Struct ExemplarSampler 

pub struct ExemplarSampler { /* private fields */ }

Sampling + squelch gate for exemplar submission.

Two independent controls compose (read live from the ExemplarConfig cell, so a dynamic control moves them mid-run):

• rate ∈ [0, 1] — the fraction of caught errors that become exemplar candidates. 0.0 (the default) disables the sampler entirely; the caller’s hot path pays one atomic load. The roll is DETERMINISTIC on (cycle, attempt) so runs replay.
• max_hz — ceiling on emitted exemplars per second. Candidates over the ceiling are squelched and COUNTED; the count drains onto the next admitted exemplar, and any leftover flushes at Debug on drop. 0 or non-finite = no ceiling.

Implementations

impl ExemplarSampler

pub fn pinned(rate: f64, max_hz: f64) -> Self

A sampler over its own private cell — the authored-pin form (op-level retry_exemplar_* params); dynamic controls do not move it.

pub fn shared(cfg: Arc<ExemplarConfig>) -> Self

A sampler over a shared cell — the default form; the cell’s owner (the activity) wires it to the retry_exemplar_rate / retry_exemplar_max_hz dynamic controls.

pub fn enabled(&self) -> bool

True when any sampling can happen at all — one atomic load, paid only on the retry path.

pub fn admit(&self, cycle: u64, attempt_no: u32) -> Option<u64>

Decide one caught error. None = not sampled (failed the roll, or over the frequency ceiling — the latter counted). Some(n) = admitted, draining n squelched admissions to report on this exemplar’s line.

Trait Implementations

impl Drop for ExemplarSampler

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.