Struct TrackingInstantNow

pub struct TrackingInstantNow {
    now: Instant,
    earliest: Cell<Option<Duration>>,
}

Utility to track timeouts based on Instant (monotonic time)

Represents the current Instant (from when it was created). See the module-level documentation for the general overview.

To calculate and check a timeout, you can calculate the future Instant at which you wish to wake up, and compare it with a TrackingInstantNow, via .cmp() or inequality operators and PartialOrd.

Or you can use .checked_sub() to obtain a TrackingInstantOffsetNow.

Fields

now: Instant

Current time

earliest: Cell<Option<Duration>>

Duration until earliest time we should wake up

Implementations

impl TrackingInstantNow

pub fn new(now: Instant) -> Self

Creates a new timeout tracker, given a value for the current time

pub fn now(r: &impl SleepProvider) -> Self

Creates a new timeout tracker from the current time as seen by a runtime

pub fn get_now_untracked(&self) -> Instant

Return the “current time” value in use

If you do comparisons with this, they won’t be tracked, obviously.

fn update_unconditional( earliest: &Cell<Option<Duration>>, maybe_earlier: Duration, )

Core of a tracked update: updates earliest with maybe_earlier

fn update_conditional( o: Ordering, earliest: &Cell<Option<Duration>>, maybe_earlier: Duration, )

Core of a tracked update: updates earliest with maybe_earlier, if necessary

o is what we are about to return: Less if the current time hasn’t reached maybe_earlier yet.

impl TrackingInstantNow

pub async fn wait_for_earliest(self, runtime: &impl SleepProvider)

Wait for the earliest timeout implied by any of the comparisons

Waits until the earliest future time at which any of the comparisons performed might change their answer.

If there were no comparisons there are no timeouts, so we wait forever.

impl TrackingInstantNow

pub fn shortest(self) -> Option<Duration>

Return the shortest Duration until any future Instant with which this has been compared

impl TrackingInstantNow

fn cmp(&self, t: Instant) -> Ordering

Check if time t has been reached yet (and remember that we want to wake up then)

Also available via PartialOrd

impl TrackingInstantNow

pub fn checked_sub( &self, offset: Duration, ) -> Option<TrackingInstantOffsetNow<'_>>

Return a tracker representing a specific offset before the current time

You can use this to pre-calculate an offset from the current time, to compare other Instants with.

This can be convenient to avoid repetition; also, when working with checked time arithmetic, this can helpfully centralise the out-of-bounds error handling site.

Trait Implementations

impl Clone for TrackingInstantNow

fn clone(&self) -> TrackingInstantNow

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for TrackingInstantNow

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

Formats the value using the given formatter.

impl PartialEq<Instant> for TrackingInstantNow

Check if time t has been reached yet (and if not, remember that we want to wake up then)

Always returns Some.

fn eq(&self, t: &Instant) -> 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 PartialEq<TrackingInstantNow> for Instant

Check if we have reached time t yet (and if not, remember that we want to wake up then)

Always returns Some.

fn eq(&self, t: &TrackingInstantNow) -> 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<Instant> for TrackingInstantNow

Check if time t has been reached yet (and if not, remember that we want to wake up then)

Always returns Some.

fn partial_cmp(&self, t: &Instant) -> 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 PartialOrd<TrackingInstantNow> for Instant

Check if we have reached time t yet (and if not, remember that we want to wake up then)

Always returns Some.

fn partial_cmp(&self, t: &TrackingInstantNow) -> 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 Update<Duration> for TrackingInstantNow

fn update(&self, d: Duration)

Update the “earliest timeout” notion, to ensure it’s at least as early as t

impl Update<Instant> for TrackingInstantNow

fn update(&self, t: Instant)

Update the “earliest timeout” notion, to ensure it’s at least as early as t

impl Sealed for TrackingInstantNow