Comment 9 for bug 1850864

Reviewed: https://review.opendev.org/694560
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=8c2b944dc08377fa84d1264ce1b24fbbada44c52
Submitter: Zuul
Branch: stable/rocky

commit 8c2b944dc08377fa84d1264ce1b24fbbada44c52
Author: Slawek Kaplonski <email address hidden>
Date: Thu Oct 31 23:12:03 2019 +0100

    Switch to use cast method in dhcp_ready_on_ports method

    When DHCP agent reports to the neutron-server which ports are
    ready, it was using call() method from rpc client.
    That caused blocking dhcp agent's dhcp_ready_ports_loop thread which
    blocks to send info about other ready ports if there are any.

    Method call() should be used when RPC caller returns a value to the
    caller but that's not the case here. On neutron server side this
    RPC method is only calling provisioning_complete() method to
    finish provisioning of ports. And is not returning anything.

    So to make sending dhcp ready ports to neutron-server much faster
    this patch switch to use cast() method from rpc client.
    This method don't block to wait for return value from RPC caller.

    Change-Id: Ie119693854aa283b863a1eac2bdae3330c2b6a9d
    Closes-Bug: #1850864
    (cherry picked from commit 1a686fb401eca1843b81292fc88c13a2e6fd274d)