public void GetSpaceUsed(out ulong spaceUsed, IEmptyVolumeCacheCallback callback)
 {
     spaceUsed = ComputeSpaceUsed(new ComputeFreeSpaceProgress(callback));
 }
 public void Purge(ulong spaceToFree, IEmptyVolumeCacheCallback callback)
 {
     FreeSpace(spaceToFree, new FreeSpaceProgress(callback));
 }
 internal FreeSpaceProgress(IEmptyVolumeCacheCallback callback)
 {
     Callback = callback;
 }