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unix: always use 64-bit Timespec

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This commit is contained in:
Josh Stone 2022-03-09 12:25:46 -08:00
parent 9a251644fa
commit bee923f0df
3 changed files with 65 additions and 67 deletions
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9
library/std/src/sys/unix/futex.rs
View file

@ -24,8 +24,9 @@ pub fn futex_wait(futex: &AtomicU32, expected: u32, timeout: Option<Duration>) -
// Calculate the timeout as an absolute timespec.
//
// Overflows are rounded up to an infinite timeout (None).
let timespec =
timeout.and_then(|d| Some(Timespec::now(libc::CLOCK_MONOTONIC).checked_add_duration(&d)?));
let timespec = timeout
.and_then(|d| Some(Timespec::now(libc::CLOCK_MONOTONIC).checked_add_duration(&d)?))
.and_then(|t| t.to_timespec());
loop {
// No need to wait if the value already changed.
@ -41,7 +42,7 @@ pub fn futex_wait(futex: &AtomicU32, expected: u32, timeout: Option<Duration>) -
// identical. It supports absolute timeouts through a flag
// in the _umtx_time struct.
let umtx_timeout = timespec.map(|t| libc::_umtx_time {
_timeout: t.t,
_timeout: t,
_flags: libc::UMTX_ABSTIME,
_clockid: libc::CLOCK_MONOTONIC as u32,
});
@ -62,7 +63,7 @@ pub fn futex_wait(futex: &AtomicU32, expected: u32, timeout: Option<Duration>) -
futex as *const AtomicU32,
libc::FUTEX_WAIT_BITSET | libc::FUTEX_PRIVATE_FLAG,
expected,
timespec.as_ref().map_or(null(), |t| &t.t as *const libc::timespec),
timespec.as_ref().map_or(null(), |t| t as *const libc::timespec),
null::<u32>(), // This argument is unused for FUTEX_WAIT_BITSET.
!0u32, // A full bitmask, to make it behave like a regular FUTEX_WAIT.
)

3
library/std/src/sys/unix/thread_parker.rs
View file

@ -79,7 +79,8 @@ unsafe fn wait_timeout(
(Timespec::now(libc::CLOCK_MONOTONIC), dur)
};
let timeout = now.checked_add_duration(&dur).map(|t| t.t).unwrap_or(TIMESPEC_MAX);
let timeout =
now.checked_add_duration(&dur).and_then(|t| t.to_timespec()).unwrap_or(TIMESPEC_MAX);
let r = libc::pthread_cond_timedwait(cond, lock, &timeout);
debug_assert!(r == libc::ETIMEDOUT || r == 0);
}

