//! A basic usage example demonstrating the garbage collector.
use refuse::{CollectionGuard, Ref, Root};

fn main() {
    let guard = CollectionGuard::acquire();
    // Allocate a vec![Ref(1), Ref(2), Ref(3)].
    let values: Vec<Ref<u32>> = (1..=3).map(|value| Ref::new(value, &guard)).collect();
    let values = Root::new(values, &guard);
    drop(guard);

    // Manually execute the garbage collector. Our data will not be freed,
    // since `values` is a "root" reference.
    refuse::collect();

    // Root references allow direct access to their data, even when a
    // `CollectionGuard` isn't held.
    let (one, two, three) = (values[0], values[1], values[2]);

    // Accessing the data contained in a `Ref` requires a guard, however.
    let mut guard = CollectionGuard::acquire();
    assert_eq!(one.load(&guard), Some(&1));
    assert_eq!(two.load(&guard), Some(&2));
    assert_eq!(three.load(&guard), Some(&3));

    // Dropping our root will allow the collector to free our `Ref`s.
    drop(values);
    guard.collect();
    assert_eq!(one.load(&guard), None);
}