Enum Sampler 

#[non_exhaustive]
pub enum Sampler {
    AlwaysOn,
    AlwaysOff,
    ParentBased(Box<dyn ShouldSample>),
    TraceIdRatioBased(f64),
}

Default Sampling options

The built-in samplers allow for simple decisions. For more complex scenarios consider implementing your own sampler using ShouldSample trait.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

AlwaysOn

Always sample the trace

AlwaysOff

Never sample the trace

ParentBased(Box<dyn ShouldSample>)

Respects the parent span’s sampling decision or delegates a delegate sampler for root spans.

TraceIdRatioBased(f64)

Sample a given fraction of traces. Fractions >= 1 will always sample. If the parent span is sampled, then it’s child spans will automatically be sampled. Fractions < 0 are treated as zero, but spans may still be sampled if their parent is. Note: If this is used then all Spans in a trace will become sampled assuming that the first span is sampled as it is based on the trace_id not the span_id

Implementations

impl Sampler

pub fn parent_based( root: impl Into<Box<dyn ShouldSample>>, ) -> ParentBasedSampler

Create a ParentBasedSampler with root as the sampler used for spans with no parent or an invalid parent.

Sampler::ParentBased only lets you configure that one root case; the other 4 branches defined by the ParentBased sampler spec (remote/local parent, sampled/not-sampled) are fixed to the spec defaults. Use this instead when you need to override any of those, via ParentBasedSampler’s with_* methods.

Trait Implementations

impl Clone for Sampler

fn clone(&self) -> Sampler

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Sampler

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

Formats the value using the given formatter.

impl ShouldSample for Sampler

fn should_sample( &self, parent_context: Option<&Context>, trace_id: TraceId, name: &str, span_kind: &SpanKind, attributes: &[KeyValue], links: &[Link], ) -> SamplingResult

Returns the SamplingDecision for a Span to be created.