120
library/std/src/sys/unix/time.rs
View file

@ -1,21 +1,23 @@
use crate::cmp::Ordering;
use crate::time::Duration;
use core::hash::{Hash, Hasher};
pub use self::inner::{Instant, SystemTime, UNIX_EPOCH};
use crate::convert::TryInto;
const NSEC_PER_SEC: u64 = 1_000_000_000;
#[derive(Copy, Clone)]
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub(in crate::sys::unix) struct Timespec {
pub t: libc::timespec,
tv_sec: i64,
tv_nsec: i64,
}
impl Timespec {
const fn zero() -> Timespec {
Timespec { t: libc::timespec { tv_sec: 0, tv_nsec: 0 } }
Timespec { tv_sec: 0, tv_nsec: 0 }
}
fn new(tv_sec: i64, tv_nsec: i64) -> Timespec {
Timespec { tv_sec, tv_nsec }
}
pub fn sub_timespec(&self, other: &Timespec) -> Result<Duration, Duration> {
@ -23,22 +25,22 @@ impl Timespec {
// NOTE(eddyb) two aspects of this `if`-`else` are required for LLVM
// to optimize it into a branchless form (see also #75545):
//
// 1. `self.t.tv_sec - other.t.tv_sec` shows up as a common expression
// 1. `self.tv_sec - other.tv_sec` shows up as a common expression
// in both branches, i.e. the `else` must have its `- 1`
// subtraction after the common one, not interleaved with it
// (it used to be `self.t.tv_sec - 1 - other.t.tv_sec`)
// (it used to be `self.tv_sec - 1 - other.tv_sec`)
//
// 2. the `Duration::new` call (or any other additional complexity)
// is outside of the `if`-`else`, not duplicated in both branches
//
// Ideally this code could be rearranged such that it more
// directly expresses the lower-cost behavior we want from it.
let (secs, nsec) = if self.t.tv_nsec >= other.t.tv_nsec {
((self.t.tv_sec - other.t.tv_sec) as u64, (self.t.tv_nsec - other.t.tv_nsec) as u32)
let (secs, nsec) = if self.tv_nsec >= other.tv_nsec {
((self.tv_sec - other.tv_sec) as u64, (self.tv_nsec - other.tv_nsec) as u32)
} else {
(
(self.t.tv_sec - other.t.tv_sec - 1) as u64,
self.t.tv_nsec as u32 + (NSEC_PER_SEC as u32) - other.t.tv_nsec as u32,
(self.tv_sec - other.tv_sec - 1) as u64,
self.tv_nsec as u32 + (NSEC_PER_SEC as u32) - other.tv_nsec as u32,
)
};
@ -54,63 +56,34 @@ impl Timespec {
pub fn checked_add_duration(&self, other: &Duration) -> Option<Timespec> {
let mut secs = other
.as_secs()
.try_into() // <- target type would be `libc::time_t`
.try_into() // <- target type would be `i64`
.ok()
.and_then(|secs| self.t.tv_sec.checked_add(secs))?;
.and_then(|secs| self.tv_sec.checked_add(secs))?;
// Nano calculations can't overflow because nanos are <1B which fit
// in a u32.
let mut nsec = other.subsec_nanos() + self.t.tv_nsec as u32;
let mut nsec = other.subsec_nanos() + self.tv_nsec as u32;
if nsec >= NSEC_PER_SEC as u32 {
nsec -= NSEC_PER_SEC as u32;
secs = secs.checked_add(1)?;
}
Some(Timespec { t: libc::timespec { tv_sec: secs, tv_nsec: nsec as _ } })
Some(Timespec::new(secs, nsec as i64))
}
pub fn checked_sub_duration(&self, other: &Duration) -> Option<Timespec> {
let mut secs = other
.as_secs()
.try_into() // <- target type would be `libc::time_t`
.try_into() // <- target type would be `i64`
.ok()
.and_then(|secs| self.t.tv_sec.checked_sub(secs))?;
.and_then(|secs| self.tv_sec.checked_sub(secs))?;
// Similar to above, nanos can't overflow.
let mut nsec = self.t.tv_nsec as i32 - other.subsec_nanos() as i32;
let mut nsec = self.tv_nsec as i32 - other.subsec_nanos() as i32;
if nsec < 0 {
nsec += NSEC_PER_SEC as i32;
secs = secs.checked_sub(1)?;
}
Some(Timespec { t: libc::timespec { tv_sec: secs, tv_nsec: nsec as _ } })
}
}
impl PartialEq for Timespec {
fn eq(&self, other: &Timespec) -> bool {
self.t.tv_sec == other.t.tv_sec && self.t.tv_nsec == other.t.tv_nsec
}
}
impl Eq for Timespec {}
impl PartialOrd for Timespec {
fn partial_cmp(&self, other: &Timespec) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl Ord for Timespec {
fn cmp(&self, other: &Timespec) -> Ordering {
let me = (self.t.tv_sec, self.t.tv_nsec);
let other = (other.t.tv_sec, other.t.tv_nsec);
me.cmp(&other)
}
}
impl Hash for Timespec {
fn hash<H: Hasher>(&self, state: &mut H) {
self.t.tv_sec.hash(state);
self.t.tv_nsec.hash(state);
Some(Timespec::new(secs, nsec as i64))
}
}
@ -192,26 +165,35 @@ mod inner {
}
}
impl From<libc::timeval> for Timespec {
fn from(t: libc::timeval) -> Timespec {
Timespec::new(t.tv_sec as i64, 1000 * t.tv_usec as i64)
}
}
impl From<libc::timeval> for SystemTime {
fn from(t: libc::timeval) -> SystemTime {
SystemTime::from(libc::timespec {
tv_sec: t.tv_sec,
tv_nsec: (t.tv_usec * 1000) as libc::c_long,
})
SystemTime { t: Timespec::from(t) }
}
}
impl From<libc::timespec> for Timespec {
fn from(t: libc::timespec) -> Timespec {
Timespec::new(t.tv_sec as i64, t.tv_nsec as i64)
}
}
impl From<libc::timespec> for SystemTime {
fn from(t: libc::timespec) -> SystemTime {
SystemTime { t: Timespec { t } }
SystemTime { t: Timespec::from(t) }
}
}
impl fmt::Debug for SystemTime {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("SystemTime")
.field("tv_sec", &self.t.t.tv_sec)
.field("tv_nsec", &self.t.t.tv_nsec)
.field("tv_sec", &self.t.tv_sec)
.field("tv_nsec", &self.t.tv_nsec)
.finish()
}
}
@ -305,8 +287,8 @@ mod inner {
impl fmt::Debug for Instant {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("Instant")
.field("tv_sec", &self.t.t.tv_sec)
.field("tv_nsec", &self.t.t.tv_nsec)
.field("tv_sec", &self.t.tv_sec)
.field("tv_nsec", &self.t.tv_nsec)
.finish()
}
}
@ -329,17 +311,23 @@ mod inner {
}
}
impl From<libc::timespec> for Timespec {
fn from(t: libc::timespec) -> Timespec {
Timespec::new(t.tv_sec as i64, t.tv_nsec as i64)
}
}
impl From<libc::timespec> for SystemTime {
fn from(t: libc::timespec) -> SystemTime {
SystemTime { t: Timespec { t } }
SystemTime { t: Timespec::from(t) }
}
}
impl fmt::Debug for SystemTime {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("SystemTime")
.field("tv_sec", &self.t.t.tv_sec)
.field("tv_nsec", &self.t.t.tv_nsec)
.field("tv_sec", &self.t.tv_sec)
.field("tv_nsec", &self.t.tv_nsec)
.finish()
}
}
@ -353,7 +341,15 @@ mod inner {
pub fn now(clock: clock_t) -> Timespec {
let mut t = MaybeUninit::uninit();
cvt(unsafe { libc::clock_gettime(clock, t.as_mut_ptr()) }).unwrap();
Timespec { t: unsafe { t.assume_init() } }
Timespec::from(unsafe { t.assume_init() })
}
pub fn to_timespec(&self) -> Option<libc::timespec> {
use crate::convert::TryInto;
Some(libc::timespec {
tv_sec: self.tv_sec.try_into().ok()?,
tv_nsec: self.tv_nsec.try_into().ok()?,
})
}
}
}