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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-30 03:57:31 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-30 03:57:31 +0000 |
commit | dc0db358abe19481e475e10c32149b53370f1a1c (patch) | |
tree | ab8ce99c4b255ce46f99ef402c27916055b899ee /library/core/src/task | |
parent | Releasing progress-linux version 1.71.1+dfsg1-2~progress7.99u1. (diff) | |
download | rustc-dc0db358abe19481e475e10c32149b53370f1a1c.tar.xz rustc-dc0db358abe19481e475e10c32149b53370f1a1c.zip |
Merging upstream version 1.72.1+dfsg1.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'library/core/src/task')
-rw-r--r-- | library/core/src/task/wake.rs | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/library/core/src/task/wake.rs b/library/core/src/task/wake.rs index 7043ab5ff..b63fd5c90 100644 --- a/library/core/src/task/wake.rs +++ b/library/core/src/task/wake.rs @@ -2,6 +2,7 @@ use crate::fmt; use crate::marker::{PhantomData, Unpin}; +use crate::ptr; /// A `RawWaker` allows the implementor of a task executor to create a [`Waker`] /// which provides customized wakeup behavior. @@ -322,6 +323,45 @@ impl Waker { Waker { waker } } + /// Creates a new `Waker` that does nothing when `wake` is called. + /// + /// This is mostly useful for writing tests that need a [`Context`] to poll + /// some futures, but are not expecting those futures to wake the waker or + /// do not need to do anything specific if it happens. + /// + /// # Examples + /// + /// ``` + /// #![feature(noop_waker)] + /// + /// use std::future::Future; + /// use std::task; + /// + /// let waker = task::Waker::noop(); + /// let mut cx = task::Context::from_waker(&waker); + /// + /// let mut future = Box::pin(async { 10 }); + /// assert_eq!(future.as_mut().poll(&mut cx), task::Poll::Ready(10)); + /// ``` + #[inline] + #[must_use] + #[unstable(feature = "noop_waker", issue = "98286")] + pub const fn noop() -> Waker { + const VTABLE: RawWakerVTable = RawWakerVTable::new( + // Cloning just returns a new no-op raw waker + |_| RAW, + // `wake` does nothing + |_| {}, + // `wake_by_ref` does nothing + |_| {}, + // Dropping does nothing as we don't allocate anything + |_| {}, + ); + const RAW: RawWaker = RawWaker::new(ptr::null(), &VTABLE); + + Waker { waker: RAW } + } + /// Get a reference to the underlying [`RawWaker`]. #[inline] #[must_use] |