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# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""Provide forwards compatibility for the engine_connect event.
See the "engine_connect" event at
http://docs.sqlalchemy.org/en/rel_0_9/core/events.html.
"""
from sqlalchemy.engine import Engine
from sqlalchemy import event
from oslo.db.sqlalchemy.compat import utils
def engine_connect(engine, listener):
"""Add an engine_connect listener for the given :class:`.Engine`.
This listener uses the SQLAlchemy
:meth:`sqlalchemy.event.ConnectionEvents.engine_connect`
event for 0.9.0 and above, and implements an interim listener
for 0.8 versions.
"""
if utils.sqla_090:
event.listen(engine, "engine_connect", listener)
return
assert isinstance(engine, Engine), \
"engine argument must be an Engine instance, not a Connection"
if not getattr(engine._connection_cls,
'_oslo_engine_connect_wrapper', False):
engine._oslo_engine_connect_events = []
class Connection(engine._connection_cls):
_oslo_engine_connect_wrapper = True
def __init__(self, *arg, **kw):
super(Connection, self).__init__(*arg, **kw)
_oslo_engine_connect_events = getattr(
self.engine,
'_oslo_engine_connect_events',
False)
if _oslo_engine_connect_events:
for fn in _oslo_engine_connect_events:
fn(self, kw.get('_branch', False))
engine._connection_cls = Connection
engine._oslo_engine_connect_events.append(listener)
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