admin: localimporter can make symlink instead of copying whole files

admin/sync/importer_localfs.go

@@ -8,15 +8,20 @@ import (
 )
 
 type LocalImporter struct {
-	Base string
+	Base    string
+	Symlink bool
 }
 
 func (i LocalImporter) Kind() string {
-	return "local file importer: " + i.Base
+	if i.Symlink {
+		return "local file importer (through symlink): " + i.Base
+	} else {
+		return "local file importer: " + i.Base
+	}
 }
 
 func (i LocalImporter) exists(filename string) bool {
-	_, err := os.Stat(path.Join(i.Base, filename))
+	_, err := os.Stat(i.toURL(filename))
 	return !os.IsNotExist(err)
 }
 
@@ -24,6 +29,24 @@ func (i LocalImporter) toURL(filename string) string {
 	return path.Join(i.Base, filename)
 }
 
+func (i LocalImporter) importFile(URI string, next func(string, string) (interface{}, error)) (interface{}, error) {
+	if i.Symlink {
+		dest := getDestinationFilePath(URI)
+
+		if err := os.MkdirAll(path.Dir(dest), 0755); err != nil {
+			return nil, err
+		}
+
+		if i.exists(URI) {
+			os.Symlink(i.toURL(URI), dest)
+		} else {
+			os.Symlink(i.toURL(URI) + "_MERGED", dest)
+		}
+	}
+
+	return ImportFile(i, URI, next)
+}
+
 func (i LocalImporter) getFile(filename string, writer *bufio.Writer) error {
 	if fd, err := os.Open(path.Join(i.Base, filename)); err != nil {
 		return err