From a48d3432c2aaa76a7c0c6dbe8cc62e5bab86c1aa Mon Sep 17 00:00:00 2001
From: andig <andi@evcc.io>
Date: Sun, 5 Oct 2025 00:35:25 +0200
Subject: [PATCH] Tariffs: reduce cache cpu cycles (#24110)

---
 tariff/proxy.go | 31 +++++++++++++++++--------------
 tariff/slots.go | 15 ++++++---------
 2 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/tariff/proxy.go b/tariff/proxy.go
index b8bbfd0bd..3b470a464 100644
--- a/tariff/proxy.go
+++ b/tariff/proxy.go
@@ -24,6 +24,7 @@ type CachingProxy struct {
 	typ    string
 	config map[string]any
 
+	cached *cached
 	tariff api.Tariff
 }
 
@@ -150,16 +151,24 @@ func (p *CachingProxy) dynamicTariff() bool {
 }
 
 func (p *CachingProxy) cacheGet(until time.Time) (*cached, error) {
-	res, err := cacheGet(p.key)
-	if err != nil {
-		return nil, err
+	if p.cached == nil {
+		res, err := cacheGet(p.key)
+		if err != nil {
+			return nil, err
+		}
+
+		p.cached = res
 	}
 
-	if !ratesValid(res.Rates, until) {
+	if !ratesValid(p.cached.Rates, until) {
 		return nil, errors.New("not enough rates")
 	}
 
-	res.Rates = currentRates(res.Rates)
+	res := &cached{
+		Rates: currentRates(p.cached.Rates),
+		Type:  p.cached.Type,
+	}
+
 	if len(res.Rates) == 0 {
 		return nil, errors.New("no current rates")
 	}
@@ -186,21 +195,15 @@ func untilEndOfTomorrow() time.Time {
 }
 
 func ratesValid(rr api.Rates, until time.Time) bool {
-	if len(rr) == 0 {
-		return false
-	}
-
-	rr.Sort()
-
-	return !rr[len(rr)-1].End.Before(until)
+	return len(rr) > 0 && !rr[len(rr)-1].End.Before(until)
 }
 
 func currentRates(rr api.Rates) api.Rates {
 	res := make(api.Rates, 0, len(rr))
-	now := now.With(time.Now()).BeginningOfHour()
+	now := time.Now().Truncate(SlotDuration)
 
 	for _, r := range rr {
-		if !r.End.Before(now) {
+		if r.End.After(now) {
 			res = append(res, r)
 		}
 	}
diff --git a/tariff/slots.go b/tariff/slots.go
index b8ea47a76..8ab934953 100644
--- a/tariff/slots.go
+++ b/tariff/slots.go
@@ -23,6 +23,10 @@ func (t *SlotWrapper) Rates() (api.Rates, error) {
 	}
 
 	var res api.Rates
+	if len(rates) > 0 {
+		// assume all slots of equal length
+		res = make(api.Rates, 0, len(rates)*max(int(rates[0].End.Sub(rates[0].Start)/SlotDuration), 1))
+	}
 
 	now := time.Now().Truncate(SlotDuration)
 
@@ -31,14 +35,12 @@ func (t *SlotWrapper) Rates() (api.Rates, error) {
 			continue
 		}
 
-		interval := r.End.Sub(r.Start)
-		numSlots := max(int(interval/SlotDuration), 1)
+		numSlots := max(int(r.End.Sub(r.Start)/SlotDuration), 1)
 
 		for j := range numSlots {
 			start := r.Start.Add(time.Duration(j) * SlotDuration)
 			end := start.Add(SlotDuration)
-
-			var val float64
+			val := r.Value
 
 			switch t.Type() {
 			case api.TariffTypeSolar: //, api.TariffTypeCo2
@@ -47,12 +49,7 @@ func (t *SlotWrapper) Rates() (api.Rates, error) {
 					start1 := rates[i+1].Start
 					frac := float64(start.Sub(start0)) / float64(start1.Sub(start0))
 					val = r.Value + frac*(rates[i+1].Value-r.Value)
-				} else {
-					val = r.Value
 				}
-
-			default:
-				val = r.Value
 			}
 
 			res = append(res, api.Rate{