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//! Temporal quantification.
//!
//! # Examples
//!
//! There are multiple ways to create a new [`Duration`]:
//!
//! ```
//! # use std::time::Duration;
//! let five_seconds = Duration::from_secs(5);
//! assert_eq!(five_seconds, Duration::from_millis(5_000));
//! assert_eq!(five_seconds, Duration::from_micros(5_000_000));
//! assert_eq!(five_seconds, Duration::from_nanos(5_000_000_000));
//!
//! let ten_seconds = Duration::from_secs(10);
//! let seven_nanos = Duration::from_nanos(7);
//! let total = ten_seconds + seven_nanos;
//! assert_eq!(total, Duration::new(10, 7));
//! ```
//!
//! Using [`Instant`] to calculate how long a function took to run:
//!
//! ```ignore (incomplete)
//! let now = Instant::now();
//!
//! // Calling a slow function, it may take a while
//! slow_function();
//!
//! let elapsed_time = now.elapsed();
//! println!("Running slow_function() took {} seconds.", elapsed_time.as_secs());
//! ```
#![stable(feature = "time", since = "1.3.0")]
#[cfg(test)]
mod tests;
use crate::error::Error;
use crate::fmt;
use crate::ops::{Add, AddAssign, Sub, SubAssign};
use crate::sys::time;
use crate::sys_common::{FromInner, IntoInner};
#[stable(feature = "time", since = "1.3.0")]
pub use core::time::Duration;
#[stable(feature = "duration_checked_float", since = "1.66.0")]
pub use core::time::TryFromFloatSecsError;
/// A measurement of a monotonically nondecreasing clock.
/// Opaque and useful only with [`Duration`].
///
/// Instants are always guaranteed, barring [platform bugs], to be no less than any previously
/// measured instant when created, and are often useful for tasks such as measuring
/// benchmarks or timing how long an operation takes.
///
/// Note, however, that instants are **not** guaranteed to be **steady**. In other
/// words, each tick of the underlying clock might not be the same length (e.g.
/// some seconds may be longer than others). An instant may jump forwards or
/// experience time dilation (slow down or speed up), but it will never go
/// backwards.
/// As part of this non-guarantee it is also not specified whether system suspends count as
/// elapsed time or not. The behavior varies across platforms and rust versions.
///
/// Instants are opaque types that can only be compared to one another. There is
/// no method to get "the number of seconds" from an instant. Instead, it only
/// allows measuring the duration between two instants (or comparing two
/// instants).
///
/// The size of an `Instant` struct may vary depending on the target operating
/// system.
///
/// Example:
///
/// ```no_run
/// use std::time::{Duration, Instant};
/// use std::thread::sleep;
///
/// fn main() {
/// let now = Instant::now();
///
/// // we sleep for 2 seconds
/// sleep(Duration::new(2, 0));
/// // it prints '2'
/// println!("{}", now.elapsed().as_secs());
/// }
/// ```
///
/// [platform bugs]: Instant#monotonicity
///
/// # OS-specific behaviors
///
/// An `Instant` is a wrapper around system-specific types and it may behave
/// differently depending on the underlying operating system. For example,
/// the following snippet is fine on Linux but panics on macOS:
///
/// ```no_run
/// use std::time::{Instant, Duration};
///
/// let now = Instant::now();
/// let max_seconds = u64::MAX / 1_000_000_000;
/// let duration = Duration::new(max_seconds, 0);
/// println!("{:?}", now + duration);
/// ```
///
/// # Underlying System calls
///
/// The following system calls are [currently] being used by `now()` to find out
/// the current time:
///
/// | Platform | System call |
/// |-----------|----------------------------------------------------------------------|
/// | SGX | [`insecure_time` usercall]. More information on [timekeeping in SGX] |
/// | UNIX | [clock_gettime (Monotonic Clock)] |
/// | Darwin | [mach_absolute_time] |
/// | VXWorks | [clock_gettime (Monotonic Clock)] |
/// | SOLID | `get_tim` |
/// | WASI | [__wasi_clock_time_get (Monotonic Clock)] |
/// | Windows | [QueryPerformanceCounter] |
///
/// [currently]: crate::io#platform-specific-behavior
/// [QueryPerformanceCounter]: https://docs.microsoft.com/en-us/windows/win32/api/profileapi/nf-profileapi-queryperformancecounter
/// [`insecure_time` usercall]: https://edp.fortanix.com/docs/api/fortanix_sgx_abi/struct.Usercalls.html#method.insecure_time
/// [timekeeping in SGX]: https://edp.fortanix.com/docs/concepts/rust-std/#codestdtimecode
/// [__wasi_clock_time_get (Monotonic Clock)]: https://github.com/WebAssembly/WASI/blob/main/legacy/preview1/docs.md#clock_time_get
/// [clock_gettime (Monotonic Clock)]: https://linux.die.net/man/3/clock_gettime
/// [mach_absolute_time]: https://developer.apple.com/library/archive/documentation/Darwin/Conceptual/KernelProgramming/services/services.html
///
/// **Disclaimer:** These system calls might change over time.
