Async tasks

What it does

rustferry::spawn runs an independent Send + 'static future on a worker thread and propagates the active RustFerry runtime. Slint-local futures can instead use slint::spawn_local and return UI changes through its event loop.

Support matrix

Minimal complete example

use rustferry::network::{self, NetworkStatus, NetworkTransport};
use rustferry::testing::TestRuntime;

fn main() -> rustferry::Result<()> {
    let runtime = TestRuntime::new();
    let _guard = runtime.enter();
    runtime.set_network_status(NetworkStatus::online(NetworkTransport::Wifi));

    let task = rustferry::spawn(async { network::is_online() });
    assert!(task.join().expect("worker did not panic")?);
    Ok(())
}

Configuration

Configure only the capability used by the task; the spawn helper itself has no section.

Permissions and entitlements

Determined by the called capability. Never use a background task to bypass a platform permission or UI-thread requirement.

Expected result

The worker sees the same scoped test runtime and returns true.

Common errors

• Borrowed data does not live long enough: move owned values into the future.
• UI handle is not Send: use slint::spawn_local or send a result back with slint::invoke_from_event_loop.
• Worker panic: inspect the JoinHandle; do not convert it to success.

Platform differences

rustferry::spawn is a small thread-based helper, not a mobile background-execution service. OS background execution limits still apply.

Test example

Inject network/permission/probe behavior into TestRuntime, spawn the async operation, join it, and inspect recorded calls.

Example project

The Notifications example uses a Slint-local future for its permission request.