# octavia.db.api

# 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
    #
    #         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.

    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

    def get_engine():
        facade = _create_facade_lazily()
        return facade.get_engine()

    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)

    @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()

    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)

this page last updated: 2026-03-10 21:33:29

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