fix: Use a channel for bufferring tailnet connection updates (coder#3940)

kylecarbs · web-flow · commit 7718fa53c991 · 2022-09-07T22:18:35.000-05:00
diff --git a/go.mod b/go.mod
@@ -49,7 +49,7 @@ replace github.com/tcnksm/go-httpstat => github.com/kylecarbs/go-httpstat v0.0.0
 
 // There are a few minor changes we make to Tailscale that we're slowly upstreaming. Compare here:
 // https://github.com/tailscale/tailscale/compare/main...coder:tailscale:main
-replace tailscale.com => github.com/coder/tailscale v1.1.1-0.20220907140144-9abacd14802f
+replace tailscale.com => github.com/coder/tailscale v1.1.1-0.20220907193453-fb5ba5ab658d
 
 require (
 	cdr.dev/slog v1.4.2-0.20220525200111-18dce5c2cd5f
diff --git a/go.sum b/go.sum
@@ -352,8 +352,8 @@ github.com/coder/glog v1.0.1-0.20220322161911-7365fe7f2cd1 h1:UqBrPWSYvRI2s5RtOu
 github.com/coder/glog v1.0.1-0.20220322161911-7365fe7f2cd1/go.mod h1:EWib/APOK0SL3dFbYqvxE3UYd8E6s1ouQ7iEp/0LWV4=
 github.com/coder/retry v1.3.0 h1:5lAAwt/2Cm6lVmnfBY7sOMXcBOwcwJhmV5QGSELIVWY=
 github.com/coder/retry v1.3.0/go.mod h1:tXuRgZgWjUnU5LZPT4lJh4ew2elUhexhlnXzrJWdyFY=
-github.com/coder/tailscale v1.1.1-0.20220907140144-9abacd14802f h1:iWOlTwTwh1hCr6I0D2bWFHKRaPb7PmcxPISFkkj3DdM=
-github.com/coder/tailscale v1.1.1-0.20220907140144-9abacd14802f/go.mod h1:MO+tWkQp2YIF3KBnnej/mQvgYccRS5Xk/IrEpZ4Z3BU=
+github.com/coder/tailscale v1.1.1-0.20220907193453-fb5ba5ab658d h1:IQ8wJn8MfDS+sesYPpn3EDAyvoGMxFvyyE9uWtcfU6w=
+github.com/coder/tailscale v1.1.1-0.20220907193453-fb5ba5ab658d/go.mod h1:MO+tWkQp2YIF3KBnnej/mQvgYccRS5Xk/IrEpZ4Z3BU=
 github.com/coder/wireguard-go/tun/netstack v0.0.0-20220823170024-a78136eb0cab h1:9yEvRWXXfyKzXu8AqywCi+tFZAoqCy4wVcsXwuvZNMc=
 github.com/coder/wireguard-go/tun/netstack v0.0.0-20220823170024-a78136eb0cab/go.mod h1:TCJ66NtXh3urJotTdoYQOHHkyE899vOQl5TuF+WLSes=
 github.com/containerd/aufs v0.0.0-20200908144142-dab0cbea06f4/go.mod h1:nukgQABAEopAHvB6j7cnP5zJ+/3aVcE7hCYqvIwAHyE=
diff --git a/tailnet/conn.go b/tailnet/conn.go
@@ -260,29 +260,38 @@ func (c *Conn) SetNodeCallback(callback func(node *Node)) {
 			DERPLatency:   c.lastDERPLatency,
 		}
 	}
+	// A send queue must be used so nodes are sent in order.
+	queue := make(chan *Node, 16)
+	go func() {
+		for {
+			select {
+			case <-c.closed:
+				return
+			case node := <-queue:
+				callback(node)
+			}
+		}
+	}()
 	c.wireguardEngine.SetNetInfoCallback(func(ni *tailcfg.NetInfo) {
 		c.lastMutex.Lock()
 		c.lastPreferredDERP = ni.PreferredDERP
 		c.lastDERPLatency = ni.DERPLatency
 		node := makeNode()
+		queue <- node
 		c.lastMutex.Unlock()
-		callback(node)
 	})
 	c.wireguardEngine.SetStatusCallback(func(s *wgengine.Status, err error) {
 		if err != nil {
 			return
 		}
-		endpoints := make([]string, 0, len(s.LocalAddrs))
+		c.lastMutex.Lock()
+		c.lastEndpoints = make([]string, 0, len(s.LocalAddrs))
 		for _, addr := range s.LocalAddrs {
-			endpoints = append(endpoints, addr.Addr.String())
+			c.lastEndpoints = append(c.lastEndpoints, addr.Addr.String())
 		}
-		go func() {
-			c.lastMutex.Lock()
-			c.lastEndpoints = endpoints
-			node := makeNode()
-			c.lastMutex.Unlock()
-			callback(node)
-		}()
+		node := makeNode()
+		queue <- node
+		c.lastMutex.Unlock()
 	})
 }
 
