add a command to force compaction of a volume, removing deleted files

go/storage/store.go

@@ -126,7 +126,7 @@ func (s *Store) CompactVolume(volumeIdString string) error {
 		return fmt.Errorf("Volume Id %s is not a valid unsigned integer!", volumeIdString)
 	}
 	if v := s.findVolume(vid); v != nil {
-		return v.compact()
+		return v.Compact()
 	}
 	return fmt.Errorf("volume id %s is not found during compact!", vid)
 }

go/storage/volume.go

@@ -256,7 +256,7 @@ func (v *Volume) garbageLevel() float64 {
 	return float64(v.nm.DeletedSize()) / float64(v.ContentSize())
 }
 
-func (v *Volume) compact() error {
+func (v *Volume) Compact() error {
 	v.accessLock.Lock()
 	defer v.accessLock.Unlock()