src/libcore/time.rs - rust - Git at Google

 // 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);
     }
 }
	// 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);
	}
	}