peer+server: remove persistent connections for peers with no open channels remaining

server.go

@@ -1476,6 +1476,22 @@ func (s *server) establishPersistentConnections() error {
 	return nil
 }
 
+// prunePersistentPeerConnection removes all internal state related to
+// persistent connections to a peer within the server. This is used to avoid
+// persistent connection retries to peers we do not have any open channels with.
+func (s *server) prunePersistentPeerConnection(compressedPubKey [33]byte) {
+	srvrLog.Infof("Pruning peer %x from persistent connections, number of "+
+		"open channels is now zero", compressedPubKey)
+
+	pubKeyStr := string(compressedPubKey[:])
+
+	s.mu.Lock()
+	delete(s.persistentPeers, pubKeyStr)
+	delete(s.persistentPeersBackoff, pubKeyStr)
+	s.cancelConnReqs(pubKeyStr, nil)
+	s.mu.Unlock()
+}
+
 // BroadcastMessage sends a request to the server to broadcast a set of
 // messages to all peers other than the one specified by the `skips` parameter.
 //