///
/// > Note: mathematical operations like [`add`] may panic if the underlying
/// > structure cannot represent the new point in time.
///
/// [`add`]: Instant::add
///
/// ## Monotonicity
///
/// On all platforms `Instant` will try to use an OS API that guarantees monotonic behavior
/// if available, which is the case for all [tier 1] platforms.
/// In practice such guarantees are – under rare circumstances – broken by hardware, virtualization
/// or operating system bugs. To work around these bugs and platforms not offering monotonic clocks
/// [`duration_since`], [`elapsed`] and [`sub`] saturate to zero. In older Rust versions this
/// lead to a panic instead. [`checked_duration_since`] can be used to detect and handle situations
/// where monotonicity is violated, or `Instant`s are subtracted in the wrong order.
///
/// This workaround obscures programming errors where earlier and later instants are accidentally
/// swapped. For this reason future rust versions may reintroduce panics.
///
/// [tier 1]: https://doc.rust-lang.org/rustc/platform-support.html
/// [`duration_since`]: Instant::duration_since
/// [`elapsed`]: Instant::elapsed
/// [`sub`]: Instant::sub
/// [`checked_duration_since`]: Instant::checked_duration_since
///
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[stable(feature = "time2", since = "1.8.0")]
#[cfg_attr(not(test), rustc_diagnostic_item = "Instant")]
pub struct Instant(time::Instant);
/// A measurement of the system clock, useful for talking to
/// external entities like the file system or other processes.
///
/// Distinct from the [`Instant`] type, this time measurement **is not
/// monotonic**. This means that you can save a file to the file system, then
/// save another file to the file system, **and the second file has a
/// `SystemTime` measurement earlier than the first**. In other words, an
/// operation that happens after another operation in real time may have an
/// earlier `SystemTime`!
///
/// Consequently, comparing two `SystemTime` instances to learn about the
/// duration between them returns a [`Result`] instead of an infallible [`Duration`]
/// to indicate that this sort of time drift may happen and needs to be handled.
///
/// Although a `SystemTime` cannot be directly inspected, the [`UNIX_EPOCH`]
/// constant is provided in this module as an anchor in time to learn
/// information about a `SystemTime`. By calculating the duration from this
/// fixed point in time, a `SystemTime` can be converted to a human-readable time,
/// or perhaps some other string representation.
///
/// The size of a `SystemTime` struct may vary depending on the target operating
/// system.
///
/// A `SystemTime` does not count leap seconds.
/// `SystemTime::now()`'s behaviour around a leap second
/// is the same as the operating system's wall clock.
/// The precise behaviour near a leap second
/// (e.g. whether the clock appears to run slow or fast, or stop, or jump)
/// depends on platform and configuration,
/// so should not be relied on.
///
/// Example:
///
/// ```no_run
/// use std::time::{Duration, SystemTime};
/// use std::thread::sleep;
///
/// fn main() {
/// let now = SystemTime::now();
///
/// // we sleep for 2 seconds
/// sleep(Duration::new(2, 0));
/// match now.elapsed() {
/// Ok(elapsed) => {
/// // it prints '2'
/// println!("{}", elapsed.as_secs());
/// }
/// Err(e) => {
/// // an error occurred!
/// println!("Error: {e:?}");
/// }
/// }
/// }
/// ```
///
/// # Platform-specific behavior
///
/// The precision of `SystemTime` can depend on the underlying OS-specific time format.
