Oslo messaging port broke graceful shutdown of services in Nova

[Nikola Đipanov]

After the port of Nova to oslo.messaging (https://review.openstack.org/#/c/39929) graceful shutdown of services introduced by https://blueprints.launchpad.net/nova/+spec/graceful-shutdown in I-1 got broken.

In order to make this work again we need to make sure that Nova services call oslo.messaging MessageHandlingServer wait() method so that it gives a chance to the running greenthreads to finish.

[Nikola Đipanov (ndipanov)]

The patch is here: https://review.openstack.org/#/c/82070/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/82070
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=dd5a56ee9ad9e27e016ccbf1a1358747712edee9
Submitter: Jenkins
Branch: master

commit dd5a56ee9ad9e27e016ccbf1a1358747712edee9
Author: Nikola Dipanov <email address hidden>
Date: Fri Mar 21 12:12:18 2014 +0100

    Wait till message handling is done on service stop

    In order to be able to perform graceful shutdown of services, we need to
    wait for all the current message handling thread to finish before
    exiting from the service process.

    Oslo.messaging MessageHandlingServer class provides this facility
    through it's wait() method, so we need to call it in nova Service stop()
    method which gets called when gracefull shutdown is requested by sending
    the process SIGINT or SIGTERM.

    Closes-bug:#1295625
    Change-Id: I8556b598f6263a2d4d77e8315950ef1b298aa0a1