2 use crate::time::Duration;
4 pub use self::inner::Instant;
6 const NSEC_PER_SEC: u64 = 1_000_000_000;
7 pub const UNIX_EPOCH: SystemTime = SystemTime { t: Timespec::zero() };
9 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
11 #[rustc_layout_scalar_valid_range_start(0)]
12 #[rustc_layout_scalar_valid_range_end(999_999_999)]
13 struct Nanoseconds(u32);
15 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
16 pub struct SystemTime {
17 pub(in crate::sys::unix) t: Timespec,
20 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
21 pub(in crate::sys::unix) struct Timespec {
27 #[cfg_attr(target_os = "horizon", allow(unused))]
28 pub fn new(tv_sec: i64, tv_nsec: i64) -> SystemTime {
29 SystemTime { t: Timespec::new(tv_sec, tv_nsec) }
32 pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
33 self.t.sub_timespec(&other.t)
36 pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
37 Some(SystemTime { t: self.t.checked_add_duration(other)? })
40 pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
41 Some(SystemTime { t: self.t.checked_sub_duration(other)? })
45 impl From<libc::timespec> for SystemTime {
46 fn from(t: libc::timespec) -> SystemTime {
47 SystemTime { t: Timespec::from(t) }
51 impl fmt::Debug for SystemTime {
52 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
53 f.debug_struct("SystemTime")
54 .field("tv_sec", &self.t.tv_sec)
55 .field("tv_nsec", &self.t.tv_nsec.0)
61 pub const fn zero() -> Timespec {
65 const fn new(tv_sec: i64, tv_nsec: i64) -> Timespec {
66 assert!(tv_nsec >= 0 && tv_nsec < NSEC_PER_SEC as i64);
67 // SAFETY: The assert above checks tv_nsec is within the valid range
68 Timespec { tv_sec, tv_nsec: unsafe { Nanoseconds(tv_nsec as u32) } }
71 pub fn sub_timespec(&self, other: &Timespec) -> Result<Duration, Duration> {
73 // NOTE(eddyb) two aspects of this `if`-`else` are required for LLVM
74 // to optimize it into a branchless form (see also #75545):
76 // 1. `self.tv_sec - other.tv_sec` shows up as a common expression
77 // in both branches, i.e. the `else` must have its `- 1`
78 // subtraction after the common one, not interleaved with it
79 // (it used to be `self.tv_sec - 1 - other.tv_sec`)
81 // 2. the `Duration::new` call (or any other additional complexity)
82 // is outside of the `if`-`else`, not duplicated in both branches
84 // Ideally this code could be rearranged such that it more
85 // directly expresses the lower-cost behavior we want from it.
86 let (secs, nsec) = if self.tv_nsec.0 >= other.tv_nsec.0 {
87 ((self.tv_sec - other.tv_sec) as u64, self.tv_nsec.0 - other.tv_nsec.0)
90 (self.tv_sec - other.tv_sec - 1) as u64,
91 self.tv_nsec.0 + (NSEC_PER_SEC as u32) - other.tv_nsec.0,
95 Ok(Duration::new(secs, nsec))
97 match other.sub_timespec(self) {
104 pub fn checked_add_duration(&self, other: &Duration) -> Option<Timespec> {
107 .try_into() // <- target type would be `i64`
109 .and_then(|secs| self.tv_sec.checked_add(secs))?;
111 // Nano calculations can't overflow because nanos are <1B which fit
113 let mut nsec = other.subsec_nanos() + self.tv_nsec.0;
114 if nsec >= NSEC_PER_SEC as u32 {
115 nsec -= NSEC_PER_SEC as u32;
116 secs = secs.checked_add(1)?;
118 Some(Timespec::new(secs, nsec as i64))
121 pub fn checked_sub_duration(&self, other: &Duration) -> Option<Timespec> {
124 .try_into() // <- target type would be `i64`
126 .and_then(|secs| self.tv_sec.checked_sub(secs))?;
128 // Similar to above, nanos can't overflow.
