1use crate::time::Duration;
2use crate::{fmt, io};
3
4const NSEC_PER_SEC: u64 = 1_000_000_000;
5pub const UNIX_EPOCH: SystemTime = SystemTime { t: Timespec::zero() };
6#[allow(dead_code)] // Used for pthread condvar timeouts
7pub const TIMESPEC_MAX: libc::timespec =
8 libc::timespec { tv_sec: <libc::time_t>::MAX, tv_nsec: 1_000_000_000 - 1 };
9
10// This additional constant is only used when calling
11// `libc::pthread_cond_timedwait`.
12#[cfg(target_os = "nto")]
13pub(in crate::sys) const TIMESPEC_MAX_CAPPED: libc::timespec = libc::timespec {
14 tv_sec: (u64::MAX / NSEC_PER_SEC) as i64,
15 tv_nsec: (u64::MAX % NSEC_PER_SEC) as i64,
16};
17
18#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
19#[repr(transparent)]
20#[rustc_layout_scalar_valid_range_start(0)]
21#[rustc_layout_scalar_valid_range_end(999_999_999)]
22struct Nanoseconds(u32);
23
24#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
25pub struct SystemTime {
26 pub(crate) t: Timespec,
27}
28
29#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
30pub(crate) struct Timespec {
31 tv_sec: i64,
32 tv_nsec: Nanoseconds,
33}
34
35impl SystemTime {
36 #[cfg_attr(any(target_os = "horizon", target_os = "hurd"), allow(unused))]
37 pub fn new(tv_sec: i64, tv_nsec: i64) -> Result<SystemTime, io::Error> {
38 Ok(SystemTime { t: Timespec::new(tv_sec, tv_nsec)? })
39 }
40
41 pub fn now() -> SystemTime {
42 SystemTime { t: Timespec::now(libc::CLOCK_REALTIME) }
43 }
44
45 pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
46 self.t.sub_timespec(&other.t)
47 }
48
49 pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
50 Some(SystemTime { t: self.t.checked_add_duration(other)? })
51 }
52
53 pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
54 Some(SystemTime { t: self.t.checked_sub_duration(other)? })
55 }
56}
57
58impl fmt::Debug for SystemTime {
59 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
60 f&mut DebugStruct<'_, '_>.debug_struct("SystemTime")
61 .field("tv_sec", &self.t.tv_sec)
62 .field(name:"tv_nsec", &self.t.tv_nsec.0)
63 .finish()
64 }
65}
66
67impl Timespec {
68 const unsafe fn new_unchecked(tv_sec: i64, tv_nsec: i64) -> Timespec {
69 Timespec { tv_sec, tv_nsec: unsafe { Nanoseconds(tv_nsec as u32) } }
70 }
71
72 pub const fn zero() -> Timespec {
73 unsafe { Self::new_unchecked(0, 0) }
74 }
75
76 const fn new(tv_sec: i64, tv_nsec: i64) -> Result<Timespec, io::Error> {
77 // On Apple OS, dates before epoch are represented differently than on other
78 // Unix platforms: e.g. 1/10th of a second before epoch is represented as `seconds=-1`
79 // and `nanoseconds=100_000_000` on other platforms, but is `seconds=0` and
80 // `nanoseconds=-900_000_000` on Apple OS.
81 //
82 // To compensate, we first detect this special case by checking if both
83 // seconds and nanoseconds are in range, and then correct the value for seconds
84 // and nanoseconds to match the common unix representation.
85 //
86 // Please note that Apple OS nonetheless accepts the standard unix format when
87 // setting file times, which makes this compensation round-trippable and generally
88 // transparent.
89 #[cfg(any(
90 target_os = "macos",
91 target_os = "ios",
92 target_os = "tvos",
93 target_os = "watchos",
94 target_os = "visionos",
95 ))]
96 let (tv_sec, tv_nsec) =
97 if (tv_sec <= 0 && tv_sec > i64::MIN) && (tv_nsec < 0 && tv_nsec > -1_000_000_000) {
98 (tv_sec - 1, tv_nsec + 1_000_000_000)
99 } else {
100 (tv_sec, tv_nsec)
101 };
102 if tv_nsec >= 0 && tv_nsec < NSEC_PER_SEC as i64 {
103 Ok(unsafe { Self::new_unchecked(tv_sec, tv_nsec) })
104 } else {
105 Err(io::const_io_error!(io::ErrorKind::InvalidData, "Invalid timestamp"))
106 }
107 }
108
109 pub fn now(clock: libc::clockid_t) -> Timespec {
110 use crate::mem::MaybeUninit;
111 use crate::sys::cvt;
112
113 // Try to use 64-bit time in preparation for Y2038.
