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#![stable(feature = "duration_core", since = "1.25.0")]
//! 时间量化。
//!
//! # Examples:
//!
//! 有多种方法可以创建新的 [`Duration`]:
//!
//! ```
//! # use std::time::Duration;
//! let five_seconds = Duration::from_secs(5);
//! assert_eq!(five_seconds, Duration::from_millis(5_000));
//! assert_eq!(five_seconds, Duration::from_micros(5_000_000));
//! assert_eq!(five_seconds, Duration::from_nanos(5_000_000_000));
//!
//! let ten_seconds = Duration::from_secs(10);
//! let seven_nanos = Duration::from_nanos(7);
//! let total = ten_seconds + seven_nanos;
//! assert_eq!(total, Duration::new(10, 7));
//! ```
use crate::fmt;
use crate::iter::Sum;
use crate::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Sub, SubAssign};
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;
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(transparent)]
#[rustc_layout_scalar_valid_range_start(0)]
#[rustc_layout_scalar_valid_range_end(999_999_999)]
struct Nanoseconds(u32);
impl Default for Nanoseconds {
#[inline]
fn default() -> Self {
// SAFETY: 0 在有效范围内
unsafe { Nanoseconds(0) }
}
}
/// `Duration` 类型代表时间跨度,通常用于系统超时。
///
/// 每个 `Duration` 由整数秒和以纳秒表示的小数部分组成。
/// 如果底层系统不支持纳秒级精度,则绑定系统超时的 API 通常会将纳秒数四舍五入。
///
/// [`Duration`] 实现了许多常见的 traits,包括 [`Add`],[`Sub`] 和其他 [`ops`] traits。它通过返回零长度 `Duration` 来实现 [`Default`]。
///
/// [`ops`]: crate::ops
///
/// # 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);
/// ```
///
/// # 格式化 `Duration` 值
///
/// `Duration` 故意不实现 `Display` impl,因为有多种方法可以设置时间跨度的格式,以提高人类的可读性。
/// `Duration` 提供了一个 `Debug` impl,它显示了值的完整精度。
///
/// `Debug` 输出使用非 ASCII "µs" 后缀微秒。
/// 如果您的程序输出可能出现在不依赖于完全 Unicode 兼容性的上下文中,则您可能希望自己格式化 `Duration` 对象或使用 crate 这样做。
///
///
///
///
///
///
///
#[stable(feature = "duration", since = "1.3.0")]
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
#[cfg_attr(not(test), rustc_diagnostic_item = "Duration")]
pub struct Duration {
secs: u64,
nanos: Nanoseconds, // Always 0 <= nanos < NANOS_PER_SEC
}
impl Duration {
/// 持续时间为一秒。
///
/// # Examples
///
/// ```
/// #![feature(duration_constants)]
/// use std::time::Duration;
///
/// assert_eq!(Duration::SECOND, Duration::from_secs(1));
/// ```
#[unstable(feature = "duration_constants", issue = "57391")]
pub const SECOND: Duration = Duration::from_secs(1);
/// 一毫秒的持续时间。
///
/// # Examples
///
/// ```
/// #![feature(duration_constants)]
/// use std::time::Duration;
///
/// assert_eq!(Duration::MILLISECOND, Duration::from_millis(1));
/// ```
#[unstable(feature = "duration_constants", issue = "57391")]
pub const MILLISECOND: Duration = Duration::from_millis(1);
/// 一微秒的持续时间。
///
/// # Examples
///
/// ```
/// #![feature(duration_constants)]
/// use std::time::Duration;
///
/// assert_eq!(Duration::MICROSECOND, Duration::from_micros(1));
/// ```
#[unstable(feature = "duration_constants", issue = "57391")]
pub const MICROSECOND: Duration = Duration::from_micros(1);
/// 一纳秒的持续时间。
///
/// # Examples
///
/// ```
/// #![feature(duration_constants)]
/// use std::time::Duration;
///
/// assert_eq!(Duration::NANOSECOND, Duration::from_nanos(1));
/// ```
#[unstable(feature = "duration_constants", issue = "57391")]
pub const NANOSECOND: Duration = Duration::from_nanos(1);
/// 持续时间为零。
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// let duration = Duration::ZERO;
/// assert!(duration.is_zero());
/// assert_eq!(duration.as_nanos(), 0);
/// ```
#[stable(feature = "duration_zero", since = "1.53.0")]
pub const ZERO: Duration = Duration::from_nanos(0);
/// 最大持续时间。
///
/// 根据平台的需要可能有所不同。
/// 必须能够包含两个 [`Instant`] 实例或两个 [`SystemTime`] 实例之间的差异。
/// 该约束使其在实践中的值约为 584,942,417,355 年,目前在所有平台上都使用。
///
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// assert_eq!(Duration::MAX, Duration::new(u64::MAX, 1_000_000_000 - 1));
/// ```
/// [`Instant`]: ../../std/time/struct.Instant.html
/// [`SystemTime`]: ../../std/time/struct.SystemTime.html
#[stable(feature = "duration_saturating_ops", since = "1.53.0")]
pub const MAX: Duration = Duration::new(u64::MAX, NANOS_PER_SEC - 1);
/// 根据指定的整数秒数和其他纳秒数创建一个新的 `Duration`。
///
/// 如果纳秒数大于 10 亿 (十亿分之一秒),则它将延续到提供的秒数中。
///
///
/// # Panics
///
/// 如果纳秒的进位溢出秒计数器,则此构造方法将为 panic。
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// let five_seconds = Duration::new(5, 0);
/// ```
///
///
#[stable(feature = "duration", since = "1.3.0")]
#[inline]
#[must_use]
#[rustc_const_stable(feature = "duration_consts_2", since = "1.58.0")]
pub const fn new(secs: u64, nanos: u32) -> Duration {
let secs = match secs.checked_add((nanos / NANOS_PER_SEC) as u64) {
Some(secs) => secs,
None => panic!("overflow in Duration::new"),
};
