From 6716f8c9f4bd0116a9b8737b889e9e395d3dd632 Mon Sep 17 00:00:00 2001 From: Sean Quah Date: Thu, 26 Jan 2023 18:43:42 +0000 Subject: [PATCH] Make sqlite database migrations transactional again, part two #14910 fixed the regression introduced by #13873 where sqlite database migrataions would no longer run inside a transaction. However, it committed the transaction before Synapse updated its bookkeeping of which migrations have been run, which means that migrations may be run again after they have completed successfully. Leave the transaction open at the end of `executescript`, to restore the old, correct behaviour. Fixes #14909. Signed-off-by: Sean Quah --- changelog.d/14926.bugfix | 1 + synapse/storage/engines/_base.py | 5 +- synapse/storage/engines/sqlite.py | 6 +- tests/storage/test_database.py | 96 +++++++++++++++++++++++++++++++ 4 files changed, 104 insertions(+), 4 deletions(-) create mode 100644 changelog.d/14926.bugfix diff --git a/changelog.d/14926.bugfix b/changelog.d/14926.bugfix new file mode 100644 index 000000000000..f1f34cd6badb --- /dev/null +++ b/changelog.d/14926.bugfix @@ -0,0 +1 @@ +Fix a regression introduced in Synapse 1.69.0 which can result in database corruption when database migrations are interrupted on sqlite. diff --git a/synapse/storage/engines/_base.py b/synapse/storage/engines/_base.py index bc9ca3a53c40..9cd6883745be 100644 --- a/synapse/storage/engines/_base.py +++ b/synapse/storage/engines/_base.py @@ -133,8 +133,9 @@ def executescript(cursor: CursorType, script: str) -> None: This is not provided by DBAPI2, and so needs engine-specific support. - Some database engines may automatically COMMIT the ongoing transaction both - before and after executing the script. + Some database engines may automatically COMMIT the ongoing transaction before + executing the script in its own transaction. The script transaction is left + open and it is the responsibility of the caller to commit it. """ ... diff --git a/synapse/storage/engines/sqlite.py b/synapse/storage/engines/sqlite.py index 2f7df85ce4fd..28751e89a5a5 100644 --- a/synapse/storage/engines/sqlite.py +++ b/synapse/storage/engines/sqlite.py @@ -135,14 +135,16 @@ def executescript(cursor: sqlite3.Cursor, script: str) -> None: > than one statement with it, it will raise a Warning. Use executescript() if > you want to execute multiple SQL statements with one call. - The script is wrapped in transaction control statemnets, since the docs for + The script is prefixed with a `BEGIN TRANSACTION`, since the docs for `executescript` warn: > If there is a pending transaction, an implicit COMMIT statement is executed > first. No other implicit transaction control is performed; any transaction > control must be added to sql_script. """ - cursor.executescript(f"BEGIN TRANSACTION;\n{script}\nCOMMIT;") + # The implementation of `executescript` can be found at + # https://github.com/python/cpython/blob/3.11/Modules/_sqlite/cursor.c#L1035. + cursor.executescript(f"BEGIN TRANSACTION; {script}") # Following functions taken from: https://github.com/coleifer/peewee diff --git a/tests/storage/test_database.py b/tests/storage/test_database.py index 543cce6b3e12..8cd7c89ca2f8 100644 --- a/tests/storage/test_database.py +++ b/tests/storage/test_database.py @@ -22,6 +22,7 @@ from synapse.server import HomeServer from synapse.storage.database import ( DatabasePool, + LoggingDatabaseConnection, LoggingTransaction, make_tuple_comparison_clause, ) @@ -37,6 +38,101 @@ def test_native_tuple_comparison(self) -> None: self.assertEqual(args, [1, 2]) +class ExecuteScriptTestCase(unittest.HomeserverTestCase): + """Tests for `BaseDatabaseEngine.executescript` implementations.""" + + def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None: + self.store = hs.get_datastores().main + self.db_pool: DatabasePool = self.store.db_pool + self.get_success( + self.db_pool.runInteraction( + "create", + lambda txn: txn.execute("CREATE TABLE foo (name TEXT PRIMARY KEY)"), + ) + ) + + def test_transaction(self) -> None: + """Test that all statements are run in a single transaction.""" + + def run(conn: LoggingDatabaseConnection) -> None: + cur = conn.cursor(txn_name="test_transaction") + self.db_pool.engine.executescript( + cur, + ";".join( + [ + "INSERT INTO foo (name) VALUES ('transaction test')", + # This next statement will fail. When `executescript` is not + # transactional, the previous row will be observed later. + "INSERT INTO foo (name) VALUES ('transaction test')", + ] + ), + ) + + self.get_failure( + self.db_pool.runWithConnection(run), + self.db_pool.engine.module.IntegrityError, + ) + + self.assertIsNone( + self.get_success( + self.db_pool.simple_select_one_onecol( + "foo", + keyvalues={"name": "transaction test"}, + retcol="name", + allow_none=True, + ) + ), + "executescript is not running statements inside a transaction", + ) + + def test_commit(self) -> None: + """Test that the script transaction remains open and can be committed.""" + + def run(conn: LoggingDatabaseConnection) -> None: + cur = conn.cursor(txn_name="test_commit") + self.db_pool.engine.executescript( + cur, "INSERT INTO foo (name) VALUES ('commit test')" + ) + cur.execute("COMMIT") + + self.get_success(self.db_pool.runWithConnection(run)) + + self.assertIsNotNone( + self.get_success( + self.db_pool.simple_select_one_onecol( + "foo", + keyvalues={"name": "commit test"}, + retcol="name", + allow_none=True, + ) + ), + ) + + def test_rollback(self) -> None: + """Test that the script transaction remains open and can be rolled back.""" + + def run(conn: LoggingDatabaseConnection) -> None: + cur = conn.cursor(txn_name="test_rollback") + self.db_pool.engine.executescript( + cur, "INSERT INTO foo (name) VALUES ('rollback test')" + ) + cur.execute("ROLLBACK") + + self.get_success(self.db_pool.runWithConnection(run)) + + self.assertIsNone( + self.get_success( + self.db_pool.simple_select_one_onecol( + "foo", + keyvalues={"name": "rollback test"}, + retcol="name", + allow_none=True, + ) + ), + "executescript is not leaving the script transaction open", + ) + + class CallbacksTestCase(unittest.HomeserverTestCase): """Tests for transaction callbacks."""