main-loop-async 0.1.0

//! Example of usage with egui. Base example copied from
//! <https://github.com/emilk/egui/blob/main/examples/hello_world_simple/src/main.rs>
//!
//! NB: This one is not run as part of the test since it's interactive. Run by
//! using the following command:
//!
//! ```rust
//! cargo run --example egui_simple --features="egui"
//! ```

#[cfg(all(
    not(target_arch = "wasm32"),
    feature = "native-tokio",
    feature = "egui"
))]
use std::sync::{
    Arc,
    atomic::{AtomicU8, Ordering},
};

#[cfg(all(
    not(target_arch = "wasm32"),
    feature = "native-tokio",
    feature = "egui"
))]
use main_loop_async::{DataState, DataStateRetry, spawn_with_return};

#[cfg(all(
    not(target_arch = "wasm32"),
    feature = "native-tokio",
    feature = "egui"
))]
fn main() -> eframe::Result {
    use eframe::egui;

    // Setup Tokio Runtime on a separate thread
    let rt = Helper::create_tokio_runtime();
    let _enter = rt.enter(); // This Guard must be held to call `tokio::spawn` anywhere in the program
    Helper::start_background_worker(rt); // This is also needed to prevent the runtime from stopping

    // Our application state:
    let mut name = "Arthur".to_owned();
    let mut age = 42;
    let mut data_state = DataState::None;
    // This is more intended for use with things that load automatically, if you do
    // not intend to use it this way you will need a separate variable to track if
    // it should be attempting to load
    let mut data_state_retry = DataStateRetry::new(3, 5000..10_000);
    let mut seconds_required_to_load = 10;
    let atomic_load_count = Arc::new(AtomicU8::new(0));

    eframe::run_ui_native(
        "egui Example",
        eframe::NativeOptions::default(),
        move |ui, _frame| {
            egui::CentralPanel::default().show_inside(ui, |ui| {
                ui.heading("egui Example");
                ui.horizontal(|ui| {
                    let name_label = ui.label("Your name: ");
                    ui.text_edit_singleline(&mut name)
                        .labelled_by(name_label.id);
                });
                ui.add(egui::Slider::new(&mut age, 0..=120).text("age"));
                if ui.button("Increment").clicked() {
                    age += 1;
                }
                ui.label(format!("Hello '{name}', age {age}"));

                // Data from the spawned task will show here after the user clicks
                ui.separator();
                Helper::ui_show_data(
                    ui,
                    &mut data_state,
                    &mut seconds_required_to_load,
                    &atomic_load_count,
                );

                // Alternate version to show data with automatic retry and automatically starts
                // trying to load
                ui.separator();
                Helper::ui_show_data_retry(
                    ui,
                    &mut data_state_retry,
                    seconds_required_to_load,
                    &atomic_load_count,
                );
            });
        },
    )
}

/// To group function to avoid too many `cfg` calls with duplicate values
#[cfg(all(
    not(target_arch = "wasm32"),
    feature = "native-tokio",
    feature = "egui"
))]
struct Helper;

#[cfg(all(
    not(target_arch = "wasm32"),
    feature = "native-tokio",
    feature = "egui"
))]
impl Helper {
    fn ui_show_data(
        ui: &mut egui::Ui,
        data_state: &mut DataState<String>,
        seconds_required_to_load: &mut u64,
        atomic_load_count: &Arc<AtomicU8>,
    ) {
        ui.heading(format!(
            "Load Data Without Retry (NB: Load randomly fails, {} attempts so far)",
            atomic_load_count.load(Ordering::Relaxed)
        ));
        if let Some(data) = data_state.egui_poll_mut(ui, None) {
            ui.horizontal(|ui| {
                ui.label("Editable Data from spawned task");
                ui.text_edit_singleline(data);
            });
            if ui.button("Clear Data").clicked() {
                *data_state = DataState::None;
            }
        } else if data_state.is_none() {
            ui.add(
                egui::Slider::new(seconds_required_to_load, 0..=30)
                    .text("Seconds needed to load data"),
            );
            if ui.button("Spawn task to load data").clicked() {
                let secs = *seconds_required_to_load;
                let atomic_load_count = Arc::clone(atomic_load_count);
                let can_make_progress = data_state.egui_start_task(ui, || {
                    spawn_with_return(move || Helper::load_data(secs, atomic_load_count))
                });
                assert!(
                    can_make_progress.is_able_to_make_progress(),
                    "checks that we don't have a logic error, this should always be able to make progress from this point"
                );
            }
        } else if data_state.is_awaiting_response() {
            // Currently loading allowing the user to abort, might not make sense for your
            // application
            if ui.button("Cancel Loading").clicked() {
                *data_state = DataState::None;
            }
        }
    }

    fn ui_show_data_retry(
        ui: &mut egui::Ui,
        data_state: &mut DataStateRetry<String>,
        secs: u64,
        atomic_load_count: &Arc<AtomicU8>,
    ) {
        ui.heading(format!(
            "Load Data With Retry (NB: Load randomly fails, {} attempts so far)",
            atomic_load_count.load(Ordering::Relaxed)
        ));
        if let Some(data) = data_state.present_mut() {
            ui.horizontal(|ui| {
                ui.label("Editable Data from spawned task");
                ui.text_edit_singleline(data);
            });
            if ui.button("Clear Data").clicked() {
                data_state.clear();
            }
        } else {
            let atomic_load_count = Arc::clone(atomic_load_count);
            let can_make_progress = data_state.egui_start_or_poll(ui, None, || {
                spawn_with_return(move || Helper::load_data(secs, atomic_load_count))
            });
            assert!(
                can_make_progress.is_able_to_make_progress(),
                "checks that we don't have a logic error, this should always be able to make progress from this point"
            );
        }
        if data_state.is_awaiting_response() {
            // Currently loading allowing the user to abort, might not make sense for your
            // application
            if ui.button("Cancel Loading").clicked() {
                data_state.clear();
            }
        }
    }

    fn create_tokio_runtime() -> tokio::runtime::Runtime {
        tokio::runtime::Builder::new_multi_thread()
            .enable_all()
            .build()
            .expect("Unable to create Runtime")
    }

    fn start_background_worker(rt: tokio::runtime::Runtime) {
        // Execute the runtime in its own thread.
        std::thread::spawn(move || {
            rt.block_on(async {
                loop {
                    tokio::time::sleep(std::time::Duration::from_secs(3600)).await;
                }
            })
        });
    }

    async fn load_data(secs: u64, atomic_load_count: Arc<AtomicU8>) -> anyhow::Result<String> {
        atomic_load_count.fetch_add(1, Ordering::Relaxed);
        if Helper::should_fail() {
            anyhow::bail!("there was a random problem loading the data, try again");
        }

        tokio::time::sleep_until(
            tokio::time::Instant::now() + std::time::Duration::from_secs(secs),
        )
        .await;

        Ok(format!("loaded the data after {secs} seconds"))
    }

    fn should_fail() -> bool {
        rand::random()
    }
}
#[cfg(not(all(
    not(target_arch = "wasm32"),
    feature = "native-tokio",
    feature = "egui"
)))]
fn main() {}