getFileFromMemory() method still uses file system IO and returns a Future

## 💬 Questions and Help

Hello, I have a question - how can I access the file from in-memory storage synchronously, ideally without touching the file system IO? The `getFileFromMemory()` method returns future, and I really need the file access to be instantaneous.

Start by inspecting the getFileFromMemory() method and the in-memory cache implementation. Determine whether synchronous access without file-system I/O is supported by the current design, then identify the API behavior and tests needed to establish what a completed change would mean.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.