Struct RoundTripMeasurementState 

pub struct RoundTripMeasurementState {
    pub phase: RoundTripMeasurementPhase,
    pub threshold: f32,
    pub impulse_sent_at: Option<Instant>,
    /* private fields */
}

All mutable state required to run one complete round-trip measurement session.

RoundTripMeasurementState is entirely owned by the session thread — there is no shared ownership, no Arc, and no locking. It is driven sample-by-sample through tick until a terminal outcome is reached.

Fields

phase: RoundTripMeasurementPhase

Current phase in the calibration/measurement lifecycle.

threshold: f32

Derived amplitude threshold an incoming sample must exceed to be accepted as an echo.

Set at the end of CalibrationAmbient and held constant for the rest of the session.

impulse_sent_at: Option<Instant>

Wall-clock time at which the currently active impulse was written to the output buffer.

None before the first impulse is emitted and between echo detection and the next impulse emission. The elapsed time from this instant to echo detection is the raw round-trip duration.

Implementations

impl RoundTripMeasurementState

pub fn new() -> Self

Creates a fresh measurement state, starting in CalibrationAmbient phase.

All counters are zeroed and no impulse timer is active. The first call to tick will begin consuming ambient samples.

pub fn tick( &mut self, sample: f32, push_output: &mut impl FnMut(f32) -> bool, per_impulse_timeout: Duration, ) -> RoundTripTickOutcome

Advances the measurement state machine by one input sample.

This is the core driver of the entire measurement protocol. The caller must invoke it for every sample that arrives from the input ring buffer.

Arguments

• sample — The raw f32 sample captured from the audio input.
• push_output — A closure that writes one f32 value to the output ring buffer and returns true if the push succeeded. The state machine uses this to emit either silence (0.0) or the test impulse (IMPULSE_AMPLITUDE).
• per_impulse_timeout — How long to wait for an echo after each impulse before declaring a timeout.

State machine transitions

Current phase	Event	Next phase
CalibrationAmbient	CALIBRATION_SAMPLES consumed	WaitingForEcho(0)
WaitingForEcho(n)	Impulse push succeeds	(same, timer armed)
WaitingForEcho(n)	Echo detected, more impulses remain	WaitingForEcho(n+1)
WaitingForEcho(n)	Echo detected, all impulses done	Idle → Complete
WaitingForEcho(n)	Deadline exceeded	Idle → TimedOut

Returns

A RoundTripTickOutcome indicating whether the session should continue, has finished successfully, or has timed out.

Trait Implementations

impl Default for RoundTripMeasurementState

fn default() -> Self

Returns the “default value” for a type.