cancel_nested.rs

use std::{
    sync::{mpsc, Arc},
    thread,
    time::Duration,
};

use sitrep::{Controller, Event, Progress, State, StdMpscObserver, Task, UpdateEvent};

fn main() {
    let (sender, receiver) = mpsc::channel();
    let observer = Arc::new(StdMpscObserver::from(sender));

    let (parent, controller) = Progress::new(Task::default(), observer);

    // The sending end of the progress report:
    let worker_handle = thread::spawn(move || {
        let worker_handles: Vec<_> = (0..3)
            .map(|_| {
                let parent = Arc::clone(&parent);
                thread::spawn(move || {
                    let child = Progress::new_with_parent(Task::default(), &parent);

                    let total = 100;
                    child.set_total(total);

                    for completed in 1..=total {
                        thread::sleep(Duration::from_millis(25));

                        // Check if the user canceled the task from the controller end of things:
                        if child.state() == State::Canceled {
                            println!("Task got canceled by user, aborting.");
                            break;
                        }

                        child.set_completed(completed);
                    }
                })
            })
            .collect();

        for worker_handle in worker_handles {
            worker_handle.join().unwrap();
        }
    });

    // The receiving end of the progress report:
    let controller_handle = thread::spawn(move || {
        while let Ok(event) = receiver.recv() {
            let Event::Update(UpdateEvent { id: _ }) = event else {
                // For the sake of brevity we'll only handle the update events here:
                continue;
            };

            // The controller is only available as long as
            // the corresponding progress is alive, too:
            let Some(controller) = controller.upgrade() else {
                break;
            };

            // Cancel the task from the controller end of things:
            controller.cancel().ok();
        }
    });

    worker_handle.join().unwrap();
    controller_handle.join().unwrap();
}