From 78d6841bd13ece95d3d738b3b9e920403626cd3d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=B8ren=20Rasmussen?= <sr@jondahl.net>
Date: Tue, 2 Aug 2022 20:59:27 +0200
Subject: [PATCH] Refactor configuration reload

---
 cmd/fermentord/loop.go             |  3 ++-
 cmd/fermentord/main.go             |  4 ++--
 internal/configuration/config.go   | 11 ++++++++---
 internal/configuration/observer.go | 15 ++++++++++++++-
 internal/lcd/hd44780.go            |  3 ++-
 5 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/cmd/fermentord/loop.go b/cmd/fermentord/loop.go
index 8924577..b3fddf2 100644
--- a/cmd/fermentord/loop.go
+++ b/cmd/fermentord/loop.go
@@ -38,7 +38,7 @@ func mainLoop(ctx context.Context, wg *sync.WaitGroup, js nats.JetStream) {
 
 	chConfigChange := make(chan configuration.Configuration, 1)
 	chn := configuration.NewChangeNotifier()
-	viper.OnConfigChange(chn.OnConfigChange)
+	defer chn.Close()
 
 	// Configuration updates
 	chn.Subscribe(chConfigChange)
@@ -46,6 +46,7 @@ func mainLoop(ctx context.Context, wg *sync.WaitGroup, js nats.JetStream) {
 	chn.Subscribe(ctrl.ConfigUpdates)
 	//chn.Subscribe(display.ConfiguUpdate)
 	chn.Notify(configuration.Global())
+	viper.OnConfigChange(chn.OnConfigChange)
 	viper.WatchConfig()
 
 	// NATS
diff --git a/cmd/fermentord/main.go b/cmd/fermentord/main.go
index 8c0f262..1996348 100644
--- a/cmd/fermentord/main.go
+++ b/cmd/fermentord/main.go
@@ -29,10 +29,10 @@ func main() {
 	defer sentry.Flush(10 * time.Second)
 
 	// Configuration
-	configuration.LoadConfiguration()
+	configuration.Initialize()
+	config := configuration.LoadConfiguration()
 
 	// NATS
-	config := configuration.Global()
 	servers := strings.Join(config.NATS.Servers, ",")
 	userInfo := nats.UserInfo(config.NATS.Username, config.NATS.Password)
 	nc, err := nats.Connect(servers, userInfo)
diff --git a/internal/configuration/config.go b/internal/configuration/config.go
index 9759cf1..0adbeb1 100644
--- a/internal/configuration/config.go
+++ b/internal/configuration/config.go
@@ -24,7 +24,7 @@ func Global() (c Configuration) {
 	return
 }
 
-func LoadConfiguration() {
+func Initialize() {
 	setDefaults()
 
 	viper.AddConfigPath("/etc")
@@ -32,6 +32,11 @@ func LoadConfiguration() {
 	viper.AddConfigPath(".")
 	viper.SetConfigName("fermentord")
 	viper.SetConfigType("toml")
+}
+
+func LoadConfiguration() Configuration {
+	globalLock.Lock()
+	defer globalLock.Unlock()
 
 	if err := viper.ReadInConfig(); err != nil {
 		log.Printf("Error loading configuration: %v", err)
@@ -43,7 +48,7 @@ func LoadConfiguration() {
 		log.Fatal(err)
 	}
 
-	globalLock.Lock()
 	globalConfig = *config
-	globalLock.Unlock()
+
+	return globalConfig
 }
diff --git a/internal/configuration/observer.go b/internal/configuration/observer.go
index 00d0b6d..7401069 100644
--- a/internal/configuration/observer.go
+++ b/internal/configuration/observer.go
@@ -1,21 +1,30 @@
 package configuration
 
 import (
+	"fmt"
 	"log"
+	"time"
 
 	"github.com/fsnotify/fsnotify"
+	"github.com/getsentry/sentry-go"
 )
 
 type ChangeNotifier struct {
 	channels []chan<- Configuration
+	hub      *sentry.Hub
 }
 
 func NewChangeNotifier() *ChangeNotifier {
 	return &ChangeNotifier{
 		channels: make([]chan<- Configuration, 0),
+		hub:      sentry.CurrentHub().Clone(),
 	}
 }
 
+func (p *ChangeNotifier) Close() {
+	p.hub.Flush(10 * time.Second)
+}
+
 func (p *ChangeNotifier) Subscribe(ch chan<- Configuration) {
 	p.channels = append(p.channels, ch)
 }
@@ -24,13 +33,17 @@ func (p *ChangeNotifier) Notify(config Configuration) {
 	for _, ch := range p.channels {
 		select {
 		case ch <- config:
+
 		default:
+			err := fmt.Errorf("channel overflow on a ChangeNotifier notification channel")
+			p.hub.CaptureException(err)
+			log.Print(err)
 		}
 	}
 }
 
 func (p *ChangeNotifier) OnConfigChange(in fsnotify.Event) {
 	log.Print("Reloading configuration")
-	config := Global()
+	config := LoadConfiguration()
 	p.Notify(config)
 }
diff --git a/internal/lcd/hd44780.go b/internal/lcd/hd44780.go
index d1e1c5c..4a516b9 100644
--- a/internal/lcd/hd44780.go
+++ b/internal/lcd/hd44780.go
@@ -79,6 +79,8 @@ func (p *LCD) Close() error {
 		log.Print(err)
 	}
 
+	p.hub.Flush(10 * time.Second)
+
 	return p.bus.Close()
 }
 
@@ -120,7 +122,6 @@ func (p *LCD) SetState(state controllers.ChamberState) {
 
 func (p *LCD) Run(ctx context.Context, wg *sync.WaitGroup) {
 	defer wg.Done()
-	defer p.hub.Flush(10 * time.Second)
 
 	for {
 		select {