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

Provided by KDAB

Privacy Policy
Learn Rust with the experts
Find out more