Merge pull request #690 from wtfutil/20191011-transmission-race-conditions

Fix some of the transmission module race conditions

modules/transmission/display.go

@@ -9,15 +9,24 @@ import (
 	"github.com/wtfutil/wtf/utils"
 )
 
+func (widget *Widget) display() {
+	widget.ScrollableWidget.Redraw(widget.content)
+}
+
 func (widget *Widget) content() (string, string, bool) {
+	widget.mu.Lock()
+	defer widget.mu.Unlock()
+
 	title := widget.CommonSettings().Title
 	if widget.err != nil {
 		return title, widget.err.Error(), true
 	}
+
 	data := widget.torrents
 	if data == nil || len(data) == 0 {
 		return title, "No data", false
 	}
+
 	str := ""
 
 	for idx, torrent := range data {
@@ -38,10 +47,6 @@ func (widget *Widget) content() (string, string, bool) {
 	return title, str, false
 }
 
-func (widget *Widget) display() {
-	widget.ScrollableWidget.Redraw(widget.content)
-}
-
 func (widget *Widget) prettyTorrentName(name string) string {
 	str := strings.Replace(name, "[", "(", -1)
 	str = strings.Replace(str, "]", ")", -1)

modules/transmission/widget.go

@@ -2,6 +2,7 @@ package transmission
 
 import (
 	"errors"
+	"sync"
 
 	"github.com/hekmon/transmissionrpc"
 	"github.com/rivo/tview"
@@ -15,6 +16,7 @@ type Widget struct {
 
 	client   *transmissionrpc.Client
 	settings *Settings
+	mu       sync.Mutex
 	torrents []*transmissionrpc.Torrent
 	err      error
 }
@@ -43,6 +45,9 @@ func NewWidget(app *tview.Application, pages *tview.Pages, settings *Settings) *
 
 // Fetch retrieves torrent data from the Transmission daemon
 func (widget *Widget) Fetch() ([]*transmissionrpc.Torrent, error) {
+	widget.mu.Lock()
+	widget.mu.Unlock()
+
 	if widget.client == nil {
 		return nil, errors.New("client was not initialized")
 	}
@@ -58,16 +63,18 @@ func (widget *Widget) Fetch() ([]*transmissionrpc.Torrent, error) {
 // Refresh updates the data for this widget and displays it onscreen
 func (widget *Widget) Refresh() {
 	torrents, err := widget.Fetch()
-	if err != nil {
+	count := 0
-		widget.err = err
+
-		widget.torrents = nil
+	if err == nil {
-		widget.SetItemCount(0)
+		count = len(torrents)
-	} else {
-		widget.err = nil
-		widget.torrents = torrents
-		widget.SetItemCount(len(torrents))
 	}
 
+	widget.mu.Lock()
+	widget.err = err
+	widget.torrents = torrents
+	widget.SetItemCount(count)
+	widget.mu.Unlock()
+
 	widget.display()
 }
 
@@ -96,6 +103,9 @@ func (widget *Widget) Unselect() {
 
 // buildClient creates a persisten transmission client
 func buildClient(widget *Widget) {
+	widget.mu.Lock()
+	defer widget.mu.Unlock()
+
 	client, err := transmissionrpc.New(widget.settings.host, widget.settings.username, widget.settings.password,
 		&transmissionrpc.AdvancedConfig{
 			Port: widget.settings.port,
@@ -103,9 +113,8 @@ func buildClient(widget *Widget) {
 	if err != nil {
 		client = nil
 	}
-	widget.client = client
 
-	widget.Refresh()
+	widget.client = client
 }
 
 func (widget *Widget) currentTorrent() *transmissionrpc.Torrent {