Adapt read and write paths to async I/O about libsql HOT 4 OPEN

Lack of async fs APIs currently blocks SQLite from working with most web apis when compiled to WASM. Eg it requires sync versions of https://developer.mozilla.org/en-US/docs/Web/API/FileSystem which aren't available in many contexts

from libsql.

Is this going to be done by polling, multithreading or by being event-driven? Are you going to provide callbacks that the caller program can hook into their event loop? Making it event-driven seems preferable to polling. And of course threading introduces its own complexity issues.

from libsql.

Event-driven is preferable from the performance perspective, but it would also mean overhauling most of the existing architecture, which we'd rather avoid. So as for now, the first iteration is planned to be implemented with polling.

from libsql.

Event-driven is preferable from the performance perspective

and that's not always the case either - in a busy system, polling actually tends to cause less overhead

from libsql.