FUSE3 vs read-write IMAP for lei

[Eric Wong <e@80x24.org>]

Eric Wong <e@80x24.org> wrote:
> I don't think lei+FUSE will be as portable or useful as a
> local IMAP server (and maybe JMAP, eventually); but r/w IMAP
> support would be nice..

One thing about lei which really bothers me is that it needs to
write out mail already in local git repos to the FS to be read
by regular MUAs.

This is wasteful, of course; so there's 2 ways I can imagine
exposing mail to ordinary MUAs without excessive disk
traffic/wear:


== read-write IMAP for lei

* connect via localhost (127.0.0.1, [::1]) (don't think local sockets
  are supported by any MUAs)

* May be extended to JMAP; but it's hard to be motivated on JMAP
  since my favorite MUA doesn't do JMAP, yet.

+ portable (can be done in pure Perl + DBD::SQLite + Xapian)

+ we already have a read-only IMAP server which can be extended
  for read/write

- still needs login w/ username+password due to multi-user systems

- may still susceptible to abuse and from multi-user systems

- IMAP gets pretty complex, and MUAs sometimes don't do it well



== FUSE3 - Maildir-oriented FS


+ will require C compiler since old FUSE XS modules don't do
  FUSE3 (for readdirplus); and going w/o readdirplus is
  unimaginable for Maildir.

+ I already have existing (unreleased) AGPL-3 work based on
  FUSE3 + URCU + Perl5 with just-ahead-of-time (JAOT) compilation

* I've seen the light w/ URCU, and can't go back to C without it :P

- likely Linux-only (not sure how good FUSE support will be if
  depending on FUSE3 features)

- kernel caches still incur nasty memory overhead w/ Maildir

- readdir(3) userspace API still sucks


Of course, doing both is an option, too, given enough time...