Enum UnavailableReason 

pub enum UnavailableReason {
    CounterReset,
    DeviceDisappeared,
    InterfaceRenamed,
    ProcessExited,
    ReadFailed,
    ParseFailed,
    Timeout,
    SkippedUnderLoad,
    LinkSpeedUnknown,
    NeedsSecondSample,
}

Why a normally-available metric is missing from this particular sample.

The specification sketches TemporarilyUnavailable { reason: String }, but §4 explicitly permits a typed enum when a per-sample String is too costly. It is: a String in every field of every sample would allocate thousands of times per second. The human-readable message is produced at the UI layer by UnavailableReason::message.

Variants

CounterReset

A cumulative counter moved backwards, so this sample’s delta is invalid.

§8.2 requires returning this rather than a huge or negative rate.

DeviceDisappeared

The device, mount, or interface vanished between two reads.

InterfaceRenamed

The interface was renamed, invalidating the previous counter baseline.

ProcessExited

The process exited between enumeration and the detail read (§8.2).

Expected during normal sampling and never worth a warning log (§14.1).

ReadFailed

The underlying read failed for a reason other than permissions.

ParseFailed

The data was present but did not match the expected format.

Timeout

Collection exceeded its time budget and was abandoned for this sample.

SkippedUnderLoad

Enrichment was skipped to stay inside a budget under high load (§16.2).

LinkSpeedUnknown

A utilization percentage was requested but the link speed is unknown.

§7.4 forbids rendering a network utilization percentage without a known link capacity.

NeedsSecondSample

The metric requires at least two samples and only one exists so far.

Implementations

impl UnavailableReason

pub const fn message(self) -> &'static str

A short, lower-case explanation suitable for a status line or tooltip.

Trait Implementations

impl Clone for UnavailableReason

fn clone(&self) -> UnavailableReason

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for UnavailableReason

impl Debug for UnavailableReason

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

Formats the value using the given formatter.

impl Display for UnavailableReason

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

Formats the value using the given formatter.

impl Eq for UnavailableReason

impl Hash for UnavailableReason

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for UnavailableReason

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for UnavailableReason