From cb99e97f5f12c51a9ab03ada1a2d783eb14b49f7 Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Wed, 3 Jun 2020 17:28:31 +0200
Subject: [PATCH] Introduce network.isClosed

---
 user.go | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/user.go b/user.go
index a58fecd..ca9d801 100644
--- a/user.go
+++ b/user.go
@@ -88,14 +88,20 @@ func (net *network) forEachDownstream(f func(*downstreamConn)) {
 	})
 }
 
+func (net *network) isStopped() bool {
+	select {
+	case <-net.stopped:
+		return true
+	default:
+		return false
+	}
+}
+
 func (net *network) run() {
 	var lastTry time.Time
 	for {
-		select {
-		case <-net.stopped:
+		if net.isStopped() {
 			return
-		default:
-			// This space is intentionally left blank
 		}
 
 		if dur := time.Now().Sub(lastTry); dur < retryConnectMinDelay {
@@ -120,6 +126,9 @@ func (net *network) run() {
 			continue
 		}
 
+		// TODO: this is racy with net.stopped. If the network is stopped
+		// before the user goroutine receives eventUpstreamConnected, the
+		// connection won't be closed.
 		net.user.events <- eventUpstreamConnected{uc}
 		if err := uc.readMessages(net.user.events); err != nil {
 			uc.logger.Printf("failed to handle messages: %v", err)
@@ -131,10 +140,7 @@ func (net *network) run() {
 }
 
 func (net *network) stop() {
-	select {
-	case <-net.stopped:
-		return
-	default:
+	if !net.isStopped() {
 		close(net.stopped)
 	}