proxy/grpcproxy/watcher.go
func (w *watcher) post(wr *pb.WatchResponse) bool {
	select {
	case w.wps.watchCh <- wr:
	case <-time.After(50 * time.Millisecond):
		w.wps.cancel()
		return false
	}
	return true
}
func (w *watcher) post(wr *pb.WatchResponse) bool {
	select {
	case w.wps.watchCh <- wr:
	case <-time.After(50 * time.Millisecond):
		w.wps.cancel()
		return false
	}
	return true
}
// post puts a watch response on the watcher's proxy stream channel