This one is a little more involved because there are persistent objects
and versioned notifications to worry about, neither of which we can
remove right now.

Change-Id: Ic7c330ee1cccdc44a2a555c16cb6090eecbf6ce1
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

Part of blueprint remove-cells-v1

Change-Id: I27719a2c44ebea90161c3032485581a6d8e4ba68
Signed-off-by: Stephen Finucane <sfinucan@redhat.com>

nova/db/__init__.py was importing * from nova.db.api. This meant that
any time any code anywhere within the nova.db package was imported
then nova.db.api was too, leading to a cascade of imports that may
not have been desired. Also, in general, code in __init__.py is a pain.

Therefore, this change adjusts code that so that either:

* nova.db.api is used directly
* nova.db.api is imported as 'db'

In either case, the functionality remains the same.

The primary goal of this change was to make it possible to import the
model files without having to import the db api. Moving the model files
to a different place in the directory hierarchy was considered, but
given that "code in __init__.py is a pain" this mode was chosen.

This looks like a very large change, but it is essentially adjusting
package names, many in mocks.

Change-Id: Ic1fd7c87ceda05eeb96735da2a415ef37060bb1a

Cleanup subclassing on NovaObjectDictCompat. A minor change to a unit
tests is also required.

Change-Id: I4ac17ccaa54424ac52fe0d1a83fc062c180f11db
Partially-Implements: bp rm-object-dict-compat-newton

Use enginefacade in 'bw_usage', 'vol_usage' and 's3_image' sections.

Implements: blueprint new-oslodb-enginefacade

Co-Authored-By: Sergey Nikitin <snikitin@mirantis.com>

Change-Id: I32202f044ebe52276bc44bb5ff22ea012c7373d0

In Liberty, we converted to using the manifest-based class
action and backport methods, which no longer rely on these
object relationship maps. They provide a full manifest of
client-side versions with each call, which is far more
robust than us trying to hand-edit these mappings (which
we get incorrect a lot).

Since we're now in Mitaka, we can drop compatibility with
clients that don't make the version-manifest calls. Those
have also been deprecated in oslo.versionedobjects.

Change-Id: Iea8b6348e3b01aaa335ec5408f07826f1e758d20

List objects used to use child_versions, which was tested in a more
shallow way than test_relationships() tests obj_relationships. This
change moves over all list classes to use obj_relationships (and
therefore are now tested in test_relationships() with all other
objects).

Change-Id: I334dba243de45bf11ccb5ab55e2aa8390fe9d8c2
Closes-Bug: #1470154

The BandwidthUsage database model stores the instance relation as 'uuid'
but the BandwidthUsage Nova Object stores it as instance_uuid.  The
_from_db_object needs to handle this discrepancy.

This wasn't caught before because unit tests were passing back a
simulated db return which didn't match reality.

Change-Id: I9aeac709cbbf0f9ddfa6cf724d55af8fa3a962ee
Closes-Bug: 1463039

In oslo.versionedobjects, the registry is opt-in instead of implicit.
This patch sets the stage for moving to that by defining a no-op
registry with a compatible register method so that we can go ahead and
decorate the object classes and then move the registry underneath them.

Related to blueprint use-oslo-objects

Change-Id: Iddc68a2d8a9b103621bc60a7426fe495edf80aad