Struct ObservationLog 

pub struct ObservationLog { /* private fields */ }

The bounded in-memory sink, in one of two shapes. A capture (Self::with_capacity, the default) keeps the first capacity facts and counts the rest as dropped: the trace is a complete prefix or says how much of the session it missed, which is what a comparison wants. A ring (Self::ring) keeps the last capacity facts and counts what it let go: a long-running host always sees its recent past, which is what a dashboard wants. Either way Self::drain takes what is kept and starts over, so a host that exports periodically never fills up.

Implementations

impl ObservationLog

pub fn with_capacity(capacity: usize) -> Self

A capture keeping the first capacity facts; later ones are counted as dropped.

pub fn ring(capacity: usize) -> Self

Keeps the last capacity facts and counts evictions as dropped. Capacity zero is raised to one.

pub fn drain(&self) -> ObservationTrace

Take the kept facts and start over: the session name and the sequence continue, the kept facts and the dropped count reset. A host that exports its trace periodically drains rather than letting a capture fill and stop.

pub fn with_clock(self, clock: Arc<dyn Clock + Send + Sync>) -> Self

Stamp every fact with clock’s elapsed time.

pub fn with_session(self, session: impl Into<String>) -> Self

Name the session the trace belongs to.

pub fn finalize(&self)

The session finished normally: later readers know the trace is not a partial artifact of a killed process. A later fact reopens the capture. Hosts must drain their producers before exporting a finalized snapshot.

pub fn trace(&self) -> ObservationTrace

The facts so far.

pub fn len(&self) -> usize

How many facts are kept.

pub fn is_empty(&self) -> bool

Whether no observations are currently retained.

Trait Implementations

impl Debug for ObservationLog

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

Formats the value using the given formatter.

impl Default for ObservationLog

fn default() -> Self

Returns the “default value” for a type.

impl Witness for ObservationLog

fn observe(&self, observation: Observation)

One fact. The sink assigns its sequence.