Comment 6 for bug 1708178

Reviewed: https://review.openstack.org/480196
Committed: https://git.openstack.org/cgit/openstack/dragonflow/commit/?id=ba93ad9a2e421ae16ebbb2b7cf895008e9cfeafd
Submitter: Zuul
Branch: master

commit ba93ad9a2e421ae16ebbb2b7cf895008e9cfeafd
Author: Omer Anson <email address hidden>
Date: Sun Jun 11 16:47:19 2017 +0300

    A model instance update also sends an update on all referred instances

    When an instance is updated/created in the DF local controller, the
    DF local controller now iterates all references within the instance,
    and sends an update/create event for all instances referenced by that
    instance.

    For instance, logical port P references security group S. Suppose the
    local controller did not receive the event that S was created (yet).
    Once the event on P is received, that event cannot be processed until
    the event that S is created is received. This change adds that queuing
    behaviour.

    Related-Bug: #1690775
    Related-Bug: #1708178
    Change-Id: Ic2ee535c0898b37c200719381f61c954b9ff7ddf