If a hinted Node is no longer in the cluster snapshot (e.g. it was
a fake upcoming Node and the real one appeared).
This was introduced in the recent PredicateChecker->PredicateSnapshot
refactor. Previously, PredicateChecker.CheckPredicates() would return
an error if the hinted Node was gone, and HintingSimulator treated
this error the same as failing predicates - it would move on to the
non-hinting logic. After the refactor, HintingSimulator explicitly
errors out if it can't retrieve the hinted Node from the snapshot,
so the behavior changed.
I checked other CheckPredicates()/SchedulePod() callsites, and this is
the only one when ignoring the missing Node makes sense. For the others,
the Node is added to the snapshot just before the call, so it being
missing should cause an error.
RemoveNode is renamed to RemoveNodeInfo for consistency with other
NodeInfo methods.
For DRA, the snapshot will have to potentially allocate ResourceClaims
when adding a Pod to a Node, and deallocate them when removing a Pod
from a Node. This will happen in new methods added to ClusterSnapshot
in later commits - SchedulePod and UnschedulePod. These new methods
should be the "default" way of moving pods around the snapshot going
forward.
However, we'll still need to be able to add and remove pods from the
snapshot "forcefully" to handle some corner cases (e.g. expendable pods).
AddPod is renamed to ForceAddPod, and RemovePod to ForceRemovePod to
highlight that these are no longer the "default" methods of moving pods
around the snapshot, and are bypassing something important.
The new wrapper types should behave like the direct schedulerframework
types for most purposes, so most of the migration is just changing
the imported package.
Constructors look a bit different, so they have to be adapted -
mostly in test code. Accesses to the Pods field have to be changed
to a method call.
After this, the schedulerframework types are only used in the new
wrappers, and in the parts of simulator/ that directly interact with
the scheduler framework. The rest of CA codebase operates on the new
wrapper types.
Kuba Tużnik
Aleksandra Malinowska
Daniel Gutowski
Bartłomiej Wróblewski
Daniel Kłobuszewski