rust/src/libcore/time.rs
2018-02-10 21:20:42 +00:00

604 lines
20 KiB
Rust

// Copyright 2012-2017 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#![stable(feature = "duration_core", since = "1.25.0")]
//! Temporal quantification.
//!
//! Example:
//!
//! ```
//! use std::time::Duration;
//!
//! let five_seconds = Duration::new(5, 0);
//! // both declarations are equivalent
//! assert_eq!(Duration::new(5, 0), Duration::from_secs(5));
//! ```
use iter::Sum;
use ops::{Add, Sub, Mul, Div, AddAssign, SubAssign, MulAssign, DivAssign};
const NANOS_PER_SEC: u32 = 1_000_000_000;
const NANOS_PER_MILLI: u32 = 1_000_000;
const NANOS_PER_MICRO: u32 = 1_000;
const MILLIS_PER_SEC: u64 = 1_000;
const MICROS_PER_SEC: u64 = 1_000_000;
/// A `Duration` type to represent a span of time, typically used for system
/// timeouts.
///
/// Each `Duration` is composed of a whole number of seconds and a fractional part
/// represented in nanoseconds. If the underlying system does not support
/// nanosecond-level precision, APIs binding a system timeout will typically round up
/// the number of nanoseconds.
///
/// `Duration`s implement many common traits, including [`Add`], [`Sub`], and other
/// [`ops`] traits.
///
/// [`Add`]: ../../std/ops/trait.Add.html
/// [`Sub`]: ../../std/ops/trait.Sub.html
/// [`ops`]: ../../std/ops/index.html
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// let five_seconds = Duration::new(5, 0);
/// let five_seconds_and_five_nanos = five_seconds + Duration::new(0, 5);
///
/// assert_eq!(five_seconds_and_five_nanos.as_secs(), 5);
/// assert_eq!(five_seconds_and_five_nanos.subsec_nanos(), 5);
///
/// let ten_millis = Duration::from_millis(10);
/// ```
#[stable(feature = "duration", since = "1.3.0")]
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Hash, Default)]
pub struct Duration {
secs: u64,
nanos: u32, // Always 0 <= nanos < NANOS_PER_SEC
}
impl Duration {
/// Creates a new `Duration` from the specified number of whole seconds and
/// additional nanoseconds.
///
/// If the number of nanoseconds is greater than 1 billion (the number of
/// nanoseconds in a second), then it will carry over into the seconds provided.
///
/// # Panics
///
/// This constructor will panic if the carry from the nanoseconds overflows
/// the seconds counter.
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// let five_seconds = Duration::new(5, 0);
/// ```
#[stable(feature = "duration", since = "1.3.0")]
#[inline]
pub fn new(secs: u64, nanos: u32) -> Duration {
let secs = secs.checked_add((nanos / NANOS_PER_SEC) as u64)
.expect("overflow in Duration::new");
let nanos = nanos % NANOS_PER_SEC;
Duration { secs: secs, nanos: nanos }
}
/// Creates a new `Duration` from the specified number of whole seconds.
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// let duration = Duration::from_secs(5);
///
/// assert_eq!(5, duration.as_secs());
/// assert_eq!(0, duration.subsec_nanos());
/// ```
#[stable(feature = "duration", since = "1.3.0")]
#[inline]
pub const fn from_secs(secs: u64) -> Duration {
Duration { secs: secs, nanos: 0 }
}
/// Creates a new `Duration` from the specified number of milliseconds.
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// let duration = Duration::from_millis(2569);
///
/// assert_eq!(2, duration.as_secs());
/// assert_eq!(569_000_000, duration.subsec_nanos());
/// ```
#[stable(feature = "duration", since = "1.3.0")]
#[inline]
pub const fn from_millis(millis: u64) -> Duration {
Duration {
secs: millis / MILLIS_PER_SEC,
nanos: ((millis % MILLIS_PER_SEC) as u32) * NANOS_PER_MILLI,
}
}
/// Creates a new `Duration` from the specified number of microseconds.
