Slow listing projects for user with many role assignments

This seems like something we should be able to fix and backport to Ocata since it has an impact on performance.

Looks like the slow code here is strip_domain_roles:

    def _strip_domain_roles(self, role_refs):
        """Post process assignment list for domain roles.

        Domain roles are only designed to do the job of inferring other roles
        and since that has been done before this method is called, we need to
        remove any assignments that include a domain role.

        """
        def _role_is_global(role_id):
            ref = self.role_api.get_role(role_id)
            return (ref['domain_id'] is None)

        filter_results = []
        for ref in role_refs:
            if _role_is_global(ref['role_id']):
                filter_results.append(ref)
        return filter_results

With caching the time would probably go away, but as it is, it's making a DB lookup for each role.

Fix proposed to branch: master
Review: https://review.openstack.org/487143

Steve, I've proposed a patch that implements caching for the API in question [0]. Let me know if that helps in any way. It might end up being a work-around until we can get some patches proposed to speed up the assignment API.

[0] https://review.openstack.org/#/c/487143/

Related fix proposed to branch: master
Review: https://review.openstack.org/491921

Reviewed: https://review.openstack.org/491921
Committed: https://git.openstack.org/cgit/openstack/keystone/commit/?id=9fccd38d1b177664c64bbf987a8c31d06d7cfc60
Submitter: Jenkins
Branch: master

commit 9fccd38d1b177664c64bbf987a8c31d06d7cfc60
Author: Lance Bragstad <email address hidden>
Date: Tue Aug 8 20:37:10 2017 +0000

    Remove unused hints from assignment APIs

    The controller is responsible for listing user projects based on role
    assignments and would build a hints objects and pass it to the
    assignment manager. This is a common pattern used across keystone's
    APIs. But, the assignment API never actually passed the hints objects
    to the backend implementation.

    This commit removes the hints from being passed to the manager for
    list_projects_for_user and list_domains_for_user because those
    APIs never use the hints object. This should allow us to implement
    caching to speed up those calls later.

    Change-Id: I9b1c8c30ca6a78dd6e78add7de278e467ceea046
    Related-Bug: 1700852

Reviewed: https://review.openstack.org/487143
Committed: https://git.openstack.org/cgit/openstack/keystone/commit/?id=63124f703a81074793360c1b91711b6ee5a76196
Submitter: Jenkins
Branch: master

commit 63124f703a81074793360c1b91711b6ee5a76196
Author: Lance Bragstad <email address hidden>
Date: Tue Jul 25 17:03:55 2017 +0000

    Cache list projects and domains for user

    Listing projects and domains for a user based on their role
    assignments was noted as being really slow, especially when users
    have a lot of assignments. This commit implements caching to mitigate
    the issue while we continue to investigate ways to speed up the
    assignment API.

    Change-Id: I72e398c65f01aa4f9a37f817d184a13ed01089ce
    Closes-Bug: 1700852

This issue was fixed in the openstack/keystone 12.0.0.0rc1 release candidate.