refactor lockedobjects_db.py

[Omer Anson]

There are several issues with lockedobjects_db.py:

It is a decorator, which gets a 'type' (defined only locally), which tells it how to find the 'id' by which it locks. This code is overly complex, error prone, and unintuitive.

A more intuitive method would be one of the following:

1. Have a specific decorator per type. The decorator passes a method to extract the lock 'id', rather than figuring it out during locking with a huge (15 elements and counting) if-else dispatch list.

2. Have a context (e.g. 'with lockedobjects_db.lock(id):' which locks when we enter the block, and unlocks when we leave. The ID is given during call. The benefit of this is that we can lock only the calls to nb_api (which is what we want to lock), additional mangling of e.g. Neutron data is outside the lock, and this solution is more general i.e. it is not Neutron specific (unlike the current solution)

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/560792
Committed: https://git.openstack.org/cgit/openstack/dragonflow/commit/?id=d083aa621178d283a98d9f0a7d57d7b412a68b4b
Submitter: Zuul
Branch: master

commit d083aa621178d283a98d9f0a7d57d7b412a68b4b
Author: Omer Anson <email address hidden>
Date: Wed Apr 11 12:29:39 2018 +0300

    lockedobjects_db: Extract nested lock detection to a method

    Partial-Bug: #1740667
    Change-Id: If349f337ae0279b0b846ec92e0df209700bc83c5

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/560793
Committed: https://git.openstack.org/cgit/openstack/dragonflow/commit/?id=dc8610a2bcefbd4ca46710a0df0446b2cf4df438
Submitter: Zuul
Branch: master

commit dc8610a2bcefbd4ca46710a0df0446b2cf4df438
Author: Omer Anson <email address hidden>
Date: Wed Apr 11 13:07:36 2018 +0300

    lockedobjects_db: Move lock logic to a context-manager method

    Partial-Bug: #1740667
    Change-Id: I4b1fd42e05785dc7ec3b06ba69c3655f60d43a19

[OpenStack Infra (hudson-openstack)]

Change abandoned by Sean McGinnis (<email address hidden>) on branch: master
Review: https://review.opendev.org/560794