better control for reader caching

weed/server/filer_server_handlers_read.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"fmt"
+	"github.com/chrislusf/seaweedfs/weed/util/mem"
 	"io"
 	"mime"
 	"net/http"
@@ -189,7 +190,9 @@ func (fs *FilerServer) GetOrHeadHandler(w http.ResponseWriter, r *http.Request)
 		}
 		width, height, mode, shouldResize := shouldResizeImages(ext, r)
 		if shouldResize {
-			data, err := filer.ReadAll(fs.filer.MasterClient, entry.Chunks)
+			data := mem.Allocate(int(totalSize))
+			defer mem.Free(data)
+			err := filer.ReadAll(data, fs.filer.MasterClient, entry.Chunks)
 			if err != nil {
 				glog.Errorf("failed to read %s: %v", path, err)
 				w.WriteHeader(http.StatusNotModified)