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689 lines
26 KiB
Rust
689 lines
26 KiB
Rust
//! Temporal quantification.
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//!
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//! # Examples:
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//!
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//! There are multiple ways to create a new [`Duration`]:
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//!
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//! ```
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//! # use std::time::Duration;
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//! let five_seconds = Duration::from_secs(5);
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//! assert_eq!(five_seconds, Duration::from_millis(5_000));
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//! assert_eq!(five_seconds, Duration::from_micros(5_000_000));
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//! assert_eq!(five_seconds, Duration::from_nanos(5_000_000_000));
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//!
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//! let ten_seconds = Duration::from_secs(10);
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//! let seven_nanos = Duration::from_nanos(7);
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//! let total = ten_seconds + seven_nanos;
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//! assert_eq!(total, Duration::new(10, 7));
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//! ```
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//!
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//! Using [`Instant`] to calculate how long a function took to run:
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//!
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//! ```ignore (incomplete)
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//! let now = Instant::now();
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//!
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//! // Calling a slow function, it may take a while
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//! slow_function();
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//!
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//! let elapsed_time = now.elapsed();
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//! println!("Running slow_function() took {} seconds.", elapsed_time.as_secs());
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//! ```
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#![stable(feature = "time", since = "1.3.0")]
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#[cfg(test)]
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mod tests;
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use crate::error::Error;
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use crate::fmt;
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use crate::ops::{Add, AddAssign, Sub, SubAssign};
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use crate::sys::time;
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use crate::sys_common::FromInner;
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#[stable(feature = "time", since = "1.3.0")]
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pub use core::time::Duration;
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#[unstable(feature = "duration_checked_float", issue = "83400")]
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pub use core::time::FromFloatSecsError;
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/// A measurement of a monotonically nondecreasing clock.
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/// Opaque and useful only with [`Duration`].
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///
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/// Instants are always guaranteed, barring [platform bugs], to be no less than any previously
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/// measured instant when created, and are often useful for tasks such as measuring
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/// benchmarks or timing how long an operation takes.
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///
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/// Note, however, that instants are **not** guaranteed to be **steady**. In other
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/// words, each tick of the underlying clock might not be the same length (e.g.
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/// some seconds may be longer than others). An instant may jump forwards or
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/// experience time dilation (slow down or speed up), but it will never go
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/// backwards.
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///
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/// Instants are opaque types that can only be compared to one another. There is
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/// no method to get "the number of seconds" from an instant. Instead, it only
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/// allows measuring the duration between two instants (or comparing two
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/// instants).
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///
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/// The size of an `Instant` struct may vary depending on the target operating
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/// system.
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///
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/// Example:
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///
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/// ```no_run
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/// use std::time::{Duration, Instant};
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/// use std::thread::sleep;
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///
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/// fn main() {
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/// let now = Instant::now();
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///
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/// // we sleep for 2 seconds
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/// sleep(Duration::new(2, 0));
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/// // it prints '2'
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/// println!("{}", now.elapsed().as_secs());
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/// }
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/// ```
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///
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/// [platform bugs]: Instant#monotonicity
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///
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/// # OS-specific behaviors
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///
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/// An `Instant` is a wrapper around system-specific types and it may behave
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/// differently depending on the underlying operating system. For example,
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/// the following snippet is fine on Linux but panics on macOS:
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///
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/// ```no_run
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/// use std::time::{Instant, Duration};
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///
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/// let now = Instant::now();
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/// let max_seconds = u64::MAX / 1_000_000_000;
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/// let duration = Duration::new(max_seconds, 0);
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/// println!("{:?}", now + duration);
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/// ```
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///
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/// # Underlying System calls
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///
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/// The following system calls are [currently] being used by `now()` to find out
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/// the current time:
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///
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/// | Platform | System call |
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/// |-----------|----------------------------------------------------------------------|
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/// | SGX | [`insecure_time` usercall]. More information on [timekeeping in SGX] |
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/// | UNIX | [clock_gettime (Monotonic Clock)] |
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/// | Darwin | [mach_absolute_time] |
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/// | VXWorks | [clock_gettime (Monotonic Clock)] |
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/// | SOLID | `get_tim` |
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/// | WASI | [__wasi_clock_time_get (Monotonic Clock)] |
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/// | Windows | [QueryPerformanceCounter] |
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///
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/// [currently]: crate::io#platform-specific-behavior
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/// [QueryPerformanceCounter]: https://docs.microsoft.com/en-us/windows/win32/api/profileapi/nf-profileapi-queryperformancecounter
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/// [`insecure_time` usercall]: https://edp.fortanix.com/docs/api/fortanix_sgx_abi/struct.Usercalls.html#method.insecure_time
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/// [timekeeping in SGX]: https://edp.fortanix.com/docs/concepts/rust-std/#codestdtimecode
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/// [__wasi_clock_time_get (Monotonic Clock)]: https://github.com/WebAssembly/WASI/blob/master/phases/snapshot/docs.md#clock_time_get
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/// [clock_gettime (Monotonic Clock)]: https://linux.die.net/man/3/clock_gettime
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/// [mach_absolute_time]: https://developer.apple.com/library/archive/documentation/Darwin/Conceptual/KernelProgramming/services/services.html
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///
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/// **Disclaimer:** These system calls might change over time.
