atomic-wait 1.1.0

Cross-platform atomic wait and wake (aka futex) functionality.

Cross platform atomic wait and wake (aka futex) functionality.

This crate only supports functionality that's available on all of Linux, FreeBSD, Windows, and macOS. That is:

  • Only AtomicU32 is supported. (Linux currently only supports 32-bit futexes.)
  • Only the "wait", "wake one", and "wake all" operations are supported. (Linux supports more operations, but Windows and macOS don't.)
  • No timeouts. (macOS doesn't have a stable/public API for timeouts.)
  • The wake operations don't return the number of threads woken up. (Only Linux supports this.)

Supported platforms: Linux 2.6.22+, FreeBSD 11+, Windows 8+, Windows Server 2012+, macOS 11+, iOS 14+, watchOS 7+.


use std::sync::atomic::AtomicU32;
use atomic_wait::{wait, wake_one, wake_all};

let a = AtomicU32::new(0);

wait(&a, 1); // If the value is 1, wait.

wake_one(&a); // Wake one waiting thread.

wake_all(&a); // Wake all waiting threads.


On Linux, this uses the SYS_futex syscall.

On FreeBSD, this uses the _umtx_op syscall.

On Windows, this uses the WaitOnAddress and WakeByAddress APIs.

On macOS (and iOS and watchOS), this uses libc++, making use of the same (ABI-stable) functions behind C++20's atomic_wait and atomic_notify functions.