[SSSD] [sssd PR#453][opened] Speed up by-ID lookups with the help of the Global Catalog

URL: https://github.com/SSSD/sssd/pull/453 Author: jhrozek Title: #453: Speed up by-ID lookups with the help of the Global Catalog Action: opened PR body: """ These patches implement the RFE requested in https://pagure.io/SSSD/sssd/issue/3468 The design page was sent to sssd-devel for review as: https://lists.fedorahosted.org/archives/list/sssd-devel@lists.fedorahoste... but so far was not merged. Please see the design page for explanation of the general flow, but also feel free to point out if more comments should be added to the code so that developers don't have to go back to design pages. There are still some things I'm working on, but I think at least the cache_req part should be ready for review. Here's what I think is not finished yet: - I don't think the locate domain request works for MPG domains - unit tests should be added for the negcache API additions as well as the DP interface to not decrease the code coverage - I still haven't made up my mind if we should support also the object-by-ID request. I think it would be nice for completeness but I also think it's not strictly required - I only ran several downstream tests, not all, so I don't know if there are some regressions or not """ To pull the PR as Git branch: git remote add ghsssd https://github.com/SSSD/sssd git fetch ghsssd pull/453/head:pr453 git checkout pr453