Rollup merge of #151161 - joboet:move-pal-time, r=tgross35

std: move time implementations to `sys`

This is probably the most complex step of #117276 so far. Unfortunately, quite some of the internal time logic defined in the PAL is also used in other places like the filesystem code, so this isn't just a series of simple moves. I've left all that logic inside the PAL and only moved the actual `SystemTime`/`Instant` implementations.

While there are no functional changes, this PR also contains some slight code cleanups on Windows and Hermit, these are explained in the relevant commits.

For additional details see the individual commits, I've tried to make the messages as helpful as possible about what's going on.

Author: JonathanBrouwer

library/std/src/sys/fs/uefi.rs

@@ -580,7 +580,8 @@ mod uefi_fs {
     use crate::path::Path;
     use crate::ptr::NonNull;
     use crate::sys::pal::helpers::{self, UefiBox};
-    use crate::sys::time::{self, SystemTime};
+    use crate::sys::pal::system_time;
+    use crate::sys::time::SystemTime;
 
     pub(crate) struct File {
         protocol: NonNull<file::Protocol>,
@@ -879,7 +880,7 @@ mod uefi_fs {
     /// conversion to SystemTime, we use the current time to get the timezone in such cases.
     pub(crate) fn uefi_to_systemtime(mut time: r_efi::efi::Time) -> Option<SystemTime> {
         time.timezone = if time.timezone == r_efi::efi::UNSPECIFIED_TIMEZONE {
-            time::system_time_internal::now().timezone
+            system_time::now().timezone
         } else {
             time.timezone
         };
@@ -888,7 +889,7 @@ mod uefi_fs {
 
     /// Convert to UEFI Time with the current timezone.
     pub(crate) fn systemtime_to_uefi(time: SystemTime) -> r_efi::efi::Time {
-        let now = time::system_time_internal::now();
+        let now = system_time::now();
         time.to_uefi_loose(now.timezone, now.daylight)
     }
 

library/std/src/sys/fs/unix.rs

@@ -1822,7 +1822,7 @@ impl File {
             _ => {
                 #[cfg(all(target_os = "linux", target_env = "gnu", target_pointer_width = "32", not(target_arch = "riscv32")))]
                 {
-                    use crate::sys::{time::__timespec64, weak::weak};
+                    use crate::sys::pal::{time::__timespec64, weak::weak};
 
                     // Added in glibc 2.34
                     weak!(
@@ -2258,7 +2258,7 @@ fn set_times_impl(p: &CStr, times: FileTimes, follow_symlinks: bool) -> io::Resu
             let flags = if follow_symlinks { 0 } else { libc::AT_SYMLINK_NOFOLLOW };
             #[cfg(all(target_os = "linux", target_env = "gnu", target_pointer_width = "32", not(target_arch = "riscv32")))]
             {
-                use crate::sys::{time::__timespec64, weak::weak};
+                use crate::sys::pal::{time::__timespec64, weak::weak};
 
                 // Added in glibc 2.34
                 weak!(

library/std/src/sys/mod.rs

@@ -26,6 +26,7 @@ pub mod stdio;
 pub mod sync;
 pub mod thread;
 pub mod thread_local;
+pub mod time;
 
 // FIXME(117276): remove this, move feature implementations into individual
 //                submodules.

library/std/src/sys/net/connection/socket/hermit.rs

@@ -9,10 +9,9 @@ use crate::io::{self, BorrowedBuf, BorrowedCursor, IoSlice, IoSliceMut};
 use crate::net::{Shutdown, SocketAddr};
 use crate::os::hermit::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, RawFd};
 use crate::sys::fd::FileDesc;
-use crate::sys::time::Instant;
 use crate::sys::{AsInner, FromInner, IntoInner};
 pub use crate::sys::{cvt, cvt_r};
-use crate::time::Duration;
+use crate::time::{Duration, Instant};
 use crate::{cmp, mem};
 
 #[expect(non_camel_case_types)]

library/std/src/sys/pal/hermit/time.rs

@@ -1,35 +1,32 @@
-#![allow(dead_code)]
+use hermit_abi::{self, timespec};
 
-use core::hash::{Hash, Hasher};
-
-use super::hermit_abi::{self, CLOCK_MONOTONIC, CLOCK_REALTIME, timespec};
 use crate::cmp::Ordering;
-use crate::ops::{Add, AddAssign, Sub, SubAssign};
+use crate::hash::{Hash, Hasher};
 use crate::time::Duration;
 
 const NSEC_PER_SEC: i32 = 1_000_000_000;
 
 #[derive(Copy, Clone, Debug)]
-struct Timespec {
-    t: timespec,
+pub struct Timespec {
+    pub t: timespec,
 }
 
 impl Timespec {
-    const MAX: Timespec = Self::new(i64::MAX, 1_000_000_000 - 1);
+    pub const MAX: Timespec = Self::new(i64::MAX, 1_000_000_000 - 1);
 
