| #![stable(feature = "futures_api", since = "1.36.0")] |
| |
| //! Asynchronous basic functionality. |
| //! |
| //! Please see the fundamental [`async`] and [`await`] keywords and the [async book] |
| //! for more information on asynchronous programming in Rust. |
| //! |
| //! [`async`]: ../../std/keyword.async.html |
| //! [`await`]: ../../std/keyword.await.html |
| //! [async book]: https://rust-lang.github.io/async-book/ |
| |
| use crate::ptr::NonNull; |
| use crate::task::Context; |
| |
| mod future; |
| mod into_future; |
| mod join; |
| mod pending; |
| mod poll_fn; |
| mod ready; |
| |
| #[stable(feature = "futures_api", since = "1.36.0")] |
| pub use self::future::Future; |
| |
| #[unstable(feature = "future_join", issue = "91642")] |
| pub use self::join::join; |
| |
| #[stable(feature = "into_future", since = "1.64.0")] |
| pub use into_future::IntoFuture; |
| |
| #[stable(feature = "future_readiness_fns", since = "1.48.0")] |
| pub use pending::{pending, Pending}; |
| #[stable(feature = "future_readiness_fns", since = "1.48.0")] |
| pub use ready::{ready, Ready}; |
| |
| #[stable(feature = "future_poll_fn", since = "1.64.0")] |
| pub use poll_fn::{poll_fn, PollFn}; |
| |
| /// This type is needed because: |
| /// |
| /// a) Generators cannot implement `for<'a, 'b> Generator<&'a mut Context<'b>>`, so we need to pass |
| /// a raw pointer (see <https://github.com/rust-lang/rust/issues/68923>). |
| /// b) Raw pointers and `NonNull` aren't `Send` or `Sync`, so that would make every single future |
| /// non-Send/Sync as well, and we don't want that. |
| /// |
| /// It also simplifies the HIR lowering of `.await`. |
| #[lang = "ResumeTy"] |
| #[doc(hidden)] |
| #[unstable(feature = "gen_future", issue = "50547")] |
| #[derive(Debug, Copy, Clone)] |
| pub struct ResumeTy(NonNull<Context<'static>>); |
| |
| #[unstable(feature = "gen_future", issue = "50547")] |
| unsafe impl Send for ResumeTy {} |
| |
| #[unstable(feature = "gen_future", issue = "50547")] |
| unsafe impl Sync for ResumeTy {} |
| |
| #[lang = "get_context"] |
| #[doc(hidden)] |
| #[unstable(feature = "gen_future", issue = "50547")] |
| #[must_use] |
| #[inline] |
| pub unsafe fn get_context<'a, 'b>(cx: ResumeTy) -> &'a mut Context<'b> { |
| // SAFETY: the caller must guarantee that `cx.0` is a valid pointer |
| // that fulfills all the requirements for a mutable reference. |
| unsafe { &mut *cx.0.as_ptr().cast() } |
| } |