Comment 2 for bug 1196924

Reviewed: https://review.openstack.org/35303
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=b32d01d44ca5711c96d192df51bf7acd34f52556
Submitter: Jenkins
Branch: master

commit b32d01d44ca5711c96d192df51bf7acd34f52556
Author: Phil Day <email address hidden>
Date: Tue Jul 2 15:32:57 2013 +0100

    Stop, Rescue, and Delete should give guest a chance to shutdown

    Currently in libvirt stop, shelve, rescue, and delete simply
    destroy the underlying VM. Some GuestOS's do not react well to this
    type of power failure, and so it would be better if these operations
    followed the same approach as soft_reboot and give the guest as
    chance to shutdown gracefully. Even where VM is being deleted,
    it may be booted from a volume which will be reused on another
    server.

    The change is implemented by adding a clean_shutdown parameter
    to the relevant methods from the compute/api layer downwards
    and into the virt drivers. The implementation in the libvirt
    driver is also provided. Other drivers are modified just to
    expect the additional parameter.

    The timer configuration value previous used by soft_reboot in
    libvirt is moved up to virt/driver so it can be used by other drivers.

    The timer logic itself is changed from simple loop counting with one
    second sleeps to a more precise approach, since testing showed that
    other calls in the loop could introduce a difference of up to +50% on
    the expected duration. This can extent the default two minute to
    three minutes, which would not be acceptable in some environments
    and breaks some of the tempest tests.

    A separate config value defines what the default shutdown
    behaviour for delete should be (default False to keep compatibility
    with current behaviour).

    This code is structured to enable a subsequent API change to add
    clean/forced options to the stop and delete methods

    Also as a minor tidy-up moved the repeated definition of
    FakeLoopingCall in test_libvirt be common across tests

    Partially-Implements: blueprint user-defined-shutdown
    Closes-Bug: #1196924

    DocImpact

    Change-Id: Ie69aa2621cb52d6fefdc19f664247b069d6782ee