OpenStack Study: env.py

**** CubicPower OpenStack Study ****

def run_migrations_offline():

    """Run migrations in 'offline' mode.

    This configures the context with just a URL

    and not an Engine, though an Engine is acceptable

    here as well.  By skipping the Engine creation

    we don't even need a DBAPI to be available.

    Calls to context.execute() here emit the given string to the

    script output.

    """

    context.configure(url=neutron_config.database.connection)

    with context.begin_transaction():

        context.run_migrations(active_plugins=active_plugins,

                               options=build_options())

**** CubicPower OpenStack Study ****

def run_migrations_online():

    """Run migrations in 'online' mode.

    In this scenario we need to create an Engine

    and associate a connection with the context.

    """

    engine = create_engine(

        neutron_config.database.connection,

        poolclass=pool.NullPool)

    connection = engine.connect()

    context.configure(

        connection=connection,

        target_metadata=target_metadata

    )

    try:

        with context.begin_transaction():

            context.run_migrations(active_plugins=active_plugins,

                                   options=build_options())

    finally:

        connection.close()

**** CubicPower OpenStack Study ****

def build_options():

    return {'folsom_quota_db_enabled': is_db_quota_enabled()}

**** CubicPower OpenStack Study ****

def is_db_quota_enabled():

    return neutron_config.QUOTAS.quota_driver == DATABASE_QUOTA_DRIVER

if context.is_offline_mode():

    run_migrations_offline()

else:

    run_migrations_online()