/// For example, on Windows the time is represented in 100 nanosecond intervals whereas Linux
/// can represent nanosecond intervals.
///
/// The following system calls are [currently] being used by `now()` to find out
/// the current time:
///
/// | Platform | System call |
/// |-----------|----------------------------------------------------------------------|
/// | SGX | [`insecure_time` usercall]. More information on [timekeeping in SGX] |
/// | UNIX | [clock_gettime (Realtime Clock)] |
/// | Darwin | [gettimeofday] |
/// | VXWorks | [clock_gettime (Realtime Clock)] |
/// | SOLID | `SOLID_RTC_ReadTime` |
/// | WASI | [__wasi_clock_time_get (Realtime Clock)] |
/// | Windows | [GetSystemTimePreciseAsFileTime] / [GetSystemTimeAsFileTime] |
///
/// [currently]: crate::io#platform-specific-behavior
/// [`insecure_time` usercall]: https://edp.fortanix.com/docs/api/fortanix_sgx_abi/struct.Usercalls.html#method.insecure_time
/// [timekeeping in SGX]: https://edp.fortanix.com/docs/concepts/rust-std/#codestdtimecode
/// [gettimeofday]: https://man7.org/linux/man-pages/man2/gettimeofday.2.html
/// [clock_gettime (Realtime Clock)]: https://linux.die.net/man/3/clock_gettime
/// [__wasi_clock_time_get (Realtime Clock)]: https://github.com/WebAssembly/WASI/blob/main/legacy/preview1/docs.md#clock_time_get
/// [GetSystemTimePreciseAsFileTime]: https://docs.microsoft.com/en-us/windows/win32/api/sysinfoapi/nf-sysinfoapi-getsystemtimepreciseasfiletime
/// [GetSystemTimeAsFileTime]: https://docs.microsoft.com/en-us/windows/win32/api/sysinfoapi/nf-sysinfoapi-getsystemtimeasfiletime
///
/// **Disclaimer:** These system calls might change over time.
///
/// > Note: mathematical operations like [`add`] may panic if the underlying
/// > structure cannot represent the new point in time.
///
/// [`add`]: SystemTime::add
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[stable(feature = "time2", since = "1.8.0")]
pub struct SystemTime(time::SystemTime);
/// An error returned from the `duration_since` and `elapsed` methods on
/// `SystemTime`, used to learn how far in the opposite direction a system time
/// lies.
///
/// # Examples
///
/// ```no_run
/// use std::thread::sleep;
/// use std::time::{Duration, SystemTime};
///
/// let sys_time = SystemTime::now();
/// sleep(Duration::from_secs(1));
/// let new_sys_time = SystemTime::now();
/// match sys_time.duration_since(new_sys_time) {
/// Ok(_) => {}
/// Err(e) => println!("SystemTimeError difference: {:?}", e.duration()),
/// }
/// ```
#[derive(Clone, Debug)]
#[stable(feature = "time2", since = "1.8.0")]
pub struct SystemTimeError(Duration);
impl Instant {
/// Returns an instant corresponding to "now".
///
/// # Examples
///
/// ```
/// use std::time::Instant;
///
/// let now = Instant::now();
/// ```
#[must_use]
#[stable(feature = "time2", since = "1.8.0")]
pub fn now() -> Instant {
Instant(time::Instant::now())
}
/// 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 `earlier` was later than `self`. Currently this
/// method saturates. Future versions may reintroduce the panic in some circumstances.
/// See [Monotonicity].
///
/// [Monotonicity]: Instant#monotonicity
///
/// # Examples
///
/// ```no_run
/// use std::time::{Duration, Instant};
/// use std::thread::sleep;
///
/// let now = Instant::now();
/// sleep(Duration::new(1, 0));
/// let new_now = Instant::now();
/// println!("{:?}", new_now.duration_since(now));
/// println!("{:?}", now.duration_since(new_now)); // 0ns
/// ```
#[must_use]
#[stable(feature = "time2", since = "1.8.0")]
pub fn duration_since(&self, earlier: Instant) -> Duration {
self.checked_duration_since(earlier).unwrap_or_default()
}
/// Returns the amount of time elapsed from another instant to this one,
/// or None if that instant is later than this one.
///
/// Due to [monotonicity bugs], even under correct logical ordering of the passed `Instant`s,
/// this method can return `None`.
