MongoDB prepare needs to wait for Mongo to actually start

[Matthew Van Dijk]

The code in the manager's prepare function tells the service to start but does not wait for it to complete. This causes errors if the process startup takes a while (frequently happens for config servers). A poll on the service status needs to be done right after this line: https://github.com/openstack/trove/blob/master/trove/guestagent/datastore/experimental/mongodb/manager.py#L64

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/203650

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/203650
Committed: https://git.openstack.org/cgit/openstack/trove/commit/?id=df5da486ebdfa9221f2df7cb4ba302177d5e5eab
Submitter: Jenkins
Branch: master

commit df5da486ebdfa9221f2df7cb4ba302177d5e5eab
Author: Matt Van Dijk <email address hidden>
Date: Wed Jul 15 11:31:11 2015 -0400

    MongoDB prepare needs to wait for Mongo to start

    MongoDB's prepare method assumes that the mongod service has finished
    starting. This may not be the case. It needs to wait.
    The fix is to use the polling code in the start_db function, so factor
    this out.

    Change-Id: I2f1e6ecec3f9c0b438007f01334168ea4fbe3884
    Closes-bug: #1474522