let nanos = nanos % NANOS_PER_SEC;
// SAFETY: nanos % NANOS_PER_SEC < NANOS_PER_SEC,因此 nanos 在有效范围内
Duration { secs, nanos: unsafe { Nanoseconds(nanos) } }
}
/// 根据指定的整数秒创建一个新的 `Duration`。
///
/// # 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")]
#[must_use]
#[inline]
#[rustc_const_stable(feature = "duration_consts", since = "1.32.0")]
pub const fn from_secs(secs: u64) -> Duration {
Duration::new(secs, 0)
}
/// 从指定的毫秒数创建一个新的 `Duration`。
///
/// # 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")]
#[must_use]
#[inline]
#[rustc_const_stable(feature = "duration_consts", since = "1.32.0")]
pub const fn from_millis(millis: u64) -> Duration {
Duration::new(millis / MILLIS_PER_SEC, ((millis % MILLIS_PER_SEC) as u32) * NANOS_PER_MILLI)
}
/// 从指定的微秒数创建一个新的 `Duration`。
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// let duration = Duration::from_micros(1_000_002);
///
/// assert_eq!(1, duration.as_secs());
/// assert_eq!(2000, duration.subsec_nanos());
/// ```
#[stable(feature = "duration_from_micros", since = "1.27.0")]
#[must_use]
#[inline]
#[rustc_const_stable(feature = "duration_consts", since = "1.32.0")]
pub const fn from_micros(micros: u64) -> Duration {
Duration::new(micros / MICROS_PER_SEC, ((micros % MICROS_PER_SEC) as u32) * NANOS_PER_MICRO)
}
/// 从指定的纳秒数创建一个新的 `Duration`。
///
/// # Examples
///
/// ```
/// 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());
/// ```
#[stable(feature = "duration_extras", since = "1.27.0")]
#[must_use]
#[inline]
#[rustc_const_stable(feature = "duration_consts", since = "1.32.0")]
pub const fn from_nanos(nanos: u64) -> Duration {
Duration::new(nanos / (NANOS_PER_SEC as u64), (nanos % (NANOS_PER_SEC as u64)) as u32)
}
/// 如果此 `Duration` 不跨越时间,则返回 true。
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// assert!(Duration::ZERO.is_zero());
/// assert!(Duration::new(0, 0).is_zero());
/// assert!(Duration::from_nanos(0).is_zero());
/// assert!(Duration::from_secs(0).is_zero());
///
/// assert!(!Duration::new(1, 1).is_zero());
/// assert!(!Duration::from_nanos(1).is_zero());
/// assert!(!Duration::from_secs(1).is_zero());
/// ```
#[must_use]
#[stable(feature = "duration_zero", since = "1.53.0")]
#[rustc_const_stable(feature = "duration_zero", since = "1.53.0")]
#[inline]
pub const fn is_zero(&self) -> bool {
self.secs == 0 && self.nanos.0 == 0
}
/// 返回此 `Duration` 包含的 _whole_ 秒数。
///
/// 返回的值不包括持续时间的小数 (nanosecond) 部分,可以使用 [`subsec_nanos`] 获得。
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// let duration = Duration::new(5, 730023852);
/// assert_eq!(duration.as_secs(), 5);
/// ```
///
/// 要确定由 `Duration` 表示的总秒数 (包括小数部分),请使用 [`as_secs_f64`] 或 [`as_secs_f32`]
///
///
/// [`as_secs_f64`]: Duration::as_secs_f64
/// [`as_secs_f32`]: Duration::as_secs_f32
/// [`subsec_nanos`]: Duration::subsec_nanos
///
#[stable(feature = "duration", since = "1.3.0")]
#[rustc_const_stable(feature = "duration_consts", since = "1.32.0")]
#[must_use]
#[inline]
pub const fn as_secs(&self) -> u64 {
self.secs
}
/// 以毫秒为单位返回此 `Duration` 的小数部分。
///
/// 当以毫秒表示时,这个方法不会返回持续时间的长度。
/// 返回的数字始终代表秒的小数部分 (即,小于一千)。
///
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// let duration = Duration::from_millis(5432);
/// assert_eq!(duration.as_secs(), 5);
/// assert_eq!(duration.subsec_millis(), 432);
/// ```
#[stable(feature = "duration_extras", since = "1.27.0")]
#[rustc_const_stable(feature = "duration_consts", since = "1.32.0")]
#[must_use]
#[inline]
pub const fn subsec_millis(&self) -> u32 {
self.nanos.0 / NANOS_PER_MILLI
}
/// 以整个微秒为单位返回此 `Duration` 的小数部分。
///
/// 当以微秒表示时,这个方法不会返回持续时间的长度。
/// 返回的数字始终代表秒的小数部分 (即,小于一百万)。
///
///
/// # Examples
///
/// ```
/// 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);
/// ```
#[stable(feature = "duration_extras", since = "1.27.0")]
#[rustc_const_stable(feature = "duration_consts", since = "1.32.0")]
#[must_use]
#[inline]
pub const fn subsec_micros(&self) -> u32 {
self.nanos.0 / NANOS_PER_MICRO
}
/// 返回此 `Duration` 的小数部分,以纳秒为单位。
///
/// 当以纳秒表示时,这个方法不会返回持续时间的长度。
/// 返回的数字始终代表秒的小数部分 (即,小于十亿)。
///
///
/// # 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")]
#[rustc_const_stable(feature = "duration_consts", since = "1.32.0")]
#[must_use]
#[inline]
pub const fn subsec_nanos(&self) -> u32 {
self.nanos.0
}
/// 返回此 `Duration` 包含的总毫秒数。
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// let duration = Duration::new(5, 730023852);
/// assert_eq!(duration.as_millis(), 5730);
/// ```
#[stable(feature = "duration_as_u128", since = "1.33.0")]
#[rustc_const_stable(feature = "duration_as_u128", since = "1.33.0")]
#[must_use]
#[inline]
pub const fn as_millis(&self) -> u128 {
