34fae18639cac0d738fc9 Mon Sep 17 00:00:00 2001 From: Erik Johnston Date: Wed, 7 Oct 2020 15:15:57 +0100 Subject: Reduce serialization errors in MultiWriterIdGen (#8456) We call `_update_stream_positions_table_txn` a lot, which is an UPSERT that can conflict in `REPEATABLE READ` isolation level. Instead of doing a transaction consisting of a single query we may as well run it outside of a transaction. --- synapse/storage/engines/_base.py | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'synapse/storage/engines/_base.py') diff --git a/synapse/storage/engines/_base.py b/synapse/storage/engines/_base.py index 908cbc79e3..d6d632dc10 100644 --- a/synapse/storage/engines/_base.py +++ b/synapse/storage/engines/_base.py @@ -97,3 +97,20 @@ class BaseDatabaseEngine(Generic[ConnectionType], metaclass=abc.ABCMeta): """Gets a string giving the server version. For example: '3.22.0' """ ... + + @abc.abstractmethod + def in_transaction(self, conn: Connection) -> bool: + """Whether the connection is currently in a transaction. + """ + ... + + @abc.abstractmethod + def attempt_to_set_autocommit(self, conn: Connection, autocommit: bool): + """Attempt to set the connections autocommit mode. + + When True queries are run outside of transactions. + + Note: This has no effect on SQLite3, so callers still need to + commit/rollback the connections. + """ + ... -- cgit 1.5.1