///
/// # Examples
///
/// ```
/// #![feature(duration_from_micros)]
/// use std::time::Duration;
///
/// let duration = Duration::from_micros(1_000_002);
///
/// assert_eq!(1, duration.as_secs());
/// assert_eq!(2000, duration.subsec_nanos());
/// ```
#[unstable(feature = "duration_from_micros", issue = "44400")]
#[inline]
pub const fn from_micros(micros: u64) -> Duration {
Duration {
secs: micros / MICROS_PER_SEC,
nanos: ((micros % MICROS_PER_SEC) as u32) * NANOS_PER_MICRO,
}
}
/// Creates a new `Duration` from the specified number of nanoseconds.
///
/// # Examples
///
/// ```
/// #![feature(duration_extras)]
/// use std::time::Duration;
///
/// let duration = Duration::from_nanos(1_000_000_123);
///
/// assert_eq!(1, duration.as_secs());
/// assert_eq!(123, duration.subsec_nanos());
/// ```
#[unstable(feature = "duration_extras", issue = "46507")]
#[inline]
pub const fn from_nanos(nanos: u64) -> Duration {
Duration {
secs: nanos / (NANOS_PER_SEC as u64),
nanos: (nanos % (NANOS_PER_SEC as u64)) as u32,
}
}
/// Returns the number of _whole_ seconds contained by this `Duration`.
///
/// The returned value does not include the fractional (nanosecond) part of the
/// duration, which can be obtained using [`subsec_nanos`].
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// let duration = Duration::new(5, 730023852);
/// assert_eq!(duration.as_secs(), 5);
/// ```
///
/// To determine the total number of seconds represented by the `Duration`,
/// use `as_secs` in combination with [`subsec_nanos`]:
///
/// ```
/// use std::time::Duration;
///
/// let duration = Duration::new(5, 730023852);
///
/// assert_eq!(5.730023852,
/// duration.as_secs() as f64
/// + duration.subsec_nanos() as f64 * 1e-9);
/// ```
///
/// [`subsec_nanos`]: #method.subsec_nanos
#[stable(feature = "duration", since = "1.3.0")]
#[inline]
pub fn as_secs(&self) -> u64 { self.secs }
/// Returns the fractional part of this `Duration`, in milliseconds.
///
/// This method does **not** return the length of the duration when
/// represented by milliseconds. The returned number always represents a
/// fractional portion of a second (i.e. it is less than one thousand).
///
/// # Examples
///
/// ```
/// #![feature(duration_extras)]
/// use std::time::Duration;
///
/// let duration = Duration::from_millis(5432);
/// assert_eq!(duration.as_secs(), 5);
/// assert_eq!(duration.subsec_millis(), 432);
/// ```
#[unstable(feature = "duration_extras", issue = "46507")]
#[inline]
pub fn subsec_millis(&self) -> u32 { self.nanos / NANOS_PER_MILLI }
/// Returns the fractional part of this `Duration`, in microseconds.
///
/// This method does **not** return the length of the duration when
/// represented by microseconds. The returned number always represents a
/// fractional portion of a second (i.e. it is less than one million).
///
/// # Examples
///
/// ```
/// #![feature(duration_extras, duration_from_micros)]
/// use std::time::Duration;
///
/// let duration = Duration::from_micros(1_234_567);
/// assert_eq!(duration.as_secs(), 1);
/// assert_eq!(duration.subsec_micros(), 234_567);
/// ```
#[unstable(feature = "duration_extras", issue = "46507")]
#[inline]
pub fn subsec_micros(&self) -> u32 { self.nanos / NANOS_PER_MICRO }
/// Returns the fractional part of this `Duration`, in nanoseconds.
///
/// This method does **not** return the length of the duration when
/// represented by nanoseconds. The returned number always represents a
/// fractional portion of a second (i.e. it is less than one billion).
