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tamirdtamird
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time: use clock_gettime on macos
Replace `mach_{absolute_time,timebase_info}` with `clock_gettime(CLOCK_REALTIME)` on: ``` all(target_os = "macos", not(target_arch = "aarch64")), target_os = "ios", target_os = "watchos", target_os = "tvos" ))] ``` `mach_{absolute_time,timebase_info}` were first used in time-rs/time@cc367ed which predated the introduction of `clock_gettime` support in macOS 10.12 Sierra which became the minimum supported version in 58bbca9. Note that this change was made for aarch64 in 5008a31 which predated 10.12 becoming the minimum supported version. The discussion took place in #91417 and in particular #91417 (comment) and #91417 (comment) are relevant.
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‎library/std/src/sys/unix/time.rs

+44-148
Original file line numberDiff line numberDiff line change
@@ -1,8 +1,6 @@
11
use crate::fmt;
22
use crate::time::Duration;
33

4-
pub use self::inner::Instant;
5-
64
const NSEC_PER_SEC: u64 = 1_000_000_000;
75
pub const UNIX_EPOCH: SystemTime = SystemTime { t: Timespec::zero() };
86
#[allow(dead_code)] // Used for pthread condvar timeouts
@@ -250,161 +248,59 @@ impl From<__timespec64> for Timespec {
250248
}
251249
}
252250

253-
#[cfg(any(
254-
all(target_os = "macos", not(target_arch = "aarch64")),
255-
target_os = "ios",
256-
target_os = "watchos",
257-
target_os = "tvos"
258-
))]
259-
mod inner {
260-
use crate::sync::atomic::{AtomicU64, Ordering};
261-
use crate::sys_common::mul_div_u64;
262-
use crate::time::Duration;
263-
264-
use super::{SystemTime, Timespec, NSEC_PER_SEC};
265-
266-
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
267-
pub struct Instant {
268-
t: u64,
269-
}
270-
271-
#[repr(C)]
272-
#[derive(Copy, Clone)]
273-
struct mach_timebase_info {
274-
numer: u32,
275-
denom: u32,
276-
}
277-
type mach_timebase_info_t = *mut mach_timebase_info;
278-
type kern_return_t = libc::c_int;
279-
280-
impl Instant {
281-
pub fn now() -> Instant {
282-
extern "C" {
283-
fn mach_absolute_time() -> u64;
284-
}
285-
Instant { t: unsafe { mach_absolute_time() } }
286-
}
287-
288-
pub fn checked_sub_instant(&self, other: &Instant) -> Option<Duration> {
289-
let diff = self.t.checked_sub(other.t)?;
290-
let info = info();
291-
let nanos = mul_div_u64(diff, info.numer as u64, info.denom as u64);
292-
Some(Duration::new(nanos / NSEC_PER_SEC, (nanos % NSEC_PER_SEC) as u32))
293-
}
294-
295-
pub fn checked_add_duration(&self, other: &Duration) -> Option<Instant> {
296-
Some(Instant { t: self.t.checked_add(checked_dur2intervals(other)?)? })
297-
}
298-
299-
pub fn checked_sub_duration(&self, other: &Duration) -> Option<Instant> {
300-
Some(Instant { t: self.t.checked_sub(checked_dur2intervals(other)?)? })
301-
}
302-
}
303-
304-
impl From<libc::timeval> for Timespec {
305-
fn from(t: libc::timeval) -> Timespec {
306-
Timespec::new(t.tv_sec as i64, 1000 * t.tv_usec as i64)
307-
}
308-
}
309-
310-
impl From<libc::timeval> for SystemTime {
311-
fn from(t: libc::timeval) -> SystemTime {
312-
SystemTime { t: Timespec::from(t) }
313-
}
314-
}
315-
316-
fn checked_dur2intervals(dur: &Duration) -> Option<u64> {
317-
let nanos =
318-
dur.as_secs().checked_mul(NSEC_PER_SEC)?.checked_add(dur.subsec_nanos() as u64)?;
319-
let info = info();
320-
Some(mul_div_u64(nanos, info.denom as u64, info.numer as u64))
321-
}
251+
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
252+
pub struct Instant {
253+
t: Timespec,
254+
}
322255

323-
fn info() -> mach_timebase_info {
324-
// INFO_BITS conceptually is an `Option<mach_timebase_info>`. We can do
325-
// this in 64 bits because we know 0 is never a valid value for the
326-
// `denom` field.
256+
impl Instant {
257+
pub fn now() -> Instant {
258+
// https://www.manpagez.com/man/3/clock_gettime/
327259
//
328-
// Encoding this as a single `AtomicU64` allows us to use `Relaxed`
329-
// operations, as we are only interested in the effects on a single
330-
// memory location.
331-
static INFO_BITS: AtomicU64 = AtomicU64::new(0);
332-
333-
// If a previous thread has initialized `INFO_BITS`, use it.
334-
let info_bits = INFO_BITS.load(Ordering::Relaxed);
335-
if info_bits != 0 {
336-
return info_from_bits(info_bits);
337-
}
338-
339-
// ... otherwise learn for ourselves ...
340-
extern "C" {
341-
fn mach_timebase_info(info: mach_timebase_info_t) -> kern_return_t;
342-
}
343-
344-
let mut info = info_from_bits(0);
345-
unsafe {
346-
mach_timebase_info(&mut info);
347-
}
348-
INFO_BITS.store(info_to_bits(info), Ordering::Relaxed);
349-
info
260+
// CLOCK_UPTIME_RAW clock that increments monotonically, in the same man-
261+
// ner as CLOCK_MONOTONIC_RAW, but that does not incre-
262+
// ment while the system is asleep. The returned value
263+
// is identical to the result of mach_absolute_time()
264+
// after the appropriate mach_timebase conversion is
265+
// applied.
266+
//
267+
// Instant on macos was historically implemented using mach_absolute_time;
268+
// we preserve this value domain out of an abundance of caution.
269+
#[cfg(any(
270+
target_os = "macos",
271+
target_os = "ios",
272+
target_os = "watchos",
273+
target_os = "tvos"
274+
))]
275+
const clock_id: libc::clockid_t = libc::CLOCK_UPTIME_RAW;
276+
#[cfg(not(any(
277+
target_os = "macos",
278+
target_os = "ios",
279+
target_os = "watchos",
280+
target_os = "tvos"
281+
)))]
282+
const clock_id: libc::clockid_t = libc::CLOCK_MONOTONIC;
283+
Instant { t: Timespec::now(clock_id) }
350284
}
351285

