Results of some YAQL/Jinja functions that hit DB can be cached per transaction

[Renat Akhmerov]

A workflow can use lots of YAQL/Jinja functions like task(), execution() that hit database within one DB transaction. However, those calls to DB are not cached by the SQLAlchemy session since access is not done using primary key (id) but rather things like name or other filters. At the same time some of these functions can be safely cached per one TX if we know that possible changes in parallel transactions can be ignored. "task()" is one of such functions.

[OpenStack Infra (hudson-openstack)]

Change abandoned by Eyal (<email address hidden>) on branch: master
Review: https://review.opendev.org/709693

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/709693
Committed: https://git.openstack.org/cgit/openstack/mistral/commit/?id=756bd5566ac965f62626dd70dc3d09041248f40f
Submitter: Zuul
Branch: master

commit 756bd5566ac965f62626dd70dc3d09041248f40f
Author: Renat Akhmerov <email address hidden>
Date: Tue Feb 25 18:27:29 2020 +0700

    Add caching for YAQL/Jinja expression functions

    * Functions like task() can be safely cached per one DB
      transaction. It will decrease the number of DB hits.
      This patch adds @tx_cached decorator that caches
      any function result using a thread local cache having
      same scope as a DB transaction.
    * Style changes.

    Closes-Bug: #1864823
    Change-Id: Id00eae3cb8483dfe08f549ce7dd981b3c92df09a

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/711172

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/711172
Committed: https://git.openstack.org/cgit/openstack/mistral/commit/?id=77b450d78553d131c70b8c94a269b250d39fc956
Submitter: Zuul
Branch: master

commit 77b450d78553d131c70b8c94a269b250d39fc956
Author: Renat Akhmerov <email address hidden>
Date: Wed Mar 4 14:28:49 2020 +0700

    Add a unit test for @tx_cached and fix a bug in it

    * Added a unit tests for the decorator @tx_cached. The tests
      helped find a bug in the implementation. One of the conditions
      in the decorator was wrong.

    Closes-Bug: #1864823
    Change-Id: I441310539f7949aea569d85ed998deea4fa0d0b0

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/mistral 10.0.0.0b3 development milestone.