Crate poll_promise

poll-promise is a Rust crate for polling the result of a concurrent (e.g. async) operation.

It is particularly useful in games and immediate mode GUI:s, where one often wants to start a background operation and then ask “are we there yet?” on each subsequent frame until the operation completes.

Example:

let promise = Promise::spawn_thread("slow_operation", something_slow);

// Then in the game loop or immediate mode GUI code:
if let Some(result) = promise.ready() {
    // Use/show result
} else {
    // Show a loading screen
}

Features

poll-promise can be used with any async runtime, but a few convenience methods are added when compiled with the following features:

tokio

If you enable the tokio feature you can use Promise::spawn_async and Promise::spawn_blocking which will spawn tasks in the surrounding tokio runtime.

web

If you enable the web feature you can use Promise::spawn_async which will spawn tasks using wasm_bindgen_futures::spawn_local.