self.secs as u128 * MILLIS_PER_SEC as u128 + (self.nanos.0 / NANOS_PER_MILLI) as u128
}
/// 返回此 `Duration` 包含的总微秒数。
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// let duration = Duration::new(5, 730023852);
/// assert_eq!(duration.as_micros(), 5730023);
/// ```
#[stable(feature = "duration_as_u128", since = "1.33.0")]
#[rustc_const_stable(feature = "duration_as_u128", since = "1.33.0")]
#[must_use]
#[inline]
pub const fn as_micros(&self) -> u128 {
self.secs as u128 * MICROS_PER_SEC as u128 + (self.nanos.0 / NANOS_PER_MICRO) as u128
}
/// 返回此 `Duration` 包含的纳秒总数。
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// let duration = Duration::new(5, 730023852);
/// assert_eq!(duration.as_nanos(), 5730023852);
/// ```
#[stable(feature = "duration_as_u128", since = "1.33.0")]
#[rustc_const_stable(feature = "duration_as_u128", since = "1.33.0")]
#[must_use]
#[inline]
pub const fn as_nanos(&self) -> u128 {
self.secs as u128 * NANOS_PER_SEC as u128 + self.nanos.0 as u128
}
/// 检查 `Duration` 的添加。
/// 计算 `self + other`,如果发生溢出则返回 [`None`]。
///
/// # Examples
///
/// 基本用法:
///
/// ```
/// 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(u64::MAX, 0)), None);
/// ```
#[stable(feature = "duration_checked_ops", since = "1.16.0")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
#[rustc_const_stable(feature = "duration_consts_2", since = "1.58.0")]
pub const fn checked_add(self, rhs: Duration) -> Option<Duration> {
if let Some(mut secs) = self.secs.checked_add(rhs.secs) {
let mut nanos = self.nanos.0 + rhs.nanos.0;
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::new(secs, nanos))
} else {
None
}
}
/// `Duration` 饱和添加。
/// 计算 `self + other`,如果发生溢出则返回 [`Duration::MAX`]。
///
/// # Examples
///
/// ```
/// #![feature(duration_constants)]
/// use std::time::Duration;
///
/// assert_eq!(Duration::new(0, 0).saturating_add(Duration::new(0, 1)), Duration::new(0, 1));
/// assert_eq!(Duration::new(1, 0).saturating_add(Duration::new(u64::MAX, 0)), Duration::MAX);
/// ```
#[stable(feature = "duration_saturating_ops", since = "1.53.0")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
#[rustc_const_stable(feature = "duration_consts_2", since = "1.58.0")]
pub const fn saturating_add(self, rhs: Duration) -> Duration {
match self.checked_add(rhs) {
Some(res) => res,
None => Duration::MAX,
}
}
/// 检查 `Duration` 减法。
/// 计算 `self - other`,如果结果为负或发生溢出,则返回 [`None`]。
///
/// # Examples
///
/// 基本用法:
///
/// ```
/// 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")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
#[rustc_const_stable(feature = "duration_consts_2", since = "1.58.0")]
pub const fn checked_sub(self, rhs: Duration) -> Option<Duration> {
if let Some(mut secs) = self.secs.checked_sub(rhs.secs) {
let nanos = if self.nanos.0 >= rhs.nanos.0 {
self.nanos.0 - rhs.nanos.0
} else if let Some(sub_secs) = secs.checked_sub(1) {
secs = sub_secs;
self.nanos.0 + NANOS_PER_SEC - rhs.nanos.0
} else {
return None;
};
debug_assert!(nanos < NANOS_PER_SEC);
Some(Duration::new(secs, nanos))
} else {
None
}
}
/// `Duration` 减法饱和。
/// 计算 `self - other`,如果结果为负或发生溢出,则返回 [`Duration::ZERO`]。
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// assert_eq!(Duration::new(0, 1).saturating_sub(Duration::new(0, 0)), Duration::new(0, 1));
/// assert_eq!(Duration::new(0, 0).saturating_sub(Duration::new(0, 1)), Duration::ZERO);
/// ```
#[stable(feature = "duration_saturating_ops", since = "1.53.0")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
#[rustc_const_stable(feature = "duration_consts_2", since = "1.58.0")]
pub const fn saturating_sub(self, rhs: Duration) -> Duration {
match self.checked_sub(rhs) {
Some(res) => res,
None => Duration::ZERO,
}
}
/// 检查 `Duration` 乘法。
/// 计算 `self * other`,如果发生溢出则返回 [`None`]。
///
/// # Examples
///
/// 基本用法:
///
/// ```
/// use std::time::Duration;
///
/// assert_eq!(Duration::new(0, 500_000_001).checked_mul(2), Some(Duration::new(1, 2)));
/// assert_eq!(Duration::new(u64::MAX - 1, 0).checked_mul(2), None);
/// ```
#[stable(feature = "duration_checked_ops", since = "1.16.0")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
#[rustc_const_stable(feature = "duration_consts_2", since = "1.58.0")]
pub const fn checked_mul(self, rhs: u32) -> Option<Duration> {
// 将 u64 乘以纳秒,因为它不能那样溢出。
let total_nanos = self.nanos.0 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(s) = self.secs.checked_mul(rhs as u64) {
if let Some(secs) = s.checked_add(extra_secs) {
debug_assert!(nanos < NANOS_PER_SEC);
return Some(Duration::new(secs, nanos));
}
}
None
}
/// 饱和 `Duration` 乘法。
/// 计算 `self * other`,如果发生溢出则返回 [`Duration::MAX`]。
///
/// # Examples
///
/// ```
