From 0e36a57b60f37ef1cb2d031bd988afe42077940e Mon Sep 17 00:00:00 2001 From: Nick Mills-Barrett Date: Mon, 13 Nov 2023 16:57:44 +0000 Subject: [PATCH] Remove whole table locks on push rule add/delete (#16051) The statements are already executed within a transaction thus a table level lock is unnecessary. --- changelog.d/16051.misc | 1 + synapse/storage/databases/main/push_rule.py | 43 +++++++++++++-------- 2 files changed, 28 insertions(+), 16 deletions(-) create mode 100644 changelog.d/16051.misc diff --git a/changelog.d/16051.misc b/changelog.d/16051.misc new file mode 100644 index 0000000000..1420d2eb3f --- /dev/null +++ b/changelog.d/16051.misc @@ -0,0 +1 @@ +Remove whole table locks on push rule modifications. Contributed by Nick @ Beeper (@fizzadar). diff --git a/synapse/storage/databases/main/push_rule.py b/synapse/storage/databases/main/push_rule.py index f72a23c584..cf622e195c 100644 --- a/synapse/storage/databases/main/push_rule.py +++ b/synapse/storage/databases/main/push_rule.py @@ -449,26 +449,28 @@ class PushRuleStore(PushRulesWorkerStore): before: str, after: str, ) -> None: - # Lock the table since otherwise we'll have annoying races between the - # SELECT here and the UPSERT below. - self.database_engine.lock_table(txn, "push_rules") - relative_to_rule = before or after - res = self.db_pool.simple_select_one_txn( - txn, - table="push_rules", - keyvalues={"user_name": user_id, "rule_id": relative_to_rule}, - retcols=["priority_class", "priority"], - allow_none=True, - ) + sql = """ + SELECT priority, priority_class FROM push_rules + WHERE user_name = ? AND rule_id = ? + """ - if not res: + if isinstance(self.database_engine, PostgresEngine): + sql += " FOR UPDATE" + else: + # Annoyingly SQLite doesn't support row level locking, so lock the whole table + self.database_engine.lock_table(txn, "push_rules") + + txn.execute(sql, (user_id, relative_to_rule)) + row = txn.fetchone() + + if row is None: raise RuleNotFoundException( "before/after rule not found: %s" % (relative_to_rule,) ) - base_priority_class, base_rule_priority = res + base_rule_priority, base_priority_class = row if base_priority_class != priority_class: raise InconsistentRuleException( @@ -516,9 +518,18 @@ class PushRuleStore(PushRulesWorkerStore): conditions_json: str, actions_json: str, ) -> None: - # Lock the table since otherwise we'll have annoying races between the - # SELECT here and the UPSERT below. - self.database_engine.lock_table(txn, "push_rules") + if isinstance(self.database_engine, PostgresEngine): + # Postgres doesn't do FOR UPDATE on aggregate functions, so select the rows first + # then re-select the count/max below. + sql = """ + SELECT * FROM push_rules + WHERE user_name = ? and priority_class = ? + FOR UPDATE + """ + txn.execute(sql, (user_id, priority_class)) + else: + # Annoyingly SQLite doesn't support row level locking, so lock the whole table + self.database_engine.lock_table(txn, "push_rules") # find the highest priority rule in that class sql = (