You are never guaranteed to be able to do anything during a crash. You are better off handling these kinds of edge cases in a recovery phase during the start of your app.

[–] bleistift2@sopuli.xyz 23 points 2 days ago (1 children)

It’s not a crash. It’s a graceful shutdown. I expected that to also shutdown my app gracefully.

I’m actually trying to store the program state that hasn’t been persisted yet to disk. Good luck doing that after the next boot.

[–] chonglibloodsport@lemmy.world 5 points 2 days ago (1 children)

Persist everything to disk in real time. When the signal hits exit immediately.

[–] bleistift2@sopuli.xyz 8 points 2 days ago (2 children)

Persist everything to disk in real time.

That’s the thing I’m trying to avoid.

[–] barsoap@lemm.ee 3 points 2 days ago* (last edited 2 days ago) (1 children)

Easier to do than to get never-exercised edge-case code to work flawlessly. Are you sure you can't just throw sqlite at the problem? It's often overkill but, hey, it's there on the shelf, might as well use it and I've seen it out-perform hand-rolled data structures. Non-persistent ones, written by very confident C coders. And remember crashes are unavoidable, if nothing else then someone can trip over the power cord.

[–] bleistift2@sopuli.xyz 2 points 2 days ago* (last edited 2 days ago) (1 children)

You can’t know that from my issue description, but throwing a database at that problem really is ridiculous overkill.

Still thanks for the suggestion

[–] barsoap@lemm.ee 1 points 1 day ago* (last edited 1 day ago)

It's mostly about throwing ACID at the problem, sqlite just happens to be battle-tested to a ludicrous degree, it's light enough to not be unconscionable overhead in simple situations (unless you're on embedded), and performant enough to also deal with nastier situations so I prefer it over some random K/V store with the same guarantees. It's also a widely-used and stable data format which might come in handy.

That said, if you want to go lightweight do consider good, ole, POSIX filesystem guarantees, in particular that mv is atomic (as long as you stay on the same filesystem but that's easy to ensure by mv'ing within a directory). That's not durable on its own, you'll need to fsync for that, and consistency and integrity is up to your code.

[–] chonglibloodsport@lemmy.world 1 points 2 days ago

Admittedly it’s very difficult if you want to maintain consistency but the benefits are enormous!

[–] barsoap@lemm.ee 3 points 2 days ago* (last edited 2 days ago)

Crash-only software. To be resilient you need some kind of ACID anyway which means that you can let go of your shutdown procedure and just send yourself SIGKILL instead.