def _lock_subnetpool(self):
"""Lock subnetpool associated row.
This method disallows to allocate concurrently 2 subnets in the same
subnetpool, it's required to ensure non-overlapping cidrs in the same
subnetpool.
"""
with db_api.CONTEXT_READER.using(self._context):
current_hash = (self._context.session.query(
models_v2.SubnetPool.hash).filter_by(
id=self._subnetpool['id']).scalar())
if current_hash is None:
# NOTE(cbrandily): subnetpool has been deleted
raise exceptions.SubnetPoolNotFound(
subnetpool_id=self._subnetpool['id'])
new_hash = uuidutils.generate_uuid()
# NOTE(cbrandily): the update disallows 2 concurrent subnet allocation
# to succeed: at most 1 transaction will succeed, others will be
# rolled back and be caught in neutron.db.v2.base
with db_api.CONTEXT_WRITER.using(self._context):
query = (self._context.session.query(
models_v2.SubnetPool).filter_by(id=self._subnetpool['id'],
hash=current_hash))
count = query.update({'hash': new_hash})
if not count:
raise db_exc.RetryRequest(
exceptions.SubnetPoolInUse(
subnet_pool_id=self._subnetpool['id']))
def _get_subnetpool(self, context, id):
subnetpool = subnetpool_obj.SubnetPool.get_object(
context, id=id)
if not subnetpool:
raise exceptions.SubnetPoolNotFound(subnetpool_id=id)
return subnetpool