Extend cloud file system with copy and compression

In-Memory Cloud File System V2: Copy, Capacity Updates, Compress/Decompress

Design an in-memory file system with per-user quotas and additional operations.

Data model / rules

• Each file has:
  • name (unique string)
  • size (positive int)
  • owner (user id)
• Each user has:
  • capacity
  • used
• A user may only own files such that used <= capacity .

API

1. add_user(user_id, capacity) -> bool
   • Create a user with used = 0 .
2. add_file_by(user_id, name, size) -> bool
   • Add a new file owned by user_id .
   • Fail if user missing, name exists, or would exceed capacity.
3. add_file(name, size) -> bool
   • Add a file owned by a special admin user with effectively unlimited capacity (or explicitly create admin with very large capacity).
4. copy_file(from_name, to_name) -> bool
   • Duplicate an existing file to a new name.
   • The copy has the same size and owner as the source.
   • Fail if from_name missing, to_name already exists, or the owner’s capacity would be exceeded.
5. get_file_size(name) -> int | null
   • Return size or null if missing.
6. get_n_largest(prefix, suffix, n) -> list<string>
   • Filter files with name starting with prefix and ending with suffix .
   • Return up to n formatted: "name(size)" .
   • Sort by size desc, then name asc.
7. update_capacity(user_id, new_capacity) -> bool
   • Update the user’s capacity.
   • If used > new_capacity , repeatedly delete the user’s largest files (tie-break by name asc/desc—state your tie-break clearly) until used <= new_capacity .
   • Return false if user missing.
8. compress_file(name) -> bool
   • Convert a file into a compressed version:
     • Only if name exists and does not already represent a compressed file.
     • New file name becomes name + "compress" (or another fixed suffix; be consistent).
     • New size becomes floor(old_size / 2) .
     • Ownership stays the same.
     • Replace the original (remove old name, add new name).
     • Update the owner’s used accordingly.
9. decompress_file(name) -> bool
   • Only valid if name ends with the compression suffix.
   • New name removes the suffix; new size becomes old_size * 2 .
   • Fail if the decompressed name already exists or if the owner would exceed capacity.
   • Replace the compressed file with the decompressed one.

Notes

• Aim for correct bookkeeping of used and efficient deletion of largest files (e.g., heap + lazy deletion).
• Assume up to ~1e5 operations.