user0/rust
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Rollup merge of #151450 - joboet:sleep_clock_monotonic, r=Amanieu

Browse source 
std: use `clock_nanosleep` for `sleep` where available

`nanosleep` is specified to use `CLOCK_REALTIME` but the documentation (especially the example) for `sleep` imply that it measures time using `Instant`, which uses `CLOCK_MONOTONIC`. Thus, this PR makes `sleep` use a relative `clock_nanosleep` with `CLOCK_MONOTONIC` where available. This doesn't make a difference for Linux (which uses `CLOCK_MONOTONIC` for `nanosleep` anyway) but is relevant for e.g. FreeBSD.

This also restores nanosecond-sleep precision for WASI, since https://github.com/rust-lang/rust/issues/150290 was caused by `nanosleep` internally using `clock_nanosleep` with `CLOCK_REALTIME` which is unsupported on WASIp2.

CC @alexcrichton for the WASI fix
This commit is contained in:
Jacob Pratt 2026-01-22 20:16:50 -05:00 • committed by GitHub
commit d2acb11cd0
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
1 changed files with 48 additions and 10 deletions
Download patch file Download diff file Expand all files Collapse all files

58
library/std/src/sys/thread/unix.rs
View file

@ -528,8 +528,51 @@ pub fn set_name(name: &CStr) {
debug_assert_eq!(res, libc::OK);
}
#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
#[cfg(not(target_os = "espidf"))]
pub fn sleep(dur: Duration) {
cfg_select! {
// Any unix that has clock_nanosleep
// If this list changes update the MIRI chock_nanosleep shim
any(
target_os = "freebsd",
target_os = "netbsd",
target_os = "linux",
target_os = "android",
target_os = "solaris",
target_os = "illumos",
target_os = "dragonfly",
target_os = "hurd",
target_os = "fuchsia",
target_os = "vxworks",
target_os = "wasi",
) => {
// POSIX specifies that `nanosleep` uses CLOCK_REALTIME, but is not
// affected by clock adjustments. The timing of `sleep` however should
// be tied to `Instant` where possible. Thus, we use `clock_nanosleep`
// with a relative time interval instead, which allows explicitly
// specifying the clock.
//
// In practice, most systems (like e.g. Linux) actually use
// CLOCK_MONOTONIC for `nanosleep` anyway, but others like FreeBSD don't
// so it's better to be safe.
//
// wasi-libc prior to WebAssembly/wasi-libc#696 has a broken implementation
// of `nanosleep` which used `CLOCK_REALTIME` even though it is unsupported
// on WASIp2. Using `clock_nanosleep` directly bypasses the issue.
unsafe fn nanosleep(rqtp: *const libc::timespec, rmtp: *mut libc::timespec) -> libc::c_int {
unsafe { libc::clock_nanosleep(crate::sys::time::Instant::CLOCK_ID, 0, rqtp, rmtp) }
}
}
_ => {
unsafe fn nanosleep(rqtp: *const libc::timespec, rmtp: *mut libc::timespec) -> libc::c_int {
let r = unsafe { libc::nanosleep(rqtp, rmtp) };
// `clock_nanosleep` returns the error number directly, so mimic
// that behaviour to make the shared code below simpler.
if r == 0 { 0 } else { sys::io::errno() }
}
}
}
let mut secs = dur.as_secs();
let mut nsecs = dur.subsec_nanos() as _;
@ -543,8 +586,9 @@ pub fn sleep(dur: Duration) {
};
secs -= ts.tv_sec as u64;
let ts_ptr = &raw mut ts;
if libc::nanosleep(ts_ptr, ts_ptr) == -1 {
assert_eq!(sys::io::errno(), libc::EINTR);
let r = nanosleep(ts_ptr, ts_ptr);
if r != 0 {
assert_eq!(r, libc::EINTR);
secs += ts.tv_sec as u64;
nsecs = ts.tv_nsec;
} else {
@ -554,13 +598,7 @@ pub fn sleep(dur: Duration) {
}
}
#[cfg(any(
target_os = "espidf",
// wasi-libc prior to WebAssembly/wasi-libc#696 has a broken implementation
// of `nanosleep`, used above by most platforms, so use `usleep` until
// that fix propagates throughout the ecosystem.
target_os = "wasi",
))]
#[cfg(target_os = "espidf")]
pub fn sleep(dur: Duration) {
// ESP-IDF does not have `nanosleep`, so we use `usleep` instead.
// As per the documentation of `usleep`, it is expected to support