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.
pull/16637/head
Nick Mills-Barrett 2023-11-13 16:57:44 +00:00 committed by GitHub
parent 69afe3f7a0
commit 0e36a57b60
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2 changed files with 28 additions and 16 deletions

1
changelog.d/16051.misc Normal file
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@ -0,0 +1 @@
Remove whole table locks on push rule modifications. Contributed by Nick @ Beeper (@fizzadar).

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@ -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 = (