Struct AdaptiveThreshold 

pub struct AdaptiveThreshold { /* private fields */ }

A threshold that follows the trend it is judging.

Why it adapts

A fixed threshold cannot work on both a datacentre path and a mobile one: set low enough to detect congestion on a link with microseconds of jitter, it fires constantly on a link with tens of milliseconds of it. Worse, a fixed threshold is what lets a GCC flow be starved by a concurrent loss-based flow — the queue grows past the fixed point, GCC backs off, the other flow takes the space, and GCC never comes back.

So the threshold rises when the trend is outside it and falls when the trend is inside, slowly, and at different rates: K_u (moving away) is larger than K_d (moving back), so it yields quickly to a genuine overuse and returns to sensitivity only gradually.

Implementations

impl AdaptiveThreshold

pub fn new() -> Self

A threshold at the draft’s starting value.

pub fn value_ms(&self) -> f64

The current threshold, in milliseconds.

pub fn update(&mut self, now: Instant, estimate_ms: f64) -> f64

Move the threshold towards estimate_ms, given how long since the last update.

Returns the updated threshold. now is a parameter rather than read from a clock: upstream reads time.Now() here, which is why its own threshold tests cannot pin a trajectory.

pub fn since_update(&self, now: Instant) -> Option<Duration>

How long since this threshold was last updated, if ever.

Trait Implementations

impl Clone for AdaptiveThreshold

fn clone(&self) -> AdaptiveThreshold

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for AdaptiveThreshold

impl Debug for AdaptiveThreshold

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

Formats the value using the given formatter.

impl Default for AdaptiveThreshold

fn default() -> Self

Returns the “default value” for a type.