/// #![feature(duration_constants)]
/// use std::time::Duration;
///
/// assert_eq!(Duration::new(0, 500_000_001).saturating_mul(2), Duration::new(1, 2));
/// assert_eq!(Duration::new(u64::MAX - 1, 0).saturating_mul(2), Duration::MAX);
/// ```
#[stable(feature = "duration_saturating_ops", since = "1.53.0")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
#[rustc_const_stable(feature = "duration_consts_2", since = "1.58.0")]
pub const fn saturating_mul(self, rhs: u32) -> Duration {
match self.checked_mul(rhs) {
Some(res) => res,
None => Duration::MAX,
}
}
/// 检查 `Duration` 分区。
/// 计算 `self / other`,如果为 `other == 0`,则返回 [`None`]。
///
/// # Examples
///
/// 基本用法:
///
/// ```
/// 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")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
#[rustc_const_stable(feature = "duration_consts_2", since = "1.58.0")]
pub const 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.0 / rhs + (extra_nanos as u32);
debug_assert!(nanos < NANOS_PER_SEC);
Some(Duration::new(secs, nanos))
} else {
None
}
}
/// 以 `f64` 形式返回此 `Duration` 包含的秒数。
///
/// 返回的值的确包含持续时间的小数 (nanosecond) 部分。
///
/// # Examples
/// ```
/// use std::time::Duration;
///
/// let dur = Duration::new(2, 700_000_000);
/// assert_eq!(dur.as_secs_f64(), 2.7);
/// ```
#[stable(feature = "duration_float", since = "1.38.0")]
#[must_use]
#[inline]
#[rustc_const_unstable(feature = "duration_consts_float", issue = "72440")]
pub const fn as_secs_f64(&self) -> f64 {
(self.secs as f64) + (self.nanos.0 as f64) / (NANOS_PER_SEC as f64)
}
/// 以 `f32` 形式返回此 `Duration` 包含的秒数。
///
/// 返回的值的确包含持续时间的小数 (nanosecond) 部分。
///
/// # Examples
/// ```
/// use std::time::Duration;
///
/// let dur = Duration::new(2, 700_000_000);
/// assert_eq!(dur.as_secs_f32(), 2.7);
/// ```
#[stable(feature = "duration_float", since = "1.38.0")]
#[must_use]
#[inline]
#[rustc_const_unstable(feature = "duration_consts_float", issue = "72440")]
pub const fn as_secs_f32(&self) -> f32 {
(self.secs as f32) + (self.nanos.0 as f32) / (NANOS_PER_SEC as f32)
}
/// 从指定的秒数 (表示为 `f64`) 创建一个新的 `Duration`。
///
/// # Panics
/// 如果 `secs` 为 negative、溢出 `Duration` 或不是有限的,此构造函数将出现 panic。
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// let res = Duration::from_secs_f64(0.0);
/// assert_eq!(res, Duration::new(0, 0));
/// let res = Duration::from_secs_f64(1e-20);
/// assert_eq!(res, Duration::new(0, 0));
/// let res = Duration::from_secs_f64(4.2e-7);
/// assert_eq!(res, Duration::new(0, 420));
/// let res = Duration::from_secs_f64(2.7);
/// assert_eq!(res, Duration::new(2, 700_000_000));
/// let res = Duration::from_secs_f64(3e10);
/// assert_eq!(res, Duration::new(30_000_000_000, 0));
/// // subnormal 浮点
/// let res = Duration::from_secs_f64(f64::from_bits(1));
/// assert_eq!(res, Duration::new(0, 0));
/// // 转换使用舍入
/// let res = Duration::from_secs_f64(0.999e-9);
/// assert_eq!(res, Duration::new(0, 1));
/// ```
#[stable(feature = "duration_float", since = "1.38.0")]
#[must_use]
#[inline]
pub fn from_secs_f64(secs: f64) -> Duration {
match Duration::try_from_secs_f64(secs) {
Ok(v) => v,
Err(e) => panic!("{}", e.description()),
}
}
/// 从指定的秒数 (表示为 `f32`) 创建一个新的 `Duration`。
///
/// # Panics
/// 如果 `secs` 为 negative、溢出 `Duration` 或不是有限的,此构造函数将出现 panic。
///
/// # Examples
///
/// ```
/// use std::time::Duration;
///
/// let res = Duration::from_secs_f32(0.0);
/// assert_eq!(res, Duration::new(0, 0));
/// let res = Duration::from_secs_f32(1e-20);
/// assert_eq!(res, Duration::new(0, 0));
/// let res = Duration::from_secs_f32(4.2e-7);
/// assert_eq!(res, Duration::new(0, 420));
/// let res = Duration::from_secs_f32(2.7);
/// assert_eq!(res, Duration::new(2, 700_000_048));
/// let res = Duration::from_secs_f32(3e10);
/// assert_eq!(res, Duration::new(30_000_001_024, 0));
/// // subnormal 浮点
/// let res = Duration::from_secs_f32(f32::from_bits(1));
/// assert_eq!(res, Duration::new(0, 0));
/// // 转换使用舍入
/// let res = Duration::from_secs_f32(0.999e-9);
/// assert_eq!(res, Duration::new(0, 1));
/// ```
#[stable(feature = "duration_float", since = "1.38.0")]
#[must_use]
#[inline]
pub fn from_secs_f32(secs: f32) -> Duration {
match Duration::try_from_secs_f32(secs) {
Ok(v) => v,
Err(e) => panic!("{}", e.description()),
}
}
/// 将 `Duration` 乘以 `f64`。
///
/// # Panics
/// 如果结果为 negative、溢出 `Duration` 或不是有限的,此方法将出现 panic。
///
/// # Examples
/// ```
/// use std::time::Duration;
///
/// let dur = Duration::new(2, 700_000_000);
/// assert_eq!(dur.mul_f64(3.14), Duration::new(8, 478_000_000));
/// assert_eq!(dur.mul_f64(3.14e5), Duration::new(847_800, 0));
/// ```
#[stable(feature = "duration_float", since = "1.38.0")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
