the caching layer on endpoint is redundant.
Here are the 3 related objects in picture:
devicemanager <-> endpoint <-> plugin
Plugin is the source of truth for devices
and device health status.
devicemanager maintain healthyDevices,
unhealthyDevices, allocatedDevices based on updates
from plugin.
So there is no point for endpoint caching devices,
this patch is removing this caching layer on endpoint,
Also removing the Manager.Devices() since i didn't
find any caller of this other than test, i am adding a
notification channel to facilitate testing,
If we need to get all devices from manager in future,
it just need to return healthyDevices + unhealthyDevices,
we don't have to call endpoint after all.
This patch makes code more readable, data model been simplified.
incompatible changes:
- Add GetDevicePluginOptions rpc call. This is needed when we switch
from Registration service to probe-based plugin watcher.
- Change AllocateRequest and AllocateResponse to allow device requests
from multiple containers in a pod. Currently only made mechanical
change on the devicemanager and test code to cope with the API but
still issues an Allocate call per container. We can modify the
devicemanager in 1.11 to issue a single Allocate call per pod.
The change will also facilitate incremental API change to communicate
pod level information through Allocate rpc if there is such future
need.