-    const MIN: Timespec = Self::new(i64::MIN, 0);
+    pub const MIN: Timespec = Self::new(i64::MIN, 0);
 
-    const fn zero() -> Timespec {
+    pub const fn zero() -> Timespec {
         Timespec { t: timespec { tv_sec: 0, tv_nsec: 0 } }
     }
 
-    const fn new(tv_sec: i64, tv_nsec: i32) -> Timespec {
+    pub const fn new(tv_sec: i64, tv_nsec: i32) -> Timespec {
         assert!(tv_nsec >= 0 && tv_nsec < NSEC_PER_SEC);
         // SAFETY: The assert above checks tv_nsec is within the valid range
         Timespec { t: timespec { tv_sec, tv_nsec } }
     }
 
-    fn sub_timespec(&self, other: &Timespec) -> Result<Duration, Duration> {
+    pub fn sub_timespec(&self, other: &Timespec) -> Result<Duration, Duration> {
         fn sub_ge_to_unsigned(a: i64, b: i64) -> u64 {
             debug_assert!(a >= b);
             a.wrapping_sub(b).cast_unsigned()
@@ -57,7 +54,7 @@ impl Timespec {
         }
     }
 
-    fn checked_add_duration(&self, other: &Duration) -> Option<Timespec> {
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<Timespec> {
         let mut secs = self.t.tv_sec.checked_add_unsigned(other.as_secs())?;
 
         // Nano calculations can't overflow because nanos are <1B which fit
@@ -70,7 +67,7 @@ impl Timespec {
         Some(Timespec { t: timespec { tv_sec: secs, tv_nsec: nsec as _ } })
     }
 
-    fn checked_sub_duration(&self, other: &Duration) -> Option<Timespec> {
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<Timespec> {
         let mut secs = self.t.tv_sec.checked_sub_unsigned(other.as_secs())?;
 
         // Similar to above, nanos can't overflow.
@@ -111,132 +108,3 @@ impl Hash for Timespec {
         self.t.tv_nsec.hash(state);
     }
 }
-
-#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
-pub struct Instant(Timespec);
-
-impl Instant {
-    pub fn now() -> Instant {
-        let mut time: Timespec = Timespec::zero();
-        let _ = unsafe { hermit_abi::clock_gettime(CLOCK_MONOTONIC, &raw mut time.t) };
-
-        Instant(time)
-    }
-
-    #[stable(feature = "time2", since = "1.8.0")]
-    pub fn elapsed(&self) -> Duration {
-        Instant::now() - *self
-    }
-
-    pub fn duration_since(&self, earlier: Instant) -> Duration {
-        self.checked_duration_since(earlier).unwrap_or_default()
-    }
-
-    pub fn checked_duration_since(&self, earlier: Instant) -> Option<Duration> {
-        self.checked_sub_instant(&earlier)
-    }
-
-    pub fn checked_sub_instant(&self, other: &Instant) -> Option<Duration> {
-        self.0.sub_timespec(&other.0).ok()
-    }
-
-    pub fn checked_add_duration(&self, other: &Duration) -> Option<Instant> {
-        Some(Instant(self.0.checked_add_duration(other)?))
-    }
-
-    pub fn checked_sub_duration(&self, other: &Duration) -> Option<Instant> {
-        Some(Instant(self.0.checked_sub_duration(other)?))
-    }
-
-    pub fn checked_add(&self, duration: Duration) -> Option<Instant> {
-        self.0.checked_add_duration(&duration).map(Instant)
-    }
-
-    pub fn checked_sub(&self, duration: Duration) -> Option<Instant> {
-        self.0.checked_sub_duration(&duration).map(Instant)
-    }
-}
-
-impl Add<Duration> for Instant {
-    type Output = Instant;
-
-    /// # Panics
-    ///
-    /// This function may panic if the resulting point in time cannot be represented by the
-    /// underlying data structure. See [`Instant::checked_add`] for a version without panic.
-    fn add(self, other: Duration) -> Instant {
-        self.checked_add(other).expect("overflow when adding duration to instant")
-    }
-}
-
-impl AddAssign<Duration> for Instant {
-    fn add_assign(&mut self, other: Duration) {
-        *self = *self + other;
-    }
-}
-
-impl Sub<Duration> for Instant {
-    type Output = Instant;
-
-    fn sub(self, other: Duration) -> Instant {
-        self.checked_sub(other).expect("overflow when subtracting duration from instant")
-    }
-}
-
-impl SubAssign<Duration> for Instant {
-    fn sub_assign(&mut self, other: Duration) {
-        *self = *self - other;
-    }
-}
-
-impl Sub<Instant> for Instant {
-    type Output = Duration;
-
-    /// Returns the amount of time elapsed from another instant to this one,
-    /// or zero duration if that instant is later than this one.
-    ///
-    /// # Panics
-    ///
-    /// Previous Rust versions panicked when `other` was later than `self`. Currently this
-    /// method saturates. Future versions may reintroduce the panic in some circumstances.
-    /// See [Monotonicity].
-    ///
-    /// [Monotonicity]: Instant#monotonicity
-    fn sub(self, other: Instant) -> Duration {
-        self.duration_since(other)
-    }
-}
-
-#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
-pub struct SystemTime(Timespec);
-
-pub const UNIX_EPOCH: SystemTime = SystemTime(Timespec::zero());
-
-impl SystemTime {
-    pub const MAX: SystemTime = SystemTime(Timespec::MAX);
-
-    pub const MIN: SystemTime = SystemTime(Timespec::MIN);
-
-    pub fn new(tv_sec: i64, tv_nsec: i32) -> SystemTime {
-        SystemTime(Timespec::new(tv_sec, tv_nsec))
-    }
-
-    pub fn now() -> SystemTime {
-        let mut time: Timespec = Timespec::zero();
-        let _ = unsafe { hermit_abi::clock_gettime(CLOCK_REALTIME, &raw mut time.t) };
-
-        SystemTime(time)
-    }
-
-    pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
-        self.0.sub_timespec(&other.0)
-    }
-
-    pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
-        Some(SystemTime(self.0.checked_add_duration(other)?))
-    }
-
-    pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
-        Some(SystemTime(self.0.checked_sub_duration(other)?))
-    }
-}

