derive(Serialize) state: Fsm vs AsyncSeek

[dishmaker]

Any async io function over trait AsyncSeek can be turned into a sans-io FSM.

I think that's a fact - just calling future.poll(..) on a clever object that pauses on seek and read calls is enough to simulate an ArchiveFsm.
So for example async_zip::ZipFileReader can be made into a sync sans-io interface with a wrapper.

Therefore, my open questions are:

• Which paradigm is easier to write in Rust? sans-io or async?¹
• Which paradigm is faster to execute? sans-io or async?
• Can we clone the EntryFsm state to remember decompressor state in the middle of 100 GB file with sans-io? ²
• Can we serialize/save the EntryFsm state into JSON and resume it later with sans-io?³

Some answers are already in video fasterthanlime: The case for sans-io

Footnotes

1. async fn is actually an FSM https://users.rust-lang.org/t/serde-async-state-machine/99648 ↩

2. DecompressorOxide implements Clone ↩

3. async_zip ZipFileReader implements Clone, but not Serialize ↩

[dishmaker]

Well, sans-io rc-zip definitely wins.

async_zip::ZipEntryReader does not implement Clone.