Comment 14 for bug 1451576

Reviewed: https://review.openstack.org/187985
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=03b70b109449f3b9329834c7aa88fd26ed71cf26
Submitter: Jenkins
Branch: master

commit 03b70b109449f3b9329834c7aa88fd26ed71cf26
Author: Cedric Brandily <email address hidden>
Date: Thu May 28 18:35:17 2015 +0200

    Ensure non-overlapping cidrs in subnetpools with galera

    This change enables galera support in _lock_subnetpool[1]. It uses an
    update to disallow 2 transactions performing concurrent subnet
    allocation in the same subnetpool to succeed: the 2 transactions will
    conflict because they update the same row so the db (including Galera
    multi-writer cluster) will discard the last transaction and
    Controller.create[2] will catch and retry the "discarded" allocation.

    This change adds the "hash" attribute in "subnetpools" table to enable
    previous update.

    [1] neutron.ipam.subnet_alloc.SubnetAllocator
    [2] neutron.api.v2.base

    Change-Id: I74f7100a6fd9b7787be693adffec15ec468d0018
    Closes-Bug: #1451576