Need to drop unused DB API - vol_get_usage_by_time

[Davanum Srinivas (DIMS)]

When Matt and i were working on https://bugs.launchpad.net/nova/+bug/1426867 Matt noticed one more table.

mriedem: dimsum__: huh, interesting, vol_get_usage_by_time
mriedem: there is another table you can probably remove, but would need to remove the conductor stuff first
mriedem: which would require an rpcapi version bump i guess?
mriedem: even though there are no entry points to getting to that code
mriedem: vol_get_usage_by_time isn't in conductor manager so that is probably completely broken at this point anyway

[Matt Riedemann (mriedem)]

We can't remove the volume_usages table since db api vol_usage_update is still using it and that's called in the detach_volume flow through conductor, but I don't see any entry points (API or nova-manage) that exposes what's in volume_usages so vol_usage_update seems pointless.

[Matt Riedemann (mriedem)]

There is also a periodic task _poll_volume_usage in the compute manager which has a config option to poll on an interval there, but I don't see how any of that information gets back to the user.

[Matt Riedemann (mriedem)]

This added the volume usages stuff: https://review.openstack.org/#/c/11141/

At the time that had a method to send volume usage notifications in the compute manager:

_send_volume_usage_notifications

But that's no longer in the trunk code.

[Matt Riedemann (mriedem)]

_send_volume_usage_notifications was removed in havana:

https://review.openstack.org/#/c/29915/

So now conductor sends the notification:

https://github.com/openstack/nova/blob/master/nova/conductor/manager.py#L269

[Matt Riedemann (mriedem)]

vol_get_usage_by_time was removed from conductor manager in juno here:

https://review.openstack.org/#/c/84254/

[Matt Riedemann (mriedem)]

So the messy part about removing vol_get_usage_by_time is that there are db api tests for volume_usages that are using it to get information out of the database to verify that vol_usage_update is working correctly.

It seems when https://review.openstack.org/#/c/84254/ happened it cut a bit too deep, else we could drop the methods from conductor api/rpcapi since they won't work w/o the method in the conductor manager, but we could leave the DB APIs in for testing purposes.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/166370

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/166370
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=307e998efbb0f481cb36e47b822337995810a389
Submitter: Jenkins
Branch: master

commit 307e998efbb0f481cb36e47b822337995810a389
Author: Matt Riedemann <email address hidden>
Date: Fri Mar 20 13:29:09 2015 -0700

    Remove vol_get_usage_by_time from conductor api/rpcapi

    In Havana, commit 3cf4cb253 moved the volume usage notify code to
    conductor.

    In Juno, commit 47f6ffad8 dropped vol_get_usage_by_time from conductor
    manager but not from the conductor api/rpcapi modules. Without
    vol_get_usage_by_time being in conductor manager it's an API pointing to
    nothing and won't work so we should remove it.

    The DB APIs are left in since the vol_usage_update DB API is tested
    using vol_get_usage_by_time.

    If we were to leave the conductor APIs in tree, we should add the
    conductor manager method back in and convert the volume_usages table to
    nova objects, and possibly also expose it via a v2.1 API extension.

    Closes-Bug: #1434687

    Change-Id: Ie2980d681c62cd3457b359fbe4f5c32a2bcfc5db