129 let mut nsec = self.tv_nsec.0 as i32 - other.subsec_nanos() as i32;
131 nsec += NSEC_PER_SEC as i32;
132 secs = secs.checked_sub(1)?;
134 Some(Timespec::new(secs, nsec as i64))
138 pub fn to_timespec(&self) -> Option<libc::timespec> {
139 Some(libc::timespec {
140 tv_sec: self.tv_sec.try_into().ok()?,
141 tv_nsec: self.tv_nsec.0.try_into().ok()?,
146 impl From<libc::timespec> for Timespec {
147 fn from(t: libc::timespec) -> Timespec {
148 Timespec::new(t.tv_sec as i64, t.tv_nsec as i64)
153 all(target_os = "macos", any(not(target_arch = "aarch64"))),
155 target_os = "watchos"
158 use crate::sync::atomic::{AtomicU64, Ordering};
160 use crate::sys_common::mul_div_u64;
161 use crate::time::Duration;
163 use super::{SystemTime, Timespec, NSEC_PER_SEC};
165 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
171 #[derive(Copy, Clone)]
172 struct mach_timebase_info {
176 type mach_timebase_info_t = *mut mach_timebase_info;
177 type kern_return_t = libc::c_int;
180 pub fn now() -> Instant {
182 fn mach_absolute_time() -> u64;
184 Instant { t: unsafe { mach_absolute_time() } }
187 pub fn checked_sub_instant(&self, other: &Instant) -> Option<Duration> {
188 let diff = self.t.checked_sub(other.t)?;
190 let nanos = mul_div_u64(diff, info.numer as u64, info.denom as u64);
191 Some(Duration::new(nanos / NSEC_PER_SEC, (nanos % NSEC_PER_SEC) as u32))
194 pub fn checked_add_duration(&self, other: &Duration) -> Option<Instant> {
195 Some(Instant { t: self.t.checked_add(checked_dur2intervals(other)?)? })
198 pub fn checked_sub_duration(&self, other: &Duration) -> Option<Instant> {
199 Some(Instant { t: self.t.checked_sub(checked_dur2intervals(other)?)? })
204 pub fn now() -> SystemTime {
207 let mut s = libc::timeval { tv_sec: 0, tv_usec: 0 };
208 cvt(unsafe { libc::gettimeofday(&mut s, ptr::null_mut()) }).unwrap();
209 return SystemTime::from(s);
213 impl From<libc::timeval> for Timespec {
214 fn from(t: libc::timeval) -> Timespec {
215 Timespec::new(t.tv_sec as i64, 1000 * t.tv_usec as i64)
219 impl From<libc::timeval> for SystemTime {
220 fn from(t: libc::timeval) -> SystemTime {
221 SystemTime { t: Timespec::from(t) }
225 fn checked_dur2intervals(dur: &Duration) -> Option<u64> {
227 dur.as_secs().checked_mul(NSEC_PER_SEC)?.checked_add(dur.subsec_nanos() as u64)?;
229 Some(mul_div_u64(nanos, info.denom as u64, info.numer as u64))
232 fn info() -> mach_timebase_info {
233 // INFO_BITS conceptually is an `Option<mach_timebase_info>`. We can do
234 // this in 64 bits because we know 0 is never a valid value for the
237 // Encoding this as a single `AtomicU64` allows us to use `Relaxed`
238 // operations, as we are only interested in the effects on a single
240 static INFO_BITS: AtomicU64 = AtomicU64::new(0);
242 // If a previous thread has initialized `INFO_BITS`, use it.
243 let info_bits = INFO_BITS.load(Ordering::Relaxed);
245 return info_from_bits(info_bits);
248 // ... otherwise learn for ourselves ...
250 fn mach_timebase_info(info: mach_timebase_info_t) -> kern_return_t;
253 let mut info = info_from_bits(0);
255 mach_timebase_info(&mut info);
257 INFO_BITS.store(info_to_bits(info), Ordering::Relaxed);
262 fn info_to_bits(info: mach_timebase_info) -> u64 {
263 ((info.denom as u64) << 32) | (info.numer as u64)
267 fn info_from_bits(bits: u64) -> mach_timebase_info {
268 mach_timebase_info { numer: bits as u32, denom: (bits >> 32) as u32 }
273 all(target_os = "macos", any(not(target_arch = "aarch64"))),
275 target_os = "watchos"
279 use crate::mem::MaybeUninit;
281 use crate::time::Duration;
283 use super::{SystemTime, Timespec};
285 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
291 pub fn now() -> Instant {
292 #[cfg(target_os = "macos")]
293 const clock_id: libc::clockid_t = libc::CLOCK_UPTIME_RAW;
294 #[cfg(not(target_os = "macos"))]
295 const clock_id: libc::clockid_t = libc::CLOCK_MONOTONIC;
296 Instant { t: Timespec::now(clock_id) }
299 pub fn checked_sub_instant(&self, other: &Instant) -> Option<Duration> {
300 self.t.sub_timespec(&other.t).ok()
303 pub fn checked_add_duration(&self, other: &Duration) -> Option<Instant> {
304 Some(Instant { t: self.t.checked_add_duration(other)? })
307 pub fn checked_sub_duration(&self, other: &Duration) -> Option<Instant> {
308 Some(Instant { t: self.t.checked_sub_duration(other)? })
312 impl fmt::Debug for Instant {
313 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
314 f.debug_struct("Instant")
315 .field("tv_sec", &self.t.tv_sec)
316 .field("tv_nsec", &self.t.tv_nsec.0)
322 pub fn now() -> SystemTime {
323 SystemTime { t: Timespec::now(libc::CLOCK_REALTIME) }
328 pub fn now(clock: libc::clockid_t) -> Timespec {
329 // Try to use 64-bit time in preparation for Y2038.
330 #[cfg(all(target_os = "linux", target_env = "gnu", target_pointer_width = "32"))]
332 use crate::sys::weak::weak;
334 // __clock_gettime64 was added to 32-bit arches in glibc 2.34,
335 // and it handles both vDSO calls and ENOSYS fallbacks itself.
336 weak!(fn __clock_gettime64(libc::clockid_t, *mut __timespec64) -> libc::c_int);
339 struct __timespec64 {
341 #[cfg(target_endian = "big")]
344 #[cfg(target_endian = "little")]
348 if let Some(clock_gettime64) = __clock_gettime64.get() {
349 let mut t = MaybeUninit::uninit();
350 cvt(unsafe { clock_gettime64(clock, t.as_mut_ptr()) }).unwrap();
351 let t = unsafe { t.assume_init() };
352 return Timespec::new(t.tv_sec, t.tv_nsec as i64);
356 let mut t = MaybeUninit::uninit();
357 cvt(unsafe { libc::clock_gettime(clock, t.as_mut_ptr()) }).unwrap();
358 Timespec::from(unsafe { t.assume_init() })