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// let duration = Duration::from_millis(5010);
/// assert_eq!(duration.as_secs(), 5);
/// assert_eq!(duration.subsec_nanos(), 10_000_000);
/// ```
#[stable(feature = "duration", since = "1.3.0")]
#[inline]
pub fn subsec_nanos(&self) -> u32 { self.nanos }
/// Checked `Duration` addition. Computes `self + other`, returning [`None`]
/// if overflow occurred.
///
/// [`None`]: ../../std/option/enum.Option.html#variant.None
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::time::Duration;
///
/// assert_eq!(Duration::new(0, 0).checked_add(Duration::new(0, 1)), Some(Duration::new(0, 1)));
/// assert_eq!(Duration::new(1, 0).checked_add(Duration::new(std::u64::MAX, 0)), None);
/// ```
#[stable(feature = "duration_checked_ops", since = "1.16.0")]
#[inline]
pub fn checked_add(self, rhs: Duration) -> Option<Duration> {
if let Some(mut secs) = self.secs.checked_add(rhs.secs) {
let mut nanos = self.nanos + rhs.nanos;
if nanos >= NANOS_PER_SEC {
nanos -= NANOS_PER_SEC;
if let Some(new_secs) = secs.checked_add(1) {
secs = new_secs;
} else {
return None;
}
}
debug_assert!(nanos < NANOS_PER_SEC);
Some(Duration {
secs,
nanos,
})
} else {
None
}
}
/// Checked `Duration` subtraction. Computes `self - other`, returning [`None`]
/// if the result would be negative or if overflow occurred.
///
/// [`None`]: ../../std/option/enum.Option.html#variant.None
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::time::Duration;
///
/// assert_eq!(Duration::new(0, 1).checked_sub(Duration::new(0, 0)), Some(Duration::new(0, 1)));
/// assert_eq!(Duration::new(0, 0).checked_sub(Duration::new(0, 1)), None);
/// ```
#[stable(feature = "duration_checked_ops", since = "1.16.0")]
#[inline]
pub fn checked_sub(self, rhs: Duration) -> Option<Duration> {
if let Some(mut secs) = self.secs.checked_sub(rhs.secs) {
let nanos = if self.nanos >= rhs.nanos {
self.nanos - rhs.nanos
} else {
if let Some(sub_secs) = secs.checked_sub(1) {
secs = sub_secs;
self.nanos + NANOS_PER_SEC - rhs.nanos
} else {
return None;
}
};
debug_assert!(nanos < NANOS_PER_SEC);
Some(Duration { secs: secs, nanos: nanos })
} else {
None
}
}
/// Checked `Duration` multiplication. Computes `self * other`, returning
/// [`None`] if overflow occurred.
///
/// [`None`]: ../../std/option/enum.Option.html#variant.None
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::time::Duration;
///
/// assert_eq!(Duration::new(0, 500_000_001).checked_mul(2), Some(Duration::new(1, 2)));
/// assert_eq!(Duration::new(std::u64::MAX - 1, 0).checked_mul(2), None);
/// ```
#[stable(feature = "duration_checked_ops", since = "1.16.0")]
#[inline]
pub fn checked_mul(self, rhs: u32) -> Option<Duration> {
// Multiply nanoseconds as u64, because it cannot overflow that way.
let total_nanos = self.nanos as u64 * rhs as u64;
let extra_secs = total_nanos / (NANOS_PER_SEC as u64);
let nanos = (total_nanos % (NANOS_PER_SEC as u64)) as u32;
if let Some(secs) = self.secs
.checked_mul(rhs as u64)
.and_then(|s| s.checked_add(extra_secs)) {
debug_assert!(nanos < NANOS_PER_SEC);
Some(Duration {
secs,
nanos,
})
} else {
None
}
}
/// Checked `Duration` division. Computes `self / other`, returning [`None`]
/// if `other == 0`.
