Merge pull request filecoin-project#5254 from turuslan/fix/chainxchg-…

…buffered

Chainxchg write response timeout

chain/exchange/server.go

@@ -56,7 +56,11 @@ func (s *server) HandleStream(stream inet.Stream) {
 	}
 
 	_ = stream.SetDeadline(time.Now().Add(WriteResDeadline))
-	if err := cborutil.WriteCborRPC(stream, resp); err != nil {
+	buffered := bufio.NewWriter(stream)
+	if err = cborutil.WriteCborRPC(buffered, resp); err == nil {
+		err = buffered.Flush()
+	}
+	if err != nil {
 		_ = stream.SetDeadline(time.Time{})
 		log.Warnw("failed to write back response for handle stream",
 			"err", err, "peer", stream.Conn().RemotePeer())