Struct FieldObservation 

pub struct FieldObservation {
    pub entries: Vec<FieldObservationEntry>,
    pub events_observed: u64,
    pub unique_keys: usize,
    pub overflow_dropped: u64,
    pub lifetime_events_observed: u64,
    pub lifetime_overflow_dropped: u64,
    pub max_keys: usize,
    pub uptime_seconds: f64,
}

Immutable snapshot of an observer’s state at one moment in time.

Returned by FieldObserver::snapshot; consumers (the daemon’s HTTP handlers, the engine eval report writer) render coverage reports from this against a RuleFieldSet.

Fields

entries: Vec<FieldObservationEntry>

Per-field counters, sorted by descending count then ascending name.

events_observed: u64

Number of events evaluated by the observer since construction or the last reset.

unique_keys: usize

Distinct field names tracked (saturates at max_keys).

overflow_dropped: u64

Number of insert attempts dropped because the observer was at capacity since the last reset.

lifetime_events_observed: u64

Lifetime total of events evaluated since the observer was constructed, ignoring resets. Drives Prometheus counters, which must be monotonic.

lifetime_overflow_dropped: u64

Lifetime total of insert attempts dropped because the observer was at capacity, ignoring resets. Drives Prometheus counters.

max_keys: usize

Configured ceiling for distinct keys.

uptime_seconds: f64

Seconds since the observer was created (or last reset).

Implementations

impl FieldObservation

pub fn coverage<'a>( &'a self, rule_field_set: &'a RuleFieldSet, ) -> FieldCoverage<'a>

Join the snapshot against a RuleFieldSet and return the partitioned coverage view in a single pass.

Returned references borrow from self (the entries) and the supplied rule_field_set (the missing entries), so this is allocation-light: one Vec for the unknown borrows, one Vec for the missing borrows, one HashSet for the seen lookup.

Centralises the logic shared between the daemon’s GET /api/v1/fields* handlers and the engine eval end-of-run report so the two surfaces cannot drift on field semantics.

Trait Implementations

impl Clone for FieldObservation

fn clone(&self) -> FieldObservation

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for FieldObservation

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

Formats the value using the given formatter.

impl Default for FieldObservation

fn default() -> FieldObservation

Returns the “default value” for a type.