Struct SuspendUnawareInstant 

pub struct SuspendUnawareInstant { /* private fields */ }

Similar to the standard library’s implementation of Instant, except it is consistently unaware of system suspends across all platforms supported by this library.

Historically, this has been inconsistent in the standard library, with windows allowing time to pass when the system is suspended/hibernating, however unix systems do not “pass time” during system suspension. In this library, time never passes when the system is suspended on any platform.

This instant implementation is:

• Opaque (you cannot manually create an Instant. You must call ::now())
• Cross platform (windows, macOS)
• Monotonic (time never goes backwards)
• Suspend-unaware (when you put your computer to sleep, “time” does not pass.)

Undefined behavior / Invariants

1. When polling the system clock, nanoseconds should never exceed 10^9 (the number of nanoseconds in 1 second). If this happens, we simply return zero. The standard library has a similar invariant (0 <= nanos <= 10^9), but handles it differently.
2. If an instant in the future is subtracted from an instant in the past, we return a Duration of 0.
3. If a duration is subtracted that would cause an instant to be negative, we return an instant set at 0.
4. If a duration is added to an instant that would cause the instant to exceed 2^64 seconds, we return an instant set to 0.

Underlying System calls

The following system calls are currently being used by now() to find out the current time:

Platform	System call
UNIX	clock_gettime (CLOCK_UPTIME_RAW)
Darwin	clock_gettime (CLOCK_UPTIME_RAW)
VXWorks	clock_gettime (CLOCK_UPTIME_RAW)
Windows	QueryUnbiasedInterruptTimePrecise

Certain overflows are dependent on how the standard library implements Duration. For example, right now it is implemented as a u64 counting seconds. As such, to prevent overflow we must check if the number of seconds in two Durations exceeds the bounds of a u64. To avoid being dependent on the standard library for cases like this, we choose our own representation of time which matches the “apple” libc platform implementation.

Implementations

impl SuspendUnawareInstant

pub fn now() -> SuspendUnawareInstant

Returns an instant corresponding to “now”.

Examples

use suspend_time::SuspendUnawareInstant;

let now = SuspendUnawareInstant::now();

pub fn elapsed(&self) -> Duration

Returns the amount of system unsuspended time elapsed since this suspend unaware instant was created, or zero duration if that this instant is in the future.

Examples

use std::{thread, time};
use suspend_time::{SuspendUnawareInstant};

let instant = SuspendUnawareInstant::now();
let one_sec = time::Duration::from_secs(1);
thread::sleep(one_sec);
assert!(instant.elapsed() >= one_sec);

Trait Implementations

impl Add<Duration> for SuspendUnawareInstant

type Output = SuspendUnawareInstant

The resulting type after applying the + operator.

fn add(self, rhs: Duration) -> SuspendUnawareInstant

Performs the + operation.

impl Clone for SuspendUnawareInstant

fn clone(&self) -> SuspendUnawareInstant

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SuspendUnawareInstant

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Ord for SuspendUnawareInstant

fn cmp(&self, other: &SuspendUnawareInstant) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for SuspendUnawareInstant

fn eq(&self, other: &SuspendUnawareInstant) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for SuspendUnawareInstant

fn partial_cmp(&self, other: &SuspendUnawareInstant) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Sub<Duration> for SuspendUnawareInstant

type Output = SuspendUnawareInstant

The resulting type after applying the - operator.

fn sub(self, rhs: Duration) -> SuspendUnawareInstant

Performs the - operation.

impl Sub for SuspendUnawareInstant

type Output = Duration

The resulting type after applying the - operator.

fn sub(self, rhs: SuspendUnawareInstant) -> Duration

Performs the - operation.

impl Copy for SuspendUnawareInstant

impl Eq for SuspendUnawareInstant

impl StructuralPartialEq for SuspendUnawareInstant