Fix #277: Periodically write config file while app is running

backend/app.go

@@ -7,6 +7,7 @@ import (
 	"log"
 	"os"
 	"path"
+	"reflect"
 	"time"
 
 	"github.com/dweymouth/supersonic/backend/util"
@@ -50,6 +51,8 @@ type App struct {
 	isFirstLaunch bool // set by config file reader
 	bgrndCtx      context.Context
 	cancel        context.CancelFunc
+
+	lastWrittenCfg Config
 }
 
 func (a *App) VersionTag() string {
@@ -80,6 +83,7 @@ func StartupApp(appName, displayAppName, appVersionTag, configFile, latestReleas
 	a := &App{appName: appName, appVersionTag: appVersionTag, configFile: configFile}
 	a.bgrndCtx, a.cancel = context.WithCancel(context.Background())
 	a.readConfig()
+	a.startConfigWriter(a.bgrndCtx)
 
 	if !a.Config.Application.AllowMultiInstance {
 		log.Println("Creating session lock file")
@@ -166,6 +170,23 @@ func (a *App) startSessionWatcher(sessionPath string) {
 	}
 }
 
+// periodically save config file so abnormal exit won't lose settings
+func (a *App) startConfigWriter(ctx context.Context) {
+	tick := time.NewTicker(2 * time.Minute)
+	go func() {
+		select {
+		case <-ctx.Done():
+			tick.Stop()
+			return
+		case <-tick.C:
+			if !reflect.DeepEqual(&a.lastWrittenCfg, a.Config) {
+				a.Config.WriteConfigFile(a.configPath())
+				a.lastWrittenCfg = *a.Config
+			}
+		}
+	}()
+}
+
 func (a *App) callOnReactivate() {
 	if a.OnReactivate != nil {
 		a.OnReactivate()
@@ -276,6 +297,11 @@ func (a *App) Shutdown() {
 	os.RemoveAll(configdir.LocalConfig(a.appName, sessionDir))
 }
 
+func (a *App) SaveConfigFile() {
+	a.Config.WriteConfigFile(a.configPath())
+	a.lastWrittenCfg = *a.Config
+}
+
 func (a *App) configPath() string {
 	return path.Join(configdir.LocalConfig(a.appName), a.configFile)
 }

backend/config.go

@@ -2,6 +2,7 @@ package backend
 
 import (
 	"os"
+	"sync"
 
 	"github.com/google/uuid"
 	"github.com/pelletier/go-toml/v2"
@@ -206,7 +207,14 @@ func ReadConfigFile(filepath, appVersionTag string) (*Config, error) {
 	return c, nil
 }
 
+var writeLock sync.Mutex
+
 func (c *Config) WriteConfigFile(filepath string) error {
+	if !writeLock.TryLock() {
+		return nil // another write in progress
+	}
+	defer writeLock.Unlock()
+
 	b, err := toml.Marshal(c)
 	if err != nil {
 		return err

ui/mainwindow.go

@@ -100,11 +100,13 @@ func NewMainWindow(fyneApp fyne.App, appName, displayAppName, appVersion string,
 				m.ShowWhatsNewDialog()
 			}
 			m.App.Config.Application.LastLaunchedVersion = app.VersionTag()
+			m.App.SaveConfigFile()
 		} else if t := app.UpdateChecker.VersionTagFound(); t != "" && t != app.Config.Application.LastCheckedVersion {
 			if t != app.VersionTag() {
 				m.ShowNewVersionDialog(displayAppName, t)
 			}
 			m.App.Config.Application.LastCheckedVersion = t
+			m.App.SaveConfigFile()
 		}
 		// register callback for the ongoing periodic update check
 		m.App.UpdateChecker.OnUpdatedVersionFound = func() {