Safety level may not be changed inside a transaction on SQLite with synchronous=normal if PySqlite 2.8.1 (3.8.2)

[Jun Omae]

2016-03-28 00:56:58,865 Trac[pool] ERROR: Exception caught on create
Traceback (most recent call last):
  File "/home/jun66j5/src/tracdev/svn/branches/1.0-stable/trac/db/pool.py", line 105, in get_cnx
    cnx = connector.get_connection(**kwargs)
  File "/home/jun66j5/src/tracdev/svn/branches/1.0-stable/trac/db/sqlite_backend.py", line 190, in get_connection
    return SQLiteConnection(path, log, params)
  File "/home/jun66j5/src/tracdev/svn/branches/1.0-stable/trac/db/sqlite_backend.py", line 298, in __init__
    _set_synchronous(cursor, params.get('synchronous'))
  File "/home/jun66j5/src/tracdev/svn/branches/1.0-stable/trac/db/sqlite_backend.py", line 408, in _set_synchronous
    cursor.execute('PRAGMA synchronous = %s' % _quote(value))
OperationalError: Safety level may not be changed inside a transaction
2016-03-28 00:56:58,865 Trac[chrome] ERROR: Error during check of EMAIL_VIEW: TimeoutError: Unable to get database connection within 0 seconds. (OperationalError: Safety level may not be changed inside a transaction)

[Jun Omae]

After pysqlite 2.8.0, this issue is reproduced. Also, the same issue is raised with journal_mode=wal parameter.

======================================================================
ERROR: test_insert_empty (trac.db.tests.api.StringsTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/jun66j5/src/tracdev/git/trac/db/tests/api.py", line 311, in setUp
    self.env = EnvironmentStub()
  File "/home/jun66j5/src/tracdev/git/trac/core.py", line 124, in __call__
    self.__init__(*args, **kwargs)
  File "/home/jun66j5/src/tracdev/git/trac/test.py", line 405, in __init__
    self.reset_db(default_data)
  File "/home/jun66j5/src/tracdev/git/trac/test.py", line 452, in reset_db
    self.global_databasemanager.init_db()
  File "/home/jun66j5/src/tracdev/git/trac/db/api.py", line 253, in init_db
    connector.init_db(**args)
  File "/home/jun66j5/src/tracdev/git/trac/db/sqlite_backend.py", line 212, in init_db
    _set_journal_mode(cursor, params.get('journal_mode'))
  File "/home/jun66j5/src/tracdev/git/trac/db/sqlite_backend.py", line 392, in _set_journal_mode
    cursor.execute('PRAGMA journal_mode = %s' % _quote(value))
OperationalError: cannot change into wal mode from within a transaction

[Christian Boos]

Patch (jomae.git@t12420) looks good to me. I tested it on trunk with PySqlite 2.8.1, SQLite 3.12, Python 2.7.10 Windows x64.

• TRAC_TEST_DB_URL=sqlite:test.db
• TRAC_TEST_DB_URL=sqlite:test.db?journal_mode=wal
• TRAC_TEST_DB_URL=sqlite:test.db?journal_mode=wal&synchronous=normal

All tests pass.

[Jun Omae]

Thanks for the reviewing and testing! I'm going to push it.