plugins/driver: update driver interface to support streaming stats
client/tr: use streaming stats api
TODO:
* how to handle errors and closed channel during stats streaming
* prevent tight loop if Stats(ctx) returns an error
drivers: update drivers TaskStats RPC to handle streaming results
executor: better error handling in stats rpc
docker: better control and error handling of stats rpc
driver: allow stats to return a recoverable error
This PR plumbs the plugins done ctx through the base and driver plugin
clients (device already had it). Further, it adds generic handling of
gRPC stream errors.
Driver plugin framework to facilitate development of driver plugins.
Implementing plugins only need to implement the DriverPlugin interface.
The framework proxies this interface to the go-plugin GRPC interface generated
from the driver.proto spec.
A testing harness is provided to allow implementing drivers to test the full
lifecycle of the driver plugin. An example use:
func TestMyDriver(t *testing.T) {
harness := NewDriverHarness(t, &MyDiverPlugin{})
// The harness implements the DriverPlugin interface and can be used as such
taskHandle, err := harness.StartTask(...)
}