Add download speed limit support (#3408)

weed/server/filer_server.go

@@ -68,6 +68,7 @@ type FilerOption struct {
 	SaveToFilerLimit      int64
 	ConcurrentUploadLimit int64
 	ShowUIDirectoryDelete bool
+	DownloadMaxBytesPs    int64
 }
 
 type FilerServer struct {

weed/server/filer_server_handlers_read.go

@@ -238,7 +238,7 @@ func (fs *FilerServer) GetOrHeadHandler(w http.ResponseWriter, r *http.Request)
 			}
 		}
 
-		err = filer.StreamContent(fs.filer.MasterClient, writer, chunks, offset, size)
+		err = filer.StreamContentWithThrottler(fs.filer.MasterClient, writer, chunks, offset, size, fs.option.DownloadMaxBytesPs)
 		if err != nil {
 			stats.FilerRequestCounter.WithLabelValues(stats.ErrorReadStream).Inc()
 			glog.Errorf("failed to stream content %s: %v", r.URL, err)