Currently, the patch does the following:
Kicks off workflow from stack.update_or_create:
Once the dependency graph is calculated, the leaves
of the graph are all casted into the RPC worker bus.
Worker RPC check_resource worfklow:
Workers will then start working on each resource
individually. Once a resource operation is finished,
sync points are used to check if the parent resource
can be worked on. Resources that finish early will
wait for their siblings to finish. The sibling that
finishes last will trigger the creation/updation/deletion
of it's parent. This process then goes on for all nodes
until the roots of the graph are processed.
Marks stack as complete when roots have finished.
Once the roots of the graph are successfully processed,
the previous raw template which was needed for rollback
in case something went wrong will now be deleted from the
database. The stack is then marked as complete.
Largely follows the convergence prototype code in
Implements blueprint convergence-check-workflow