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use crate::runtime::task::{Header, RawTask};
use std::fmt;
use std::panic::{RefUnwindSafe, UnwindSafe};
/// An owned permission to abort a spawned task, without awaiting its completion.
///
/// Unlike a [`JoinHandle`], an `AbortHandle` does *not* represent the
/// permission to await the task's completion, only to terminate it.
///
/// The task may be aborted by calling the [`AbortHandle::abort`] method.
/// Dropping an `AbortHandle` releases the permission to terminate the task
/// --- it does *not* abort the task.
///
/// [`JoinHandle`]: crate::task::JoinHandle
#[cfg_attr(docsrs, doc(cfg(feature = "rt")))]
pub struct AbortHandle {
raw: RawTask,
}
impl AbortHandle {
pub(super) fn new(raw: RawTask) -> Self {
Self { raw }
}
/// Abort the task associated with the handle.
///
/// Awaiting a cancelled task might complete as usual if the task was
/// already completed at the time it was cancelled, but most likely it
/// will fail with a [cancelled] `JoinError`.
///
/// If the task was already cancelled, such as by [`JoinHandle::abort`],
/// this method will do nothing.
///
/// [cancelled]: method@super::error::JoinError::is_cancelled
/// [`JoinHandle::abort`]: method@super::JoinHandle::abort
pub fn abort(&self) {
self.raw.remote_abort();
}
/// Checks if the task associated with this `AbortHandle` has finished.
///
/// Please note that this method can return `false` even if `abort` has been
/// called on the task. This is because the cancellation process may take
/// some time, and this method does not return `true` until it has
/// completed.
pub fn is_finished(&self) -> bool {
let state = self.raw.state().load();
state.is_complete()
}
/// Returns a [task ID] that uniquely identifies this task relative to other
/// currently spawned tasks.
///
/// **Note**: This is an [unstable API][unstable]. The public API of this type
/// may break in 1.x releases. See [the documentation on unstable
/// features][unstable] for details.
///
/// [task ID]: crate::task::Id
/// [unstable]: crate#unstable-features
#[cfg(tokio_unstable)]
#[cfg_attr(docsrs, doc(cfg(tokio_unstable)))]
pub fn id(&self) -> super::Id {
// Safety: The header pointer is valid.
unsafe { Header::get_id(self.raw.header_ptr()) }
}
}
unsafe impl Send for AbortHandle {}
unsafe impl Sync for AbortHandle {}
impl UnwindSafe for AbortHandle {}
impl RefUnwindSafe for AbortHandle {}
impl fmt::Debug for AbortHandle {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
// Safety: The header pointer is valid.
let id_ptr = unsafe { Header::get_id_ptr(self.raw.header_ptr()) };
let id = unsafe { id_ptr.as_ref() };
fmt.debug_struct("AbortHandle").field("id", id).finish()
}
}
impl Drop for AbortHandle {
fn drop(&mut self) {
self.raw.drop_abort_handle();
}
}