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///
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/// > Note: mathematical operations like [`add`] may panic if the underlying
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/// > structure cannot represent the new point in time.
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///
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/// [`add`]: Instant::add
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///
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/// ## Monotonicity
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///
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/// On all platforms `Instant` will try to use an OS API that guarantees monotonic behavior
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/// if available, which is the case for all [tier 1] platforms.
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/// In practice such guarantees are – under rare circumstances – broken by hardware, virtualization
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/// or operating system bugs. To work around these bugs and platforms not offering monotonic clocks
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/// [`duration_since`], [`elapsed`] and [`sub`] saturate to zero. In older Rust versions this
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/// lead to a panic instead. [`checked_duration_since`] can be used to detect and handle situations
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/// where monotonicity is violated, or `Instant`s are subtracted in the wrong order.
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///
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/// This workaround obscures programming errors where earlier and later instants are accidentally
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/// swapped. For this reason future rust versions may reintroduce panics.
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///
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/// [tier 1]: https://doc.rust-lang.org/rustc/platform-support.html
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/// [`duration_since`]: Instant::duration_since
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/// [`elapsed`]: Instant::elapsed
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/// [`sub`]: Instant::sub
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/// [`checked_duration_since`]: Instant::checked_duration_since
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///
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#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
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#[stable(feature = "time2", since = "1.8.0")]
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pub struct Instant(time::Instant);
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/// A measurement of the system clock, useful for talking to
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/// external entities like the file system or other processes.
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///
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/// Distinct from the [`Instant`] type, this time measurement **is not
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/// monotonic**. This means that you can save a file to the file system, then
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/// save another file to the file system, **and the second file has a
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/// `SystemTime` measurement earlier than the first**. In other words, an
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/// operation that happens after another operation in real time may have an
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/// earlier `SystemTime`!
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///
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/// Consequently, comparing two `SystemTime` instances to learn about the
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/// duration between them returns a [`Result`] instead of an infallible [`Duration`]
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/// to indicate that this sort of time drift may happen and needs to be handled.
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///
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/// Although a `SystemTime` cannot be directly inspected, the [`UNIX_EPOCH`]
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/// constant is provided in this module as an anchor in time to learn
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/// information about a `SystemTime`. By calculating the duration from this
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/// fixed point in time, a `SystemTime` can be converted to a human-readable time,
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/// or perhaps some other string representation.
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///
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/// The size of a `SystemTime` struct may vary depending on the target operating
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/// system.
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///
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/// Example:
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///
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/// ```no_run
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/// use std::time::{Duration, SystemTime};
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/// use std::thread::sleep;
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///
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/// fn main() {
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/// let now = SystemTime::now();
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///
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/// // we sleep for 2 seconds
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/// sleep(Duration::new(2, 0));
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/// match now.elapsed() {
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/// Ok(elapsed) => {
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/// // it prints '2'
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/// println!("{}", elapsed.as_secs());
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/// }
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/// Err(e) => {
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/// // an error occurred!
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/// println!("Error: {e:?}");
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/// }
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/// }
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/// }
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/// ```
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///
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/// # Platform-specific behavior
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///
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/// The precision of `SystemTime` can depend on the underlying OS-specific time format.
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/// For example, on Windows the time is represented in 100 nanosecond intervals whereas Linux
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/// can represent nanosecond intervals.
