Comment 7 for bug 1723030

Reviewed: https://review.openstack.org/584082
Committed: https://git.openstack.org/cgit/openstack/oslo.policy/commit/?id=3e3820600174a67933cc1dd986066354bf3c25d3
Submitter: Zuul
Branch: stable/pike

commit 3e3820600174a67933cc1dd986066354bf3c25d3
Author: Mateusz Kowalski <email address hidden>
Date: Tue Oct 24 09:32:45 2017 +0200

    Avoid redundant policy syntax checks

    Introduce a private variable inside Enforcer class to remember
    status of the last policy syntax checks in order to avoid
    redundant calls to the check_rules() method.

    Having this flag makes the whole rules mechanism faster, as under
    certain conditions check_rules() method was being executed
    multiple times even when not needed.

    Change-Id: Id3992fc0cb567451049a12ebdc6851e737573bb8
    Closes-bug: #1723030
    Co-Authored-By: Ben Nemec <email address hidden>
    (cherry picked from commit 909a1ea3a7aceb6e0637058b9c6a53d14043d6d1)