stream read large files

weed/server/volume_server_handlers_read.go

@@ -127,6 +127,7 @@ func (vs *VolumeServer) GetOrHeadHandler(w http.ResponseWriter, r *http.Request)
 
 	var count int
 	var needleSize types.Size
+	readOption.AttemptMetaOnly, readOption.MustMetaOnly = shouldAttemptStreamWrite(hasVolume, ext, r)
 	onReadSizeFn := func(size types.Size) {
 		needleSize = size
 		atomic.AddInt64(&vs.inFlightDownloadDataSize, int64(needleSize))
@@ -218,13 +219,33 @@ func (vs *VolumeServer) GetOrHeadHandler(w http.ResponseWriter, r *http.Request)
 		}
 	}
 
-	rs := conditionallyResizeImages(bytes.NewReader(n.Data), ext, r)
-
-	if e := writeResponseContent(filename, mtype, rs, w, r); e != nil {
-		glog.V(2).Infoln("response write error:", e)
+	if !readOption.IsMetaOnly {
+		rs := conditionallyResizeImages(bytes.NewReader(n.Data), ext, r)
+		if e := writeResponseContent(filename, mtype, rs, w, r); e != nil {
+			glog.V(2).Infoln("response write error:", e)
+		}
+	} else {
+		vs.streamWriteResponseContent(filename, mtype, volumeId, n, w, r, readOption)
 	}
 }
 
+func shouldAttemptStreamWrite(hasLocalVolume bool, ext string, r *http.Request) (shouldAttempt bool, mustMetaOnly bool) {
+	if !hasLocalVolume {
+		return false, false
+	}
+	if len(ext) > 0 {
+		ext = strings.ToLower(ext)
+	}
+	if r.Method == "HEAD" {
+		return true, true
+	}
+	_, _, _, shouldResize := shouldResizeImages(ext, r)
+	if shouldResize {
+		return false, false
+	}
+	return true, false
+}
+
 func (vs *VolumeServer) tryHandleChunkedFile(n *needle.Needle, fileName string, ext string, w http.ResponseWriter, r *http.Request) (processed bool) {
 	if !n.IsChunkedManifest() || r.URL.Query().Get("cm") == "false" {
 		return false
@@ -318,3 +339,27 @@ func writeResponseContent(filename, mimeType string, rs io.ReadSeeker, w http.Re
 	})
 	return nil
 }
+
+func (vs *VolumeServer) streamWriteResponseContent(filename string, mimeType string, volumeId needle.VolumeId, n *needle.Needle, w http.ResponseWriter, r *http.Request, readOption *storage.ReadOption) {
+	totalSize := int64(n.DataSize)
+	if mimeType == "" {
+		if ext := filepath.Ext(filename); ext != "" {
+			mimeType = mime.TypeByExtension(ext)
+		}
+	}
+	if mimeType != "" {
+		w.Header().Set("Content-Type", mimeType)
+	}
+	w.Header().Set("Accept-Ranges", "bytes")
+	adjustPassthroughHeaders(w, r, filename)
+
+	if r.Method == "HEAD" {
+		w.Header().Set("Content-Length", strconv.FormatInt(totalSize, 10))
+		return
+	}
+
+	processRangeRequest(r, w, totalSize, mimeType, func(writer io.Writer, offset int64, size int64) error {
+		return vs.store.ReadVolumeNeedleDataInto(volumeId, n, readOption, writer, offset, size)
+	})
+
+}