Incorrect compute node stats

[Brian Elliott]

There is an issue where compute node stats can record incorrect counter values for things like vm_state and task_state. This is related to how the code tracks changes in instance state.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/12476

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/12476
Committed: http://github.com/openstack/nova/commit/8dc34a0aba7f29f3514e3f95abc67596a49317c7
Submitter: Jenkins
Branch: master

commit 8dc34a0aba7f29f3514e3f95abc67596a49317c7
Author: Brian Elliott <email address hidden>
Date: Sun Sep 2 19:29:56 2012 +0000

    Fix and cleanup compute node stat tracking

    Fix an issue where compute node stats are not reported correctly
    if the instance's state was modified from outside of the compute
    host. (e.g. nova-api server changing task_state prior to invoking
    a rebuild_instance on the compute manager)

    Also did some general cleanup on the stats code.

    bug 1046591

    Change-Id: I5d9fc78f22df6854777c5957cbc69c8dd5ec10d3