Comment 13 for bug 1751923

Reviewed: https://review.openstack.org/591607
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=ba44c155ce1dcefede9741722a0525820d6da2b8
Submitter: Zuul
Branch: master

commit ba44c155ce1dcefede9741722a0525820d6da2b8
Author: Matt Riedemann <email address hidden>
Date: Tue Aug 14 17:57:53 2018 +0800

    Force refresh instance info_cache during heal

    If the instance info_cache is corrupted somehow, like during
    a host reboot and the ports aren't wired up properly or
    a mistaken policy change in neutron results in nova resetting
    the info_cache to an empty list, the _heal_instance_info_cache
    is meant to fix it (once the current state of the ports for
    the instance in neutron is corrected). However, the task is
    currently only refreshing the cache *based* on the current contents
    of the cache, which defeats the purpose of neutron being the source
    of truth for the ports attached to the instance.

    This change makes the _heal_instance_info_cache periodic task
    pass a "force_refresh" kwarg, which defaults to False for backward
    compatibility with other methods that refresh the cache after
    operations like attach/detach interface, and if True will make
    nova get the current state of the ports for the instance from neutron
    and fully rebuild the info_cache.

    To not lose port order in info_cache this change takes original order
    from nova historical data that are stored as VirtualInterfaceList
    objects. For ports that are not registered as VirtualInterfaces
    objects it will add them at the end of port_order list. Due to this
    for instances older than Newton another patch was introduced to fill
    missing VirtualInterface objects in the DB [1].

    Long-term we should be able to refactor some of the older refresh
    code which leverages the cache to instead use the refresh_vif_id
    kwarg so that we do targeted cache updates when we do things like
    attach and detach ports, but that's a change for another day.

    [1] https://review.openstack.org/#/c/614167

    Co-Authored-By: Maciej Jozefczyk <email address hidden>
    Change-Id: I629415236b2447128ae9a980d4ebe730a082c461
    Closes-Bug: #1751923