pub fn mul_f64(self, rhs: f64) -> Duration {
Duration::from_secs_f64(rhs * self.as_secs_f64())
}
/// 将 `Duration` 乘以 `f32`。
///
/// # Panics
/// 如果结果为 negative、溢出 `Duration` 或不是有限的,此方法将出现 panic。
///
/// # Examples
/// ```
/// use std::time::Duration;
///
/// let dur = Duration::new(2, 700_000_000);
/// assert_eq!(dur.mul_f32(3.14), Duration::new(8, 478_000_641));
/// assert_eq!(dur.mul_f32(3.14e5), Duration::new(847800, 0));
/// ```
#[stable(feature = "duration_float", since = "1.38.0")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
pub fn mul_f32(self, rhs: f32) -> Duration {
Duration::from_secs_f32(rhs * self.as_secs_f32())
}
/// 将 `Duration` 除以 `f64`。
///
/// # Panics
/// 如果结果为 negative、溢出 `Duration` 或不是有限的,此方法将出现 panic。
///
/// # Examples
/// ```
/// use std::time::Duration;
///
/// let dur = Duration::new(2, 700_000_000);
/// assert_eq!(dur.div_f64(3.14), Duration::new(0, 859_872_611));
/// assert_eq!(dur.div_f64(3.14e5), Duration::new(0, 8_599));
/// ```
#[stable(feature = "duration_float", since = "1.38.0")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
pub fn div_f64(self, rhs: f64) -> Duration {
Duration::from_secs_f64(self.as_secs_f64() / rhs)
}
/// 将 `Duration` 除以 `f32`。
///
/// # Panics
/// 如果结果为 negative、溢出 `Duration` 或不是有限的,此方法将出现 panic。
///
/// # Examples
/// ```
/// use std::time::Duration;
///
/// let dur = Duration::new(2, 700_000_000);
/// // 请注意,由于舍入错误,结果与 0.859_872_611 略有不同
/////
/// assert_eq!(dur.div_f32(3.14), Duration::new(0, 859_872_580));
/// assert_eq!(dur.div_f32(3.14e5), Duration::new(0, 8_599));
/// ```
#[stable(feature = "duration_float", since = "1.38.0")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
pub fn div_f32(self, rhs: f32) -> Duration {
Duration::from_secs_f32(self.as_secs_f32() / rhs)
}
/// 将 `Duration` 除以 `Duration`,然后返回 `f64`。
///
/// # Examples
/// ```
/// #![feature(div_duration)]
/// use std::time::Duration;
///
/// let dur1 = Duration::new(2, 700_000_000);
/// let dur2 = Duration::new(5, 400_000_000);
/// assert_eq!(dur1.div_duration_f64(dur2), 0.5);
/// ```
#[unstable(feature = "div_duration", issue = "63139")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
#[rustc_const_unstable(feature = "duration_consts_float", issue = "72440")]
pub const fn div_duration_f64(self, rhs: Duration) -> f64 {
self.as_secs_f64() / rhs.as_secs_f64()
}
/// 将 `Duration` 除以 `Duration`,然后返回 `f32`。
///
/// # Examples
/// ```
/// #![feature(div_duration)]
/// use std::time::Duration;
///
/// let dur1 = Duration::new(2, 700_000_000);
/// let dur2 = Duration::new(5, 400_000_000);
/// assert_eq!(dur1.div_duration_f32(dur2), 0.5);
/// ```
#[unstable(feature = "div_duration", issue = "63139")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
#[rustc_const_unstable(feature = "duration_consts_float", issue = "72440")]
pub const fn div_duration_f32(self, rhs: Duration) -> f32 {
self.as_secs_f32() / rhs.as_secs_f32()
}
}
#[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 = "symmetric_u32_duration_mul", since = "1.31.0")]
impl Mul<Duration> for u32 {
type Output = Duration;
fn mul(self, rhs: Duration) -> Duration {
rhs * self
}
}
#[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;
}
}
macro_rules! sum_durations {
($iter:expr) => {{
let mut total_secs: u64 = 0;
let mut total_nanos: u64 = 0;
for entry in $iter {
total_secs =
total_secs.checked_add(entry.secs).expect("overflow in iter::sum over durations");
total_nanos = match total_nanos.checked_add(entry.nanos.0 as u64) {
Some(n) => n,
None => {
total_secs = total_secs
.checked_add(total_nanos / NANOS_PER_SEC as u64)
.expect("overflow in iter::sum over durations");
(total_nanos % NANOS_PER_SEC as u64) + entry.nanos.0 as u64
}
};
}
total_secs = total_secs
.checked_add(total_nanos / NANOS_PER_SEC as u64)
.expect("overflow in iter::sum over durations");
total_nanos = total_nanos % NANOS_PER_SEC as u64;
Duration::new(total_secs, total_nanos as u32)
}};
}
#[stable(feature = "duration_sum", since = "1.16.0")]
impl Sum for Duration {
fn sum<I: Iterator<Item = Duration>>(iter: I) -> Duration {
sum_durations!(iter)
}
}
#[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 {
sum_durations!(iter)
}
}
#[stable(feature = "duration_debug_impl", since = "1.27.0")]
impl fmt::Debug for Duration {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
/// 用十进制表示法格式化浮点数。
///
/// 数字以 `integer_part` 和小数形式给出。
/// 小数部分的值为 `fractional_part / divisor`。
/// 因此 `integer_part` =3,`fractional_part` =12,`divisor` =100 代表数字 `3.012`。
/// 尾随零被省略。
///
/// `divisor` 不能超过 100_000_000。
/// 它也应该是 10 的幂,其他所有都没有意义。
/// `fractional_part` 必须小于 `10 * divisor`!
