Comment 29 for bug 1933234

Reviewed: https://review.opendev.org/c/openstack/neutron/+/803578
Committed: https://opendev.org/openstack/neutron/commit/6bd15da7ea77ec1d36df99a45eb26a57578f3d15
Submitter: "Zuul (22348)"
Branch: stable/train

commit 6bd15da7ea77ec1d36df99a45eb26a57578f3d15
Author: Slawek Kaplonski <email address hidden>
Date: Wed Jul 7 12:00:14 2021 +0200

    [L3] Use processing queue for network update events

    Router_info's _process_internal_ports() method is the one which is
    manipulating router_info.internal_ports cache and network_update()
    method from the L3 agent is relying on that Router_info's cache to
    check if updated network is connected to the router or not.
    So they shouldn't be run together as that may cause some race conditions
    and unexpected issues, like e.g. described in the related bug.

    Until now, network_update event was the only one which was processed
    without using queue of events. And because of that such race condition
    as described above were possible.
    To fix that, this patch changes network_update method in the way that it
    now adds update events for each router hosted by agent to the queue.
    Those events for single routers are then processed, checks if network is
    actually connected to the router and if yes, schedules router update to
    be processed.

    Conflicts:
        neutron/agent/l3/agent.py

    Closes-Bug: #1933234
    Change-Id: I2efe66a7415f7a18fb85bd2536a1901e751d6203
    (cherry picked from commit 6ce48c30bdc153e75c4b9b409203f472b065c11b)
    (cherry picked from commit 604b055c71c374bcf517359c118ace267e3a4ab1)
    (cherry picked from commit 05d0bc6d500aaafe26fd667a761dae408a8c8ef8)
    (cherry picked from commit 463083c71387b249b9aa834e126a17a1a0f3a189)