peer: make ping manager send sync

In this commit, we make the ping manager sync blocking. This ensures
that we don't start the ping timer until after we've actually sent out
the ping on the wire. Otherwise, it's possible that if processing the
normal outgoing queue is very delayed, that we expire the ping timer
before we even send anything out to the remote peer.

We also increase the msg size buffer. As otherwise, due to TCP head of
the line blocking, we can still timeout the ping sends if we're just
waiting for the remote party to receive the ping in the first place
after a flurry of sends.

Author: Roasbeef

peer/brontide.go

@@ -94,7 +94,7 @@ const (
 	torTimeoutMultiplier = 3
 
 	// msgStreamSize is the size of the message streams.
-	msgStreamSize = 5
+	msgStreamSize = 256
 )
 
 var (
@@ -733,7 +733,15 @@ func NewBrontide(cfg Config) *Brontide {
 		IntervalDuration: p.scaleTimeout(pingInterval),
 		TimeoutDuration:  p.scaleTimeout(pingTimeout),
 		SendPing: func(ping *lnwire.Ping) {
-			p.queueMsg(ping, nil)
+			// We'll provide an errChan so we can make this a fully
+			// synchronous send.
+			errChan := make(chan error, 1)
+			p.queueMsg(ping, errChan)
+
+			select {
+			case <-errChan:
+			case <-p.cg.Done():
+			}
 		},
 		OnPongFailure: func(err error) {
 			eStr := "pong response failure for %s: %v " +

peer/ping_manager.go

@@ -141,15 +141,15 @@ func (m *PingManager) pingHandler() {
 				PaddingBytes: m.cfg.NewPingPayload(),
 			}
 
-			// Set up our bookkeeping for the new Ping.
+			m.cfg.SendPing(ping)
+
+			// Set up our bookkeeping as we've sent the ping.
 			if err := m.setPingState(pongSize); err != nil {
 				m.cfg.OnPongFailure(err)
 
 				return
 			}
 
-			m.cfg.SendPing(ping)
-
 		case <-m.pingTimeout.C:
 			m.resetPingState()