Comment 6 for bug 1253993

Reviewed: https://review.openstack.org/63100
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=3046c4ae22b10f9e4fa83a47bfe089554d4a4681
Submitter: Jenkins
Branch: master

commit 3046c4ae22b10f9e4fa83a47bfe089554d4a4681
Author: Salvatore Orlando <email address hidden>
Date: Thu Dec 19 00:26:38 2013 -0800

    Improve handling of security group updates

    Currently updates to security group rules or membership
    are handled by immediately triggering a call to refresh_firewall.
    This call is quite expensive, and it is often executed with a
    very high frequency.

    With this patch, the notification handler simply adds devices for
    which the firewall should be refreshed to a set, which will then
    be processed in another routine. The latter is supposed to
    be called in the main agent loop.

    This patch for 'provider updates' simply sets a flag for refreshing
    the firewall for all devices.

    In order to avoid breaking other agents leveraging the security
    group RPC mixin, the reactive behaviour is still available, and is
    still the default way of handling security group updates.

    Partial-Bug: #1253993
    Partially implements blueprint: neutron-tempest-parallel

    Change-Id: I1574544734865506ff5383404516cc9349c16ec4