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///
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/// The following system calls are [currently] being used by `now()` to find out
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/// the current time:
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///
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/// | Platform | System call |
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/// |-----------|----------------------------------------------------------------------|
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/// | SGX | [`insecure_time` usercall]. More information on [timekeeping in SGX] |
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/// | UNIX | [clock_gettime (Realtime Clock)] |
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/// | Darwin | [gettimeofday] |
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/// | VXWorks | [clock_gettime (Realtime Clock)] |
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/// | SOLID | `SOLID_RTC_ReadTime` |
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/// | WASI | [__wasi_clock_time_get (Realtime Clock)] |
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/// | Windows | [GetSystemTimePreciseAsFileTime] / [GetSystemTimeAsFileTime] |
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///
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/// [currently]: crate::io#platform-specific-behavior
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/// [`insecure_time` usercall]: https://edp.fortanix.com/docs/api/fortanix_sgx_abi/struct.Usercalls.html#method.insecure_time
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/// [timekeeping in SGX]: https://edp.fortanix.com/docs/concepts/rust-std/#codestdtimecode
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/// [gettimeofday]: https://man7.org/linux/man-pages/man2/gettimeofday.2.html
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/// [clock_gettime (Realtime Clock)]: https://linux.die.net/man/3/clock_gettime
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/// [__wasi_clock_time_get (Realtime Clock)]: https://github.com/WebAssembly/WASI/blob/master/phases/snapshot/docs.md#clock_time_get
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/// [GetSystemTimePreciseAsFileTime]: https://docs.microsoft.com/en-us/windows/win32/api/sysinfoapi/nf-sysinfoapi-getsystemtimepreciseasfiletime
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/// [GetSystemTimeAsFileTime]: https://docs.microsoft.com/en-us/windows/win32/api/sysinfoapi/nf-sysinfoapi-getsystemtimeasfiletime
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///
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/// **Disclaimer:** These system calls might change over time.
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///
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/// > Note: mathematical operations like [`add`] may panic if the underlying
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/// > structure cannot represent the new point in time.
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///
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/// [`add`]: SystemTime::add
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#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
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#[stable(feature = "time2", since = "1.8.0")]
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pub struct SystemTime(time::SystemTime);
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/// An error returned from the `duration_since` and `elapsed` methods on
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/// `SystemTime`, used to learn how far in the opposite direction a system time
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/// lies.
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///
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/// # Examples
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///
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/// ```no_run
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/// use std::thread::sleep;
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/// use std::time::{Duration, SystemTime};
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///
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/// let sys_time = SystemTime::now();
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/// sleep(Duration::from_secs(1));
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/// let new_sys_time = SystemTime::now();
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/// match sys_time.duration_since(new_sys_time) {
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/// Ok(_) => {}
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/// Err(e) => println!("SystemTimeError difference: {:?}", e.duration()),
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/// }
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/// ```
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#[derive(Clone, Debug)]
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#[stable(feature = "time2", since = "1.8.0")]
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pub struct SystemTimeError(Duration);
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impl Instant {
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/// Returns an instant corresponding to "now".
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///
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/// # Examples
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///
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/// ```
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/// use std::time::Instant;
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///
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/// let now = Instant::now();
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/// ```
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#[must_use]
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#[stable(feature = "time2", since = "1.8.0")]
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pub fn now() -> Instant {
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Instant(time::Instant::now())
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}
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/// Returns the amount of time elapsed from another instant to this one,
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/// or zero duration if that instant is later than this one.
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///
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/// # Panics
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///
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/// Previous rust versions panicked when `earlier` was later than `self`. Currently this
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/// method saturates. Future versions may reintroduce the panic in some circumstances.
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/// See [Monotonicity].
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///
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/// [Monotonicity]: Instant#monotonicity
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///
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/// # Examples
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///
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/// ```no_run
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/// use std::time::{Duration, Instant};
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/// use std::thread::sleep;
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///
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/// let now = Instant::now();
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/// sleep(Duration::new(1, 0));
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/// let new_now = Instant::now();
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/// println!("{:?}", new_now.duration_since(now));
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/// println!("{:?}", now.duration_since(new_now)); // 0ns
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/// ```
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#[must_use]
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#[stable(feature = "time2", since = "1.8.0")]
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pub fn duration_since(&self, earlier: Instant) -> Duration {
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self.checked_duration_since(earlier).unwrap_or_default()
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}
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/// Returns the amount of time elapsed from another instant to this one,
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/// or None if that instant is later than this one.
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///
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/// Due to [monotonicity bugs], even under correct logical ordering of the passed `Instant`s,
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/// this method can return `None`.
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///
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/// [monotonicity bugs]: Instant#monotonicity
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///
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/// # Examples
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///
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/// ```no_run
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/// use std::time::{Duration, Instant};
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/// use std::thread::sleep;
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///
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/// let now = Instant::now();
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/// sleep(Duration::new(1, 0));
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/// let new_now = Instant::now();
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/// println!("{:?}", new_now.checked_duration_since(now));
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/// println!("{:?}", now.checked_duration_since(new_now)); // None
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/// ```
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#[must_use]
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#[stable(feature = "checked_duration_since", since = "1.39.0")]
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pub fn checked_duration_since(&self, earlier: Instant) -> Option<Duration> {
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self.0.checked_sub_instant(&earlier.0)
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}
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/// Returns the amount of time elapsed from another instant to this one,
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/// or zero duration if that instant is later than this one.