///
/// [`None`]: ../../std/option/enum.Option.html#variant.None
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::time::Duration;
///
/// assert_eq!(Duration::new(2, 0).checked_div(2), Some(Duration::new(1, 0)));
/// assert_eq!(Duration::new(1, 0).checked_div(2), Some(Duration::new(0, 500_000_000)));
/// assert_eq!(Duration::new(2, 0).checked_div(0), None);
/// ```
#[stable(feature = "duration_checked_ops", since = "1.16.0")]
#[inline]
pub fn checked_div(self, rhs: u32) -> Option<Duration> {
if rhs != 0 {
let secs = self.secs / (rhs as u64);
let carry = self.secs - secs * (rhs as u64);
let extra_nanos = carry * (NANOS_PER_SEC as u64) / (rhs as u64);
let nanos = self.nanos / rhs + (extra_nanos as u32);
debug_assert!(nanos < NANOS_PER_SEC);
Some(Duration { secs: secs, nanos: nanos })
} else {
None
}
}
}
#[stable(feature = "duration", since = "1.3.0")]
impl Add for Duration {
type Output = Duration;
fn add(self, rhs: Duration) -> Duration {
self.checked_add(rhs).expect("overflow when adding durations")
}
}
#[stable(feature = "time_augmented_assignment", since = "1.9.0")]
impl AddAssign for Duration {
fn add_assign(&mut self, rhs: Duration) {
*self = *self + rhs;
}
}
#[stable(feature = "duration", since = "1.3.0")]
impl Sub for Duration {
type Output = Duration;
fn sub(self, rhs: Duration) -> Duration {
self.checked_sub(rhs).expect("overflow when subtracting durations")
}
}
#[stable(feature = "time_augmented_assignment", since = "1.9.0")]
impl SubAssign for Duration {
fn sub_assign(&mut self, rhs: Duration) {
*self = *self - rhs;
}
}
#[stable(feature = "duration", since = "1.3.0")]
impl Mul<u32> for Duration {
type Output = Duration;
fn mul(self, rhs: u32) -> Duration {
self.checked_mul(rhs).expect("overflow when multiplying duration by scalar")
}
}
#[stable(feature = "time_augmented_assignment", since = "1.9.0")]
impl MulAssign<u32> for Duration {
fn mul_assign(&mut self, rhs: u32) {
*self = *self * rhs;
}
}
#[stable(feature = "duration", since = "1.3.0")]
impl Div<u32> for Duration {
type Output = Duration;
fn div(self, rhs: u32) -> Duration {
self.checked_div(rhs).expect("divide by zero error when dividing duration by scalar")
}
}
#[stable(feature = "time_augmented_assignment", since = "1.9.0")]
impl DivAssign<u32> for Duration {
fn div_assign(&mut self, rhs: u32) {
*self = *self / rhs;
}
}
#[stable(feature = "duration_sum", since = "1.16.0")]
impl Sum for Duration {
fn sum<I: Iterator<Item=Duration>>(iter: I) -> Duration {
iter.fold(Duration::new(0, 0), |a, b| a + b)
}
}
#[stable(feature = "duration_sum", since = "1.16.0")]
impl<'a> Sum<&'a Duration> for Duration {
fn sum<I: Iterator<Item=&'a Duration>>(iter: I) -> Duration {
iter.fold(Duration::new(0, 0), |a, b| a + *b)
}
}
#[cfg(test)]
mod tests {
use super::Duration;
#[test]
fn creation() {
assert!(Duration::from_secs(1) != Duration::from_secs(0));
assert_eq!(Duration::from_secs(1) + Duration::from_secs(2),
Duration::from_secs(3));
assert_eq!(Duration::from_millis(10) + Duration::from_secs(4),
Duration::new(4, 10 * 1_000_000));
assert_eq!(Duration::from_millis(4000), Duration::new(4, 0));
}
#[test]
