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.

1. 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.

1. 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).

1. 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.

1. get_file_size(name) -> int | null

• Return size or null if missing.

1. 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.

1. 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.

1. 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.

1. 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.