lock not purged if engine restarted

[Chaoyi Huang]

If kingbird engine was restarted(use Ctrl+C to exit kingbird-engine to repeat this bug, it may happen in production if the node is powered-off suddenly, or other reason), then the lock will be remained in the DB, the periodic sync-job can't get the lock, while no sync-job is running.

[Dimitri Mazmanov (sorantis)]

I've registered a blueprint that covers a more general problem https://blueprints.launchpad.net/kingbird/+spec/engine-reporting
The blueprint should also fix this bug

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/353386
Committed: https://git.openstack.org/cgit/openstack/kingbird/commit/?id=62fea4fa062f23ba99e095796f7a8014498ca735
Submitter: Jenkins
Branch: master

commit 62fea4fa062f23ba99e095796f7a8014498ca735
Author: Dimitri Mazmanov <email address hidden>
Date: Wed Aug 10 13:07:32 2016 +0200

    Add service registry

    The proposed service registry provides a mechanism to track all running
    kingbird engines by making them periodically update service entries in
    the database. If one of the engines fails to update the database it will
    be removed from the registry and corresponding lock entries will also be
    purged.

    Change-Id: Ifd785073343c5873f69dfb10146f1957d7b92264
    Closes-Bug: #1610609
    Implements: blueprint engine-reporting