fn secs() {
assert_eq!(Duration::new(0, 0).as_secs(), 0);
assert_eq!(Duration::from_secs(1).as_secs(), 1);
assert_eq!(Duration::from_millis(999).as_secs(), 0);
assert_eq!(Duration::from_millis(1001).as_secs(), 1);
}
#[test]
fn nanos() {
assert_eq!(Duration::new(0, 0).subsec_nanos(), 0);
assert_eq!(Duration::new(0, 5).subsec_nanos(), 5);
assert_eq!(Duration::new(0, 1_000_000_001).subsec_nanos(), 1);
assert_eq!(Duration::from_secs(1).subsec_nanos(), 0);
assert_eq!(Duration::from_millis(999).subsec_nanos(), 999 * 1_000_000);
assert_eq!(Duration::from_millis(1001).subsec_nanos(), 1 * 1_000_000);
}
#[test]
fn add() {
assert_eq!(Duration::new(0, 0) + Duration::new(0, 1),
Duration::new(0, 1));
assert_eq!(Duration::new(0, 500_000_000) + Duration::new(0, 500_000_001),
Duration::new(1, 1));
}
#[test]
fn checked_add() {
assert_eq!(Duration::new(0, 0).checked_add(Duration::new(0, 1)),
Some(Duration::new(0, 1)));
assert_eq!(Duration::new(0, 500_000_000).checked_add(Duration::new(0, 500_000_001)),
Some(Duration::new(1, 1)));
assert_eq!(Duration::new(1, 0).checked_add(Duration::new(::u64::MAX, 0)), None);
}
#[test]
fn sub() {
assert_eq!(Duration::new(0, 1) - Duration::new(0, 0),
Duration::new(0, 1));
assert_eq!(Duration::new(0, 500_000_001) - Duration::new(0, 500_000_000),
Duration::new(0, 1));
assert_eq!(Duration::new(1, 0) - Duration::new(0, 1),
Duration::new(0, 999_999_999));
}
#[test]
fn checked_sub() {
let zero = Duration::new(0, 0);
let one_nano = Duration::new(0, 1);
let one_sec = Duration::new(1, 0);
assert_eq!(one_nano.checked_sub(zero), Some(Duration::new(0, 1)));
assert_eq!(one_sec.checked_sub(one_nano),
Some(Duration::new(0, 999_999_999)));
assert_eq!(zero.checked_sub(one_nano), None);
assert_eq!(zero.checked_sub(one_sec), None);
}
#[test] #[should_panic]
fn sub_bad1() {
Duration::new(0, 0) - Duration::new(0, 1);
}
#[test] #[should_panic]
fn sub_bad2() {
Duration::new(0, 0) - Duration::new(1, 0);
}
#[test]
fn mul() {
assert_eq!(Duration::new(0, 1) * 2, Duration::new(0, 2));
assert_eq!(Duration::new(1, 1) * 3, Duration::new(3, 3));
assert_eq!(Duration::new(0, 500_000_001) * 4, Duration::new(2, 4));
assert_eq!(Duration::new(0, 500_000_001) * 4000,
Duration::new(2000, 4000));
}
#[test]
fn checked_mul() {
assert_eq!(Duration::new(0, 1).checked_mul(2), Some(Duration::new(0, 2)));
assert_eq!(Duration::new(1, 1).checked_mul(3), Some(Duration::new(3, 3)));
assert_eq!(Duration::new(0, 500_000_001).checked_mul(4), Some(Duration::new(2, 4)));
assert_eq!(Duration::new(0, 500_000_001).checked_mul(4000),
Some(Duration::new(2000, 4000)));
assert_eq!(Duration::new(::u64::MAX - 1, 0).checked_mul(2), None);
}
#[test]
fn div() {
assert_eq!(Duration::new(0, 1) / 2, Duration::new(0, 0));
assert_eq!(Duration::new(1, 1) / 3, Duration::new(0, 333_333_333));
assert_eq!(Duration::new(99, 999_999_000) / 100,
Duration::new(0, 999_999_990));
}
#[test]
fn checked_div() {
assert_eq!(Duration::new(2, 0).checked_div(2), Some(Duration::new(1, 0)));
assert_eq!(Duration::new(1, 0).checked_div(2), Some(Duration::new(0, 500_000_000)));
assert_eq!(Duration::new(2, 0).checked_div(0), None);
}
}