///
/// 可以添加前缀和后缀。
/// 如果指定,整个内容都填充到格式化程序的 `width` 中。
fn fmt_decimal(
f: &mut fmt::Formatter<'_>,
integer_part: u64,
mut fractional_part: u32,
mut divisor: u32,
prefix: &str,
postfix: &str,
) -> fmt::Result {
// 将小数部分编码到临时缓冲区中。
// 缓冲区仅需要容纳 9 个元素,因为 `fractional_part` 必须小于 10 ^ 9。
//
// 缓冲区中预填充了 '0' 数字,以简化下面的代码。
let mut buf = [b'0'; 9];
// 下一个数字写在这个位置
let mut pos = 0;
// 当剩余的数字不为零时,我们一直在将数字写入缓冲区,但尚未写入足够的数字。
//
while fractional_part > 0 && pos < f.precision().unwrap_or(9) {
// 将新数字写入缓冲区
buf[pos] = b'0' + (fractional_part / divisor) as u8;
fractional_part %= divisor;
divisor /= 10;
pos += 1;
}
// 如果指定的精度 < 9,则可能还有一些未写入缓冲区的非零数字。
// 在那种情况下,我们需要进行舍入以匹配打印普通浮点数的语义。
// 但是,我们只需要在四舍五入时进行工作。
// 如果剩余的第一个数字是 >=,就会发生这种情况 5.
//
//
let integer_part = if fractional_part > 0 && fractional_part >= divisor * 5 {
// 将缓冲区中包含的数字向上舍入。
// 我们向后经过缓冲区,并保留跟踪进位。
let mut rev_pos = pos;
let mut carry = true;
while carry && rev_pos > 0 {
rev_pos -= 1;
// 如果缓冲区中的数字不是 '9',我们只需要递增它就可以停止 (因为我们再也没有进位)。
// 否则,我们将其设置为 '0' (overflow) 并继续。
//
//
if buf[rev_pos] < b'9' {
buf[rev_pos] += 1;
carry = false;
} else {
buf[rev_pos] = b'0';
}
}
// 如果我们仍然设置了进位位,则意味着我们将整个缓冲区设置为 `0`,并且需要增加整数部分。
//
//
if carry {
// 如果 `integer_part == u64::MAX` 且精度 < 9,则在将 `fractional_part` 舍入到 `integer_part` 期间溢出的任何进位都会导致 `integer_part` 本身溢出。
// 通过使用 `Option<u64>` 来避免这种情况,`None` 代表 `u64::MAX + 1`。
//
//
//
integer_part.checked_add(1)
} else {
Some(integer_part)
}
} else {
Some(integer_part)
};
// 确定缓冲区的末尾:如果设置了精度,我们将使用缓冲区中的尽可能多的数字 (上限为 9)。
// 如果未设置,我们将仅使用所有数字,直到最后一个非零数字。
//
let end = f.precision().map(|p| crate::cmp::min(p, 9)).unwrap_or(pos);
// 这个闭包发出格式化的持续时间而不发出任何填充 (填充计算如下)。
//
let emit_without_padding = |f: &mut fmt::Formatter<'_>| {
if let Some(integer_part) = integer_part {
write!(f, "{}{}", prefix, integer_part)?;
} else {
// u64::MAX + 1 == 18446744073709551616
write!(f, "{}18446744073709551616", prefix)?;
}
// 写出小数点和小数部分 (如果有)。
if end > 0 {
// SAFETY: 我们仅将 ASCII 数字写入缓冲区,并且已将其初始化为 0,因此它包含有效的 UTF8。
//
let s = unsafe { crate::str::from_utf8_unchecked(&buf[..end]) };
// 如果用户要求精度 > 9,则在末尾填充 '0'。
let w = f.precision().unwrap_or(pos);
write!(f, ".{:0<width$}", s, width = w)?;
}
write!(f, "{}", postfix)
};
match f.width() {
None => {
// 未指定 `width`。
// 在这种情况下,不需要计算输出的长度,只需发出它。
emit_without_padding(f)
}
Some(requested_w) => {
// 指定了 `width`。
// 计算输出的实际宽度,以便计算所需的填充。
// 它由 4 个部分组成:
// 1. 前缀:是 "+" 或 "",所以我们可以只使用 len()。
// 2. 后缀:可以是 "µs" 所以我们必须计算 UTF8 字符。
let mut actual_w = prefix.len() + postfix.chars().count();
// 3. 整数部分:
if let Some(integer_part) = integer_part {
if let Some(log) = integer_part.checked_ilog10() {
// integer_part 是 > 0 的,所以长度是 log10(x)+1
actual_w += 1 + log as usize;
} else {
// integer_part 为 0,因此长度为 1.
