### Description of Changes
Issue: https://coreosdev.atlassian.net/browse/QUAY-632
## Reviewer Checklist
- [ ] It works!
- [ ] Comments provide sufficient explanations for the next contributor
- [ ] Tests cover changes and corner cases
- [ ] Follows Quay syntax patterns and format
this creates an interface for hidding details of the data model for pre oci and post oci code
Issue: https://coreosdev.atlassian.net/browse/QUAY-632
- [ ] It works!
- [ ] Comments provide sufficient explanations for the next contributor
- [ ] Tests cover changes and corner cases
- [ ] Follows Quay syntax patterns and format
Makes the lookup query underneath the transaction smaller if there are a lot of images referenced directly by tag. We still must do the direct referenced check within the transaction, but this should reduce the scope of the search space a bit.
This prevents us from creating a massive join when there are a large number of tags in the repository, which can result in locking the entire DB for long periods of time. Instead of the join, we just iteratively lookup any images found to be directly referenced by a tag or found as a parent of another image, both of which should be indexed lookups. Once done, we only remove those images and then iterate until the working set stops changing.
Addresses QUAY-672 by handling all status codes that are not 404 and 5xx
and moving response decoding inside the try/except block to ensure that
the response object is in scope.
Previously, if we attempted to georeplicate storage from the existing location and, somehow, that existing location did not exist, we'd still mark the new location as invalid. This is a major problem for storage engines that are not consistent. Now, we first try a back off strategy to find the image in the existing storage and, as well, if the replication fails in any way, we log it.
before we would return a 400 without a message because the errors were not being caught
Issue: https://www.pivotaltracker.com/story/show/145459707
- [ ] It works!
- [ ] Comments provide sufficient explanations for the next contributor
- [ ] Tests cover changes and corner cases
- [ ] Follows Quay syntax patterns and format