///
/// [monotonicity bugs]: Instant#monotonicity
///
/// # Examples
///
/// ```no_run
/// use std::time::{Duration, Instant};
/// use std::thread::sleep;
///
/// let now = Instant::now();
/// sleep(Duration::new(1, 0));
/// let new_now = Instant::now();
/// println!("{:?}", new_now.checked_duration_since(now));
/// println!("{:?}", now.checked_duration_since(new_now)); // None
/// ```
#[must_use]
#[stable(feature = "checked_duration_since", since = "1.39.0")]
pub fn checked_duration_since(&self, earlier: Instant) -> Option<Duration> {
self.0.checked_sub_instant(&earlier.0)
}
/// Returns the amount of time elapsed from another instant to this one,
/// or zero duration if that instant is later than this one.
///
/// # Examples
///
/// ```no_run
/// use std::time::{Duration, Instant};
/// use std::thread::sleep;
///
/// let now = Instant::now();
/// sleep(Duration::new(1, 0));
/// let new_now = Instant::now();
/// println!("{:?}", new_now.saturating_duration_since(now));
/// println!("{:?}", now.saturating_duration_since(new_now)); // 0ns
/// ```
#[must_use]
#[stable(feature = "checked_duration_since", since = "1.39.0")]
pub fn saturating_duration_since(&self, earlier: Instant) -> Duration {
self.checked_duration_since(earlier).unwrap_or_default()
}
/// Returns the amount of time elapsed since this instant.
///
/// # Panics
///
/// Previous rust versions panicked when the current time was earlier than self. Currently this
/// method returns a Duration of zero in that case. Future versions may reintroduce the panic.
/// See [Monotonicity].
///
/// [Monotonicity]: Instant#monotonicity
///
/// # Examples
///
/// ```no_run
/// use std::thread::sleep;
/// use std::time::{Duration, Instant};
///
/// let instant = Instant::now();
/// let three_secs = Duration::from_secs(3);
/// sleep(three_secs);
/// assert!(instant.elapsed() >= three_secs);
/// ```
#[must_use]
#[stable(feature = "time2", since = "1.8.0")]
pub fn elapsed(&self) -> Duration {
Instant::now() - *self
}
/// Returns `Some(t)` where `t` is the time `self + duration` if `t` can be represented as
/// `Instant` (which means it's inside the bounds of the underlying data structure), `None`
/// otherwise.
#[stable(feature = "time_checked_add", since = "1.34.0")]
pub fn checked_add(&self, duration: Duration) -> Option<Instant> {
self.0.checked_add_duration(&duration).map(Instant)
}
/// Returns `Some(t)` where `t` is the time `self - duration` if `t` can be represented as
/// `Instant` (which means it's inside the bounds of the underlying data structure), `None`
/// otherwise.
#[stable(feature = "time_checked_add", since = "1.34.0")]
pub fn checked_sub(&self, duration: Duration) -> Option<Instant> {
self.0.checked_sub_duration(&duration).map(Instant)
}
}
#[stable(feature = "time2", since = "1.8.0")]
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")
}
}
#[stable(feature = "time_augmented_assignment", since = "1.9.0")]
impl AddAssign<Duration> for Instant {
fn add_assign(&mut self, other: Duration) {
*self = *self + other;
}
}
#[stable(feature = "time2", since = "1.8.0")]
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")
}
}
#[stable(feature = "time_augmented_assignment", since = "1.9.0")]
impl SubAssign<Duration> for Instant {
fn sub_assign(&mut self, other: Duration) {
*self = *self - other;
}
}
#[stable(feature = "time2", since = "1.8.0")]
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)
}
}
#[stable(feature = "time2", since = "1.8.0")]
impl fmt::Debug for Instant {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.0.fmt(f)
}
}
impl SystemTime {
/// An anchor in time which can be used to create new `SystemTime` instances or
/// learn about where in time a `SystemTime` lies.
//
// NOTE! this documentation is duplicated, here and in std::time::UNIX_EPOCH.
// The two copies are not quite identical, because of the difference in naming.
///
/// This constant is defined to be "1970-01-01 00:00:00 UTC" on all systems with
/// respect to the system clock. Using `duration_since` on an existing
/// `SystemTime` instance can tell how far away from this point in time a
/// measurement lies, and using `UNIX_EPOCH + duration` can be used to create a
/// `SystemTime` instance to represent another fixed point in time.