actual_w += 1;
}
} else {
// integer_part 是 u64::MAX + 1,所以长度为 20
actual_w += 20;
}
// 4. 小数部分 (如果有):
if end > 0 {
let frac_part_w = f.precision().unwrap_or(pos);
actual_w += 1 + frac_part_w;
}
if requested_w <= actual_w {
// 输出已经比 `width` 长,所以不要填充。
emit_without_padding(f)
} else {
// 我们需要添加填充。使用 `Formatter::padding` 帮助函数。
let default_align = fmt::Alignment::Left;
let post_padding = f.padding(requested_w - actual_w, default_align)?;
emit_without_padding(f)?;
post_padding.write(f)
}
}
}
}
// 如果需要,请打印前导 '+' 标志
let prefix = if f.sign_plus() { "+" } else { "" };
if self.secs > 0 {
fmt_decimal(f, self.secs, self.nanos.0, NANOS_PER_SEC / 10, prefix, "s")
} else if self.nanos.0 >= NANOS_PER_MILLI {
fmt_decimal(
f,
(self.nanos.0 / NANOS_PER_MILLI) as u64,
self.nanos.0 % NANOS_PER_MILLI,
NANOS_PER_MILLI / 10,
prefix,
"ms",
)
} else if self.nanos.0 >= NANOS_PER_MICRO {
fmt_decimal(
f,
(self.nanos.0 / NANOS_PER_MICRO) as u64,
self.nanos.0 % NANOS_PER_MICRO,
NANOS_PER_MICRO / 10,
prefix,
"µs",
)
} else {
fmt_decimal(f, self.nanos.0 as u64, 0, 1, prefix, "ns")
}
}
}
/// 将秒的浮点值转换为 [`Duration`] 时可能返回的错误。
///
/// 此错误用作 [`Duration::try_from_secs_f32`] 和 [`Duration::try_from_secs_f64`] 的错误类型。
///
///
/// # Example
///
/// ```
/// use std::time::Duration;
///
/// if let Err(e) = Duration::try_from_secs_f32(-1.0) {
/// println!("Failed conversion to Duration: {e}");
/// }
/// ```
///
#[derive(Debug, Clone, PartialEq, Eq)]
#[stable(feature = "duration_checked_float", since = "1.66.0")]
pub struct TryFromFloatSecsError {
kind: TryFromFloatSecsErrorKind,
}
impl TryFromFloatSecsError {
const fn description(&self) -> &'static str {
match self.kind {
TryFromFloatSecsErrorKind::Negative => {
"can not convert float seconds to Duration: value is negative"
}
TryFromFloatSecsErrorKind::OverflowOrNan => {
"can not convert float seconds to Duration: value is either too big or NaN"
}
}
}
}
#[stable(feature = "duration_checked_float", since = "1.66.0")]
impl fmt::Display for TryFromFloatSecsError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.description().fmt(f)
}
}
#[derive(Debug, Clone, PartialEq, Eq)]
enum TryFromFloatSecsErrorKind {
// 值是负数。
Negative,
// 值太大而不能表示为 `Duration` 或 `NaN`。
OverflowOrNan,
}
macro_rules! try_from_secs {
(
secs = $secs: expr,
mantissa_bits = $mant_bits: literal,
exponent_bits = $exp_bits: literal,
offset = $offset: literal,
bits_ty = $bits_ty:ty,
double_ty = $double_ty:ty,
) => {{
const MIN_EXP: i16 = 1 - (1i16 << $exp_bits) / 2;
const MANT_MASK: $bits_ty = (1 << $mant_bits) - 1;
const EXP_MASK: $bits_ty = (1 << $exp_bits) - 1;
if $secs < 0.0 {
return Err(TryFromFloatSecsError { kind: TryFromFloatSecsErrorKind::Negative });
}
let bits = $secs.to_bits();
let mant = (bits & MANT_MASK) | (MANT_MASK + 1);
let exp = ((bits >> $mant_bits) & EXP_MASK) as i16 + MIN_EXP;
let (secs, nanos) = if exp < -31 {
// 输入表示小于 1ns,不能四舍五入
(0u64, 0u32)
} else if exp < 0 {
// 输入小于 1 秒
let t = <$double_ty>::from(mant) << ($offset + exp);
let nanos_offset = $mant_bits + $offset;
let nanos_tmp = u128::from(NANOS_PER_SEC) * u128::from(t);
let nanos = (nanos_tmp >> nanos_offset) as u32;
let rem_mask = (1 << nanos_offset) - 1;
let rem_msb_mask = 1 << (nanos_offset - 1);
let rem = nanos_tmp & rem_mask;
let is_tie = rem == rem_msb_mask;
let is_even = (nanos & 1) == 0;
let rem_msb = nanos_tmp & rem_msb_mask == 0;
let add_ns = !(rem_msb || (is_even && is_tie));
// f32 没有足够的精度来触发第二个分支,因为它不能表示 0.999_999_940_395 和 1.0 之间的数字。
//
let nanos = nanos + add_ns as u32;
if ($mant_bits == 23) || (nanos != NANOS_PER_SEC) { (0, nanos) } else { (1, 0) }
} else if exp < $mant_bits {
let secs = u64::from(mant >> ($mant_bits - exp));
let t = <$double_ty>::from((mant << exp) & MANT_MASK);
let nanos_offset = $mant_bits;
let nanos_tmp = <$double_ty>::from(NANOS_PER_SEC) * t;
let nanos = (nanos_tmp >> nanos_offset) as u32;
let rem_mask = (1 << nanos_offset) - 1;
let rem_msb_mask = 1 << (nanos_offset - 1);
let rem = nanos_tmp & rem_mask;
let is_tie = rem == rem_msb_mask;
let is_even = (nanos & 1) == 0;
let rem_msb = nanos_tmp & rem_msb_mask == 0;
let add_ns = !(rem_msb || (is_even && is_tie));
// f32 没有足够的精度来触发第二个分支。
// 比如不能表示 1.999_999_880 之间的数字...
