diff options
Diffstat (limited to 'vendor/futures-core/src/task/__internal/atomic_waker.rs')
| -rw-r--r-- | vendor/futures-core/src/task/__internal/atomic_waker.rs | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/vendor/futures-core/src/task/__internal/atomic_waker.rs b/vendor/futures-core/src/task/__internal/atomic_waker.rs index d49d04361..2fc594b8a 100644 --- a/vendor/futures-core/src/task/__internal/atomic_waker.rs +++ b/vendor/futures-core/src/task/__internal/atomic_waker.rs @@ -1,9 +1,16 @@ use core::cell::UnsafeCell; use core::fmt; -use core::sync::atomic::AtomicUsize; -use core::sync::atomic::Ordering::{AcqRel, Acquire, Release}; use core::task::Waker; +use atomic::AtomicUsize; +use atomic::Ordering::{AcqRel, Acquire, Release}; + +#[cfg(feature = "portable-atomic")] +use portable_atomic as atomic; + +#[cfg(not(feature = "portable-atomic"))] +use core::sync::atomic; + /// A synchronization primitive for task wakeup. /// /// Sometimes the task interested in a given event will change over time. @@ -264,7 +271,12 @@ impl AtomicWaker { WAITING => { unsafe { // Locked acquired, update the waker cell - *self.waker.get() = Some(waker.clone()); + + // Avoid cloning the waker if the old waker will awaken the same task. + match &*self.waker.get() { + Some(old_waker) if old_waker.will_wake(waker) => (), + _ => *self.waker.get() = Some(waker.clone()), + } // Release the lock. If the state transitioned to include // the `WAKING` bit, this means that at least one wake has |