Comment 3 for bug 1029911

Reviewed: https://review.openstack.org/10532
Committed: http://github.com/openstack/nova/commit/6a5f095b0a9a73c57469b4e5f10694d1b738527f
Submitter: Jenkins
Branch: master

commit 6a5f095b0a9a73c57469b4e5f10694d1b738527f
Author: Eoghan Glynn <email address hidden>
Date: Fri Jul 27 20:34:05 2012 +0100

    Avoid associating floating IP with two instances.

    Addresses LP 1029911.

    Associating an already-associated floating IP with another instance
    results in the floating IP being first disassociated from the original
    instance and then associated with the second instance.

    However when this transfer of the floating IP to the second instance
    occurs, the network info held in the database instance info cache was
    previously only updated for the second instance (via the
    @nova.network.api.refresh_cache decorator).

    As a result, the floating IP was initially reported as being associated
    with *both* instances. This misreporting is temporary - eventually the
    periodic heal_instance_info_cache task will roll around and purge the
    inaccurante network info for the original instance. However depending
    on the frequency configured for this task and the size of the instance
    population, it could take a while for the refresh to occur.

    This issue is addressed by immediately purging the obsolute network info
    when the reassignment occurs.

    Change-Id: Ibfb04997ff4a983d144d81350857cb07475aff54