imap: improve reconnect stability

improves the robustness of the imap reconnect feature which was
introduced in commit beae17a6da ("imap: auto-reconnects on connection
error").

If a connection error is emitted, the message list is cleared and a
corresponding error message is shown in the ui. Status bar is updated as
well. Upon reconnect, the directories and the message list will be
re-fetched (same behavior as the connect command).

Reconnect can be enabled and disabled with the connect and the
disconnect commands.

Signed-off-by: Koni Marti <koni.marti@gmail.com>

widgets/account.go

@@ -289,8 +289,10 @@ func (acct *AccountView) onMessage(msg types.WorkerMessage) {
 	case *types.LabelList:
 		acct.labels = msg.Labels
 	case *types.ConnError:
-		acct.logger.Printf("Connection error = %v", msg.Error)
+		acct.logger.Printf("connection error: %v", msg.Error)
+		acct.host.SetStatus("Disconnected.")
 		acct.aerc.PushError(fmt.Sprintf("%v", msg.Error))
+		acct.msglist.SetStore(nil)
 		acct.worker.PostAction(&types.Reconnect{}, nil)
 	case *types.Error:
 		acct.logger.Printf("%v", msg.Error)

worker/imap/worker.go

@@ -85,6 +85,11 @@ func (w *IMAPWorker) handleMessage(msg types.WorkerMessage) error {
 		}
 	}()
 
+	checkConn := func() {
+		w.stopConnectionObserver()
+		w.startConnectionObserver()
+	}
+
 	var reterr error // will be returned at the end, needed to support idle
 
 	switch msg := msg.(type) {
@@ -171,9 +176,15 @@ func (w *IMAPWorker) handleMessage(msg types.WorkerMessage) error {
 		}
 	case *types.Connect:
 		if w.client != nil && w.client.State() == imap.SelectedState {
+			if !w.autoReconnect {
+				w.autoReconnect = true
+				checkConn()
+			}
 			reterr = fmt.Errorf("Already connected")
 			break
 		}
+
+		w.autoReconnect = true
 		c, err := w.connect()
 		if err != nil {
 			reterr = err
@@ -187,7 +198,6 @@ func (w *IMAPWorker) handleMessage(msg types.WorkerMessage) error {
 
 		w.startConnectionObserver()
 
-		w.autoReconnect = true
 		w.worker.PostMessage(&types.Done{types.RespondTo(msg)}, nil)
 	case *types.Reconnect:
 		if !w.autoReconnect {
@@ -196,6 +206,7 @@ func (w *IMAPWorker) handleMessage(msg types.WorkerMessage) error {
 		}
 		c, err := w.connect()
 		if err != nil {
+			checkConn()
 			reterr = err
 			break
 		}
@@ -209,18 +220,17 @@ func (w *IMAPWorker) handleMessage(msg types.WorkerMessage) error {
 
 		w.worker.PostMessage(&types.Done{types.RespondTo(msg)}, nil)
 	case *types.Disconnect:
+		w.autoReconnect = false
+		w.stopConnectionObserver()
 		if w.client == nil || w.client.State() != imap.SelectedState {
 			reterr = fmt.Errorf("Not connected")
 			break
 		}
 
-		w.stopConnectionObserver()
-
 		if err := w.client.Logout(); err != nil {
 			reterr = err
 			break
 		}
-		w.autoReconnect = false
 		w.worker.PostMessage(&types.Done{types.RespondTo(msg)}, nil)
 	case *types.ListDirectories:
 		w.handleListDirectories(msg)
@@ -306,9 +316,11 @@ func (w *IMAPWorker) startConnectionObserver() {
 	go func() {
 		select {
 		case <-w.client.LoggedOut():
+			if w.autoReconnect {
 				w.worker.PostMessage(&types.ConnError{
-				Error: fmt.Errorf("Logged Out"),
+					Error: fmt.Errorf("imap: logged out"),
 				}, nil)
+			}
 		case <-w.done:
 			return
 		}