[TODO-nova-dpm] get_available_nodes refresh handling is missing

[preethi]

get_available_nodes(self, refresh=False) in the driver code has a refresh flag which is meant to determine if the host names have to be fetched for the hypervisors managed by the compute service or to simple return cached data.

In nova-dpm we have only one CPCSubset managed by a compute service. So refresh = True/False, the name of the CPCsubset will remain to be constant.

Hence the implementation could be:
* If refresh set to false, dont have to invoke the host properties completely, but just return cached data
* If refresh is set to True, pull the properties for Host again but however the CPCsubset name would not have changed.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/461693

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/461693
Committed: https://git.openstack.org/cgit/openstack/nova-dpm/commit/?id=f331120a631d71ebd125b1cba824ed11c0f715ec
Submitter: Jenkins
Branch: master

commit f331120a631d71ebd125b1cba824ed11c0f715ec
Author: Prabhat Ranjan <email address hidden>
Date: Tue May 2 15:01:22 2017 +0530

    get_available_nodes refresh handling is missing

    Closes-Bug: #1669302

    Change-Id: Ibc820b4b63e147e5ca2c4642d0536c3a1dffa649
    Signed-off-by: Prabhat Ranjan <email address hidden>