Metrics: interpolate single missing slots (#26800)

core/metrics/db.go

@@ -5,6 +5,7 @@ import (
 	"time"
 
 	"github.com/evcc-io/evcc/server/db"
+	"github.com/evcc-io/evcc/tariff"
 	"gorm.io/gorm"
 )
 
@@ -51,6 +52,7 @@ func Profile(from time.Time) (*[96]float64, error) {
 	}
 	defer rows.Close()
 
+	var prev time.Time
 	res := make([]float64, 0, 96)
 
 	for rows.Next() {
@@ -61,6 +63,12 @@ func Profile(from time.Time) (*[96]float64, error) {
 			return nil, err
 		}
 
+		// interpolate single missing value, maybe due to regular restarts?
+		if time.Time(ts).Sub(prev) == 2*tariff.SlotDuration {
+			res = append(res, (val+res[len(res)-1])/2)
+		}
+		prev = time.Time(ts)
+
 		res = append(res, val)
 	}
 
@@ -74,8 +82,3 @@ func Profile(from time.Time) (*[96]float64, error) {
 
 	return (*[96]float64)(res), nil
 }
-
-func SlotNum(ts time.Time) int {
-	ts = ts.Local()
-	return ts.Hour()*4 + ts.Minute()/15
-}