// 和 2.0。
// 较大的值会导致小数部分的精度更小。
let nanos = nanos + add_ns as u32;
if ($mant_bits == 23) || (nanos != NANOS_PER_SEC) {
(secs, nanos)
} else {
(secs + 1, 0)
}
} else if exp < 64 {
// 输入没有小数部分
let secs = u64::from(mant) << (exp - $mant_bits);
(secs, 0)
} else {
return Err(TryFromFloatSecsError { kind: TryFromFloatSecsErrorKind::OverflowOrNan });
};
Ok(Duration::new(secs, nanos))
}};
}
impl Duration {
/// [`from_secs_f32`] 的检查版本。
///
/// [`from_secs_f32`]: Duration::from_secs_f32
///
/// 如果 `secs` 为 negative、溢出 `Duration` 或不是有限的,则此构造函数将返回 `Err`。
///
/// # Examples
/// ```
/// use std::time::Duration;
///
/// let res = Duration::try_from_secs_f32(0.0);
/// assert_eq!(res, Ok(Duration::new(0, 0)));
/// let res = Duration::try_from_secs_f32(1e-20);
/// assert_eq!(res, Ok(Duration::new(0, 0)));
/// let res = Duration::try_from_secs_f32(4.2e-7);
/// assert_eq!(res, Ok(Duration::new(0, 420)));
/// let res = Duration::try_from_secs_f32(2.7);
/// assert_eq!(res, Ok(Duration::new(2, 700_000_048)));
/// let res = Duration::try_from_secs_f32(3e10);
/// assert_eq!(res, Ok(Duration::new(30_000_001_024, 0)));
/// // subnormal 浮点:
/// let res = Duration::try_from_secs_f32(f32::from_bits(1));
/// assert_eq!(res, Ok(Duration::new(0, 0)));
///
/// let res = Duration::try_from_secs_f32(-5.0);
/// assert!(res.is_err());
/// let res = Duration::try_from_secs_f32(f32::NAN);
/// assert!(res.is_err());
/// let res = Duration::try_from_secs_f32(2e19);
/// assert!(res.is_err());
///
/// // 转换使用带平局分辨率的舍入来均匀
/// let res = Duration::try_from_secs_f32(0.999e-9);
/// assert_eq!(res, Ok(Duration::new(0, 1)));
///
/// // 这个浮点数正好代表 976562.5e-9
/// let val = f32::from_bits(0x3A80_0000);
/// let res = Duration::try_from_secs_f32(val);
/// assert_eq!(res, Ok(Duration::new(0, 976_562)));
///
/// // 这个浮点数正好代表 2929687.5e-9
/// let val = f32::from_bits(0x3B40_0000);
/// let res = Duration::try_from_secs_f32(val);
/// assert_eq!(res, Ok(Duration::new(0, 2_929_688)));
///
/// // 这个浮点数正好代表 1.000_976_562_5
/// let val = f32::from_bits(0x3F802000);
/// let res = Duration::try_from_secs_f32(val);
/// assert_eq!(res, Ok(Duration::new(1, 976_562)));
///
/// // 这个浮点数正好代表 1.002_929_687_5
/// let val = f32::from_bits(0x3F806000);
/// let res = Duration::try_from_secs_f32(val);
/// assert_eq!(res, Ok(Duration::new(1, 2_929_688)));
/// ```
#[stable(feature = "duration_checked_float", since = "1.66.0")]
#[inline]
pub fn try_from_secs_f32(secs: f32) -> Result<Duration, TryFromFloatSecsError> {
try_from_secs!(
secs = secs,
mantissa_bits = 23,
exponent_bits = 8,
offset = 41,
bits_ty = u32,
double_ty = u64,
)
}
/// [`from_secs_f64`] 的检查版本。
///
/// [`from_secs_f64`]: Duration::from_secs_f64
///
/// 如果 `secs` 为 negative、溢出 `Duration` 或不是有限的,则此构造函数将返回 `Err`。
///
/// # Examples
/// ```
/// use std::time::Duration;
///
/// let res = Duration::try_from_secs_f64(0.0);
/// assert_eq!(res, Ok(Duration::new(0, 0)));
/// let res = Duration::try_from_secs_f64(1e-20);
/// assert_eq!(res, Ok(Duration::new(0, 0)));
/// let res = Duration::try_from_secs_f64(4.2e-7);
/// assert_eq!(res, Ok(Duration::new(0, 420)));
/// let res = Duration::try_from_secs_f64(2.7);
/// assert_eq!(res, Ok(Duration::new(2, 700_000_000)));
/// let res = Duration::try_from_secs_f64(3e10);
/// assert_eq!(res, Ok(Duration::new(30_000_000_000, 0)));
/// // subnormal 浮点
/// let res = Duration::try_from_secs_f64(f64::from_bits(1));
/// assert_eq!(res, Ok(Duration::new(0, 0)));
///
/// let res = Duration::try_from_secs_f64(-5.0);
/// assert!(res.is_err());
/// let res = Duration::try_from_secs_f64(f64::NAN);
/// assert!(res.is_err());
/// let res = Duration::try_from_secs_f64(2e19);
/// assert!(res.is_err());
///
/// // 转换使用带平局分辨率的舍入来均匀
/// let res = Duration::try_from_secs_f64(0.999e-9);
/// assert_eq!(res, Ok(Duration::new(0, 1)));
/// let res = Duration::try_from_secs_f64(0.999_999_999_499);
/// assert_eq!(res, Ok(Duration::new(0, 999_999_999)));
/// let res = Duration::try_from_secs_f64(0.999_999_999_501);
/// assert_eq!(res, Ok(Duration::new(1, 0)));
/// let res = Duration::try_from_secs_f64(42.999_999_999_499);
/// assert_eq!(res, Ok(Duration::new(42, 999_999_999)));
/// let res = Duration::try_from_secs_f64(42.999_999_999_501);
/// assert_eq!(res, Ok(Duration::new(43, 0)));
///
/// // 这个浮点数正好代表 976562.5e-9
/// let val = f64::from_bits(0x3F50_0000_0000_0000);
/// let res = Duration::try_from_secs_f64(val);
/// assert_eq!(res, Ok(Duration::new(0, 976_562)));
///
/// // 这个浮点数正好代表 2929687.5e-9
/// let val = f64::from_bits(0x3F68_0000_0000_0000);
/// let res = Duration::try_from_secs_f64(val);
/// assert_eq!(res, Ok(Duration::new(0, 2_929_688)));
///
/// // 这个浮点数正好代表 1.000_976_562_5
/// let val = f64::from_bits(0x3FF0_0400_0000_0000);
/// let res = Duration::try_from_secs_f64(val);
/// assert_eq!(res, Ok(Duration::new(1, 976_562)));
///
/// // 这个浮点数正好代表 1.002_929_687_5
/// let val = f64::from_bits(0x3_FF00_C000_0000_000);
/// let res = Duration::try_from_secs_f64(val);
/// assert_eq!(res, Ok(Duration::new(1, 2_929_688)));
/// ```
#[stable(feature = "duration_checked_float", since = "1.66.0")]
#[inline]
pub fn try_from_secs_f64(secs: f64) -> Result<Duration, TryFromFloatSecsError> {
try_from_secs!(
secs = secs,
mantissa_bits = 52,
exponent_bits = 11,
offset = 44,
bits_ty = u64,
double_ty = u128,
)
}
}