From 6b1b8bf8ae07709b7c227ff62b614cf683152d55 Mon Sep 17 00:00:00 2001
From: andig <cpuidle@gmx.de>
Date: Tue, 27 Feb 2024 21:46:49 +0100
Subject: [PATCH] Retry pv meter reads on error (#12514)

---
 core/helper.go | 10 ++++++++++
 core/site.go   | 35 +++++++++++++----------------------
 2 files changed, 23 insertions(+), 22 deletions(-)

diff --git a/core/helper.go b/core/helper.go
index e03a7f19f..471523d2a 100644
--- a/core/helper.go
+++ b/core/helper.go
@@ -1,6 +1,9 @@
 package core
 
 import (
+	"time"
+
+	"github.com/cenkalti/backoff/v4"
 	"github.com/evcc-io/evcc/util"
 )
 
@@ -12,6 +15,13 @@ var (
 	Voltage float64
 )
 
+// bo returns an exponential backoff for reading meter power quickly
+func bo() *backoff.ExponentialBackOff {
+	bo := backoff.NewExponentialBackOff()
+	bo.MaxElapsedTime = time.Second
+	return bo
+}
+
 // powerToCurrent is a helper function to convert power to per-phase current
 func powerToCurrent(power float64, phases int) float64 {
 	if Voltage == 0 {
diff --git a/core/site.go b/core/site.go
index 12d8b1cfa..81487ea19 100644
--- a/core/site.go
+++ b/core/site.go
@@ -400,9 +400,9 @@ func (site *Site) publishDelta(key string, val interface{}) {
 }
 
 // updatePvMeters updates pv meters. All measurements are optional.
-func (site *Site) updatePvMeters() {
+func (site *Site) updatePvMeters() error {
 	if len(site.pvMeters) == 0 {
-		return
+		return nil
 	}
 
 	var totalEnergy float64
@@ -413,8 +413,7 @@ func (site *Site) updatePvMeters() {
 
 	for i, meter := range site.pvMeters {
 		// pv power
-		power, err := meter.CurrentPower()
-
+		power, err := backoff.RetryWithData(meter.CurrentPower, bo())
 		if err == nil {
 			// ignore negative values which represent self-consumption
 			site.pvPower += max(0, power)
@@ -422,8 +421,8 @@ func (site *Site) updatePvMeters() {
 				site.log.WARN.Printf("pv %d power: %.0fW is negative - check configuration if sign is correct", i+1, power)
 			}
 		} else {
-			err = fmt.Errorf("pv %d power: %v", i+1, err)
-			site.log.ERROR.Println(err)
+			// power is required- return on error
+			return fmt.Errorf("pv %d power: %v", i+1, err)
 		}
 
 		// pv energy (production)
@@ -447,6 +446,8 @@ func (site *Site) updatePvMeters() {
 	site.publish(keys.PvPower, site.pvPower)
 	site.publish(keys.PvEnergy, totalEnergy)
 	site.publish(keys.Pv, mm)
+
+	return nil
 }
 
 // updateBatteryMeters updates battery meters. Power is retried, other measurements are optional.
@@ -455,9 +456,6 @@ func (site *Site) updateBatteryMeters() error {
 		return nil
 	}
 
-	bo := backoff.NewExponentialBackOff()
-	bo.MaxElapsedTime = time.Second
-
 	var totalCapacity, totalEnergy float64
 
 	site.batteryPower = 0
@@ -466,9 +464,7 @@ func (site *Site) updateBatteryMeters() error {
 	mm := make([]batteryMeasurement, len(site.batteryMeters))
 
 	for i, meter := range site.batteryMeters {
-		bo.Reset()
-
-		power, err := backoff.RetryWithData(meter.CurrentPower, bo)
+		power, err := backoff.RetryWithData(meter.CurrentPower, bo())
 		if err == nil {
 			site.batteryPower += power
 			if len(site.batteryMeters) > 1 {
@@ -549,10 +545,7 @@ func (site *Site) updateGridMeter() error {
 		return nil
 	}
 
-	bo := backoff.NewExponentialBackOff()
-	bo.MaxElapsedTime = time.Second
-
-	res, err := backoff.RetryWithData(site.gridMeter.CurrentPower, bo)
+	res, err := backoff.RetryWithData(site.gridMeter.CurrentPower, bo())
 	if err == nil {
 		site.gridPower = res
 		site.log.DEBUG.Printf("grid meter: %.0fW", res)
@@ -601,15 +594,13 @@ func (site *Site) updateGridMeter() error {
 
 // updateMeter updates and publishes single meter
 func (site *Site) updateMeters() error {
-	// errors ignored
-	site.updatePvMeters()
-
-	// power errors returned
+	// TODO parallelize once modbus supports that
+	if err := site.updatePvMeters(); err != nil {
+		return err
+	}
 	if err := site.updateBatteryMeters(); err != nil {
 		return err
 	}
-
-	// power errors returned
 	return site.updateGridMeter()
 }