///
/// `duration_since(UNIX_EPOCH).unwrap().as_secs()` returns
/// the number of non-leap seconds since the start of 1970 UTC.
/// This is a POSIX `time_t` (as a `u64`),
/// and is the same time representation as used in many Internet protocols.
///
/// # Examples
///
/// ```no_run
/// use std::time::SystemTime;
///
/// match SystemTime::now().duration_since(SystemTime::UNIX_EPOCH) {
/// Ok(n) => println!("1970-01-01 00:00:00 UTC was {} seconds ago!", n.as_secs()),
/// Err(_) => panic!("SystemTime before UNIX EPOCH!"),
/// }
/// ```
#[stable(feature = "assoc_unix_epoch", since = "1.28.0")]
pub const UNIX_EPOCH: SystemTime = UNIX_EPOCH;
/// Returns the system time corresponding to "now".
///
/// # Examples
///
/// ```
/// use std::time::SystemTime;
///
/// let sys_time = SystemTime::now();
/// ```
#[must_use]
#[stable(feature = "time2", since = "1.8.0")]
pub fn now() -> SystemTime {
SystemTime(time::SystemTime::now())
}
/// Returns the amount of time elapsed from an earlier point in time.
///
/// This function may fail because measurements taken earlier are not
/// guaranteed to always be before later measurements (due to anomalies such
/// as the system clock being adjusted either forwards or backwards).
/// [`Instant`] can be used to measure elapsed time without this risk of failure.
///
/// If successful, <code>[Ok]\([Duration])</code> is returned where the duration represents
/// the amount of time elapsed from the specified measurement to this one.
///
/// Returns an [`Err`] if `earlier` is later than `self`, and the error
/// contains how far from `self` the time is.
///
/// # Examples
///
/// ```no_run
/// use std::time::SystemTime;
///
/// let sys_time = SystemTime::now();
/// let new_sys_time = SystemTime::now();
/// let difference = new_sys_time.duration_since(sys_time)
/// .expect("Clock may have gone backwards");
/// println!("{difference:?}");
/// ```
#[stable(feature = "time2", since = "1.8.0")]
pub fn duration_since(&self, earlier: SystemTime) -> Result<Duration, SystemTimeError> {
self.0.sub_time(&earlier.0).map_err(SystemTimeError)
}
/// Returns the difference from this system time to the
/// current clock time.
///
/// This function may fail as the underlying system clock is susceptible to
/// drift and updates (e.g., the system clock could go backwards), so this
/// function might not always succeed. If successful, <code>[Ok]\([Duration])</code> is
/// returned where the duration represents the amount of time elapsed from
/// this time measurement to the current time.
///
/// To measure elapsed time reliably, use [`Instant`] instead.
///
/// Returns an [`Err`] if `self` is later than the current system time, and
/// the error contains how far from the current system time `self` is.
///
/// # Examples
///
/// ```no_run
/// use std::thread::sleep;
/// use std::time::{Duration, SystemTime};
///
/// let sys_time = SystemTime::now();
/// let one_sec = Duration::from_secs(1);
/// sleep(one_sec);
/// assert!(sys_time.elapsed().unwrap() >= one_sec);
/// ```
#[stable(feature = "time2", since = "1.8.0")]
pub fn elapsed(&self) -> Result<Duration, SystemTimeError> {
SystemTime::now().duration_since(*self)
}
/// Returns `Some(t)` where `t` is the time `self + duration` if `t` can be represented as
/// `SystemTime` (which means it's inside the bounds of the underlying data structure), `None`
/// otherwise.
#[stable(feature = "time_checked_add", since = "1.34.0")]
pub fn checked_add(&self, duration: Duration) -> Option<SystemTime> {
self.0.checked_add_duration(&duration).map(SystemTime)
}
/// Returns `Some(t)` where `t` is the time `self - duration` if `t` can be represented as
/// `SystemTime` (which means it's inside the bounds of the underlying data structure), `None`
/// otherwise.
