Struct WatermarkController 

pub struct WatermarkController<C: Clock = MonotonicClock> { /* private fields */ }

Per-pipeline-thread pause/resume state machine with hysteresis.

WatermarkController::tick returns a Transition and the driver applies it; the controller calls nothing itself. Transitions strictly alternate (Pause, Resume, Pause, …) and each full cycle takes at least BackpressureParams::min_pause.

Implementations

impl WatermarkController<MonotonicClock>

pub fn new(params: BackpressureParams) -> Self

Controller on the real monotonic clock.

impl<C: Clock> WatermarkController<C>

pub fn with_clock(params: BackpressureParams, clock: C) -> Self

Controller with an injected clock (tests).

pub fn on_send_rejected(&mut self)

Record that a try_send to a downstream queue was rejected. Cheap; call from the poll loop’s rejection path. While paused this restarts the minimum-pause timer.

pub fn tick( &mut self, budget: &InflightBudget, queues_below_low: bool, ) -> Option<Transition>

Evaluate the state machine once per poll iteration.

queues_below_low is the driver’s view of its downstream queues (all below the low-watermark fill ratio). Returns a transition for the driver to apply, or None.

pub fn is_paused(&self) -> bool

Whether the controller currently holds its lanes paused.

pub fn params(&self) -> &BackpressureParams

The hysteresis parameters in force.

Trait Implementations

impl<C: Debug + Clock> Debug for WatermarkController<C>

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

Formats the value using the given formatter.