hyperv: Refactor collector, added DataStore, Virtual SMB and Dynamic Memory Balancer metrics (click PR number for more information) (#1712)

Signed-off-by: Jan-Otto Kröpke <mail@jkroepke.de>

internal/perfdata/collector.go

@@ -112,7 +112,7 @@ func NewCollector(object string, instances []string, counters []string) (*Collec
 	}
 
 	if _, err := collector.Collect(); err != nil {
-		return nil, fmt.Errorf("failed to collect initial data: %w", err)
+		return collector, fmt.Errorf("failed to collect initial data: %w", err)
 	}
 
 	return collector, nil

internal/perfdata/error.go

@@ -4,6 +4,8 @@ package perfdata
 
 import "errors"
 
+var ErrNoData = NewPdhError(PdhNoData)
+
 // Error represents error returned from Performance Counters API.
 type Error struct {
 	ErrorCode uint32