#[stable(feature = "time_checked_add", since = "1.34.0")]
pub fn checked_sub(&self, duration: Duration) -> Option<SystemTime> {
self.0.checked_sub_duration(&duration).map(SystemTime)
}
}
#[stable(feature = "time2", since = "1.8.0")]
impl Add<Duration> for SystemTime {
type Output = SystemTime;
/// # Panics
///
/// This function may panic if the resulting point in time cannot be represented by the
/// underlying data structure. See [`SystemTime::checked_add`] for a version without panic.
fn add(self, dur: Duration) -> SystemTime {
self.checked_add(dur).expect("overflow when adding duration to instant")
}
}
#[stable(feature = "time_augmented_assignment", since = "1.9.0")]
impl AddAssign<Duration> for SystemTime {
fn add_assign(&mut self, other: Duration) {
*self = *self + other;
}
}
#[stable(feature = "time2", since = "1.8.0")]
impl Sub<Duration> for SystemTime {
type Output = SystemTime;
fn sub(self, dur: Duration) -> SystemTime {
self.checked_sub(dur).expect("overflow when subtracting duration from instant")
}
}
#[stable(feature = "time_augmented_assignment", since = "1.9.0")]
impl SubAssign<Duration> for SystemTime {
fn sub_assign(&mut self, other: Duration) {
*self = *self - other;
}
}
#[stable(feature = "time2", since = "1.8.0")]
impl fmt::Debug for SystemTime {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.0.fmt(f)
}
}
/// An anchor in time which can be used to create new `SystemTime` instances or
/// learn about where in time a `SystemTime` lies.
//
// NOTE! this documentation is duplicated, here and in SystemTime::UNIX_EPOCH.
// The two copies are not quite identical, because of the difference in naming.
///
/// This constant is defined to be "1970-01-01 00:00:00 UTC" on all systems with
/// respect to the system clock. Using `duration_since` on an existing
/// [`SystemTime`] instance can tell how far away from this point in time a
/// measurement lies, and using `UNIX_EPOCH + duration` can be used to create a
/// [`SystemTime`] instance to represent another fixed point in time.
///
/// `duration_since(UNIX_EPOCH).unwrap().as_secs()` returns
/// the number of non-leap seconds since the start of 1970 UTC.
/// This is a POSIX `time_t` (as a `u64`),
/// and is the same time representation as used in many Internet protocols.
///
/// # Examples
///
/// ```no_run
/// use std::time::{SystemTime, UNIX_EPOCH};
///
/// match SystemTime::now().duration_since(UNIX_EPOCH) {
/// Ok(n) => println!("1970-01-01 00:00:00 UTC was {} seconds ago!", n.as_secs()),
/// Err(_) => panic!("SystemTime before UNIX EPOCH!"),
/// }
/// ```
#[stable(feature = "time2", since = "1.8.0")]
pub const UNIX_EPOCH: SystemTime = SystemTime(time::UNIX_EPOCH);
impl SystemTimeError {
/// Returns the positive duration which represents how far forward the
/// second system time was from the first.
///
/// A `SystemTimeError` is returned from the [`SystemTime::duration_since`]
/// and [`SystemTime::elapsed`] methods whenever the second system time
/// represents a point later in time than the `self` of the method call.
///
/// # Examples
///
/// ```no_run
/// use std::thread::sleep;
/// use std::time::{Duration, SystemTime};
///
/// let sys_time = SystemTime::now();
/// sleep(Duration::from_secs(1));
/// let new_sys_time = SystemTime::now();
/// match sys_time.duration_since(new_sys_time) {
/// Ok(_) => {}
/// Err(e) => println!("SystemTimeError difference: {:?}", e.duration()),
/// }
/// ```
#[must_use]
#[stable(feature = "time2", since = "1.8.0")]
pub fn duration(&self) -> Duration {
self.0
}
}
#[stable(feature = "time2", since = "1.8.0")]
impl Error for SystemTimeError {
#[allow(deprecated)]
fn description(&self) -> &str {
"other time was not earlier than self"
}
}
#[stable(feature = "time2", since = "1.8.0")]
impl fmt::Display for SystemTimeError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "second time provided was later than self")
}
}
impl FromInner<time::SystemTime> for SystemTime {
fn from_inner(time: time::SystemTime) -> SystemTime {
SystemTime(time)
}
}
impl IntoInner<time::SystemTime> for SystemTime {
fn into_inner(self) -> time::SystemTime {
self.0
}
}