switch from oslo-incubator cache code to dogpile

[Ihar Hrachyshka]

Oslo-incubator is about to stop support for cache module, so we should get rid of it. The best candidate is probably dogpile. There is also oslo.cache library released, but it has different API and is overkill for our needs (metadata agent optimizations).

[Ihar Hrachyshka (ihar-hrachyshka)]

There are some complications with switching from the module to something different. The main one is that we exposed cache_url from the module into metadata config as-is: https://github.com/openstack/neutron/blob/master/neutron/openstack/common/cache/cache.py#L51

So to switch to something different, we would need to make sure we support the url config option for a cycle the least.

[fangzhen (zhen-fang)]

Hi, I'd like to work on this bug. Do we have a firm prefer on dogpile to oslo.cache? I''m thinking if oslo.cache a more standard way for openstack?

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/290305

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/290305
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=56efc8ac76415070041d125a6e30523caf9b3cbd
Submitter: Jenkins
Branch: master

commit 56efc8ac76415070041d125a6e30523caf9b3cbd
Author: Fang Zhen <email address hidden>
Date: Wed Mar 9 14:46:12 2016 +0800

    Switch to oslo.cache

    Oslo incubator is about to stop for cache module. We could use
    oslo.cache instead. The legacy memory backend is replaced by
    oslo_cache.dict.

    Closes-Bug: #1517883

    Change-Id: I108242ca9f27c9ec47959ce7615bc7d84cae014b

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/325154

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/325154
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=60a8f961377c208c2d72715889c7c4020a0fd03a
Submitter: Jenkins
Branch: master

commit 60a8f961377c208c2d72715889c7c4020a0fd03a
Author: Jakub Libosvar <email address hidden>
Date: Fri Jun 3 11:26:07 2016 +0200

    oslo.cache: Remove memory alias for cache

    Current code replaces 'memory' backend with 'oslo_cache.dict' backend in
    order to keep backward compatibility.

    Related-Bug: 1517883
    Change-Id: Ibcefa13eaf4b1021322eb5bd4320b8306aa0c510

[Doug Hellmann (doug-hellmann)]

This issue was fixed in the openstack/neutron 9.0.0.0b2 development milestone.