[−][src]Struct quanta::Clock
Unified clock for taking measurements.
Implementations
impl Clock
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pub fn new() -> Clock
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Creates a new clock with the optimal reference and source clocks.
Support for TSC, etc, are checked at the time of creation, not compile-time.
pub fn mock() -> (Clock, Arc<Mock>)
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Creates a new clock that is mocked for controlling the underlying time.
Returns a Clock
instance and a handle to the underlying Mock
source so that the
caller can control the passage of time.
pub fn now(&mut self) -> Instant
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Gets the current time, scaled to reference time.
This method is the spiritual equivalent of std::time::Instant::now
. It is guaranteed
to return a monotonically increasing value between calls to the same Clock
instance.
Returns an Instant
.
pub fn raw(&self) -> u64
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Gets the underlying time from the fastest available clock source.
As the clock source may or may not be the TSC, value is not guaranteed to be in nanoseconds
or to be monotonic. Value can be scaled to reference time by calling either scaled
or delta
.
If you need maximum accuracy in your measurements, consider using start
and end
.
pub fn start(&self) -> u64
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Gets the underlying time from the source clock, specific to starting an operation.
Value is not guaranteed to be in nanoseconds.
Provides the same functionality as raw
, but tries to ensure that no extra CPU
instructions end up executing after the measurement is taken. Since normal processors are
typically out-of-order, other operations that logically come before a call to this method
could be reordered to come after the measurement, thereby skewing the overall time
measured.
pub fn end(&self) -> u64
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Gets the underlying time from the source clock, specific to ending an operation.
Value is not guaranteed to be in nanoseconds.
Provides the same functionality as raw
, but tries to ensure that no extra CPU
instructions end up executing before the measurement is taken. Since normal processors are
typically out-of-order, other operations that logically come after a call to this method
could be reordered to come before the measurement, thereby skewing the overall time
measured.
pub fn scaled(&self, value: u64) -> Instant
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Scales a raw measurement to reference time.
You must scale raw measurements to ensure your result is in nanoseconds. The raw measurement is not guaranteed to be in nanoseconds and may vary. It is only OK to avoid scaling raw measurements if you don't need actual nanoseconds.
Returns an Instant
.
pub fn delta(&self, start: u64, end: u64) -> Duration
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Calculates the delta between two measurements, and scales to reference time.
This method is slightly faster when you know you need the delta between two raw
measurements, or a start/end measurement, than using scaled
for both conversions.
pub fn recent(&self) -> Instant
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Gets the most recent current time, scaled to reference time.
This method provides ultra-low-overhead access to a slightly-delayed version of the current time. Instead of querying the underlying source clock directly, a shared, global value is read directly without the need to scale to reference time.
The upkeep thread must be started in order to update the time. You can read the
documentation for [Builder
] for more information on starting the upkeep thread, as well
as the details of the "current time" mechanism.
If the upkeep thread has not been started, the return value will be 0
.
Returns an Instant
.
Trait Implementations
Auto Trait Implementations
impl RefUnwindSafe for Clock
impl Send for Clock
impl Sync for Clock
impl Unpin for Clock
impl UnwindSafe for Clock
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
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impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
fn to_owned(&self) -> T
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fn clone_into(&self, target: &mut T)
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impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,