Comment 110 for bug 1578989

Reviewed: https://review.openstack.org/626210
Committed: https://git.openstack.org/cgit/openstack/neutron-lib/commit/?id=5dcccd2c668a0ae62aa04a6a5f3e390fb56e0053
Submitter: Zuul
Branch: master

commit 5dcccd2c668a0ae62aa04a6a5f3e390fb56e0053
Author: Bence Romsics <email address hidden>
Date: Wed Dec 19 15:49:52 2018 +0100

    New agent attribute: resources_synced

    Agents supporting the guaranteed minimum bandwidth feature need to share
    their resource view with neutron-server and in turn with Placement too.
    The resource information is synchronized to neutron-server via the
    periodic agent heartbeat therefore transient synchronization errors are
    fixed by the next heartbeat. But synchronization to Placement is not
    done periodically, but on a (mostly) on demand basis. Therefore to fix
    transient errors of the synchronization to Placement we must remember
    the success/failure of the last synchronization attempt.

    This change introduces a new boolean agent attribute: resources_synced

    This attribute is:
    * admin-only (just like the whole agent extension)
    * read-only (it is only updated by the internal synchronization process)

    If this attribute is not set then no synchronization to Placement ever
    happened (which is the natural state of agents not tracking their
    resources via Placement).

    If it is False, then another successful synchronization is needed before
    the contents of Placement can be considered up to date.

    If it is True, then this agent's resources are up to date in Placement.

    Change-Id: Ia3dea82fabe5e068192fbe931db8d341d3d37149
    Needed-By: https://review.openstack.org/630999
    Partial-Bug: #1578989
    See-Also: https://review.openstack.org/502306 (nova spec)
    See-Also: https://review.openstack.org/508149 (neutron spec)