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 time

from sqlalchemy.sql.expression import select

from oslo_config import cfg
from oslo_db.sqlalchemy import enginefacade
from oslo_log import log as logging

LOG = logging.getLogger(__name__)
_FACADE = None

def _create_facade_lazily():
    global _FACADE
    if _FACADE is None:
        _FACADE = True
        enginefacade.configure(sqlite_fk=True, expire_on_commit=True)

def _get_transaction_context(reader=False):
    # TODO(gthiemonge) Create and use new functions to get read-only sessions
    if reader:
        context = enginefacade.reader
        context = enginefacade.writer
    return context

def _get_sessionmaker(reader=False):
    context = _get_transaction_context(reader)
    return context.get_sessionmaker()

[docs] def get_engine(): context = _get_transaction_context() return context.get_engine()
[docs] def get_session(): """Helper method to grab session.""" return _get_sessionmaker()()
[docs] def session(): return _get_sessionmaker()
[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)