Struct DiscreteRateCounter

pub struct DiscreteRateCounter { /* private fields */ }

A very basic non-rolling update counter. It counts n updates, calculates, and then resets (where n is the sample rate), which means that it takes at least n updates to react to a change in rate appropriately.

Generally, the RollingRateCounter is a better instrument, but it has to recalculate its measured rate every time it is queried whereas the DiscreteRateCounter only recalculates every n cycles.

Usage

Call .update() every time your system starts a new update/cycle; for instance, an FPS counter would call this at the beginning of every frame. The sample rate (set with set_sample_rate() and in the first argument to new()) governs how many .update() calls are required before a meaningful result is produced.

You can also use .update_immut() for this. Since DiscreteRateCounter is small and easily copyable, this is negligibly less efficient.

Implementations

impl DiscreteRateCounter

pub fn new(samples: u64) -> Self

Create a new DiscreteRateCounter which calculates the update rate every samples cycles. Until that many cycles occur, rate() will return a useless value, typically 0.0.

If this isn’t acceptable, one strategy is to start the samples value at 0 and keep ramping it up until it reaches your target samples value; however, the data near the beginning will not be useful.

pub fn rate_age_cycles(&self) -> u64

Return the number of cycles since the rate was last recalculated.

pub fn rate_age_duration(&self) -> Duration

Return the amount of time since the rate was last recalculated. This requires examining the system clock and is thus relatively expensive.

Trait Implementations

impl Clone for DiscreteRateCounter

fn clone(&self) -> DiscreteRateCounter

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for DiscreteRateCounter

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

Formats the value using the given formatter.

impl Display for DiscreteRateCounter

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

Formats the value using the given formatter.

impl RateCounter for DiscreteRateCounter

fn samples(&self) -> u64

Return the current number of samples the UpdateRateCounter is measuring.

fn set_samples(&mut self, samples: u64)

Set the number of updates which the UpdateRateCounter considers.

fn update(&mut self)

Updates the struct in place, but requires a mutable binding. Call either this OR update_immut() at the beginning of each cycle of the periodic activity being measured.

fn rate(&self) -> f64

Return the last calculated rate of operation, in Hertz (updates per second).

impl RateCounterImmut for DiscreteRateCounter

fn update_immut(self) -> Self

Consumes the struct and returns an updated version. Call this at the beginning of each cycle of the periodic activity being measured.

Examples

use update_rate::DiscreteRateCounter;
use update_rate::{RateCounter, RateCounterImmut};
let c = DiscreteRateCounter::new(5);
for i in 1..101 {
    let c = c.update_immut();
    if i % 10 == 0 {println!("Rate: {}", c.rate())}
    // Do work here
}

impl Copy for DiscreteRateCounter