在 Rocket 或 Tauri 中异步加载 state

Question

I have an app written in tauri (for a standalone app) and rocket (for the web version).

The app uses a large(-ish) file that's kept in memory (basically an in-memory database) and takes somewhere between 1-10s to load, but I don't want the app to block for that duration before opening.

My code (the rocket part) currently looks something like this:

#[rocket::get("/api/search?<searchTerm>&<take>&<skip>")]
pub fn search<'a>(
    searchTerm: &str,
    take: Option<u32>,
    skip: Option<u32>,
    db: &rocket::State<Database>
) -> Json<SearchResult>
{
    Json(db.search(searchTerm, take, skip))
}

#[rocket::launch]
fn rocket() {
    // ...
    let db = Database::load().expect("Failed loading database");
    rocket::build()
        .mount("/", rocket::routes![search])
        .manage(db);
}

How can I run Database::load() asynchronously, without blocking the startup of the rocket server/tauri app and still be able to get it in search ?

Answer 1

I ended up using global state and a RwLock like this:

static DB: RwLock::<Option<Database>> = RwLock::<Option<Database>>::new(None);

#[rocket::get("/api/search?<searchTerm>&<take>&<skip>")]
pub fn search<'a>(
    searchTerm: &str,
    take: Option<u32>,
    skip: Option<u32>,
    db: &rocket::State<Database>
) -> Json<SearchResult>
{
    if let Some(db) = DB.read().expect("Cannot read the database because it failed to load.").as_ref() {
        Json(jdict_shared::shared_api::search(db, searchTerm, take, skip))
    }
    else {
        // TODO: return proper error code
        Json(jdict_shared::shared_api::SearchResult::default())
    }
}

#[rocket::launch]
fn rocket() {
    // ...
    std::thread::spawn(|| {
        *DB.write().unwrap() = Some(Database::load(cfg.jdict));
    });

    rocket::build().mount("/", rocket::routes![search]);
}

This works, but is a really ugly solution in my opinion.