Public bug reported:
I found out that some methods like _create_ha_interfaces
https://github.com/openstack/neutron/blob/master/neutron/db/l3_hamode_db.py#L329-L345
contain the following logic:
def create():
create_something()
try:
_do_other_thing()
except Exception:
with excutils.save_and_reraise_exception():
delete_something()
def _do_other_thing():
with context.session.begin(subtransactions=True):
....
The problem is that when exception is raised in _do_other_thing it is caught in
except block, but the object cannot be deleted in except section because
internal transaction has been rolled back. We have tests on these methods, but
they also are not correct (for example
https://github.com/openstack/neutron/blob/master/neutron/tests/unit/db/test_l3_hamode_db.py#L360-L377)
as methods _do_other_thing() are mocked so inside transaction is never
created and aborted.
The possible solution is to use nested transaction in such places like
this:
def create()
with context.session.begin(subtransactions=True):
create_something()
try:
_do_other_thing()
except Exception:
with excutils.save_and_reraise_exception():
delete_something()
def _do_other_thing():
with context.session.begin(nested=True):
....
** Affects: neutron
Importance: Undecided
Assignee: Ann Kamyshnikova (akamyshnikova)
Status: New
** Tags: db
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https://bugs.launchpad.net/bugs/1501686
Title:
Incorrect exception handling in DB code involving rollbacked
transactions.
Status in neutron:
New
Bug description:
I found out that some methods like _create_ha_interfaces
https://github.com/openstack/neutron/blob/master/neutron/db/l3_hamode_db.py#L329-L345
contain the following logic:
def create():
create_something()
try:
_do_other_thing()
except Exception:
with excutils.save_and_reraise_exception():
delete_something()
def _do_other_thing():
with context.session.begin(subtransactions=True):
....
The problem is that when exception is raised in _do_other_thing it is caught
in except block, but the object cannot be deleted in except section because
internal transaction has been rolled back. We have tests on these methods, but
they also are not correct (for example
https://github.com/openstack/neutron/blob/master/neutron/tests/unit/db/test_l3_hamode_db.py#L360-L377)
as methods _do_other_thing() are mocked so inside transaction is never
created and aborted.
The possible solution is to use nested transaction in such places like
this:
def create()
with context.session.begin(subtransactions=True):
create_something()
try:
_do_other_thing()
except Exception:
with excutils.save_and_reraise_exception():
delete_something()
def _do_other_thing():
with context.session.begin(nested=True):
....
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