DRA ResourceClaim controller: updated mutation cache based on events

The controller would recover eventually because it double-checks when seeing
the pod status update, but when reacting to events it recovers faster.

Kubernetes-commit: 03c34ede467ea16580beee3937f9997070421529

CHANGELOG.md

@@ -4,6 +4,23 @@ Go API changes are typically not included in the Kubernetes release notes, so
 noteworthy Go API changes *may* be documented here. This is currently not
 *required*, so consult the git history to see all changes.
 
+### mutation cache: support informer events
+
+Calling OnAddOrUpdate and OnDelete from event handlers is optional. Calling
+them has the advantage that the mutation cache is updated sooner. It also fixes
+incorrectly reporting a locally updated item when a) using "include adds" and
+b) the updated item got deleted in the apiserver and informer cache.
+
+Although formally a Go API break because the MutationCache interface gets
+extended, in practice that interface is expected to have only the single
+implementation in client-go itself, so no-one should be affected by this.
+
+```
+- ./tools/cache.MutationCache.OnAddOrUpdate: added
+- ./tools/cache.MutationCache.OnDelete: added
+- ./tools/cache.MutationCache.internal: added unexported method
+```
+
 ### restmapper + discovery: add context-aware APIs
 
 See [PR #129109](https://github.com/kubernetes/kubernetes/pull/129109).

tools/cache/mutation_cache.go

@@ -46,6 +46,11 @@ type MutationCache interface {
 	Mutation(interface{})
 	OnAddOrUpdate(obj runtime.Object)
 	OnDelete(obj runtime.Object)
+
+	// This interface is not meant to be implemented elsewhere.
+	// Marking it as internal enables future changes without
+	// triggering apidiff.
+	internal()
 }
 
 // ResourceVersionComparator is able to compare object versions.
@@ -356,6 +361,8 @@ func (c *mutationCache) OnDelete(obj runtime.Object) {
 	c.mutationCache.Add(key, t, c.ttl)
 }
 
+func (c *mutationCache) internal() {}
+
 // etcdObjectVersioner implements versioning and extracting etcd node information
 // for objects that have an embedded ObjectMeta or ListMeta field.
 type etcdObjectVersioner struct{}