From: Matt Joiner <anacrolix@gmail.com>
Date: Mon, 25 Oct 2021 05:15:42 +0000 (+1100)
Subject: Fix race running and closing webtorrent tracker clients
X-Git-Tag: v1.34.0^2~11
X-Git-Url: http://www.git.stargrave.org/?a=commitdiff_plain;h=e178f99f35a6d3c55352cabef55c852ff966f80e;p=btrtrc.git

Fix race running and closing webtorrent tracker clients
---

diff --git a/webtorrent/tracker_client.go b/webtorrent/tracker_client.go
index 7972fb08..e6908c74 100644
--- a/webtorrent/tracker_client.go
+++ b/webtorrent/tracker_client.go
@@ -106,9 +106,18 @@ func (tc *TrackerClient) doWebsocket() error {
 	return err
 }
 
-func (tc *TrackerClient) Run() error {
+// Finishes initialization and spawns the run routine, calling onStop when it completes with the
+// result. We don't let the caller just spawn the runner directly, since then we can race against
+// .Close to finish initialization.
+func (tc *TrackerClient) Start(onStop func(error)) {
 	tc.pingTicker = time.NewTicker(60 * time.Second)
 	tc.cond.L = &tc.mu
+	go func() {
+		onStop(tc.run())
+	}()
+}
+
+func (tc *TrackerClient) run() error {
 	tc.mu.Lock()
 	for !tc.closed {
 		tc.mu.Unlock()
diff --git a/wstracker.go b/wstracker.go
index 4e83ca5f..f93f784a 100644
--- a/wstracker.go
+++ b/wstracker.go
@@ -55,12 +55,11 @@ func (me *websocketTrackers) Get(url string) (*webtorrent.TrackerClient, func())
 				}),
 			},
 		}
-		go func() {
-			err := value.TrackerClient.Run()
+		value.TrackerClient.Start(func(err error) {
 			if err != nil {
 				me.Logger.Printf("error running tracker client for %q: %v", url, err)
 			}
-		}()
+		})
 		if me.clients == nil {
 			me.clients = make(map[string]*refCountedWebtorrentTrackerClient)
 		}