Convert single GV and lists of GVs into an interface that can handle
more complex scenarios (everything internal, nothing supported). Pass
the interface down into conversion.
We will probably readd these as an opaque object passed down to
conversions that lets the caller get access to more info (like
a negotiated serializer).
reflect.Call is fairly expensive, performing 8 allocations and having to
set up a call stack. Using a fairly straightforward to generate switch
statement, we can bypass that early in conversion (as long as the
function takes responsibility for invocation). We may also be able to
avoid an allocation for the conversion scope, but not positive yet.
```
benchmark old ns/op new ns/op delta
BenchmarkPodConversion-8 14713 12173 -17.26%
benchmark old allocs new allocs delta
BenchmarkPodConversion-8 80 72 -10.00%
benchmark old bytes new bytes delta
BenchmarkPodConversion-8 9133 8712 -4.61%
```
Replace many of the remaining s.Convert() invocations with direct
execution, and make generated methods public. Removes 10% of the
allocations during decode of a pod and ~20-40% of the total CPU time.
Currently, the validation logic validates fields in an object and supply default
values wherever applies. This change factors out defaulting to a set of
defaulting callback functions for decoding (see #1502 for more discussion).
* This change is based on pull request 2587.
* Most defaulting has been migrated to defaults.go where the defaulting
functions are added.
* validation_test.go and converter_test.go have been adapted to not testing the
default values.
* Fixed all tests with that create invalid objects with the absence of
defaulting logic.
Because time.Time doesn't work correctly with our YAML package, it is necessary
to introduce a type, util.Time, which serializes correctly to JSON and YAML.
Eventually we would like timestamping to cut across storage implementations;
for now, we set it in each storage.