114 #[cfg(all(
115 target_os = "linux",
116 target_env = "gnu",
117 target_pointer_width = "32",
118 not(target_arch = "riscv32")
119 ))]
120 {
121 use crate::sys::weak::weak;
122
123 // __clock_gettime64 was added to 32-bit arches in glibc 2.34,
124 // and it handles both vDSO calls and ENOSYS fallbacks itself.
125 weak!(fn __clock_gettime64(libc::clockid_t, *mut __timespec64) -> libc::c_int);
126
127 if let Some(clock_gettime64) = __clock_gettime64.get() {
128 let mut t = MaybeUninit::uninit();
129 cvt(unsafe { clock_gettime64(clock, t.as_mut_ptr()) }).unwrap();
130 let t = unsafe { t.assume_init() };
131 return Timespec::new(t.tv_sec as i64, t.tv_nsec as i64).unwrap();
132 }
133 }
134
135 let mut t = MaybeUninit::uninit();
136 cvt(unsafe { libc::clock_gettime(clock, t.as_mut_ptr()) }).unwrap();
137 let t = unsafe { t.assume_init() };
138 Timespec::new(t.tv_sec as i64, t.tv_nsec as i64).unwrap()
139 }
140
141 pub fn sub_timespec(&self, other: &Timespec) -> Result<Duration, Duration> {
142 if self >= other {
143 // NOTE(eddyb) two aspects of this `if`-`else` are required for LLVM
144 // to optimize it into a branchless form (see also #75545):
145 //
146 // 1. `self.tv_sec - other.tv_sec` shows up as a common expression
147 // in both branches, i.e. the `else` must have its `- 1`
148 // subtraction after the common one, not interleaved with it
149 // (it used to be `self.tv_sec - 1 - other.tv_sec`)
150 //
151 // 2. the `Duration::new` call (or any other additional complexity)
152 // is outside of the `if`-`else`, not duplicated in both branches
153 //
154 // Ideally this code could be rearranged such that it more
155 // directly expresses the lower-cost behavior we want from it.
156 let (secs, nsec) = if self.tv_nsec.0 >= other.tv_nsec.0 {
157 ((self.tv_sec - other.tv_sec) as u64, self.tv_nsec.0 - other.tv_nsec.0)
158 } else {
159 (
160 (self.tv_sec - other.tv_sec - 1) as u64,
161 self.tv_nsec.0 + (NSEC_PER_SEC as u32) - other.tv_nsec.0,
162 )
163 };
164
165 Ok(Duration::new(secs, nsec))
166 } else {
167 match other.sub_timespec(self) {
168 Ok(d) => Err(d),
169 Err(d) => Ok(d),
170 }
171 }
172 }
173
174 pub fn checked_add_duration(&self, other: &Duration) -> Option<Timespec> {
175 let mut secs = self.tv_sec.checked_add_unsigned(other.as_secs())?;
176
177 // Nano calculations can't overflow because nanos are <1B which fit
178 // in a u32.
179 let mut nsec = other.subsec_nanos() + self.tv_nsec.0;
180 if nsec >= NSEC_PER_SEC as u32 {
181 nsec -= NSEC_PER_SEC as u32;
182 secs = secs.checked_add(1)?;
183 }
184 Some(unsafe { Timespec::new_unchecked(secs, nsec.into()) })
185 }
186
187 pub fn checked_sub_duration(&self, other: &Duration) -> Option<Timespec> {
188 let mut secs = self.tv_sec.checked_sub_unsigned(other.as_secs())?;
189
190 // Similar to above, nanos can't overflow.
