Split the async fs interface, indexedDB, and sqlite-specific code

Hello ! This is very useful work you have been doing here. If I understand well, this repository contains both the Atomic and Shared Array Buffer logic required to provide an async interface on top of emscripten’s synchronous FS, and the code that implements this interface with an IndexedDB backend.

• Is there any part of this code that is specific to sql.js, or could this be reused with any emscripten-compiled code that interacts with files ? If there is code that is specific to sql.js, then would it be feasible to split it from the sync-async bridge and the IndexedDB logic ?

• Would it be possible to split the IndexedDB backend, in order to let the user provide a different implementation? I’m thinking about an HTTP backend in particular.

[kripken]

Interesting stuff here!

In general, I am hoping that we do a large rewrite of the emscripten FS code in the next few months (ASMFS, or related). So any large change might not make sense to add there atm. A small one might make sense though, as if it can be done as a small additional JS FS, then those will get ported to the new rewrite eventually (is the general plan).

I’d be interested to hear if there are things such a rewrite should do to make this easier. One goal is to write it to native code as much as possible to allow for easier sync/async interation, which from the description here sounds relevant. (cc @rstz who I’ve been talking with about this recently)

[jlongster]

@kripken Sorry for my delay – had a lot to catch up on in the last month. Going to be watching this from now on though.

I filed an issue describing the lock/unlock needs on emscripten: https://github.com/emscripten-core/emscripten/issues/15070

Sounds good about the rest of the filesystem changes. As long as there is a way to hook in some JS to those APIs.