In addition create a similar method that doesn't copy objects.
Benchmark for the new no-copy method vs the old one:
```
benchmark old ns/op new ns/op delta
BenchmarkGetControllerOf-12 214 14.8 -93.08%
benchmark old allocs new allocs delta
BenchmarkGetControllerOf-12 1 0 -100.00%
benchmark old bytes new bytes delta
BenchmarkGetControllerOf-12 80 0 -100.00%
```
Benchamrk for the new (copy) method vs the old one:
```
benchmark old ns/op new ns/op delta
BenchmarkGetControllerOf-12 128 114 -10.94%
benchmark old allocs new allocs delta
BenchmarkGetControllerOf-12 1 1 +0.00%
benchmark old bytes new bytes delta
BenchmarkGetControllerOf-12 80 80 +0.00%
```
Overall there is a 10% improvement for the old vs new (copy) method and
huge improvent (x10) for the old vs new (no-copy).
I changed the IsControlledBy and a few other methods to use the new (no-copy) method.
It is inconsistent and confusing to report pod count from all
namespaces but report message for only default namespace.
Added the namespace (default) reporting to clarify this.
Updated comments for usage clarity.
Dealing with unused functions/variables/types. (staticcheck U1000)
Dealing with value never used issue. (staticcheck SA4006)
Dealing with concurrency issue. (staticcheck SA2002 SA4010)
Remove packages from staticcheck failure files: apiextensions-apiserver
Remove the "OrDie" from the name (since it doesn't "or die") and add
an extra check that there is at least 1 node available, since many
callers already did that themselves, and many others should have.
This is needed to allow efficient preemption simulations: during preemption, we remove/add pods from each node before running the filter plugins again to evaluate whether removing/adding specific pods will allow the incoming pod to be scheduled on the node. Instead of calling prefilter again, we should allow the plugin to do incremental update to its pre-computed state.
It was previously possible to instantiate `Reflector` with
`*unstructured.Unstructured` as the expected type but this did not
support checking that event objects were of the correct API
type (e.g. if event object was `v1.Pod` in `Unstructured` form but
`v1.Service` was expected). This commit adds support for providing a
GVK via an `Unstructured` expected type to compare with the GVK of
event objects. The GVK will also be used in reflector log output.
