Source code for octavia.db.api

#    Copyright 2014 Rackspace
#    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
#    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.

import contextlib
import time

from sqlalchemy.sql.expression import select

from oslo_config import cfg
from oslo_db.sqlalchemy import session as db_session
from oslo_log import log as logging
from oslo_utils import excutils

LOG = logging.getLogger(__name__)
_FACADE = None

def _create_facade_lazily():
    global _FACADE
    if _FACADE is None:
        _FACADE = db_session.EngineFacade.from_config(cfg.CONF, sqlite_fk=True)
    return _FACADE

[docs]def get_engine(): facade = _create_facade_lazily() return facade.get_engine()
[docs]def get_session(expire_on_commit=True, autocommit=True): """Helper method to grab session.""" facade = _create_facade_lazily() return facade.get_session(expire_on_commit=expire_on_commit, autocommit=autocommit)
[docs]@contextlib.contextmanager def get_lock_session(): """Context manager for using a locking (not auto-commit) session.""" lock_session = get_session(autocommit=False) try: yield lock_session lock_session.commit() except Exception: with excutils.save_and_reraise_exception(): lock_session.rollback()
[docs]def wait_for_connection(exit_event): """Helper method to wait for DB connection""" down = True while down and not exit_event.is_set(): try: LOG.debug('Trying to re-establish connection to database.') get_engine().scalar(select([1])) down = False LOG.debug('Connection to database re-established.') except Exception: retry_interval = cfg.CONF.database.retry_interval LOG.exception('Connection to database failed. Retrying in %s ' 'seconds.', retry_interval) time.sleep(retry_interval)