352-
#[inline]
353-
fn info_to_bits(info: mach_timebase_info) -> u64 {
354-
((info.denom as u64) << 32) | (info.numer as u64)
286+
pub fn checked_sub_instant(&self, other: &Instant) -> Option<Duration> {
287+
self.t.sub_timespec(&other.t).ok()
355288
}
356289

357-
#[inline]
358-
fn info_from_bits(bits: u64) -> mach_timebase_info {
359-
mach_timebase_info { numer: bits as u32, denom: (bits >> 32) as u32 }
290+
pub fn checked_add_duration(&self, other: &Duration) -> Option<Instant> {
291+
Some(Instant { t: self.t.checked_add_duration(other)? })
360292
}
361-
}
362293

363-
#[cfg(not(any(
364-
all(target_os = "macos", not(target_arch = "aarch64")),
365-
target_os = "ios",
366-
target_os = "watchos",
367-
target_os = "tvos"
368-
)))]
369-
mod inner {
370-
use crate::fmt;
371-
use crate::time::Duration;
372-
373-
use super::Timespec;
374-
375-
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
376-
pub struct Instant {
377-
t: Timespec,
378-
}
379-
380-
impl Instant {
381-
pub fn now() -> Instant {
382-
#[cfg(target_os = "macos")]
383-
const clock_id: libc::clockid_t = libc::CLOCK_UPTIME_RAW;
384-
#[cfg(not(target_os = "macos"))]
385-
const clock_id: libc::clockid_t = libc::CLOCK_MONOTONIC;
386-
Instant { t: Timespec::now(clock_id) }
387-
}
388-
389-
pub fn checked_sub_instant(&self, other: &Instant) -> Option<Duration> {
390-
self.t.sub_timespec(&other.t).ok()
391-
}
392-
393-
pub fn checked_add_duration(&self, other: &Duration) -> Option<Instant> {
394-
Some(Instant { t: self.t.checked_add_duration(other)? })
395-
}
396-
397-
pub fn checked_sub_duration(&self, other: &Duration) -> Option<Instant> {
398-
Some(Instant { t: self.t.checked_sub_duration(other)? })
399-
}
294+
pub fn checked_sub_duration(&self, other: &Duration) -> Option<Instant> {
295+
Some(Instant { t: self.t.checked_sub_duration(other)? })
400296
}
297+
}
401298

402-
impl fmt::Debug for Instant {
403-
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
404-
f.debug_struct("Instant")
405-
.field("tv_sec", &self.t.tv_sec)
406-
.field("tv_nsec", &self.t.tv_nsec.0)
407-
.finish()
408-
}
299+
impl fmt::Debug for Instant {
300+
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
301+
f.debug_struct("Instant")
302+
.field("tv_sec", &self.t.tv_sec)
303+
.field("tv_nsec", &self.t.tv_nsec.0)
304+
.finish()
409305
}
410306
}

‎library/std/src/time.rs

+1-2
Original file line numberDiff line numberDiff line change
@@ -109,7 +109,7 @@ pub use core::time::TryFromFloatSecsError;
109109
/// |-----------|----------------------------------------------------------------------|
110110
/// | SGX | [`insecure_time` usercall]. More information on [timekeeping in SGX] |
111111
/// | UNIX | [clock_gettime (Monotonic Clock)] |
112-
/// | Darwin | [mach_absolute_time] |
112+
/// | Darwin | [clock_gettime (Monotonic Clock)] |
113113
/// | VXWorks | [clock_gettime (Monotonic Clock)] |
114114
/// | SOLID | `get_tim` |
115115
/// | WASI | [__wasi_clock_time_get (Monotonic Clock)] |
@@ -121,7 +121,6 @@ pub use core::time::TryFromFloatSecsError;
121121
/// [timekeeping in SGX]: https://edp.fortanix.com/docs/concepts/rust-std/#codestdtimecode
122122
/// [__wasi_clock_time_get (Monotonic Clock)]: https://github.com/WebAssembly/WASI/blob/main/legacy/preview1/docs.md#clock_time_get
123123
/// [clock_gettime (Monotonic Clock)]: https://linux.die.net/man/3/clock_gettime
124-
/// [mach_absolute_time]: https://developer.apple.com/library/archive/documentation/Darwin/Conceptual/KernelProgramming/services/services.html
125124
///
126125
/// **Disclaimer:** These system calls might change over time.
127126
///

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