after add_port, get_port_ofport may be called before vswitchd has assigned the ofport

[Terry Wilson]

OVSBridge.add_port() runs ovs-vsctl to add the port, then runs ovs-vsctl again to query the ofport of the newly created port. The ofport gets assigned outside of any kind of transaction, and the OVS api defines an empty set response([]) to mean that the ofport assignment is still pending and a response of '-1' to mean that there is a failure.

The current get_port_ofport code treats these responses both as failures even though '[]' will most likely later succeed. We need to implement a retry mechanism to ensure that we don't incorrectly fail port creation. Raising an exception on retry expiration also seems like a good idea.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/106517

[Kyle Mestery (mestery)]

Moving medium priority bug out of Juno-RC1.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/106517
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=cd78c7cc11940ee2e46e55001b2cfa6fbf0f7159
Submitter: Jenkins
Branch: master

commit cd78c7cc11940ee2e46e55001b2cfa6fbf0f7159
Author: Terry Wilson <email address hidden>
Date: Fri Jul 11 17:55:30 2014 -0600

    Retry on unassigned ofport instead of treating it as a failure

    Open vSwitch will return '[]' when querying an interface's ofport
    when the ofport has not yet been assigned. This doesn't signal a
    failure, but the get_port_ofport code was treating it as such.
    This patch uses a decorator from python-retrying which has been
    added as a dependency of oslo_concurrency and therefore packaged
    everywhere. The call to fetch the ofport is retried until the
    vsctl_timeout is reached and, on failure, INVALID_OFPORT is
    returned.

    The add_port function will attempt to delete the port if
    INVALID_OFPORT is returned from get_port_ofport. add_port is also
    extended to take optional Interface options so that the
    add_tunnel_port and add_patch_port functions can reuse it instead
    of just duplicating its functionality.

    Closes-Bug: #1341020
    Change-Id: Ifc52d8589c7aafd360893cb9c1cdcbf43b04ee2c