191 let mut nsec = self.tv_nsec.0 as i32 - other.subsec_nanos() as i32;
192 if nsec < 0 {
193 nsec += NSEC_PER_SEC as i32;
194 secs = secs.checked_sub(1)?;
195 }
196 Some(unsafe { Timespec::new_unchecked(secs, nsec.into()) })
197 }
198
199 #[allow(dead_code)]
200 pub fn to_timespec(&self) -> Option<libc::timespec> {
201 Some(libc::timespec {
202 tv_sec: self.tv_sec.try_into().ok()?,
203 tv_nsec: self.tv_nsec.0.try_into().ok()?,
204 })
205 }
206
207 // On QNX Neutrino, the maximum timespec for e.g. pthread_cond_timedwait
208 // is 2^64 nanoseconds
209 #[cfg(target_os = "nto")]
210 pub(in crate::sys) fn to_timespec_capped(&self) -> Option<libc::timespec> {
211 // Check if timeout in nanoseconds would fit into an u64
212 if (self.tv_nsec.0 as u64)
213 .checked_add((self.tv_sec as u64).checked_mul(NSEC_PER_SEC)?)
214 .is_none()
215 {
216 return None;
217 }
218 self.to_timespec()
219 }
220
221 #[cfg(all(
222 target_os = "linux",
223 target_env = "gnu",
224 target_pointer_width = "32",
225 not(target_arch = "riscv32")
226 ))]
227 pub fn to_timespec64(&self) -> __timespec64 {
228 __timespec64::new(self.tv_sec, self.tv_nsec.0 as _)
229 }
230}
231
232#[cfg(all(
233 target_os = "linux",
234 target_env = "gnu",
235 target_pointer_width = "32",
236 not(target_arch = "riscv32")
237))]
238#[repr(C)]
239pub(crate) struct __timespec64 {
240 pub(crate) tv_sec: i64,
241 #[cfg(target_endian = "big")]
242 _padding: i32,
243 pub(crate) tv_nsec: i32,
244 #[cfg(target_endian = "little")]
245 _padding: i32,
246}
247
248#[cfg(all(
249 target_os = "linux",
250 target_env = "gnu",
251 target_pointer_width = "32",
252 not(target_arch = "riscv32")
253))]
254impl __timespec64 {
255 pub(crate) fn new(tv_sec: i64, tv_nsec: i32) -> Self {
256 Self { tv_sec, tv_nsec, _padding: 0 }
257 }
258}
259
260#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
261pub struct Instant {
262 t: Timespec,
263}
264
265impl Instant {
266 pub fn now() -> Instant {
267 // https://www.manpagez.com/man/3/clock_gettime/
268 //
269 // CLOCK_UPTIME_RAW clock that increments monotonically, in the same man-
270 // ner as CLOCK_MONOTONIC_RAW, but that does not incre-
271 // ment while the system is asleep. The returned value
272 // is identical to the result of mach_absolute_time()
273 // after the appropriate mach_timebase conversion is
274 // applied.
275 //
276 // Instant on macos was historically implemented using mach_absolute_time;
277 // we preserve this value domain out of an abundance of caution.
278 #[cfg(any(
279 target_os = "macos",
280 target_os = "ios",
281 target_os = "watchos",
282 target_os = "visionos",
283 target_os = "tvos"
284 ))]
285 const clock_id: libc::clockid_t = libc::CLOCK_UPTIME_RAW;
286 #[cfg(not(any(
287 target_os = "macos",
288 target_os = "ios",
289 target_os = "watchos",
290 target_os = "visionos",
291 target_os = "tvos"
292 )))]
293 const clock_id: libc::clockid_t = libc::CLOCK_MONOTONIC;
294 Instant { t: Timespec::now(clock_id) }
295 }
296
297 pub fn checked_sub_instant(&self, other: &Instant) -> Option<Duration> {
298 self.t.sub_timespec(&other.t).ok()
299 }
300
301 pub fn checked_add_duration(&self, other: &Duration) -> Option<Instant> {
302 Some(Instant { t: self.t.checked_add_duration(other)? })
303 }
304
305 pub fn checked_sub_duration(&self, other: &Duration) -> Option<Instant> {
306 Some(Instant { t: self.t.checked_sub_duration(other)? })
307 }
308}
309
310impl fmt::Debug for Instant {
311 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
312 f&mut DebugStruct<'_, '_>.debug_struct("Instant")
313 .field("tv_sec", &self.t.tv_sec)
314 .field(name:"tv_nsec", &self.t.tv_nsec.0)
315 .finish()
316 }
317}
318