library/std/src/sys/pal/itron/time.rs

@@ -3,38 +3,16 @@ use super::error::expect_success;
 use crate::mem::MaybeUninit;
 use crate::time::Duration;
 
-#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
-pub struct Instant(abi::SYSTIM);
-
-impl Instant {
-    pub fn now() -> Instant {
-        // Safety: The provided pointer is valid
-        unsafe {
-            let mut out = MaybeUninit::uninit();
-            expect_success(abi::get_tim(out.as_mut_ptr()), &"get_tim");
-            Instant(out.assume_init())
-        }
-    }
-
-    pub fn checked_sub_instant(&self, other: &Instant) -> Option<Duration> {
-        self.0.checked_sub(other.0).map(|ticks| {
-            // `SYSTIM` is measured in microseconds
-            Duration::from_micros(ticks)
-        })
-    }
-
-    pub fn checked_add_duration(&self, other: &Duration) -> Option<Instant> {
-        // `SYSTIM` is measured in microseconds
-        let ticks = other.as_micros();
-
-        Some(Instant(self.0.checked_add(ticks.try_into().ok()?)?))
-    }
-
-    pub fn checked_sub_duration(&self, other: &Duration) -> Option<Instant> {
-        // `SYSTIM` is measured in microseconds
-        let ticks = other.as_micros();
+#[cfg(test)]
+mod tests;
 
-        Some(Instant(self.0.checked_sub(ticks.try_into().ok()?)?))
+#[inline]
+pub fn get_tim() -> abi::SYSTIM {
+    // Safety: The provided pointer is valid
+    unsafe {
+        let mut out = MaybeUninit::uninit();
+        expect_success(abi::get_tim(out.as_mut_ptr()), &"get_tim");
+        out.assume_init()
     }
 }
 
@@ -98,19 +76,16 @@ pub fn with_tmos_strong(dur: Duration, mut f: impl FnMut(abi::TMO) -> abi::ER) -
     // a problem in practice. (`u64::MAX` μs ≈ 584942 years)
     let ticks = dur.as_micros().min(abi::SYSTIM::MAX as u128) as abi::SYSTIM;
 
-    let start = Instant::now().0;
+    let start = get_tim();
     let mut elapsed = 0;
     let mut er = abi::E_TMOUT;
     while elapsed <= ticks {
         er = f(elapsed.min(abi::TMAX_RELTIM as abi::SYSTIM) as abi::TMO);
         if er != abi::E_TMOUT {
             break;
         }
-        elapsed = Instant::now().0.wrapping_sub(start);
+        elapsed = get_tim().wrapping_sub(start);
     }
 
     er
 }
-
-#[cfg(test)]
-mod tests;

library/std/src/sys/pal/motor/mod.rs

@@ -1,7 +1,6 @@
 #![allow(unsafe_op_in_unsafe_fn)]
 
 pub mod os;
-pub mod time;
 
 pub use moto_rt::futex;
 

library/std/src/sys/pal/motor/time.rs

@@ -12,7 +12,6 @@ pub mod abi;
 mod libunwind_integration;
 pub mod os;
 pub mod thread_parking;
-pub mod time;
 pub mod waitqueue;
 
 // SAFETY: must be called only once during runtime initialization.

library/std/src/sys/pal/sgx/mod.rs

@@ -21,7 +21,6 @@ pub mod itron {
 pub(crate) mod error;
 pub mod os;
 pub use self::itron::thread_parking;
-pub mod time;
 
 // SAFETY: must be called only once during runtime initialization.
 // NOTE: this is not guaranteed to run, for example when Rust code is called externally.