feat(batchstore): add storage radius metric (#2163)

pkg/postage/batchstore/metrics.go

@@ -14,6 +14,7 @@ type metrics struct {
 	Inner             prometheus.Gauge
 	Outer             prometheus.Gauge
 	Radius            prometheus.Gauge
+	StorageRadius     prometheus.Gauge
 }
 
 func newMetrics() metrics {
@@ -44,6 +45,12 @@ func newMetrics() metrics {
 			Name:      "radius",
 			Help:      "Radius of responsibility observed by the batchstore.",
 		}),
+		StorageRadius: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: m.Namespace,
+			Subsystem: subsystem,
+			Name:      "storage_radius",
+			Help:      "Radius of responsibility communicated to the localstore",
+		}),
 	}
 }
 

pkg/postage/batchstore/reserve.go

@@ -115,6 +115,7 @@ func (s *store) Unreserve(cb postage.UnreserveIteratorFn) error {
 
 		if s.rs.StorageRadius+1 < v.Radius {
 			s.rs.StorageRadius = v.Radius - 1
+			s.metrics.StorageRadius.Set(float64(s.rs.StorageRadius))
 			if err = s.store.Put(reserveStateKey, s.rs); err != nil {
 				return true, err
 			}