Restore Lisk transactional methods
Summary:
Restores a (simplified and improved) version of Lisk transactions.
This doesn't actually use transactions anywhere yet. DifferentialRevisionEditor
is the #1 (and only?) case where we have transaction problems right now, but
sticking save() inside a transaction unconditionally will leave us holding a
transaction open for like a million years while we run Herald rules, etc. I want
to do some refactoring there separately from this diff before making it
transactional.
NOTE: @jungejason / @nh, can one of you verify these unit tests pass on
HPHP/i/vm when you get a chance? I vaguely recall there was some problem with
(int)$resource. We can land this safely without verifying that, but should check
before we start using it anywhere.
Test Plan: Ran unit tests.
Reviewers: btrahan, nh, jungejason
Reviewed By: btrahan
CC: aran, epriestley
Maniphest Tasks: T605
Differential Revision: https://secure.phabricator.com/D1515