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///
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/// # Examples
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///
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/// ```no_run
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/// use std::time::{Duration, Instant};
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/// use std::thread::sleep;
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///
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/// let now = Instant::now();
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/// sleep(Duration::new(1, 0));
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/// let new_now = Instant::now();
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/// println!("{:?}", new_now.saturating_duration_since(now));
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/// println!("{:?}", now.saturating_duration_since(new_now)); // 0ns
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/// ```
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#[must_use]
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#[stable(feature = "checked_duration_since", since = "1.39.0")]
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pub fn saturating_duration_since(&self, earlier: Instant) -> Duration {
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self.checked_duration_since(earlier).unwrap_or_default()
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}
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/// Returns the amount of time elapsed since this instant was created.
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///
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/// # Panics
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///
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/// Previous rust versions panicked when self was earlier than the current time. Currently this
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/// method returns a Duration of zero in that case. Future versions may reintroduce the panic.
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/// See [Monotonicity].
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///
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/// [Monotonicity]: Instant#monotonicity
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///
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/// # Examples
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///
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/// ```no_run
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/// use std::thread::sleep;
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/// use std::time::{Duration, Instant};
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///
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/// let instant = Instant::now();
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/// let three_secs = Duration::from_secs(3);
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/// sleep(three_secs);
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/// assert!(instant.elapsed() >= three_secs);
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/// ```
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#[must_use]
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#[stable(feature = "time2", since = "1.8.0")]
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pub fn elapsed(&self) -> Duration {
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Instant::now() - *self
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}
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/// Returns `Some(t)` where `t` is the time `self + duration` if `t` can be represented as
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/// `Instant` (which means it's inside the bounds of the underlying data structure), `None`
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/// otherwise.
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#[stable(feature = "time_checked_add", since = "1.34.0")]
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pub fn checked_add(&self, duration: Duration) -> Option<Instant> {
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self.0.checked_add_duration(&duration).map(Instant)
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}
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/// Returns `Some(t)` where `t` is the time `self - duration` if `t` can be represented as
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/// `Instant` (which means it's inside the bounds of the underlying data structure), `None`
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/// otherwise.
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#[stable(feature = "time_checked_add", since = "1.34.0")]
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pub fn checked_sub(&self, duration: Duration) -> Option<Instant> {
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self.0.checked_sub_duration(&duration).map(Instant)
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}
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}
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#[stable(feature = "time2", since = "1.8.0")]
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impl Add<Duration> for Instant {
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type Output = Instant;
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/// # Panics
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///
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/// This function may panic if the resulting point in time cannot be represented by the
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/// underlying data structure. See [`Instant::checked_add`] for a version without panic.
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fn add(self, other: Duration) -> Instant {
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self.checked_add(other).expect("overflow when adding duration to instant")
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}
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}
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#[stable(feature = "time_augmented_assignment", since = "1.9.0")]
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impl AddAssign<Duration> for Instant {
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fn add_assign(&mut self, other: Duration) {
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*self = *self + other;
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}
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}
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#[stable(feature = "time2", since = "1.8.0")]
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impl Sub<Duration> for Instant {
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type Output = Instant;
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fn sub(self, other: Duration) -> Instant {
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self.checked_sub(other).expect("overflow when subtracting duration from instant")
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}
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}
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#[stable(feature = "time_augmented_assignment", since = "1.9.0")]
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impl SubAssign<Duration> for Instant {
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fn sub_assign(&mut self, other: Duration) {
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*self = *self - other;
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}
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}
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#[stable(feature = "time2", since = "1.8.0")]
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impl Sub<Instant> for Instant {
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type Output = Duration;
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/// Returns the amount of time elapsed from another instant to this one,
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/// or zero duration if that instant is later than this one.
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///
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/// # Panics
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///
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/// Previous rust versions panicked when `other` was later than `self`. Currently this
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/// method saturates. Future versions may reintroduce the panic in some circumstances.
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/// See [Monotonicity].
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///
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/// [Monotonicity]: Instant#monotonicity
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fn sub(self, other: Instant) -> Duration {
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self.duration_since(other)
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}
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}
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#[stable(feature = "time2", since = "1.8.0")]
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impl fmt::Debug for Instant {
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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.
|
||
///
|
||
/// 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.
|
||
///
|
||
/// # 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 between the clock time when this
|
||
/// system time was created, and 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.
|
||
///
|
||
/// 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.
|
||
///
|
||
/// # 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)
|
||
}
|
||
}
|