logging: fix race condition in startup

If a panic occurs in one of the workers, it can happen after the UI was
initialised, but before the cleanup function has been registered. With
this the start of the worker loops is deferred until the cleanup routine
was registered.

Signed-off-by: Moritz Poldrack <git@moritz.sh>

aerc.go

@@ -166,11 +166,13 @@ func main() {
 		ui   *libui.UI
 	)
 
+	deferLoop := make(chan struct{})
+
 	aerc = widgets.NewAerc(conf, logger, func(cmd []string) error {
 		return execCommand(aerc, ui, cmd)
 	}, func(cmd string) []string {
 		return getCompletions(aerc, cmd)
-	}, &commands.CmdHistory)
+	}, &commands.CmdHistory, deferLoop)
 
 	ui, err = libui.Initialize(aerc)
 	if err != nil {
@@ -180,6 +182,7 @@ func main() {
 	logging.UICleanup = func() {
 		ui.Close()
 	}
+	close(deferLoop)
 
 	if conf.Ui.MouseEnabled {
 		ui.EnableMouse()

widgets/account-wizard.go

@@ -535,7 +535,7 @@ func (wizard *AccountWizard) finish(tutorial bool) {
 	wizard.conf.Accounts = append(wizard.conf.Accounts, account)
 
 	view, err := NewAccountView(wizard.aerc, wizard.conf, &account,
-		wizard.aerc.logger, wizard.aerc)
+		wizard.aerc.logger, wizard.aerc, nil)
 	if err != nil {
 		wizard.aerc.NewTab(errorScreen(err.Error(), wizard.conf.Ui),
 			account.Name)

widgets/account.go

@@ -47,8 +47,8 @@ func (acct *AccountView) UiConfig() config.UIConfig {
 }
 
 func NewAccountView(aerc *Aerc, conf *config.AercConfig, acct *config.AccountConfig,
-	logger *log.Logger, host TabHost) (*AccountView, error) {
-
+	logger *log.Logger, host TabHost, deferLoop chan struct{},
+) (*AccountView, error) {
 	acctUiConf := conf.GetUiConfig(map[config.ContextType]string{
 		config.UI_CONTEXT_ACCOUNT: acct.Name,
 	})
@@ -90,6 +90,10 @@ func NewAccountView(aerc *Aerc, conf *config.AercConfig, acct *config.AccountCon
 	go func() {
 		defer logging.PanicHandler()
 
+		if deferLoop != nil {
+			<-deferLoop
+		}
+
 		worker.Backend.Run()
 	}()
 

widgets/aerc.go

@@ -48,8 +48,8 @@ type Choice struct {
 
 func NewAerc(conf *config.AercConfig, logger *log.Logger,
 	cmd func(cmd []string) error, complete func(cmd string) []string,
-	cmdHistory lib.History) *Aerc {
-
+	cmdHistory lib.History, deferLoop chan struct{},
+) *Aerc {
 	tabs := ui.NewTabs(&conf.Ui)
 
 	statusbar := ui.NewStack(conf.Ui)
@@ -85,7 +85,7 @@ func NewAerc(conf *config.AercConfig, logger *log.Logger,
 	conf.Triggers.ExecuteCommand = cmd
 
 	for i, acct := range conf.Accounts {
-		view, err := NewAccountView(aerc, conf, &conf.Accounts[i], logger, aerc)
+		view, err := NewAccountView(aerc, conf, &conf.Accounts[i], logger, aerc, deferLoop)
 		if err != nil {
 			tabs.Add(errorScreen(err.Error(), conf.Ui), acct.Name)
 		} else {