task_abort.rs

#![warn(rust_2018_idioms)]
#![cfg(all(feature = "full", not(tokio_wasi)))] // Wasi doesn't support panic recovery

use std::sync::Arc;
use std::thread::sleep;
use tokio::time::Duration;

use tokio::runtime::Builder;

struct PanicOnDrop;

impl Drop for PanicOnDrop {
    fn drop(&mut self) {
        panic!("Well what did you expect would happen...");
    }
}

/// Checks that a suspended task can be aborted without panicking as reported in
/// issue #3157: <https://github.com/tokio-rs/tokio/issues/3157>.
#[test]
fn test_abort_without_panic_3157() {
    let rt = Builder::new_multi_thread()
        .enable_time()
        .worker_threads(1)
        .build()
        .unwrap();

    rt.block_on(async move {
        let handle = tokio::spawn(async move { tokio::time::sleep(Duration::new(100, 0)).await });

        // wait for task to sleep.
        tokio::time::sleep(Duration::from_millis(10)).await;

        handle.abort();
        let _ = handle.await;
    });
}

/// Checks that a suspended task can be aborted inside of a current_thread
/// executor without panicking as reported in issue #3662:
/// <https://github.com/tokio-rs/tokio/issues/3662>.
#[test]
fn test_abort_without_panic_3662() {
    use std::sync::atomic::{AtomicBool, Ordering};
    use std::sync::Arc;

    struct DropCheck(Arc<AtomicBool>);

    impl Drop for DropCheck {
        fn drop(&mut self) {
            self.0.store(true, Ordering::SeqCst);
        }
    }

    let rt = Builder::new_current_thread().build().unwrap();

    rt.block_on(async move {
        let drop_flag = Arc::new(AtomicBool::new(false));
        let drop_check = DropCheck(drop_flag.clone());

        let j = tokio::spawn(async move {
            // NB: just grab the drop check here so that it becomes part of the
            // task.
            let _drop_check = drop_check;
            futures::future::pending::<()>().await;
        });

        let drop_flag2 = drop_flag.clone();

        let task = std::thread::spawn(move || {
            // This runs in a separate thread so it doesn't have immediate
            // thread-local access to the executor. It does however transition
            // the underlying task to be completed, which will cause it to be
            // dropped (but not in this thread).
            assert!(!drop_flag2.load(Ordering::SeqCst));
            j.abort();
            j
        })
        .join()
        .unwrap();

        let result = task.await;
        assert!(drop_flag.load(Ordering::SeqCst));
        assert!(result.unwrap_err().is_cancelled());

        // Note: We do the following to trigger a deferred task cleanup.
        //
        // The relevant piece of code you want to look at is in:
        // `Inner::block_on` of `scheduler/current_thread.rs`.
        //
        // We cause the cleanup to happen by having a poll return Pending once
        // so that the scheduler can go into the "auxiliary tasks" mode, at
        // which point the task is removed from the scheduler.
        let i = tokio::spawn(async move {
            tokio::task::yield_now().await;
        });

        i.await.unwrap();
    });
}

/// Checks that a suspended LocalSet task can be aborted from a remote thread
/// without panicking and without running the tasks destructor on the wrong thread.
/// <https://github.com/tokio-rs/tokio/issues/3929>
#[test]
fn remote_abort_local_set_3929() {
    struct DropCheck {
        created_on: std::thread::ThreadId,
        not_send: std::marker::PhantomData<*const ()>,
    }

    impl DropCheck {
        fn new() -> Self {
            Self {
                created_on: std::thread::current().id(),
                not_send: std::marker::PhantomData,
            }
        }
    }
    impl Drop for DropCheck {
        fn drop(&mut self) {
            if std::thread::current().id() != self.created_on {
                panic!("non-Send value dropped in another thread!");
            }
        }
    }

    let rt = Builder::new_current_thread().build().unwrap();
    let local = tokio::task::LocalSet::new();

    let check = DropCheck::new();
    let jh = local.spawn_local(async move {
        futures::future::pending::<()>().await;
        drop(check);
    });

    let jh2 = std::thread::spawn(move || {
        sleep(Duration::from_millis(10));
        jh.abort();
    });

    rt.block_on(local);
    jh2.join().unwrap();
}

/// Checks that a suspended task can be aborted even if the `JoinHandle` is immediately dropped.
/// issue #3964: <https://github.com/tokio-rs/tokio/issues/3964>.
#[test]
fn test_abort_wakes_task_3964() {
    let rt = Builder::new_current_thread().enable_time().build().unwrap();

    rt.block_on(async move {
        let notify_dropped = Arc::new(());
        let weak_notify_dropped = Arc::downgrade(&notify_dropped);

        let handle = tokio::spawn(async move {
            // Make sure the Arc is moved into the task
            let _notify_dropped = notify_dropped;
            tokio::time::sleep(Duration::new(100, 0)).await
        });

        // wait for task to sleep.
        tokio::time::sleep(Duration::from_millis(10)).await;

        handle.abort();
        drop(handle);

        // wait for task to abort.
        tokio::time::sleep(Duration::from_millis(10)).await;

        // Check that the Arc has been dropped.
        assert!(weak_notify_dropped.upgrade().is_none());
    });
}

/// Checks that aborting a task whose destructor panics does not allow the
/// panic to escape the task.
#[test]
fn test_abort_task_that_panics_on_drop_contained() {
    let rt = Builder::new_current_thread().enable_time().build().unwrap();

    rt.block_on(async move {
        let handle = tokio::spawn(async move {
            // Make sure the Arc is moved into the task
            let _panic_dropped = PanicOnDrop;
            tokio::time::sleep(Duration::new(100, 0)).await
        });

        // wait for task to sleep.
        tokio::time::sleep(Duration::from_millis(10)).await;

        handle.abort();
        drop(handle);

        // wait for task to abort.
        tokio::time::sleep(Duration::from_millis(10)).await;
    });
}

/// Checks that aborting a task whose destructor panics has the expected result.
#[test]
fn test_abort_task_that_panics_on_drop_returned() {
    let rt = Builder::new_current_thread().enable_time().build().unwrap();

    rt.block_on(async move {
        let handle = tokio::spawn(async move {
            // Make sure the Arc is moved into the task
            let _panic_dropped = PanicOnDrop;
            tokio::time::sleep(Duration::new(100, 0)).await
        });

        // wait for task to sleep.
        tokio::time::sleep(Duration::from_millis(10)).await;

        handle.abort();
        assert!(handle.await.unwrap_err().is_panic());
    });
}