fix(core): clear State map on exit

[FabianLars]

related to #14420

This is very fucked up and shouldn't be done right?

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[Legend-Master]

This is probably not what we want, someone could still be holding onto one of the pointers returned from the state manager while calling this (unless we change the states to Arc/Rc)

I honestly feel like the entire state system is a bit redundant considering it just stores things globally which you can already do with static except for maybe multiple tauri instances

[FabianLars]

Yeah exactly. I don't know how much that matters on app shutdown though.

But I only opened this PR to learn something, not to actually merge this.

[raphaelmenges]

I honestly feel like the entire state system is a bit redundant considering it just stores things globally which you can already do with static except for maybe multiple tauri instances

You mean something like this?

static STATE: OnceLock<std::sync::Mutex<State>> = OnceLock::new();

pub fn get_state() -> &'static std::sync::Mutex<State> {
    STATE.get_or_init(|| {
        std::sync::Mutex::new(State::new())
    })
}

[Legend-Master]

Yeah something like that

[WSH032]

This is probably not what we want, since someone could still be holding onto one of the pointers returned from the state manager while calling this (unless we change the states to Arc/Rc).

The state has the same lifetime as the manager, which to some extent mitigates this issue, because you shouldn’t be using tauri’s API after exit.
Nonetheless, I think this might be a breaking change, as it alters the previous behavior.
(Oh, I see — the cyclic references caused the memory leak. Then I think this is reasonable, as long as we note this in the Manager::state documentation.)

[raphaelmenges]

OnceLock appears to also not drop its contents at the end:

Static items have the static lifetime, which outlives all other lifetimes in a Rust program. Static items do not call drop at the end of the program.

[Legend-Master]

The state has the same lifetime as the manager, which to some extent mitigates this issue, because you shouldn’t be using tauri’s API after exit.

Yeah.. but from looking at how we use them in RunEvent::Exit, we can't change this until v3 at least

https://github.com/tauri-apps/plugins-workspace/blob/3019063ae1a3cda689cff6b8b786c8b770b0496b/plugins/single-instance/src/platform_impl/windows.rs#L111-L129

Static items have the static lifetime, which outlives all other lifetimes in a Rust program. Static items do not call drop at the end of the program.

Yeah, you'll need to do it manually as well...