Enum Event 

pub enum Event {
    Request {
        labels: Labels,
    },
    Miss {
        labels: Labels,
        reason: MissReason,
    },
    Disabled {
        labels: Labels,
        reason: DisabledReason,
    },
    Error {
        labels: Labels,
        error: ErrorKind,
        in_fallback: bool,
    },
    Invalidation {
        namespace: Arc<str>,
        key_type: Arc<str>,
        layer: Layer,
    },
    Coalesced {
        labels: OutcomeLabels,
        scope: CoalescingScope,
    },
    ShadowValidation {
        labels: OutcomeLabels,
        outcome: ShadowOutcome,
    },
    ShadowValueAge {
        labels: OutcomeLabels,
        outcome: ShadowOutcome,
        seconds: f64,
    },
    ShadowMismatchLogging {
        labels: OutcomeLabels,
        outcome: ShadowMismatchLoggingOutcome,
    },
    FutureTimestampOffset {
        labels: Labels,
        seconds: f64,
    },
    StaleRecovery {
        labels: OutcomeLabels,
        outcome: RecoveryOutcome,
    },
    StaleRecoveryValueAge {
        labels: OutcomeLabels,
        outcome: RecoveryOutcome,
        seconds: f64,
    },
    Compression {
        labels: Labels,
        outcome: CompressionOutcome,
    },
    Get {
        labels: Labels,
        seconds: f64,
    },
    Fallback {
        labels: Labels,
        seconds: f64,
    },
    Serialization {
        labels: Labels,
        operation: SerializationOperation,
        seconds: f64,
    },
    Size {
        labels: Labels,
        bytes: u64,
    },
    StoredSize {
        labels: Labels,
        bytes: u64,
    },
    CompressionRatio {
        labels: Labels,
        ratio: f64,
    },
    CompressionDuration {
        labels: Labels,
        operation: CompressionOperation,
        seconds: f64,
    },
}

One public diagnostic. Counters carry no value; timers report seconds; sizes report bytes.

Variants

Request

One lookup of an enabled cache layer, hit or miss. Emitted before the result for the remote layer and after it for the request-local and process-local layers; a layer whose read failed emits Error and Disabled instead.

Fields

labels: Labels

The layer that was looked up.

Miss

A layer lookup found no servable value.

Fields

labels: Labels

The layer that missed.

reason: MissReason

The bounded cause; request-local and process-local misses are always MissReason::ValueAbsent.

Disabled

A layer, or the whole call (noop), was skipped.

Fields

labels: Labels

The skipped layer, or Layer::Noop when no layer was reached.

reason: DisabledReason

Why it was skipped.

Error

A bounded failure site fired. Cache plumbing failures fail open; only source failures reach the caller.

Fields

labels: Labels

The layer whose work failed.

error: ErrorKind

The failure site.

in_fallback: bool

true when the source (fallback) failed or timed out rather than cache plumbing.

Invalidation

One explicit invalidation attempt, emitted before the remote call and even when no remote adapter is configured.

Fields

namespace: Arc<str>

The namespace whose entity watermark is advanced.

key_type: Arc<str>

The entity type being invalidated.

layer: Layer

Always Layer::Remote: watermarks live only in the remote layer.

Coalesced

A caller joined an execution already in flight for the same logical key instead of starting its own.

Fields

labels: OutcomeLabels

The identity of the joined execution.

scope: CoalescingScope

Whether the flight was registered on the request scope or the instance.

ShadowValidation

One terminal outcome of an admitted or explicitly dropped shadow job.

Fields

labels: OutcomeLabels

The identity the job validated.

outcome: ShadowOutcome

The terminal verdict.

ShadowValueAge

Age in seconds of the validated value at a match or confirmed mismatch, clamped at zero.

Fields

labels: OutcomeLabels

The identity the job validated.

outcome: ShadowOutcome

ShadowOutcome::Match or ShadowOutcome::Mismatch; no other outcome carries an age.

seconds: f64

Observing wall clock minus the frame’s created_at_ms, never negative.

ShadowMismatchLogging

One confirmed-mismatch warning attempt, emitted after the warning and only while mismatch logging is on.

Fields

labels: OutcomeLabels

The identity the job validated.

outcome: ShadowMismatchLoggingOutcome

Whether the warning was built and delivered, or why not.

FutureTimestampOffset

Positive offset in seconds of a frame dated after the observing clock.

Fields

labels: Labels

The layer whose read decoded the frame.

seconds: f64

How far the frame’s created_at_ms lies ahead of the observing wall clock.

StaleRecovery

One classifier-authorized stale-on-error recovery check after a source failure.

Fields

labels: OutcomeLabels

The identity being recovered.

outcome: RecoveryOutcome

Whether a retained frame was served.

StaleRecoveryValueAge

Age of the retained frame at the moment recovery served it; emitted only alongside RecoveryOutcome::Served.

Fields

labels: OutcomeLabels

The identity being recovered.

outcome: RecoveryOutcome

Always RecoveryOutcome::Served.

seconds: f64

Observing wall clock minus the frame’s created_at_ms, clamped at zero.

Compression

One envelope decision: on every write while compression is enabled, and on reads whose payload carried a zstd marker.

Fields

labels: Labels

The layer performing the write or read.

outcome: CompressionOutcome

Write and read outcomes are disjoint sets; see CompressionOutcome.

Get

Lookup latency of one layer, hit or miss; a remote read’s value includes any wait up to its deadline.

Fields

labels: Labels

The layer looked up.

seconds: f64

Elapsed time of the lookup.

Fallback

Time until the source settled or its deadline elapsed, once per source invocation that served the caller (shadow re-validation runs the source without it).

Fields

labels: Labels

Layer::RequestLocal when the request memo was consulted, Layer::Remote when the remote layer was consulted, otherwise Layer::Local (even with the local layer disabled), and Layer::Noop only when the call bypassed caching.

seconds: f64

Elapsed time from invoking the source until it settled or its deadline fired.

Serialization

Codec latency of one encode or decode, emitted whether or not the codec succeeded.

Fields

labels: Labels

The layer the payload was written to or read from.

operation: SerializationOperation

Encode (dump) or decode (load).

seconds: f64

Elapsed time inside the codec.

Size

Serializer output size of one remote write, before compression and escaping.

Fields

labels: Labels

The layer being written.

bytes: u64

Length of the codec output.

StoredSize

Prepared payload size of one remote write, after compression and escaping, before dispatch.

Fields

labels: Labels

The layer being written.

bytes: u64

Length of the payload handed to the adapter, excluding the ten-byte frame header.

CompressionRatio

Size ratio of one write that chose the compressed form.

Fields

labels: Labels

The layer being written.

ratio: f64

Marked compressed bytes divided by serializer output bytes.

CompressionDuration

zstd latency: on writes when compression ran (compressed or not smaller), on reads when a marked frame was decoded or rejected.

Fields

labels: Labels

The layer performing the write or read.

operation: CompressionOperation

Compress (write) or decompress (read).

seconds: f64

Elapsed time of the envelope step.

Trait Implementations

impl Clone for Event

fn clone(&self) -> Event

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Event

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

Formats the value using the given formatter.

impl PartialEq for Event

fn eq(&self, other: &Event) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for Event