How can I get the callback which means the image was really in diskCache

I wanner use fresco do something about prefetch，it means without a SimpleDraweeView target, so it seems that PipelineDraweeControllerBuilder is useless. I use BaseDataSubscriber and its onNewResultImpl, but it just stand for memoryCache exist.

And I want to known the file exists in diskcache timely ,and Guaranteed . therefore, I can tell the webView the local file path and so on.

Question two：
` CloseableReference imageReference = dataSource.getResult();
final CloseableReference closeableReference = imageReference.clone();`
I use the above code in order to get the download inputStream , For the purpose of not affecting fresco cache logic，i use clone ，Fortunately ，It works， but I am worried about whether it affects memory.

Looking forward to your reply，thanks